Perfusion bioreactor with filtration systems

Abstract

To provide a perfusion cell culture apparatus a method for culturing cells that automatically detect and respond to an ATF filter malfunction, without the need to shut down the cell culture operation.SOLUTION: The disclosure provides a filtration system for a cell culture apparatus and a method of cell culture. The filtration system comprises a bioreactor vessel and two or more alternating tangential flow (ATF) filters connected in parallel. A failure in either filter is detected by an in-line sensor, and an automated response system functions to sequester a malfunctioning filter by stopping a flow of liquid media through the filter. Media flow through remaining operable filters can be increased so that a rate of perfusion through a bioreactor remains relatively unchanged.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates generally to perfusion cell culture devices and methods. [Background technology]

[0002] In vitro cell culture is a complex process of growing cells under controlled conditions outside the cell's natural environment. Culture conditions vary for each cell type and must be precisely controlled to ensure the correct cellular phenotype and / or expression of the desired product.

[0003] Bioreactors provide a controlled environment to grow and maintain cells in accordance with their temperature, pH, nutrients, gases, and other needs. To culture cells for extended periods of time, new media must be continuously fed to the cells, and spent media must be removed at approximately the same rate. To extend the production duration of cell cultures in bioreactors, perfusion bioreactors have been developed that continuously perfuse cells with fresh media, incorporating the desired product while retaining the cells within the bioreactor. Such bioreactors allow cells to be grown at higher cell concentrations and maintained for longer periods of time compared to bioreactors without an active perfusion system.

[0004] 1 shows a schematic diagram of a typical state of the art perfusion bioreactor 100 known to those skilled in the art. The perfusion bioreactor includes a bioreactor vessel 110, an alternating tangential flow (ATF) filter 120, a harvest pump 130, and a continuous capture operation 160. The perfusion bioreactor 100 can be operated by (i) attaching an ATF filter device 120 to the bioreactor vessel 110; (ii) filling the bioreactor vessel 110 with fresh media; (iii) inoculating the bioreactor vessel 110 with cells; and (iv) perfusing the fresh media into the bioreactor vessel 110 and removing the spent media via a harvest pump 130 in series with the ATF filter 120.

[0005] Under these conditions, cells can be cultured and maintained for longer periods of time. The constant addition of media provides the cells with the nutrients they need to grow, and the removal of spent media allows cellular waste and by-products to be removed from the system, preventing them from reaching harmful levels. The ATF filter allows the spent media to be removed from the bioreactor while retaining the cells within the bioreactor. Other cell culture parameters are also typically controlled, including temperature, dissolved oxygen, pH, pCO 2 , and cell density are controlled to improve performance and robustness.

[0006] 1, the perfusion bioreactor 100 can be integrated with a continuously operating capture operation 160. In this scenario, the spent media removed from the bioreactor vessel 110 contains the product of interest and is continuously pumped to the continuous capture operation 160 where it is processed and purified in some way.

[0007] Standard perfusion bioreactors, such as the one shown in Figure 1, are intended to operate for long durations (as little as 30-60 days). However, the robustness of the equipment can prove limited. In particular, the ATF filter can fail, leading to a breakdown or disruption of the process. In some cases, the ATF filter can fail catastrophically, allowing cells to pass through the filter and into the harvest pump. Such an event can have a variety of adverse effects. First, the cells can quickly flow out of the bioreactor because they are no longer retained in the bioreactor by the ATF. This can result in reduced cell density and production rate in the bioreactor. Second, in systems integrated with downstream continuous purification steps, cells can flow directly into the operation and damage the purification system. In one example, cells can progress to a column on a periodic continuous counter-chromatography (PCC) skid, leading to clogging, overpressurization, and increased impurity ingress. In such a situation, the problem must be identified quickly and the ATF replaced quickly to protect the bioreactor. Independently, downstream operations will likely need to be shut down and cleaned, and disposable components may need to be replaced. A full response can result in several days of lost production, or even a complete shutdown. Summary of the Invention [Problem to be solved by the invention]

[0008] An apparatus and method for cell culture is provided that overcomes one or more of the shortcomings known in the art. It has been found that it is possible to provide a filtration system for a perfusion cell culture apparatus that automatically detects and responds to malfunctions of the ATF filter without stopping the cell culture operation. [Means for solving the problem]

[0009] In a first embodiment of the present disclosure, a perfusion cell culture device is provided. The device includes a bioreactor vessel, a first filtration assembly, a second filtration assembly, and a controller. The bioreactor vessel is configured to receive a liquid medium. The first filtration assembly is in fluid communication with the bioreactor vessel and includes a first filtration system, a first harvest pump, and a sensor. The first harvest pump is coupled in series with the first filtration system and configured to pump the liquid medium from the bioreactor vessel through the first filtration system. The sensor is configured to interact with the liquid medium in the first filtration assembly. The second filtration assembly is also in fluid communication with the bioreactor vessel and configured to operate in parallel with the first filtration assembly. The second filtration assembly includes a second filtration system and a second harvest pump. The second harvest pump is coupled in series with the second filtration system and configured to pump the liquid medium from the bioreactor vessel through the second filtration system. The controller executes the operations. The operations include receiving information from the sensor indicative of an operational state of the first filtration system. The operations further include determining whether the first filtration system is in an operational state based at least on the received information. The operations also include causing the first harvest pump to cease pumping liquid medium through the first filtration system in response to determining that the first filtration system is not in an operational state.

[0010] In a second embodiment of the present disclosure, a perfusion cell culture device is provided. The device includes a bioreactor vessel, a filtration assembly, and a controller. The bioreactor vessel is configured to receive a liquid medium. The filtration assembly is in fluid communication with the bioreactor vessel and includes a filtration system, a harvest pump, and a sensor. The harvest pump is coupled in series with the filtration system and configured to pump the liquid medium from the bioreactor vessel through the filtration system. The sensor is configured to interact with the liquid medium within the filtration assembly. The controller performs an operation. The operation includes receiving information from the sensor indicative of an operational state of the filtration system. The operation further includes determining whether the filtration system is in an operational state based at least on the received information. The operation further includes causing the harvest pump to stop pumping the liquid medium through the filtration system in response to determining that the filtration system is not in an operational state.

[0011] In yet another embodiment of the present disclosure, a method is provided. The method includes: The method includes at least partially filling the vessel with cells and liquid medium. The bioreactor vessel is in fluid communication with a first filtration system and a second filtration system. The second filtration system is coupled in parallel to the first filtration system. The method further includes pumping the liquid medium from the bioreactor vessel through the first filtration system using a first harvest pump. The first harvest pump is coupled in series with the first filtration system. The method also includes pumping the liquid medium from the bioreactor vessel through the second filtration system using a second harvest pump. The second harvest pump is coupled in series with the first filtration system. The method additionally includes receiving information indicative of an operational state of the first filtration system from a sensor configured to interact with the liquid medium. Furthermore, the method includes determining whether the first filtration system is in an operational state based at least on the received information. The method further includes, in response to determining that the first filtration system is not in an operable state, causing the first harvest pump to cease pumping liquid medium through the first filtration system.

