Hollow fiber membrane module and method for removing endotoxin

Abstract

A hollow fiber membrane module (1) has a first hollow fiber membrane having a screen factor of 0.12 or more and 0.28 or less for dextran having a molecular weight of 300 kDa or more and 1000 kDa or less, and the first hollow fiber membrane adsorbs endotoxin.

Description

Technical Field

[0001] This invention relates to hollow fiber membrane modules and methods for removing endotoxins. Background Technology

[0002] In medical fields such as emergency and intensive care, treatments involving the removal of endotoxins from patients with sepsis are performed through blood purification therapy. Endotoxins are inflammatory triggers, represented by pathogen-associated molecular patterns (PAMPs). Previously, as a technique for removing endotoxins, methods were known to adsorb and remove endotoxins by directly contacting blood with immobilized polymyxin molded articles, which immobilize endotoxin adsorbents such as polymyxin B on a carrier (e.g., Patent Document 1).

[0003] [Prior Technology Documents]

[0004] [Patent Literature]

[0005] Patent Document 1: Japanese Patent Application Publication No. 61-135674 Summary of the Invention

[0006] [The problem the invention aims to solve]

[0007] Patients with severe sepsis sometimes experience complications such as acute renal failure, requiring concurrent renal replacement therapy via other blood purification devices while endotoxin removal is being performed. In such cases, it is necessary to connect the endotoxin removal component and the renal replacement therapy component in series or parallel with the blood circuit. However, when using conventional immobilized polymyxin molded products as the endotoxin removal component, the increased complexity of the blood circuit structure or the higher treatment cost suggest room for improvement in practicality.

[0008] The present invention was made in view of the above circumstances, and one of its objectives is to provide a more practical endotoxin removal technology.

[0009] [Technical solutions used to address technical problems]

[0010] One aspect of the present invention is a hollow fiber membrane module. This hollow fiber membrane module includes a first hollow fiber membrane, the first hollow fiber membrane having a sieve coefficient of 0.12 to 0.28 for dextran with a molecular weight of 300 kDa or higher and 1000 kDa or lower, and the first hollow fiber membrane adsorbing endotoxins.

[0011] Another aspect of the present invention is a method for removing endotoxins. This removal method includes the step of contacting the endotoxins with the hollow fiber membrane module of any of the above embodiments.

[0012] Furthermore, any combination of the above-mentioned constituent elements, as well as the substitution of the constituent elements of the present invention among methods, apparatuses, systems, etc., are also effective solutions of the present invention.

[0013] [Invention Effects]

[0014] According to the present invention, a more practical endotoxin removal technology can be provided. Attached Figure Description

[0015] Figure 1 This is a cross-sectional view of the hollow fiber membrane assembly according to the embodiment.

[0016] Figure 2 This is a schematic diagram used to illustrate the principle of target substance removal based on hollow fiber membranes.

[0017] Figure 3 (A) is a scanning electron microscope image of the first hollow fiber membrane. Figure 3 (B) is a scanning electron microscope image of the second hollow fiber membrane.

[0018] Figure 4 This is a schematic diagram of the circulation device used in the experiment.

[0019] Figure 5 (A) is a graph representing the molecular weight cutoff curves of each hollow fiber membrane. Figure 5 (B) is a graph representing the sieve coefficients of hollow fiber membranes within the molecular weight ranges of endotoxin and interleukin-6, respectively.

[0020] Figure 6 (A) Figure 6 (D) is a graph representing the results of the endotoxin adsorption test.

[0021] Figure 7 This is a graph showing the calculated results of endotoxin adsorption.

[0022] Figure 8 (A) Figure 8 (D) is a graph representing the results of the interleukin-6 adsorption assay.

[0023] Figure 9 This is a graph showing the calculated results of interleukin-6 adsorption. Detailed Implementation

[0024] To address the aforementioned issues, one aspect of the present invention is a hollow fiber membrane module. This hollow fiber membrane module includes a first hollow fiber membrane, wherein the first hollow fiber membrane has a sieving coefficient of 0.12 to 0.28 for dextran with a molecular weight of 300 kDa or higher and 1000 kDa or lower, and the first hollow fiber membrane adsorbs endotoxins.

[0025] In the above embodiments, the first hollow fiber membrane can also adsorb endotoxins in the blood. In addition, the first hollow fiber membrane can also be composed of a polyester polymer alloy membrane, which contains: a polyarylate resin having repeating units represented by the following chemical formula (1), and a polyethersulfone resin having repeating units represented by the following chemical formula (2) or the following chemical formula (3).

[0026] [Chemistry 1]

[0027]

[0028] [In chemical formula (1), R1 and R2 are lower alkyl groups having 1 to 5 carbon atoms. R1 and R2 can be the same or different from each other.]

