FR2892949A1 - LEUCOCYTES FILTRATION UNIT WITH REDUCED PLATELET ADHESION - Google Patents

Abstract

The invention relates to a filtration unit (1) for a biological fluid such as blood or a blood component, of the type comprising an outer casing (2) provided with at least one inlet orifice (3) and at least one outlet (4), the casing (2) enclosing a porous porous element (5) interposed between said orifices (3,4), wherein the porous element comprises an adsorption-depleting leukocyte medium and or by filtration of leukocytes and the coating is based on a copolymer capable of allowing the passage of platelets through said medium, said copolymer having the general formula: HO (CH 2 CH 2 O) a (X) b (CH 2 CH 2 O) CH wherein: - (X) b is a hydrophobic polymeric block; and a, b, and c are each an integer greater than or equal to 2, wherein the coated porous element has a surface energy whose polar component is between 30 and 50 mN / m and the dispersive component is between 8 mN / m and 30 mN / m.

Description

The invention relates to a filtration unit intended to enable the

  deleucocyte a fluid and a bag system comprising such a unit.

  It typically applies to the filtration of blood or a blood component such as whole blood, red blood cell concentrate (RBC), platelet rich plasma (PRP) or platelet concentrate (CP), and 'separation and collection of blood components, especially in closed circuits.

  Whole blood consists of two types of components: blood cells including red blood cells, leukocytes and platelets, and plasma in which blood cells are suspended.

  Currently, only the blood components needed by the patients are transfused. For example, only platelet concentrates are transfused into patients with thrombocytopenia, that is, whose platelet content in the blood is reduced.

  Leukocytes have been found to have very large adverse effects, leading to the search for removal of blood components for transfusion. Indeed, leukocytes increase the risk of immune rejection such as graft-versus-host disease and promote the transmission of infectious agents. Leukocytes have also been shown to negatively affect platelet conservation. EP-A-0 792 677 discloses a filter comprising biologically active means capable of removing leukocytes from a biological fluid. Platelet adhesion to the filter may be decreased by surface treatment, for example using a tri-block copolymer of polyethylene oxide / polypropylene oxide / polyethylene oxide. That being so, the surface treatment alters the intrinsic properties of the media. The viscosity induced by this type of treatment greatly affects the porosity and permeability of the leukocyte removal medium. Therefore, a filter of this type does not allow to obtain a perfect leukocyte.

  The object of the invention is therefore to obtain an improved filter medium retaining leukocytes optimally and preventing excessive adhesion of platelets.

  To achieve this objective, the Applicant has carried out intensive tests and has selected an improved biocompatibility leukocyte depletion medium, that is to say having both optimal characteristics of leukocyte retention and non-adherence of blood platelets.

  In particular, the filtration unit incorporating such a leukocyte removal medium makes it possible to obtain a leukocyte depletion rate of greater than 3 log, with a platelet recovery rate greater than 80%.

  For this purpose, and according to a first aspect, the invention proposes a filtration unit 15 for a biological fluid such as blood or a blood component, of the type comprising an outer casing provided with at least one inlet orifice and at least one outlet port, the envelope enclosing a porous coated member which is interposed between said orifices, wherein the porous member comprises a leukocyte adsorption and / or leucocyte depletion depleting medium and the coating is a copolymer based on allowing the passage of blood platelets through said medium, said copolymer having the general formula HO (CH 2 CH 2 O) a (X) b (CH 2 CH 2 O) CH, in which: - (X) b is a block hydrophobic polymer; and - a, b, and c are each an integer greater than or equal to 2; Wherein the coated porous element has a surface energy whose polar component is between 30 and 50 mN / m and the dispersive component is between 8 mN / m and 30 mN / m.

  According to a second aspect, the invention relates to a bag system for the deleucocytation of a biological fluid comprising: - a connector intended to be connected to a collection bag containing the biological fluid, said connector being connected, via a tubing, to an inlet of a filtration unit according to the invention; and a filtrate collection bag, said bag being connected, via a tubing and at an inlet port, to an outlet port of the filtration unit.

  According to a third aspect, the invention relates to a bag system for the deleucocytation of a biological fluid such as blood or a blood component, which comprises: - a biological fluid collection bag, said bag being connected by the intermediate tubing and at an outlet port, an inlet port of a filtration unit according to the invention; and - a filtrate collection bag, said bag being connected, via a tubing and at an inlet port, to an outlet port of said filtration unit.