[0012] Other aspects, embodiments, and implementations will become apparent from the following detailed description and claims, taken in conjunction with the accompanying drawings as appropriate. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram of a standard perfusion bioreactor setup. [Diagram 2] FIG. 1 is a schematic diagram of a perfusion cell culture device with a dual filtration system and integrated capture according to one embodiment of the present disclosure. [Diagram 3] FIG. 13 is a schematic diagram of a perfusion cell culture device with a dual filtration system and integrated capture according to another embodiment of the present disclosure. [Figure 4] FIG. 13 is a schematic diagram of a perfusion cell culture device configuration with a single filtration system according to another embodiment of the present disclosure. [Diagram 5] 1 is a flow diagram of a method according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present disclosure generally relates to a filtration system for a cell culture device and a cell culture method. The perfusion cell culture device of the present disclosure includes a bioreactor vessel and two or more filtration systems (e.g., alternating tangential flow filters) connected in parallel. Any filter failure can be detected by an in-line sensor, and an automated response system functions to isolate the malfunctioning filter by stopping the flow of liquid media through the filter. Media flow through the remaining operable filters can be increased so that the rate of perfusion through the bioreactor remains relatively unchanged. The cell culture device of the present disclosure can prevent problems resulting from filter failure in conventional perfusion bioreactors, thereby improving the long-term viability of the cell culture.

[0015] Exemplary methods, devices, and systems are disclosed. It should be understood that the term "example" or "exemplary" is used in this disclosure to mean "serving as an example or illustration." Any implementation or configuration disclosed as "exemplary" or "example" should not necessarily be construed as preferred or advantageous over other implementations or configurations. Other implementations may be utilized, and other changes may be made, without departing from the scope of the subject matter presented in this disclosure.

[0016] Thus, the disclosed example implementations are not meant to be limiting. The components disclosed and illustrated in the figures can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations contemplated by this disclosure.

[0017] Additionally, unless the context indicates otherwise, the configurations shown in the figures may be used in combination with each other. As such, it should be understood that these figures should generally be viewed as components of one or more overall implementations, and that not all of the features shown are required for each implementation.

[0018] In an effort to provide technical content to the present disclosure, the information in this section may broadly describe the various components of the disclosed implementations. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Such information is provided solely for the benefit of the reader and therefore does not explicitly limit the subject matter of the claims. Furthermore, the components shown in the figures are shown for illustrative purposes only. Thus, these illustrations should not be construed as limiting. As will be appreciated, components may be added, removed, or rearranged without departing from the scope of the present disclosure.

[0019] I. Overview In certain applications, it is advantageous to provide a cell culture device that automatically detects and responds to a filtration system failure. Such a cell culture device can include built-in redundancy so that a second and / or additional filtration system can be used if a first filter fails (e.g., by rupture, clogging, fouling, or some other means). When a filter failure occurs, the automated response system can function to stop the flow of media to the affected filter while increasing the throughput through any remaining filters. This response can allow the perfusion of liquid media to continue at approximately the same rate without requiring immediate intervention by the operator of the cell culture device. Such a system can improve cell viability and reduce the probability of failure in a perfusion bioreactor system.

[0020] The disclosed apparatus and methods generally relate to a perfusion cell culture apparatus having an improved tangential flow filtration system. The apparatus can include a bioreactor vessel configured to contain a cell population and a liquid growth medium. The bioreactor vessel can be provided with fresh liquid medium and spent liquid medium can be removed at approximately equal rates through a series of filtration assemblies. Each filtration assembly can include a filtration system, a harvest pump, a sensor, and / or a guard filter.

[0021] During normal operation, spent liquid medium is removed through one or more of the filtration assemblies and pumped to a downstream capture operation. Sensors within each filtration assembly continuously monitor the operation of the filtration assemblies and can determine when a malfunction (e.g., rupture, clogging, or some other failure mode) has occurred in one of the filtration systems.

[0022] When a malfunction is detected by one or more of the sensors, the automated response system acts to change the operating parameters of the device so that perfusion of the liquid medium continues uninterrupted. The automated response system is implemented by a controller in communication with the sensors and the harvest pumps. In response to determining that one or more of the filtration systems is not in an operable state, the controller can cause the harvest pump associated with the inoperable filter to cease pumping liquid medium to the affected filter. Additionally, the controller can cause the remaining operable filtration assemblies to process an increased amount of liquid medium, for example, by causing the associated harvest pump to increase the flow of liquid medium to the operable filtration system. The controller can also cause the device to output a notification, for example, an alarm, an indicator light, or some other alert. The controller can also stop the filtration system (e.g., by causing the tangential flow pump of the filtration system to stop pumping liquid medium across the filter membrane). In some scenarios, The controller can also stop downstream capture operations or actuate valves to stop the flow of liquid media and / or divert liquid media to a waste container. In yet another scenario, the controller can completely stop flow into or out of the bioreactor vessel if a bioreactor sensor (e.g., capacitance, optical density, oxygen uptake rate, etc.) falls below a certain threshold. Other automated responses are contemplated.

[0023] II.Cell culture device A cell culture device according to one embodiment of the present disclosure is shown in FIG. 2. The cell culture device 200 includes a bioreactor vessel 210, a continuous capture operation 260, and at least a first filtration assembly 206 and a second filtration assembly 208 connected in parallel between at least one outlet of the bioreactor vessel 210 and an inlet of the continuous capture operation 260. The bioreactor vessel 210 of the cell culture device 200 is configured to receive fresh liquid medium to maintain a cell population within the vessel. As used herein, liquid medium can refer to a nutrient growth medium or culture medium designed to support cell growth. An approximately equal flow of spent liquid medium is pumped from the bioreactor vessel 210 through the multiple filtration assemblies 206, 208, thereby maintaining a constant volume of medium within the bioreactor vessel 210 while removing metabolic and protein waste materials. To monitor the environment of the cell culture, a bioreactor sensor 215 can be positioned to interact with the liquid medium within the bioreactor vessel 210. Such bioreactor sensors 215 may measure temperature, dissolved oxygen, pH, pCO 2 , and / or may be configured to measure cell density.

[0024] The cell culture device 200 can be integrated with a continuously operating capture operation 260 configured to collect a product (e.g., a desired biological or therapeutic product) from the liquid medium. The capture operation 260 is in fluid communication with the bioreactor vessel 210 by at least the first filtration assembly 206. The capture operation 260 can receive the spent liquid medium after passing through the parallel filtration assemblies 206, 208 and process and / or purify the medium to capture the desired product of interest. In various embodiments, the capture operation 260 can capture the product of interest using various techniques. For example, in some examples, the capture operation 260 can include a continuous chromatography system including one or more chromatography columns. In certain examples, the capture operation 260 can include a cyclic continuous counter chromatography (PCC) skid or a simulated moving bed (SMB) skid. In another example, the capture operation 260 can include a multi-chromatography (MCC) skid (i.e., a continuous chromatography system that includes multiple columns). Other purification methods can be envisioned by those skilled in the art.