[0029] [Chemistry 2]

[0030]

[0031] [In chemical formula (2), R3 and R4 are lower alkyl groups having 1 to 5 carbon atoms. R3 and R4 can be the same or different from each other.]

[0032] [Chemistry 3]

[0033]

[0034] Alternatively, the hollow fiber membrane module may have a second hollow fiber membrane with a sieve coefficient of 0.64 to 0.80 for dextran with a molecular weight of 20kDa to 30kDa, and the second hollow fiber membrane adsorbs interleukin-6.

[0035] Another aspect of the present invention is a method for removing endotoxins. This removal method includes the step of contacting the endotoxins with the hollow fiber membrane module of any of the above embodiments.

[0036] The present invention will now be described based on preferred embodiments and with reference to the accompanying drawings. These embodiments are illustrative rather than limiting, and not all features and combinations thereof described in the embodiments constitute the essential content of the invention. Identical or equivalent constituent elements, components, and processes shown in the various drawings are labeled with the same reference numerals, and repetitive descriptions are omitted where appropriate. Furthermore, the scales and shapes of the parts shown in the figures are conveniently set for ease of explanation and are not interpreted as limiting unless specifically mentioned. Additionally, when terms such as "first" and "second" are used in this specification or claims, these terms do not indicate any order or importance, but are used to distinguish one configuration from others. Furthermore, in the accompanying drawings, parts of less important components are omitted from the description of the embodiments.

[0037] Figure 1 This is a cross-sectional view of the hollow fiber membrane assembly of the embodiment. The hollow fiber membrane assembly 1 of this embodiment, as an example, adopts the same form as a dialyzer for hemodialysis (HD), but is not limited to this form. The hollow fiber membrane assembly 1 includes: a column 2, a hollow fiber membrane bundle 4, a sealing member 6, a first manifold 8, and a second manifold 10.

[0038] Column 2 is a cylindrical container housing the hollow fiber membrane bundle 4. Column 2 is made of resin such as polycarbonate. Column 2 has openings at both ends along its length. Additionally, near both ends along its length, column 2 has a dialysate outlet 12 and a dialysate inlet 14 protruding radially from the cylinder. Dialysate is supplied to column 2 from the outside via dialysate inlet 14 and exited from inside column 2 to the outside via dialysate outlet 12. Furthermore, when the hollow fiber membrane assembly 1 is used for hemofiltration (HF), only dialysate outlet 12 or dialysate inlet 14 is provided as a filtrate outlet.

[0039] The hollow fiber membrane bundle 4 has a structure that bundles together multiple hollow fiber membranes 16. Each hollow fiber membrane 16 extends approximately parallel to the length direction of the column 2. The openings at both ends of each hollow fiber membrane 16 are open, allowing blood to flow from one opening to the other. The structure of the hollow fiber membranes 16 will be described in detail later.

[0040] The sealing member 6, also known as the potting material, is composed of thermosetting resins such as polyurethane, phenolic resin, and epoxy resin. The sealing member 6 is filled at both ends of the hollow fiber membrane bundle 4 by embedding the gaps between multiple hollow fiber membranes 16. Furthermore, the sealing member 6 is fixed to the inner circumferential surfaces of both ends of the column 2. Thus, the hollow fiber membrane bundle 4 is fixed to the column 2, and the openings at both ends of the column 2 are sealed.

[0041] A first manifold 8 is installed at one end of the column 2, sealing the opening on that end. A second manifold 10 is installed at the other end of the column 2, sealing the opening on the other end. The first manifold 8 has a blood inlet 18 connecting the inside and outside of the column 2. The second manifold 10 has a blood outlet 20 connecting the inside and outside of the column 2. The blood inlet 18 is connected to a tube for drawing blood from the patient, and the blood outlet 20 is connected to a tube for returning blood to the patient.

[0042] Blood drawn from the patient is supplied into column 2 via blood inlet 18. The blood supplied into column 2 flows within each hollow fiber membrane 16, moving towards blood outlet 20. During this time, the blood flowing within the hollow fiber membrane 16 exchanges substances with the dialysate flowing outside the hollow fiber membrane 16. The blood passing through the hollow fiber membrane 16 is then exited from column 2 via blood outlet 20 and returned to the patient.

[0043] Next, the structure of the hollow fiber membrane 16 will be described in detail. The hollow fiber membrane 16 is composed of a porous semi-permeable membrane made of hydrophobic polymers, with polysulfone resin and polyester resin as the main components. The hollow fiber membrane 16 is, for example, a thin tube with a circular cross-section, having a membrane thickness of 5 to 150 μm and an inner diameter of about 100 to 500 μm.