  Other objects and advantages of the invention will become apparent from the following description with reference to the accompanying drawings.

  Figure 1 schematically shows a sectional view of a filtration unit according to one embodiment of the invention. FIG. 2 schematically represents a bag system according to the invention comprising a filtration unit according to FIG. 1.

  In Figure 1 there is shown a filtration unit 1 for allowing the deleucocytation of a biological fluid, such as blood or a blood component, including platelets according to one embodiment.

  A platelet-containing fluid may be, for example, whole blood, platelet rich plasma (PRP), platelet concentrate (CP) or buffy coat. Note that the filtration unit 1 can also be used to filter a fluid not containing platelets such as a concentrate of red blood cells (RBC). In particular, the filtration unit 1 is intended to filter a unit of PRP, that is to say the amount of PRP obtained after centrifugation of a whole blood donation. The filtration unit can also be used to filter whole blood, a pool of buffy coat or CP obtained after meeting two to eight units of buffy coat or CP from a donation of whole blood.

  In the description, the terms upstream and downstream are defined with respect to the flow direction of the fluid in the filtration unit, represented by the arrow d of FIG.

  In the embodiment shown in FIG. 1, the filtration unit 1 comprises an outer casing 2 provided with at least one inlet orifice 3 intended to receive the fluid to be filtered and at least one outlet orifice 4 for collecting the filtrate, between which the fluid flows in a direction (d).

  The envelope 2 is flexible, rigid or semi-rigid. In particular, when the envelope is flexible, the filtration unit is of the type described in EP-A-0 526 678.

  The filtration unit 1 further includes a porous coated member 5 which is interposed between said openings (3,4).

  The coated porous member 5 is disposed in the outer casing 2 so as to define an inlet compartment in communication with the inlet port 3 and an outlet compartment in communication with the outlet port 4.

  The coated porous member comprises a leukocyte depleting and / or filtering leukocyte depleting medium present in a blood labile product. In addition, the coating of the porous element is based on a copolymer capable of allowing the passage of blood platelets through said medium, said copolymer having the general formula: HO (CH 2 CH 2 O) a (X) b (CH 2 CH 2 O) wherein: - (X) b is a hydrophobic polymeric block; and - a, b, and c are each an integer greater than or equal to 2. The coated porous element has a surface energy whose polar component is between 30 and 50 mN / m and the dispersive component is between 8 mN / m and 30 mN / m.

  Thus, the coated porous element 5 is capable of obtaining a number of leucocytes in the filtered fluid which is less than 1 × 10 6 and allowing at least 80% of the blood platelets to pass, i.e. do not adhere to the surface of the leukocyte removal medium.

  A synthetic polymer for use as a biomaterial in contact with a labile blood product must possess certain properties to exhibit good platelet behavior, including a hydrophilic surface preventing protein adhesion.

  To do this, the surface is coated with a polymer having hydrophilic zones forming a hydrogel preventing the adhesion of proteins.

  The surface-deposited polymer must also have hydrophobic areas in order to adhere properly to the filter media.

  This is why the invention proposes the use of a hydrophilic / hydrophobic block copolymer.

  This copolymer will make it possible to minimize the interactions in the biomaterial / biological medium system. It also aims to improve the hemocompatibility of the surface of the material without modifying its intrinsic mechanical properties.

  Indeed, the adhesion of platelets by contact on a surface is always preceded by the adsorption on this surface of proteins, essentially fibrinogen. Avoiding this adsorption phenomenon allows the platelets not to adhere to the leukocyte removal medium. Thus, by grafting a hydrophilic polymer, the hydrophilicity of the surface is increased and induces a decrease in the adsorption of the proteins and consequently the decrease in platelet adhesion.

  The copolymer, capable of allowing the passage of blood platelets through said medium, has the general formula HO (CH 2 CH 2 O) a (X) b (CH 2 CH 2 O) CH, in which the polyethylene oxide is the hydrophilic part of the copolymer and (X b is a hydrophobic polymeric block such as poly-ε-caprolactam, polystyrene, poly (L, D) (lactic acid), poly (glycolic acid), poly (methyl methacrylate) or oxides of alkylene.

  In one embodiment, X is -CpH2pO- where p is an integer greater than or equal to 3. For example, X may be poly (propylene oxide) or poly (isopropylene oxide) with p equal to 3, poly (butylene oxide) with 15 equal to 4.

  In a particular example, X is the group -CH (CH3) CH2O-.