[0025] Before reaching the continuous capture operation 260, the liquid medium flows through one or more filtration assemblies 206, 208 designed to retain cells within the bioreactor vessel 210. Each filtration assembly 206, 208 is in fluid communication with the bioreactor vessel 210 and can be coupled to an outlet of the vessel 210 between the vessel 210 and the continuous capture operation 260. As shown in FIG. 2, in some examples, two filtration assemblies can be coupled in parallel to provide two parallel fluid paths. The first filtration assembly 206 includes a first filtration system 220, a first harvest pump 230, a first sensor 240, and a first guard filter 250. Similarly, the second filtration assembly 208 includes a second filtration system 222, a second harvest pump 232, a second sensor 242, and a second guard filter 252. The elements of each filtration assembly 206, 208 may be connected in series via one or more conduits, sterile tubing, or other connecting means. As shown in FIG. 2, a first harvest pump 230 may be connected downstream of the first filtration system 220, and a sensor 240 may be located downstream of the first harvest pump 230. and may be disposed between the first harvest pump 230 and a guard filter 250 coupled further downstream. In this context, "downstream" refers to the relative position or orientation of the elements with respect to the flow of liquid medium through the filtration assemblies 206, 208, and "downstream" generally refers to a direction away from the bioreactor vessel 210 toward the capture operation 260. However, the elements of the first filtration assembly 206 may be coupled in any number of configurations. The second filtration assembly 208 and / or additional filtration assemblies may be arranged and may have elements of substantially the same configuration as the first filtration assembly 206 or an entirely different configuration.

[0026] In some examples, the second filtration assembly 208 is configured to operate in parallel (i.e., simultaneously) with the first filtration assembly 206. During normal operation of the cell culture device 200, the flow rates of liquid medium through the first filtration assembly 206 and the second filtration assembly 208 can be approximately equal. In other words, each filtration assembly 206, 208 can receive an approximately equal flow rate of used liquid medium from the bioreactor vessel 210. However, in other embodiments, a single filtration assembly (e.g., the first filtration assembly 206) can operate at a time, and the second filtration assembly 208 and / or additional filtration assemblies can operate as spares.

[0027] In some examples, a third or further filtration assembly may be coupled in parallel to the first filtration assembly 206 and the second filtration assembly 208 to increase throughput, provide additional pre-filtration means in case of a system failure, or provide some other benefit.

[0028] The first filtration assembly 206 and the second filtration assembly 208 include a first filtration system 240 and a second filtration system 242, respectively. The first and second filtration systems 220, 222 can be configured to prevent cells in the bioreactor vessel 210 from entering the continuous capture operation 260 while allowing free passage of cellular waste and one or more desired products of interest. As used herein, the term "filtration system" is used to refer to a filter-based means for retaining cells in the bioreactor vessel 210. In some examples, the first filtration system 220 and the second filtration system 222 can include filters that function by flowing a fluid (e.g., liquid medium) tangentially across a filter membrane. Such filtration systems 220, 222 can include conventional tangential flow filtration (TFF) systems, cross-flow filters, and similar cell retention means. In another example, at least one of the first filtration system 220 and the second filtration system 222 includes an alternating tangential flow (ATF) filter. Such filters typically include a filter membrane and a tangential flow pump (e.g., a diaphragm pump) configured to induce fluid tangentially across the filter membrane. The tangential flow pump may include a diaphragm that operates to flow liquid medium from the bioreactor vessel 210 across the surface of the filter membrane in a repeated back and forth pattern. The repeated perturbation of the fluid near the filter membrane may prevent cell accumulation and minimize fouling of the filter surface during operation. In some examples, the first tangential flow pump provided by the first filtration system may operate independently from the second tangential flow pump provided by the second filtration system. However, in other embodiments, two or more tangential flow pumps may be uniformly controlled, such that their pumping operations are fully synchronized or asynchronous.

[0029] For the first filter assembly 206 and the second filter assembly 208, ATF or While the above has been described in terms of including other tangential flow based filters, other filtration means can be implemented to retain cells within bioreactor vessel 210. For example, in other embodiments, first filtration system 220 and second filtration system 222 can include internal spin filters (ISF), hollow fiber filters, porous membrane filters, depth filters, and / or other microfiltration or ultrafiltration systems.

[0030] The first filtration system 220 and the second filtration system 222 include a first filter membrane and a second filter membrane, respectively. The pore size of the filter membrane can be selected to allow the desired product of interest, cellular waste, and spent liquid medium to flow freely through the membrane while the cells remain retained within the bioreactor vessel 210. The filter membranes of the filtration systems 220, 222 can be constructed of any material having a suitable pore size, for example, a porous polymeric membrane. In some examples, the filter membranes are constructed of a series of selectively permeable hollow fibers organized in a parallel array inside a housing or cartridge. The pore size of the hollow fiber membranes can be selected to achieve the desired permeability of the filtration systems 220, 222. In some examples, the first filtration system 220 and the second filtration system 222 each include a pore size ranging from about 500 kilodaltons to about 10 microns, or more preferably from about 0.1 microns to about 1 micron.

[0031] Each filtration assembly 206, 208 according to the disclosed apparatus includes a harvest pump 230, 232. The first filtration assembly 206 includes a first harvest pump 230 coupled in series with the first filtration system 220. Similarly, the second filtration assembly 208 includes a second harvest pump 232 coupled in series with the second filtration system 222. The first harvest pump 230 and the second harvest pump 232 are configured to pump liquid medium from the bioreactor vessel 210 through the first filtration system 220 and the second filtration system 222, respectively, into the downstream capture operation 260. In various examples, the first harvest pump 230 and / or the second harvest pump 232 can include a peristaltic pump, a bearingless pump, a diaphragm pump, or a centrifugal pump. However, other pumps can be used to maintain sterility of the liquid medium while drawing the medium through the filtration assemblies 206, 208.

[0032] The first harvest pump 230 pumps the liquid medium from the bioreactor vessel 210 through the first filtration system 220 at a first flow rate. The second harvest pump 232 similarly pumps the liquid medium from the bioreactor vessel 210 through the second filtration system 222 at a second flow rate. In some examples, the first flow rate can be approximately equal to the second flow rate. In other words, the first harvest pump 230 and the second harvest pump 232 can be configured to pump approximately equal amounts of liquid medium through the respective filtration systems 220, 222, such that the filtration assembly processes equal amounts of spent liquid medium under normal operating conditions. However, in another embodiment, the first flow rate and the second flow rate can be different. In certain examples, the first harvest pump 230 can operate alone and independently, and the second harvest pump 232 (i.e., a second or additional harvest pump coupled to a second or additional filtration device) can be configured to operate in response to a determination that the first harvest pump 230, the first filtration system 220, and / or the first filtration assembly 206 are not in an operational state.