[0044] The hollow fiber membrane 16 of this embodiment is composed of a polyester polymer alloy (PEPA) membrane, which contains: a polyarylate resin having repeating units represented by the following chemical formula (1), and a polyethersulfone resin having repeating units represented by the following chemical formula (2) or the following chemical formula (3). Furthermore, the indication of the phthalic acid portion in chemical formula (1) refers to the fact that there is no limitation on the arrangement of the two carboxyl groups relative to the benzene ring. For example, a structure containing two carboxyl groups bonded to the benzene ring in a meta-position relative to each other (i.e., isophthalic acid), and a structure containing two carboxyl groups bonded to the benzene ring in a para-position relative to each other (i.e., terephthalic acid).

[0045] [Chemistry 4]

[0046]

[0047] [In chemical formula (1), R1 and R2 are lower alkyl groups having 1 to 5 carbon atoms. R1 and R2 can be the same or different from each other.]

[0048] [Chemistry 5]

[0049]

[0050] [In chemical formula (2), R3 and R4 are lower alkyl groups having 1 to 5 carbon atoms. R3 and R4 can be the same or different from each other.]

[0051] [Chemistry 6]

[0052]

[0053] Figure 2 This is a schematic diagram illustrating the removal principle of target substance T based on hollow fiber membrane 16. The removal principles of target substance T based on hollow fiber membrane 16 can be mainly categorized into three types: dialysis, filtration, and adsorption. For substances with large molecular weights, such as inflammatory triggers, the different removal principles have a significant impact on the removal efficiency. For example... Figure 2As shown, the hollow fiber membrane 16 of this embodiment has pores 22 with a diameter corresponding to the size of the target substance T, and removes the target substance T by adsorption. The target substance T contained in the blood flowing inside the hollow fiber membrane 16 flows to the outside of the hollow fiber membrane 16 and penetrates into the pores 22. The target substance T that has penetrated into the pores 22 adheres to the inner wall surface through van der Waals forces or hydrophobic interactions generated between it and the inner surface of the pores 22. Thus, the target substance T is captured efficiently.

[0054] The hollow fiber membrane assembly 1 of this embodiment includes a first hollow fiber membrane 16a and a second hollow fiber membrane 16b. Both the first hollow fiber membrane 16a and the second hollow fiber membrane 16b are composed of the PEPA membrane described above. Figure 3 (A) is a scanning electron microscope image of the first hollow fiber membrane 16a. Figure 3 Image (B) is a scanning electron microscope image of the second hollow fiber membrane 16b. Figure 3 As shown in (A), the first hollow fiber membrane 16a has a plurality of first pores 22a. Figure 3 As shown in (B), the second hollow fiber membrane 16b has a plurality of second pores 22b.

[0055] The target substances T in the hollow fiber membrane assembly 1 of this embodiment are endotoxin and interleukin-6. Hereinafter, interleukin-6 will be appropriately referred to as IL-6. The first hollow fiber membrane 16a adsorbs endotoxin through the first pore 22a. The endotoxin has hydrophilic and hydrophobic segments and forms a micelle structure in aqueous solution. The apparent molecular weight of the endotoxin forming the micelle structure is 300 kDa or more and 1000 kDa or less. The first hollow fiber membrane 16a has a first pore 22a with a diameter appropriate to this molecular weight. The second hollow fiber membrane 16b adsorbs IL-6 through the second pore 22b. IL-6 is an inflammatory cytokine. The molecular weight of IL-6 is 20 kDa or more and 30 kDa or less. The second hollow fiber membrane 16b has a second pore 22b with a diameter appropriate to this molecular weight.

[0056] Regarding the adsorption characteristics of endotoxins, the first hollow fiber membrane 16a exhibits a sieve coefficient of 0.12 to 0.28 for dextran with a molecular weight of 300 kDa to 1000 kDa. This sieve coefficient is due to the presence of a first pore 22a in the first hollow fiber membrane 16a. Furthermore, regarding the adsorption characteristics of IL-6, the second hollow fiber membrane 16b exhibits a sieve coefficient of 0.64 to 0.80 for dextran with a molecular weight of 20 kDa to 30 kDa. This sieve coefficient is due to the presence of a second pore 22b in the second hollow fiber membrane 16b.

[0057] In this embodiment, the first hollow fiber membrane 16a contacts the blood and absorbs endotoxins from the blood. Additionally, the second hollow fiber membrane 16b contacts the blood and absorbs IL-6 from the blood. The hollow fiber membrane assembly 1 includes a hollow fiber membrane bundle 4 that mixes the first hollow fiber membrane 16a and the second hollow fiber membrane 16b, thereby efficiently capturing endotoxins and IL-6 to purify the blood.

