Bioreactor External Loop for Gas Transfer and Transfection
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Solution Overview
Problem
High cell density bioreactors face challenges in enhanced gas transfer and transfection due to issues like mechanical and oxidative stress from spargers, foaming, and non-homogeneous conditions, which affect cell growth and efficiency in gas exchange and nucleic acid introduction.
Innovation Solution
A bioreactor system with an external loop for circulating liquid, incorporating a gas injector and a vessel for transfection material delivery, which promotes gas exchange and transfection independently, using low-shear pumps and sensors for regulated gas and liquid flow, and optionally includes a sparger or falling liquid configuration to enhance gas transfer and homogeneity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spargers are used to enhance gas transfer in high cell density bioreactors, then gas transfer efficiency is improved, but mechanical stress and oxidative stress on cells increase
Solution Approach 1:
The sparger is extracted from the bioreactor and placed in an external loop system. Gas injection occurs outside the bioreactor vessel, and the oxygenated liquid is returned to the bioreactor. This removes the source of mechanical and oxidative stress from the cell culture environment while maintaining the gas transfer function.
Solution Approach 2:
The external loop acts as an intermediary between the gas source and the bioreactor. Gas is injected into the liquid phase in the external loop, and the oxygenated liquid serves as a mediator that delivers oxygen to the bioreactor without introducing bubbles directly into the cell culture.
2Productivity
If spargers are used to support high cell density, then oxygen supply is enhanced, but excessive foaming occurs
Solution Approach 1:
The foaming problem is extracted from the bioreactor system by relocating gas injection to the external loop. Foam is generated outside the bioreactor where it cannot clog filters or damage culture media proteins, eliminating the harmful effects while maintaining oxygen transfer.
3Productivity
If bubbles are introduced into unstructured high cell density fixed bed bioreactors, then gas transfer is enhanced, but homogeneity of bioreactor conditions deteriorates
Solution Approach 1:
Bubble formation is extracted from the bioreactor interior and relocated to the external loop. This prevents bubbles from forming clouds or air pockets within the fixed bed structure, maintaining homogeneous distribution of cells and culture conditions while still achieving gas transfer through the external oxygenation system.
4Productivity
If transfection material is added directly to the bioreactor, then transfection efficiency may be improved, but non-homogeneous transfection occurs
Solution Approach 1:
Transfection material is added to the liquid phase in the external loop before the liquid enters the bioreactor. This preliminary mixing ensures homogeneous distribution of transfection material throughout the liquid phase, and the uniformly mixed liquid is then introduced into the bioreactor, guaranteeing even transfection across all cells.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system achieves enhanced gas transfer and transfection efficiency with reduced mechanical stress, maintaining homogeneity and preventing foaming, allowing for optimized cell growth and gene delivery without compromising the bioreactor's media flow.
Implementation Method 1
A gas injector is provided for injecting gas into the liquid
Implementation Method 2
A first external loop is connected to the bioreactor for circulating the liquid
Implementation Method 3
proposals have been made for enhancing the gas transfer by providing the bioreactor with one or more bubblers or spargers to form small gas bubbles in the cell culture medium
Implementation Method 4
optionally includes a sparger or falling liquid configuration to enhance gas transfer and homogeneity
Data Source
AI summary
An apparatus is provided for culturing and transfecting cells using a liquid. A bioreactor includes a cell culture bed for receiving the liquid. An external loop is connected to the bioreactor and adapted for circulating the liquid to and from the bioreactor. The external loop is adapted for introducing a gas into the liquid therein and/or for circulating a transfection material in the liquid therein to the bioreactor. In one embodiment, a first vessel is associated with the external loop for receiving the liquid, and a gas injector is provided for injecting a gas into the liquid, such as into the first vessel. A second vessel is also provided for providing a transfection material (such as a transfecting agent as part of a transfection mixture) to the liquid, such as directly to the bioreactor or to the external loop. In another embodiment, the gas injector is associated directly with the external loop. The external loop may be dedicated for gas injection and/or transfection, and maintained separate from a loop for circulating liquid media to the bioreactor, which potentially allows for operation on demand. Related methods are also disclosed.