[0033] The flow rate of liquid medium through the filtration assemblies 206, 208 can be approximately equal to the flow rate of fresh medium entering the bioreactor vessel 210, thus maintaining a stable amount of liquid medium in the vessel 210 during perfusion. In other words, the sum of the first flow rate and the second flow rate can be approximately equal to the flow rate of liquid medium entering the bioreactor vessel 210 (i.e., the flow rate of medium introduced into the vessel 210 by the feeding operation).

[0034] The flow rate of liquid medium through each filtration system 220, 222 (i.e., the first flow rate and the second flow rate) can be independently controlled by a controller 270 in communication with the first harvest pump 230 and the second harvest pump 232. The controller 270 can be configured to cause the first harvest pump 230 and / or the second harvest pump 232 to increase, decrease, or stop the flow of liquid medium through the first filtration system 240 and / or the second filtration system 242 depending on the operating conditions of the apparatus 200. For example, when a failure occurs in one or more of the filtration systems 220, 222, the harvest pump of the affected assembly can be turned off and the flow rate of liquid medium through the remaining filtration assemblies can be increased to compensate for the malfunctioning filtration assembly.

[0035] Perfusion bioreactor systems are typically configured to operate for longer periods of time, but equipment failures are expected. In particular, the filtration systems 220, 222 are susceptible to malfunctions that could potentially cause problems in the downstream capture operation 260, increasing impurities in the harvest, and possibly causing a complete shutdown. To prevent cells that have broken through the filtration systems 220, 222 from interfering with the continuous capture operation 260, guard filters 250, 252 can be coupled in series with the first filtration system 220 and / or the second filtration system 222. Such guard filters 250, 252 can be configured to prevent cells and cell debris from proceeding downstream to the capture operation 260, while allowing the diffusion of nutrients, metabolic products, and liquid medium freely. As shown in FIG. 2, the guard filter 250 can be coupled in series with the first filtration system 220 and / or the first filtration assembly 206. In some examples, the guard filter 250 is coupled downstream of the first filtration system 220 and / or the sensor 240. The second filtration assembly 208 may also include a guard filter (i.e., second guard filter 252) coupled in series with the second filtration system 222 downstream of the filtration system 222. However, in other embodiments (as shown in FIG. 3), multiple filtration assemblies may converge into a single shared guard filter, for example, located at the inlet of the continuous capture operation 260. Other locations and configurations of the guard filter 250 are also contemplated.

[0036] The guard filters 250, 252 can be constructed of any material having suitable porosity, such as porous polymeric membranes and / or hollow fiber membranes. In some cases, the guard filter 250 includes a pore size of about 500 kilodaltons to about 10 microns, or more preferably about 0.1 microns to about 1 micron. The guard filter 250 can be configured to have a pore size approximately equal to the pore size of the first filtration system 220 and / or the second filtration system 222 (i.e., to mimic the selective permeability of the filtration systems 220, 222). However, in other cases, the guard filter 250 can include a smaller or larger pore size than the filtration systems 220, 222, thereby allowing selective filtration of additional metabolic products.

[0037] In some cases, at least one sensor 240 may be provided in the filtration assemblies 206, 208 to monitor the operation of one or more filtration systems 220, 222 and / or detect filter failure. In particular, the first filtration assembly 206 may include the sensor 240. In some examples, the second filtration assembly 208 may include an additional sensor (e.g., a second sensor 242). The sensor 240 may be located along the conduit of the filtration assemblies 206, 208 and may be configured to interact with the liquid medium in the filtration assemblies 206, 208, i.e., to detect various aspects of the liquid medium passing through the filtration assemblies 206, 208. As shown in FIG. 2, the sensor 240 may be located downstream of the first filtration system 220 and upstream of the guard filter 250. In some cases, the sensor 240 may be a pressure sensor, or a more detailed can include a piezoresistive pressure sensor. The sensor 240 can be configured to detect a pressure in the first filtration assembly 206 (e.g., a pressure of the liquid medium in the first filtration assembly 206) that can indicate a clog of the guard filter 250 and / or a rupture in the upstream first filtration system 220. In various examples, the sensor 240 can be configured to detect a pressure upstream or downstream of the first guard filter 250, a pressure upstream or downstream of the first filtration system 220, and / or a membrane pressure of the first filtration system 220 or the guard filter 250. In other examples, the sensor 240 can be an optical sensor (e.g., an optical density probe), and the sensor 240 can be configured to determine a cell density in the liquid medium flowing through the first filtration assembly 206. In further examples, the sensor 240 can include a flow meter operable to measure a flow rate of the liquid medium through the filtration systems 220, 222 and / or the filtration assemblies 206, 208. In further examples, the sensor 240 can include a capacitance sensor, a Raman sensor, or a FTIR (Fourier Transform Infrared) sensor. In another example, the sensor 240 can be integrated into a continuous trapping operation (e.g., as a pressure sensor upstream of a trapping column). Other sensor types and applications are also contemplated.

[0038] 2 as being contained within the first filtration assembly 206 and the second filtration assembly 208 (i.e., disposed within the conduits between the filtration systems 220, 222 and the guard filters 250, 252), the sensors may be located in a variety of locations. For example, in some examples, the bioreactor sensor 215 may be configured to interact with the liquid medium within the bioreactor vessel 210 such that the bioreactor sensor 215 measures pressure, temperature, pH, dissolved oxygen, pCO2, and the like of the liquid medium within the vessel 210. 2 Changes in cell density, or other characteristics can be monitored.

[0039] To mitigate potential problems resulting from filter failure, the cell culture device 200 can include an automated response system. The response system can be used to detect filtration system failure (e.g., a burst filter membrane), isolate the malfunctioning filtration system, and / or adjust the operating parameters of the device 200 to continue cell perfusion relatively unchanged. The automated response system can be implemented by a controller 270 in communication with at least the harvest pumps 230, 232 and the sensors 240, 242. As described herein, the controller 270 can include at least one processor configured to execute operations (e.g., operations stored as program instructions in the data storage of the controller). However, in other examples, the controller 270 can include a comparator or another simplified control system.

[0040] The controller 270 can be configured to receive information from the sensors 240, 242 indicative of an operational state of the first filtration system 220 and / or the second filtration system 222. Such information can include a characteristic of the liquid medium flowing through the first filtration assembly 206 and / or the second filtration assembly 208. For example, the information can include a fluid pressure of the liquid medium in the filtration assemblies 206, 208, a cell density of the liquid medium, a flow rate of the liquid medium, a presence of an analyte in the liquid medium, or some other information. In another example, as previously described, the bioreactor sensor 215 can be configured to collect information about the liquid medium in the bioreactor vessel 210, such as a cell density or another characteristic.