[0058] The first hollow fiber membrane 16a and the second hollow fiber membrane 16b can be manufactured as follows: First, a composite resin comprising a polyarylate resin represented by the above chemical formula (1) and a polyethersulfone resin represented by the above chemical formula (2) or the above chemical formula (3) is dissolved in a specified organic solvent to prepare a spinning solution. The mass ratio of the polyarylate resin to the polyethersulfone resin in the first hollow fiber membrane 16a and the second hollow fiber membrane 16b is, for example, 2:1 to 1:2. The organic solvent is not particularly limited as long as it is a solvent capable of dissolving the polyarylate resin and the polyethersulfone resin, and examples include tetrahydrofuran, dioxane, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, etc. The mass ratio of the composite resin to the organic solvent is, for example, 0.5:9.5 to 3:7. The temperature at which the composite resin is dissolved in the organic solvent is, for example, 30°C or higher and 100°C or lower.

[0059] The spinning solution and the internal coagulation solution are extruded together using a dual-nozzle system and fall into a tank containing the external coagulation solution, thereby forming a first hollow fiber membrane 16a and a second hollow fiber membrane 16b. Both the internal and external coagulation solutions are mixtures of water and organic solvents. The mixing ratio of water to organic solvent in the internal and external coagulation solutions is, for example, 4:6 to 7:3. The sieve coefficient of the hollow fiber membrane for solutes can be adjusted by varying the mixing ratio of water to organic solvent in the internal coagulation solution. Furthermore, the higher the mixing ratio of organic solvent in the internal coagulation solution, the higher the sieve coefficient of the resulting hollow fiber membrane. By spinning under these conditions, the first hollow fiber membrane 16a and the second hollow fiber membrane bundle 16b can be obtained. The first hollow fiber membrane 16a has a first pore 22a with a pore size suitable for adsorbing endotoxins, and the second hollow fiber membrane 16b has a second pore 22b with a pore size suitable for adsorbing IL-6.

[0060] <Physical Property Evaluation of Hollow Fiber Membranes>

[0061] (Fabrication of hollow fiber membrane module 1)

[0062] To evaluate the adsorption-related properties of the hollow fiber membrane 16, a hollow fiber membrane module 1 filled with three types of hollow fiber membranes 16 with different permeability characteristics was fabricated. Each hollow fiber membrane 16 was fabricated according to the steps described above. Hereinafter, the three types of hollow fiber membranes 16 will be appropriately referred to as PEPA-A, PEPA-B, and PEPA-C.

[0063] (Preparation of molecular weight cutoff curves using dextran)

[0064] To understand the adsorption-related properties of each hollow fiber membrane 16, molecular weight cutoff curves for each hollow fiber membrane 16 were prepared using dextran. The molecular weight cutoff curves were prepared according to known methods. Figure 4 This is a schematic diagram of the circulation device used in the experiment.

[0065] Specifically, various dextrans were first mixed and diluted with distilled water to 500 mL to prepare dextran solution 24. 100 mL of this solution was then dispensed into container 26 for testing. The following dextrans were used as the following amounts: 0.125 g of dextran with a weight-average molecular weight of 9,000-11,000 (model D9260, manufactured by Sigma-Aldrich); 0.125 g of dextran with a weight-average molecular weight of 35,000-45,000 (model D1662, manufactured by Sigma-Aldrich); 0.5 g of dextran with a weight-average molecular weight of 150,000 (model D4876, manufactured by Sigma-Aldrich); and 0.75 g of dextran with a weight-average molecular weight of 180,000-210,000 (model 043-22611, manufactured by Fujifilm and Kazumitsu Chemical Co., Ltd.).

[0066] use Figure 4 The circulation device 28 shown implements a circulation process in which the dextran solution 24 is repeatedly flowed in PEPA-A to PEPA-C. Figure 4 In this diagram, "Bi" represents the solution inlet, "Bo" represents the solution outlet, and "F" represents the filtrate outlet. The solution inlet Bi is located at one end of the solution inlet path 30 and is connected to the container 26. The other end of the solution inlet path 30 is connected to the blood inlet 18 of the hollow fiber membrane module 1. The hollow fiber membrane module 1 uses membrane modules that respectively house PEPA-A to PEPA-C. The solution outlet Bo is located at one end of the solution outlet path 32 and is connected to the container 26. The other end of the solution outlet path 32 is connected to the blood outlet 20 of each hollow fiber membrane module 1. The filtrate outlet F is located at one end of the filtrate flow path 34 and is connected to the container 26. The other end of the filtrate flow path 34 is connected to the filtrate outlet 36 of the hollow fiber membrane module 1.