[0041] The controller 270 can then determine whether the first filtration system 220 and / or the second filtration system 222 are in an operable state based on at least the information received from the sensors 240, 242. In this context, the term "operable" refers to the system being operable as intended, i.e., selectively passing a liquid medium containing the cellular waste and the product of interest. The term "operable" is used to refer to a filtration system that is functioning to retain cells within the bioreactor vessel 210 while allowing liquid media to pass through it. Conversely, a filtration system 220, 222 that is not in an operable state may not be able to pass a desired or expected flow rate of liquid media (i.e., indicating a clogged or fouled filter membrane) or may not be able to retain cells (i.e., indicating a burst filter). Determining whether a filtration system 220, 222 is in an operable state may include determining whether the received information is within an expected range of values ​​or above or below a predetermined threshold.

[0042] In a particular example, the first filtration system 220 may have ruptured, allowing cells to break through the first filtration system 220 and collect on the guard filter 250. The controller 270 may then receive information from the sensor 240 indicating that the pressure in the liquid medium has increased due to the cells clogging the guard filter 250. Determining whether the first filtration system 220 is in an operable state may then include determining whether the pressure in the first filtration assembly 206 (i.e., the pressure of the liquid medium in the first filtration assembly 206) is greater than a threshold value. In a similar example, one or more of the sensors 240 may include an optical sensor (e.g., an optical density probe), and determining whether the filtration system is in an operable state may include determining that the cell density of the liquid medium in the first filtration assembly 206 is above a threshold level, indicating that the cells have broken through the first filtration system 220. In yet another example, the bioreactor sensor 215 may be an optical sensor, and determining whether the filtration system 220, 222 is in an operable state may include determining that the cell density of the liquid medium in the bioreactor vessel 210 is below a threshold level.

[0043] Other failure modes are also anticipated. For example, the first filtration system 220 may become inoperable due to failure of the first tangential flow pump and / or fouling of the filter membrane (e.g., if the first filtration system 220 is an ATF or other tangential flow based filter). In such a situation, cells may accumulate on the filter membrane and block or reduce the flow of liquid media through the first filtration system 220. In such an example, the sensor 240 may be configured to measure a membrane pressure of the first filtration system 220. Determining whether the first filtration system 220 is in an operable state may include determining that the membrane pressure of the filtration system 220 is above a threshold value. In a further example, the sensor 240 may include a flow meter, and determining whether the first filtration system 220 is in an operable state may include determining that the flow of liquid media through the first filtration system 220 (and / or the first filtration assembly 206) is below a threshold level. Other failure modes, sensor parameters, and determining factors may be envisioned by one of ordinary skill in the art.

[0044] After detecting one or more filtration system failures, the automated response system (i.e., controller 270) can function to isolate the malfunctioning filtration assembly 206, 208 by preventing liquid medium from flowing through the affected filtration system 220, 222. In other words, in response to determining that the first filtration system 220 is not in an operable state, the controller 270 can cause the first harvest pump 230 to stop pumping liquid medium through the first filtration system 220, for example, by disconnecting power to the harvest pump 230. The controller 270 can be further configured to shut down the first filtration system 220 by causing a tangential flow pump of the filtration system 220 to stop pumping liquid medium across the filter membrane (i.e., if the filtration system 220 contains an ATF). In another example, the controller 270 can shut down the first filtration system 220 by activating a relief valve coupled in series with the first filtration system 220 or the second filtration system 222. , diverting the liquid medium to a waste collection system. In yet another scenario, the controller 270 can completely stop flow into or out of the bioreactor vessel 210 if information from the bioreactor sensor 215 (e.g., capacitance, optical density, oxygen uptake rate, or other aspects of the liquid medium in the bioreactor vessel 210) rises above or falls below a certain threshold.

[0045] Additionally or alternatively, the first filtration assembly 206 may include one or more first isolation valves 265 coupled in series with the first filtration system 220. The first isolation valve 265 may be configured to control the flow of liquid medium through the first filtration system 220. In response to determining that the first filtration system 220 is not in an operable state, the controller 270 may be operable to close the first isolation valve 265. A second isolation valve 267 may be further coupled in series with the second filtration system 222, the second isolation valve 267 configured to control the flow of liquid medium through the second filtration system 222. As shown in FIG. 2, the isolation valves 265, 267 may optionally be coupled in series between the first filtration assembly 206 and / or the second filtration assembly 208 and the continuous capture operation 260. However, such one or more isolation valves 265, 267 can be located anywhere before, after, or within the first filtration assembly 206 or second filtration assembly 208. For example, the first isolation valve 265 and / or second isolation valve 267 can be located between the bioreactor vessel 210 and the respective filtration assembly 206, 208, can be located downstream of the filtration system 220, 222, can be located downstream of the guard filter 250, 252, or can be coupled to the inlet of the continuous capture operation 260. Upon detecting a filter malfunction, the isolation valves 265, 267 can be actuated to prevent the flow of liquid media and cellular product through the affected filtration system 220, 222, thereby preventing cells and contaminants from reaching the continuous capture operation 260 and facilitating replacement of any faulty equipment.

[0046] In addition to isolating the failed filtration system 220, 222, the controller 270 can also be operable to change various operating parameters of the cell culture device 200 after a filter failure. As previously described, a steady flow rate of liquid medium should be supplied to the bioreactor vessel 210, and an approximately equal flow rate of spent medium including waste can be continuously removed to promote cell growth in the bioreactor vessel 210. After detection of a failure in the first filtration system 220, the controller 270 can additionally be configured to increase the flow rate of liquid medium through the remaining operable second filtration system 222 such that a steady perfusion of liquid medium is maintained in the bioreactor vessel 210. The increased flow rate through the remaining operable filtration system (e.g., the second filtration system 222) should be approximately equal to the total flow rate (e.g., the sum of the first flow rate through the first filtration system 220 and the second flow rate through the second filtration system 222) before the failure through the original filtration system 220, 222. In one example, in response to determining that first filtration system 220 is not in an operable state, controller 270 may be operable to cause second harvest pump 232 to increase the flow rate of liquid medium through second filtration system 242. In some examples, causing second harvest pump 232 to increase the flow of liquid medium through second filtration system 242 may include approximately doubling the flow rate.

[0047] In some cases, the cell culture device 200 can include multiple filtration assemblies (i.e., at least a first filtration assembly 206 and a second filtration assembly 208) connected in parallel and operating simultaneously. For example, in some embodiments, the cell culture device 200 can include three, four, six, or more filtration assemblies to achieve a desired perfusion rate. The filtration systems 220, 222 of the filtration assemblies 206, 208 can be connected to each other. When one or more of the two fails, controller 270 can be operable to adjust the flow rate through any number of the remaining operable filter assemblies to maintain a steady perfusion of liquid medium within the system. For example, in response to determining that first filtration system 220 is not operable, controller 270 can instruct one or more harvest pumps associated with one or more additional filtration assemblies to increase the flow rate of liquid medium through the respective filtration systems.

[0048] In some examples, it may be desirable to notify an operator of the cell culture device 200 when a filter malfunction is detected. For example, in response to determining that the first filtration system 220 is not in an operable state, the controller 270 may be configured to output a notification. Such a notification may include a visual alert, such as a flashing light, a colored light, a visual message, text or graphic information on a display. Additionally or alternatively, the notification may include an audio alert, such as an alarm sound, a buzzer sound, a bell sound, an audio message, or some other audio component. In yet another example, the notification may include a text message, a phone call, or an email sent to a recipient associated with the cell culture device.

[0049] Although the cell culture device 200 shown in FIG. 2 includes two filtration assemblies 206, 208 including separate filtration systems 220, 222, sensors 240, 242, and guard filters 250, 252, simpler cell culture devices can also be encompassed within the scope of the present disclosure. For example, FIG. 3 shows a cell culture device 300 including a shared sensor 340, guard filter 350, and dual filtration systems 320, 322 that converge to a capture operation 360. The first filtration system 320 is connected in series with the first harvest pump 330, and the second filtration system 322 is connected in series with the second harvest pump 332. Such a configuration can allow detection of a total failure of the cell culture device 300 by the sensor 350. For example, when a rupture occurs in the first filtration system 320 or the second filtration system 322, cells from the bioreactor vessel 310 can quickly flow through the filtration systems 320, 322 and converge on the guard filter 350. Clogged guard filter 350 causes an increase in liquid medium pressure upstream of guard filter 350, which can be detected by a pressure sensor (e.g., sensor 340). However, due to the sharing of downstream sensor 340, such a system cannot distinguish between a fault in first filtration system 320 and a fault in second filtration system 322. In such an exemplary system, the automated response system can function to alert an operator of cell culture device 300, for example by outputting a notification, to divert liquid medium to a waste recovery system, or to stop continuous capture operation. Other automated responses are contemplated.

[0050] The bioreactor vessel 310, first and second filtration systems 320, 322, first and second harvest pumps 330, 332, sensor 340, guard filter 350, and capture operation 360 shown in FIG. 3 may be configured similarly to the corresponding components described above in connection with FIG. 2.

[0051] In some other examples, the cell culture device may rely on a single filtration assembly for processing spent liquid media. FIG. 4 shows an example of such a cell culture device 400, in which a bioreactor vessel 410 is fluidly connected to a capture operation 460 by a single filtration system 420, harvest pump 430, sensor 440, and guard filter 450. At least the sensor 440 and harvest pump 430 may be communicatively connected to a controller 470. In such examples, a malfunction of the filter (e.g., a burst, clogged, or otherwise defective filtration system 420) may cause the entire filtration mechanism of the cell culture device 400 to be inoperable. The filtration system 420 may be connected to a harvest pump 430, a harvest pump 430, a guard filter 450, and a filter 460. In such examples, a malfunction of the filter (e.g., a burst, clogged, or otherwise defective filtration system 420) may cause the entire filtration mechanism of the cell culture device 400 to be inoperable. In response to determining that the liquid medium is not in an operational state, the controller 470 can be operable to cause the capture operation 460 to cease collecting product from the liquid medium.

[0052] In situations where all filtration assemblies of the cell culture device are not operational (e.g., when only one filtration system 420 fails or when all of the multiple filtration systems fail), it is advantageous to divert the flow of liquid medium to the waste collection system 480. To accommodate such a scenario, one or more filtration assemblies may include a relief valve 485 coupled in series with the filtration system 420. The relief valve 485 may be configured to divert the flow of liquid medium to the waste collection system 480. The relief valve 485 may be a three-way valve, although in other examples, the relief valve 485 may include one or more two-way valves. Such a relief valve 485 may preferably be coupled downstream of the harvest pump 430 and upstream of the guard filter 450, although various locations are contemplated. In response to determining that the filtration system 420 is not operational, the controller 470 may be configured to open the relief valve 485, thereby diverting the liquid medium to waste.

[0053] Diverting the liquid medium to the waste collection system 480 may allow for temporary continuation of perfusion through the cell culture system 400. However, eventually, as more cells are pumped to waste, the cell density in the bioreactor vessel 410 may drop to an unacceptable level. To prevent loss of an undesirable amount of cell density, a sensor (e.g., sensor 440 or additional bioreactor sensors) may be configured to interact with the liquid medium in the bioreactor vessel 410 and / or monitor the cell density in the vessel 410. In response to determining that the cell density is below a threshold, the controller 470 may be configured to stop perfusion entirely, for example, by closing the relief valve 485, closing the isolation valve, causing one or more harvest pumps 430 to stop pumping the liquid medium through the one or more filtration systems 420, or by some other means.

[0054] The bioreactor vessel 410, filtration system 420, harvest pump 430, sensor 440, guard filter 450, capture operation 460, and controller 470 shown in FIG. 4 may be configured similarly to the corresponding components described above in connection with FIG.

[0055] III. Cell culture method Figure 5 is a flow diagram of a method 500 of operating a cell culture device, such as any of the devices described herein shown in Figure 2, Figure 3, or Figure 4. For purposes of illustration, a cell culture device operated in method 500 includes: (i) a bioreactor vessel; (ii) a first filtration system in fluid communication with the bioreactor vessel; (ii) a second filtration system in fluid communication with the bioreactor vessel; (iii) a first harvest pump coupled in series with the first filtration system; (iv) a second harvest pump coupled in series with the second filtration system; and (v) a sensor configured to interact with liquid medium flowing through at least the first filtration system.

[0056] Block 501 of method 500 includes at least partially filling a bioreactor vessel with cells and liquid medium. The bioreactor vessel is in fluid communication with a first filtration system and a second filtration system coupled in parallel to the first filtration system. At least partially filling the bioreactor vessel with cells and liquid medium can include providing the cells as a monolayer on an artificial substrate (i.e., adherent culture). In other examples, at least partially filling the bioreactor vessel with cells and liquid medium can include providing the cells freely suspended in the medium (i.e., suspension culture). Continuous The liquid medium for perfusion can be provided by a feeding operation configured to continuously introduce fresh liquid medium into the bioreactor vessel, the liquid medium from the feeding operation can be provided at a predetermined flow rate regulated to the nutritional needs of the cells in the bioreactor vessel.

[0057] Block 502 of method 500 includes pumping liquid medium from the bioreactor vessel through a first filtration system using a first harvest pump. Block 503 of method 500 includes pumping liquid medium from the bioreactor vessel through a second filtration system using a second harvest pump. The first harvest pump can be coupled in series with the first tangential flow. Similarly, the second harvest pump can be coupled in series with the second filtration system.

[0058] Pumping the liquid medium through the first filtration system can include pumping the liquid medium at a first flow rate. Pumping the liquid medium through the second filtration system can include pumping the liquid medium at a second flow rate. In some examples, the first flow rate can be substantially equal to the second flow rate under normal operating conditions. However, in other examples, the flow rate of the liquid medium through the first filtration system can be different than the flow rate of the liquid medium through the second filtration system. Additionally or alternatively, the sum of the first flow rate and the second flow rate can be approximately equal to the flow rate of the medium entering the bioreactor vessel via a feeding operation (e.g., the feeding operation described above in connection with block 501 of method 500).