[0067] An inlet pump 38 is provided in the solution inlet path 30. An outlet pump 40 is provided in the filtrate flow path 34. When the inlet pump 38 is activated, the dextran solution 24 in container 26 flows from the solution inlet Bi through the solution inlet path 30 and the blood inlet 18 into the hollow fiber membrane assembly 1. The dextran solution 24 flowing into the hollow fiber membrane assembly 1 passes through the hollow fiber membrane 16, through the blood outlet 20 and the solution outlet path 32, and returns to container 26 from the solution outlet Bo. When the outlet pump 40 is activated, a portion of the dextran solution 24 passing through the hollow fiber membrane 16 moves from the inside to the outside of the hollow fiber membrane 16. The dextran solution 24 that has moved to the outside of the hollow fiber membrane 16 returns to container 26 from the filtrate outlet F through the filtrate outlet 36 and the filtrate flow path 34.

[0068] The inlet pump 38 was driven at a flow rate of 1.0 mL / min for the dextran solution 24 in the solution inlet path 30, and the outlet pump 40 was driven at a flow rate of 0.1 mL / min for the filtrate in the filtrate inlet path 34. Two hours after the start of each pump's operation, samples were taken from the solutions passing through the solution inlet Bi, solution outlet Bo, and filtrate outlet F, respectively.

[0069] The molecular weight of dextran in the sampled solutions was determined by high-performance liquid chromatography (HPLC). HPLC was performed using a 2695 separation module (Waters Corporation), a 2414 differential refractive index detector (Waters Corporation), and two GF-710HQ separation columns (Shodex Corporation). The measurement conditions were set as follows: flow rate 0.6 mL / min, column temperature 40 °C, injection volume 100 μL, and measurement time 60 min. The two separation columns were used in series.

[0070] The sieve index (SC) for each holding time is calculated based on the results obtained. The sieve index is an indicator of the proportion of solute filtered. If all solute is filtered, SC = 1; if none is filtered, SC = 0. The sieve index can be calculated using the following equation (3). In equation (3), CF is the refractive index intensity of the sample collected at the filtrate outlet F. CBi is the refractive index intensity of the sample collected at the solution inlet Bi. CBo is the refractive index intensity of the sample collected at the solution outlet Bo.

[0071] SC=2CF / (CBi+CBo)…(3)

[0072] Based on the linear function of the calibration curve obtained by high-performance liquid chromatography (HPLC) of dextran solution 24, the retention time of dextran of each molecular weight in each hollow fiber membrane 16 is converted into peak molecular weight (Mp). Then, the results of each hollow fiber membrane 16 are plotted on a graph with SC on the vertical axis and Mp on the horizontal axis to obtain the molecular weight cutoff curve of each hollow fiber membrane 16. Figure 5 (A) is a graph representing the molecular weight cutoff curves of each hollow fiber membrane.

[0073] In addition, based on the obtained molecular weight cutoff curves, the sieve coefficients of each hollow fiber membrane in the molecular weight ranges of endotoxin and IL-6 were derived. Figure 5 (B) is a graph showing the sieve coefficients of hollow fiber membranes within the molecular weight ranges of endotoxins and IL-6, respectively. For example... Figure 5 As shown in (B), the sieve factor of the endotoxin in PEPA-A is 0.12 to 0.28 within the molecular weight range. Furthermore, the sieve factor of the IL-6 in PEPA-C is 0.64 to 0.80 within the molecular weight range. Therefore, PEPA-A corresponds to the first hollow fiber membrane 16a, and PEPA-C corresponds to the second hollow fiber membrane 16b.

[0074] <Evaluation of the endotoxin adsorption capacity of hollow fiber membranes>

[0075] To evaluate the endotoxin adsorption capacity of each hollow fiber membrane 16, the endotoxin adsorption test described below was performed using each hollow fiber membrane 16.

[0076] (Preparation of endotoxin solution)

[0077] First, 0.02 mL of endotoxin (1,000 EU / mL) was diluted with 20 mL of pyrogen-free water (model H20CC0124, manufactured by Merck) to prepare an endotoxin solution (1 EU / mL). Alternatively, an endotoxin standard (10,000 EU / mL, manufactured by the Pharmaceutical and Medical Devices Regulatory Science Foundation) was diluted 10-fold with pyrogen-free water. The prepared endotoxin solution was contained in a dry-heat sterilized glass container. Several glass containers, each containing 20 mL of the endotoxin solution, were also prepared.

[0078] use Figure 4 The circulation device 28 shown performs a circulation process in which the endotoxin solution is repeatedly flowed through PEPA-A to PEPA-C. Container 26 is a glass container holding 20 ml of the aforementioned endotoxin solution. Each flow path uses silicone tubing sterilized by an autoclave. PEPA-A to PEPA-C are sterilized using gamma rays.

[0079] The inlet pump 38 was driven at a flow rate of 1.0 mL / min for the endotoxin solution in the inlet path 30, and the outlet pump 40 was driven at a flow rate of 0.1 mL / min for the filtrate in the filtrate inlet path 34. Endotoxin solutions in container 26 were sampled at 0, 10, 30, 60, and 120 minutes after each pump was started. Endotoxin-free pipette tips and dry-heat sterilized glass containers were used for sampling.

[0080] Endotoxin concentrations in sampled solutions were determined by endpoint colorimetry using Endospecy ES-50M (manufactured by Biochemical Industrial Co., Ltd.) and PyroColor Diazo reagent DIA150-MP (manufactured by Biochemical Industrial Co., Ltd.). The assay procedures were performed according to the reagent kit guidelines. Each sampled solution was diluted 100-fold with pyrogen-free water. All microplates (model 900570, Biochemical Industrial Co., Ltd.) and pipette tips (models 298-35031 and 291-35021, manufactured by Fujifilm and Koden Pharmaceutical Co., Ltd.) used in the assay were endotoxin-free. The absorbance of each solution was measured using a microplate reader (Wallac 1420ARVOMX, PerkinElmer) at a measurement wavelength of 540 nm and a control wavelength of 630 nm. Three cycles of treatment and concentration determination were performed, and the average concentration obtained from each measurement was calculated.

[0081] In addition, as a control area, except that the hollow fiber membrane module 1 is not installed in the circulation device 28, and the solution inflow path 30 is directly connected to the solution outflow path 32 and the filtrate flow path 34, the above-mentioned circulation process and concentration measurement are performed in the same way.

[0082] Figure 6 (A) Figure 6 (D) is a graph representing the results of the endotoxin adsorption test. Figure 6 (A) is the result of PEPA-A. Figure 6 (B) is the result of PEPA-B. Figure 6 (C) is the result of PEPA-C. Figure 6 (D) represents the result of the control area. For example... Figure 6 (A) Figure 6 As shown in (D), a significant reduction in endotoxin concentration was confirmed in PEPA-A. The reduction in endotoxin concentration was smaller in PEPA-B and PEPA-C. Since the circulation device 28 has a flow path configuration where the endotoxin solution and filtrate are returned to the container 26 via the hollow fiber membrane module 1, the reduction in endotoxin concentration indicates that the endotoxins are adsorbed and removed by the hollow fiber membrane 16.

[0083] Furthermore, for PEPA-A to PEPA-C and the control area, the endotoxin adsorption amount (M) after 120 minutes of cyclic treatment was calculated using the following formula (4). In formula (4), CB0 is the endotoxin concentration in the endotoxin solution before the start of cyclic treatment. CB 120 This represents the endotoxin concentration in the endotoxin solution after 120 minutes of circulation. 20 represents the volume of the endotoxin solution.

[0084] M = (CB0 - CB) 120 )×20…(4)

[0085] Figure 7 This is a graph representing the calculated results of endotoxin adsorption. For example... Figure 7 As shown, PEPA-A adsorbs significantly more endotoxins compared to PEPA-B and PEPA-C. Based on the above, a first hollow fiber membrane 16a with a sieve coefficient of 0.12 to 0.28 for dextran with a molecular weight of 300 kDa to 1000 kDa has been demonstrated, which can efficiently adsorb and remove endotoxins.

[0086] <Evaluation of the IL-6 adsorption capacity of hollow fiber membranes>

[0087] To evaluate the IL-6 adsorption capacity of each hollow fiber membrane 16, the following IL-6 adsorption test was performed using each hollow fiber membrane 16.

[0088] (Preparation of IL-6 solution)

[0089] First, an IL-6 solution (10,000 pg / mL) was prepared, containing: 18 mL of PBS (model 045-29795, manufactured by Fujifilm and Koichi Chemical Co., Ltd.), 2 mL of Blocker (registered trademark) BSA (10×) in PBS (model 37525, manufactured by Thermo Fisher Scientific), and 0.02 mL of recombinant human IL-6 (IL-6, Human Recombinant, 10 μg / mL, model 206-IL-010, manufactured by R&D Systems). Furthermore, the recombinant human IL-6 was adjusted to 10 μg / mL using 1% Blocker (registered trademark) BSA / PBS. Multiple containers containing 20 mL of the prepared IL-6 solution were prepared.

[0090] use Figure 4The circulation device 28 shown performs a circulation process in which the IL-6 solution is repeatedly flowed through PEPA-A to PEPA-C. Container 26 contains 20 ml of the aforementioned IL-6 solution. The inlet pump 38 is driven at a flow rate of 1.0 mL / min for the IL-6 solution in the inlet path 30, and the outlet pump 40 is driven at a flow rate of 0.1 mL / min for the filtrate in the filtrate flow path 34. Samples of the IL-6 solution in container 26 are taken at 0, 10, 30, 60, and 120 minutes after each pump is started.