[0059] Block 504 of method 500 includes receiving information indicative of an operational state of the first filtration system from a sensor configured to interact with the liquid medium flowing through at least the first filtration system. Such a sensor may be located within a filtration assembly including the first filtration system, the first harvest pump, and / or other elements. Additionally or alternatively, the sensor may be disposed within a conduit coupled in series with the first filtration system and / or the first harvest pump.

[0060] In some examples, the sensor is a pressure sensor (e.g., a piezoresistive pressure sensor). The information indicative of the operating state of the first filtration system can include information about the pressure of the liquid medium flowing through the first filtration system. More specifically, the information can include the pressure of the liquid medium upstream of the first filtration system, the pressure of the liquid medium downstream of the first filtration system, or the transmembrane pressure of the liquid medium of the first filtration system. In some examples, the cell culture device includes a guard filter coupled in series with the first filtration system downstream of the first filtration system. In such examples, the information can include the pressure of the liquid medium upstream of the guard filter. Additionally or alternatively, the sensor can include a capacitance sensor, a Raman probe, an FTIR probe, or an optical density probe. In such examples, the information can include information about the cell density of the cells in the liquid medium (e.g., the liquid medium downstream of the first filtration system).

[0061] Block 505 of method 500 includes determining whether the first filtration system is in an operable state based on at least the received information. When the first filtration system is not in an operable state, the filter may not be able to pass a desired or expected flow rate of liquid medium (i.e., indicating a clogged or fouled filter membrane) or may not be able to retain cells (i.e., indicating the filter has burst). Determining whether the filtration system is in an operable state may include determining whether the information received from the sensor is within an expected range of values ​​or is above or below a predetermined threshold. In some examples, the sensor is a pressure sensor and determining whether the first filtration system is in an operable state includes determining that the pressure of the liquid medium is above a predetermined threshold. In some cases, determining whether the first filtration system is in an operable state may include determining that the pressure of the liquid medium is above a predetermined threshold. Determining whether the first filtration system is in an operable state can include determining that a membrane pressure of the first filtration system is above a predetermined threshold. In a further example, determining whether the first filtration system is in an operable state can include determining that a cell density of the liquid medium (e.g., the liquid medium in the bioreactor vessel or the liquid medium flowing through the first filtration system) is outside a predetermined threshold range.

[0062] Block 506 of method 500 includes, in response to determining that the first filtration system is not in an operable state, causing the first harvest pump to stop pumping liquid medium through the first filtration system. Such a response may effectively stop the flow of liquid medium through the first filtration system. Additionally or alternatively, an isolation valve may be coupled in series with the first filtration system, and the isolation valve may be configured to control the flow of liquid medium through the first filtration system. In such an example, method 500 may include, in response to determining that the first filtration system is not in an operable state, closing the isolation valve. Other responses to a filter malfunction are also contemplated.

[0063] In some examples, the method 500 can further include adjusting the flow rate of one or more remaining operable filters. For example, the method 500 can further include, in response to determining that the first filtration system is not in an operable state, causing the second harvest pump to increase the flow rate of the liquid medium through the second filtration system. Increasing the flow rate of the liquid medium through the second filtration system can allow perfusion of the liquid medium through the bioreactor vessel to continue at a stable rate after the filter failure. In other words, the adjusted flow rate of the liquid medium through the second filtration system can be approximately equal to the flow rate of the liquid medium through the operable first and second filtration systems. In some examples, causing the second harvest pump to increase the flow rate of the liquid medium through the second filtration system can include approximately doubling the flow rate of the liquid medium through the second filtration system.

[0064] In some examples, the method 500 further includes outputting a notification in response to determining that the first filtration system is not in an operable state. The notification can include a visual alert (e.g., a flashing light, a colored light, a visual message, textual or graphical information on a display) and / or an audible alert (e.g., an alarm sound, a buzzer sound, a bell sound, an audible message, or some other audible component). In further examples, the method 500 can include diverting the liquid medium to a waste recovery system, ceasing downstream capture operations, or affecting other aspects of the operation of the cell culture device.

[0065] The exemplary method 500 shown in Figure 5 is meant to be an illustrative, non-limiting example. The blocks and steps described herein may be performed sequentially or in parallel. Additionally, various blocks and steps may be performed in an order different from that described herein, and some blocks and steps may be deleted, omitted, and / or repeated. Additional or alternative elements of the methods and additional or alternative components of the systems are also contemplated.

[0066] While the apparatus and methods disclosed herein have been described in terms of various embodiments, it will be understood that variations and modifications will occur to those skilled in the art. It is therefore intended that the appended claims cover all such equivalent variations that are within the scope of the claimed apparatus and methods. Additionally, the headings used herein are for organizational purposes only and should not be construed as limiting the subject matter described.

[0067] All references cited in this application are expressly incorporated herein by reference.

Claims

1. 1. A perfusion cell culture device comprising: (a) a bioreactor vessel configured to receive a liquid medium; (b) a first filtration assembly in fluid communication with the bioreactor vessel, the first filtration assembly comprising: (i) a first filtration system; (ii) a first harvest pump coupled in series with the first filtration system and configured to pump the liquid medium from the bioreactor vessel through the first filtration system; and (iii) a first filtration assembly including a sensor configured to interact with the liquid medium within the first filtration assembly; (c) a second filtration assembly configured to operate in parallel with the first filtration assembly and in fluid communication with the bioreactor vessel, the second filtration assembly comprising: (i) a second filtration system; and (ii) a second filtration assembly including a second harvest pump coupled in series with the second filtration system and configured to pump the liquid medium from the bioreactor vessel through the second filtration system; (d) a controller comprising: (i) receiving information from the sensor indicative of an operational status of the first filtration system; (ii) determining whether the first filtration system is in an operational state based at least on the received information; and (iii) a controller that, in response to determining that the first filtration system is not in an operable state, performs actions including causing the first harvest pump to cease pumping liquid medium through the first filtration system.

2. 10. The perfusion cell culture device of claim 1, wherein at least one of the first filtration system and the second filtration system comprises an alternating tangential flow filter.

3. 10. The perfusion cell culture device of claim 1, wherein at least one of the first filtration system and the second filtration system comprises a tangential flow filter.

4. 10. The perfusion cell culture device of claim 1, wherein each of the first filtration system and the second filtration system comprises a pore size of about 0.1 microns to about 1 micron.

5. 10. The perfusion cell culture apparatus of claim 1, wherein the sensor comprises a pressure sensor, and determining that the first filtration system is not in an operable state comprises determining that a pressure in the first filtration assembly is greater than a threshold value.

6. The perfusion cell culture device of claim 1 , wherein the sensor comprises a capacitance sensor.

7. The perfusion cell culture device of claim 1 , wherein the sensor comprises an optical sensor.

8. The controller is:

10. The perfusion cell culture apparatus of claim 1, further configured to, in response to determining that the first filtration system is not in an operable state, cause the second harvest pump to increase a flow rate of the liquid medium through the second filtration system.