[0091] The IL-6 concentration of each sampled solution was determined using the Human IL-6 Quantikine ELISA Kit (Model D6050, manufactured by R&Dsystems). The assay procedure was performed according to the kit's instructions. Each sampled solution was diluted 100-fold with the dilution buffer provided with the kit. The absorbance of each solution was measured using a microplate reader (Wallac 1420ARVO MX, manufactured by PerkinElmer) at a measurement wavelength of 450 nm and a control wavelength of 540 nm. Three cycles of processing and concentration determination were performed, and the average concentration obtained from each measurement was calculated.

[0092] In addition, as a control area, except that the hollow fiber membrane module 1 is not installed in the circulation device 28, and the solution inflow path 30 is directly connected to the solution outflow path 32 and the filtrate flow path 34, the above-mentioned circulation process and concentration measurement are performed in the same way.

[0093] Figure 8 (A) Figure 8 (D) is a graph representing the results of the IL-6 adsorption test. Figure 8 (A) is the result of PEPA-A. Figure 8 (B) is the result of PEPA-B. Figure 8 (C) is the result of PEPA-C. Figure 8 (D) represents the result of the control area. For example... Figure 8 (A) Figure 8 As shown in (D), a significant decrease in IL-6 concentration was confirmed in PEPA-C. The decrease in endotoxin concentration was smaller in PEPA-A and PEPA-B. Since the circulation device 28 has a flow path configuration that returns the IL-6 solution after passing through the hollow fiber membrane module 1 and the filtrate to the container 26, the decrease in IL-6 concentration indicates that IL-6 has been adsorbed and removed by the hollow fiber membrane 16.

[0094] Furthermore, for PEPA-A to PEPA-C and the control area, the IL-6 adsorption amount (M) after 120 minutes of cycling was calculated using the above formula (4). In formula (4), CB0 is the IL-6 concentration in the IL-6 solution before the start of the cycling treatment. 120 This represents the concentration of IL-6 in the IL-6 solution after 120 minutes of cycling. 20 represents the volume of the IL-6 solution.

[0095] Figure 9 This is a graph representing the calculated amount of IL-6 adsorption. (For example...) Figure 9 As shown, PEPA-C adsorbs significantly more IL-6 compared to PEPA-A and PEPA-B. Based on the above, it has been demonstrated that a first hollow fiber membrane 16b with a sieve coefficient of 0.64 to 0.80 for dextran with a molecular weight of 20 kDa to 30 kDa can efficiently adsorb and remove IL-6.

[0096] As explained above, the hollow fiber membrane assembly 1 of this embodiment has a first hollow fiber membrane 16a. The first hollow fiber membrane 16a has a sieve coefficient of 0.12 to 0.28 for dextran with a molecular weight of 300 kDa or more and 1000 kDa or less, and the first hollow fiber membrane 16a adsorbs endotoxins. Therefore, by assembling the hollow fiber membrane assembly 1 only in the flow path of the object from which endotoxins are to be removed, endotoxins can be adsorbed and removed from the object. Therefore, compared with the conventional use of immobilized polymyxin molded articles, it is possible to suppress the increasing complexity of the blood circuit structure or the increase in treatment costs. Furthermore, since the hollow fiber membrane assembly 1 adsorbs endotoxins through the first hollow fiber membrane 16a, it is not necessary to immobilize the endotoxin adsorbent or ligand on a carrier. Therefore, this embodiment provides a more practical endotoxin removal technology.

[0097] Furthermore, the first hollow fiber membrane 16a of this embodiment adsorbs endotoxins in the blood. That is, the hollow fiber membrane assembly 1 is used as a blood purifier. Therefore, blood can be purified more efficiently.

[0098] Furthermore, the first hollow fiber membrane 16a of this embodiment is composed of a polyester polymer alloy membrane containing: a polyaryl ester resin represented by the above chemical formula (1), and a polyethersulfone resin represented by the above chemical formula (2) or the above chemical formula (3). In this case, the two hydrophobic polymers, namely polyaryl ester and polyethersulfone, shrink to different degrees, thereby forming pores 22 of the desired diameter. Therefore, the formation of pores 22 does not require the use of hydrophilic polymeric opening agents such as polyvinylpyrrolidone. Therefore, the first hollow fiber membrane 16a can be manufactured more simply.

[0099] Furthermore, the hollow fiber membrane module 1 of this embodiment includes a second hollow fiber membrane 16b, which has a sieve coefficient of 0.64 to 0.80 for dextran with a molecular weight of 20 kDa or more and 30 kDa or less, and adsorbs IL-6. Therefore, both endotoxin and IL-6 can be adsorbed and removed simultaneously. Thus, a more practical endotoxin removal technology can be provided.

[0100] The embodiments of the present invention have been described in detail above. These embodiments are merely examples illustrating specific ways of implementing the present invention. The content of the embodiments does not limit the technical scope of the present invention; various design changes, such as alterations, additions, and deletions of constituent elements, can be made without departing from the inventive concept defined by the claims. New embodiments with applied design changes possess the respective effects of both the combined embodiments and variations. In the above embodiments, the aspects enabling such design changes are emphasized by markings such as "in this embodiment" or "in this embodiment," but design changes are also permitted even without such markings. Any combination of the above constituent elements is also valid as a method of the present invention.

[0101] The invention described above can also be specified by the items described below.

[0102] [Project 1]

[0103] An endotoxin removal method includes the step of contacting the endotoxin with the hollow fiber membrane assembly (1) described in the embodiments.

[0104] [Project 2]

[0105] A blood purifier comprising the hollow fiber membrane assembly (1) described in the embodiments.

[0106] [Industrial Availability]

[0107] This invention can be used for hollow fiber membrane modules and methods for removing endotoxins.

[0108] [Explanation of reference numerals in the attached figures]

[0109] 1 Hollow fiber membrane module, 16 hollow fiber membrane, 16a first hollow fiber membrane, 16b second hollow fiber membrane, 22 fine pores, 22a first fine pore, 22b second fine pore.

Claims

1. A hollow fiber membrane module, comprising: The first hollow fiber membrane has a sieve coefficient of 0.12 to 0.28 for dextran with a molecular weight of 300kDa to 1000kDa. The first hollow fiber membrane adsorbs endotoxins, allowing the endotoxins to enter the pores of the first hollow fiber membrane and adhere to the inner surface of the pores.

2. The hollow fiber membrane module as described in claim 1, The first hollow fiber membrane has a sieve coefficient of 0.12 to 0.28 for dextran with a molecular weight of 300kDa to 1000kDa.

3. The hollow fiber membrane module as described in claim 1 or 2, The first hollow fiber membrane adsorbs the endotoxins in the blood.

4. The hollow fiber membrane module as described in claim 1 or 2, The first hollow fiber membrane is composed of a polyester polymer alloy membrane, which contains: a polyaryl ester resin having repeating units represented by the following chemical formula (1), and a polyethersulfone resin having repeating units represented by the following chemical formula (2) or the following chemical formula (3). [Chemical Formula 1] In chemical formula 1, R1 and R2 are lower alkyl groups having 1 to 5 carbon atoms. R1 and R2 can be the same or different from each other. [Chemical Formula 2] In chemical formula 2, R3 and R4 are lower alkyl groups having 1 to 5 carbon atoms. R3 and R4 can be the same or different from each other. [Chemical Formula 3] 5. The hollow fiber membrane module as described in claim 3, The first hollow fiber membrane is composed of a polyester polymer alloy membrane, which contains: a polyaryl ester resin having repeating units represented by the following chemical formula (1), and a polyethersulfone resin having repeating units represented by the following chemical formula (2) or the following chemical formula (3). [Chemical Formula 1] In chemical formula 1, R1 and R2 are lower alkyl groups having 1 to 5 carbon atoms. R1 and R2 can be the same or different from each other. [Chemical Formula 2] In chemical formula 2, R3 and R4 are lower alkyl groups having 1 to 5 carbon atoms. R3 and R4 can be the same or different from each other. [Chemical Formula 3] 6. The hollow fiber membrane module as described in claim 1 or 2, comprising: The second hollow fiber membrane has a sieve coefficient of 0.64 to 0.80 for dextran with a molecular weight of 20kDa to 30kDa. The second hollow fiber membrane adsorbs interleukin-6.

7. The hollow fiber membrane module as described in claim 3, comprising: The second hollow fiber membrane has a sieve coefficient of 0.64 to 0.80 for dextran with a molecular weight of 20kDa to 30kDa. The second hollow fiber membrane adsorbs interleukin-6.

8. The hollow fiber membrane module as described in claim 4, comprising: The second hollow fiber membrane has a sieve coefficient of 0.64 to 0.80 for dextran with a molecular weight of 20kDa to 30kDa. The second hollow fiber membrane adsorbs interleukin-6.

9. The hollow fiber membrane module as described in claim 5, comprising: The second hollow fiber membrane has a sieve coefficient of 0.64 to 0.80 for dextran with a molecular weight of 20kDa to 30kDa. The second hollow fiber membrane adsorbs interleukin-6.

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