9. 10. The perfusion cell culture apparatus of claim 8, wherein causing the second harvest pump to increase the flow of the liquid medium through the second filtration system comprises approximately doubling the flow rate.

10. The controller is:

10. The perfusion cell culture device of claim 1, further configured to output a notification in response to determining that the first filtration system is not in an operational state.

11. The perfusion cell culture device of claim 10 , wherein the notification comprises a visual or audible alert.

12. The method further includes an isolation valve coupled in series with the first filtration assembly, the valve configured to control a flow of the liquid medium through the first filtration assembly, the controller comprising:

10. The perfusion cell culture apparatus of claim 1, further configured to close the isolation valve in response to determining that the first filtration system is not in an operational state.

13. 10. The perfusion cell culture device of claim 1, wherein the first filtration assembly further comprises a guard filter coupled in series with the first filtration system, the guard filter being coupled downstream of the first filtration system and the sensor.

14. 14. The perfusion cell culture device of claim 13, wherein the guard filter comprises a pore size of about 0.1 micron to about 1 micron.

15. 10. The perfusion cell culture apparatus of claim 1, further comprising a capture operation configured to collect a product from the liquid medium, the capture operation being in fluid communication with the bioreactor vessel by at least a first filtration assembly.

16. The perfusion cell culture device of claim 15 , wherein the capture operation includes a periodic continuous counter chromatography skid.

17. 1. A perfusion cell culture device comprising: (a) a bioreactor vessel configured to receive a liquid medium; (b) a filtration assembly in fluid communication with the bioreactor vessel, comprising: (i) a filtration system; (ii) a harvest pump coupled in series with the filtration system and configured to pump liquid medium from the bioreactor vessel through the filtration system; and (iii) a filtration assembly including a sensor configured to interact with the liquid medium within the filtration assembly; (c) a controller comprising: (i) receiving information from a sensor indicative of an operational status of the filtration system; (ii) determining whether the filtration system is in an operational state based at least on the received information; and (iii) in response to determining that the filtration system is not in an operable state, a controller that performs actions including causing the harvest pump to cease pumping liquid medium through the filtration system.

18. 20. The perfusion cell culture device of claim 17, wherein the filtration system comprises alternating tangential flow filters.

19. 20. The perfusion cell culture device of claim 17, wherein the filtration system comprises a tangential flow filter.

20. 20. The perfusion cell culture device of claim 17, wherein the filtration system comprises a pore size of about 0.1 micron to about 1 micron.

21. 20. The perfusion cell culture apparatus of claim 17, wherein the sensor comprises a pressure sensor, and determining that the filtration system is not in an operable state comprises determining that the pressure in the filtration assembly is greater than a threshold value.

22. The perfusion cell culture device of claim 17 , wherein the sensor comprises a capacitance sensor.

23. 20. The perfusion cell culture device of claim 17, wherein the sensor comprises an optical sensor.

24. The controller is:

20. The perfusion cell culture device of claim 17, further configured to output a notification in response to determining that the filtration system is not in an operational state.

25. 25. The perfusion cell culture device of claim 24, wherein the notification comprises a visual or audible alert.

26. The method further includes an isolation valve coupled in series with the filtration system, the isolation valve configured to control a flow of the liquid medium through the filtration assembly, the controller comprising:

20. The perfusion cell culture apparatus of claim 17, further configured to close the isolation valve in response to determining that the filtration system is not in an operational state.

27. 20. The perfusion cell culture apparatus of claim 17, further comprising a guard filter coupled in series with the first filtration assembly, the guard filter being coupled downstream of the first filtration assembly.

28. 28. The perfusion cell culture device of claim 27, wherein the guard filter comprises a pore size of about 0.1 micron to about 1 micron.

29. 20. The perfusion cell culture apparatus of claim 17, further comprising a harvesting operation configured to harvest a product from the liquid medium, the harvesting operation being in fluid communication with the bioreactor vessel by at least a filtration assembly, such that the harvest pump is configured to pump the liquid medium through the filtration system and into the harvesting operation.

30. 30. The perfusion cell culture device of claim 29, wherein the capture operation includes a periodic continuous counter chromatography skid.

31. The controller is:

30. The perfusion cell culture device of claim 29, further configured to, in response to determining that the filtration system is not in an operational state, cause the capture operation to cease collecting product from the liquid medium.

32. The filtration assembly further includes a relief valve coupled in series with the filtration system, the relief valve configured to divert the liquid medium into the waste collection system, and the controller configured to:

20. The perfusion cell culture device of claim 17, further configured to open a relief valve in response to determining that the filtration system is not in an operational state.

33. 1. A method of culturing cells comprising: (a) at least partially filling a bioreactor vessel with cells and a liquid medium, the bioreactor vessel being in fluid communication with a first filtration system and a second filtration system coupled in parallel to the first filtration system; (b) pumping the liquid medium from the bioreactor vessel through a first filtration system using a first harvest pump, the first harvest pump being connected in series with the first filtration system; (c) pumping the liquid medium from the bioreactor vessel through a second filtration system using a second harvest pump, the second harvest pump being connected in series with the second filtration system; (d) receiving information indicative of an operational status of the first filtration system from a sensor configured to interact with the liquid medium; (e) determining whether the first filtration system is in an operational state based at least on the received information; (f) in response to determining that the first filtration system is not in an operable state, causing the first harvest pump to cease pumping liquid medium through the first filtration system.

34. 34. The method of claim 33, wherein at least one of the first filtration system and the second filtration system comprises an alternating tangential flow filter.

35. The method of claim 33 , wherein the sensor comprises a pressure sensor.

36. 36. The method of claim 35, wherein the received information includes information regarding a pressure of the liquid medium downstream of the first filtration system.

37. 36. The method of claim 35, wherein the received information includes information regarding a transmembrane pressure of the first filtration system.

38. 36. The method of claim 35, wherein determining whether the first filtration system is in an operational state comprises determining that a pressure of the liquid medium is above a predetermined threshold.

39. 34. The method of claim 33, wherein pumping the liquid medium from the bioreactor vessel through a first filtration system comprises pumping the liquid medium at a first flow rate and pumping the liquid medium from the bioreactor vessel through a second filtration system comprises pumping the liquid medium at a second flow rate, the first flow rate being approximately equal to the second flow rate.

40. In response to determining that the first filtration system is not in an operable state, causing the second harvest pump to increase the flow rate of the liquid medium through the second filtration system.

34. The method of claim 33, further comprising:

41. 41. The method of claim 40, wherein the step of causing the second harvest pump to increase the flow rate of the liquid medium through the second filtration system comprises approximately doubling the flow rate of the liquid medium through the second filtration system.

42. outputting a notification in response to determining that the first filtration system is not in an operational state.

34. The method of claim 33, further comprising:

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