  In addition, the number-average molecular weight of the copolymer, that is to say its molecular weight, is between 2000 and 18000 g / mol, in the case where X is the group described in the above paragraph.

  In addition, the degree of polymerization is represented by a, b, and c, which are each an integer greater than or equal to 2. In one embodiment of the invention, a = c.

  For example, when the formula is of the type HO (CH 2 CH 2 O) a (CH (CH 3) CH 2 O) b (CH 2 CH 2 O) c H with a = c, the copolymer is referenced by the American Pharmacopoeia (USP) as: Poloxamer 124 if a = 12 and b = 20; - Poloxamer 188 if a = 80 and b = 27; - Poloxamer 237 if a = 64 and b = 37; - Poloxamer 338 if a = 141 and b = 44; Poloxamer 407 if a = 101 and b = 56.

  More particularly, when the degree of polymerization a = c, the copolymer comprises a percentage of -CH 2 CH 2 O- of between 45 and 86% by weight of the number average molecular weight of the copolymer.

  For example, for Poloxamer 124, the molar mass of the copolymer is between 2090 and 2360, with a percentage of ethylene oxide of about 46%. For Poloxamer 188, the molar mass of the copolymer is between 7680 and 9510, with a percentage of ethylene oxide of about 81%.

  For Poloxamer 237, the molar mass of the copolymer is between 6840 and 8830, with a percentage of ethylene oxide of about 72%.

  For Poloxamer 338, the molar mass of the copolymer is between 12700 and 17400, with a percentage of ethylene oxide of about 83%.

  For Poloxamer 407, the molar mass of the copolymer is between 9840 and 14600, with a percentage of ethylene oxide of about 73%.

  The coated filter medium makes it possible, by means of physico-chemical parameters, to guarantee the optimization of the deleucocytation of a biological fluid containing platelets while allowing maximum recovery of the latter.

  To do this, the coated porous element has a surface energy whose polar component is between 30 and 50 mN / m and the dispersive component is between 8 mN / m and 30 mN / m. These physico-chemical characteristics of the filtration medium are determined by the measurement of the contact angle which makes it possible to determine the surface energy of the filtration medium.

  For solids, indirect methods of measuring surface energy are used such as measuring the wetting angle of a drop of liquid deposited on the surface of the solid. This method makes it possible to simply determine the wettability properties of a porous element. In particular, the critical wettability surface tension (CWST) determines whether a porous element is wettable when a liquid is brought into contact with the surface of the porous element. When the porous element has a value of CWST greater than the surface tension of the liquid, the porous element is said to be wettable.

  However, this method does not provide information on the nature of the interactions between the solid and the liquid. And even if the surface is considered wettable, it does not mean that it reaches the expected characteristics.

  Characterization of the nature of the surface will be possible by obtaining the polar component and the dispersive component of the surface energy.

  The equations given by D. K. Owens and R. C. Wendt in Journal of Applied Polymer Science, Vol. 13, p. 1741 (1969) are used to determine the surface energy of the leukocyte removal medium.

  As described by Owens and Wendt, measuring the contact angle of water and methylene iodide on a solid simultaneously solves the equations to obtain the polar and dispersive components of the surface energy of the solid. solid with total surface energy.

  Thus the total surface energy of a solid is given by the following relation: Ytot = yd + yp, where ytot is the total surface energy, yd is the nonpolar dispersive component of the surface energy and yp is the polar component of surface energy.

  The filtration unit combines, on the one hand, an optimal leukocyte-removal medium and, on the other hand, a coating allowing a minimum platelet retention, based on the polymer defined above, with a surface energy of which the polar component is between 30 and 50 mN / m and the dispersive component is between 8 mN / m and 30 mN / m.

  In particular, the coated porous element has a surface energy of which the polar component is between 35 and 45 mN / m and the dispersive component is between 13 mN / m and 20 mN / m.

  According to a particular embodiment, the leukocyte removal medium is coated with a copolymer mass equal to at most 8% of the mass of said medium. When the amount of copolymer is not sufficient, the platelet recovery rate of 80% can not be reached. In addition, the platelets aggregate and the filter clogs.

  When the amount of copolymer is too great, the polyethylene oxide layer becomes too thick and therefore does not have sufficient mechanical strength: there is a risk of stalling of the adsorbed material on the leukocyte removal medium and, as a result, release of the copolymer into the labile blood product can occur. On the other hand, too thick a layer of the copolymer solution greatly affects the porosity and permeability of the leukocyte removal medium, thus rendering the layers of inhomogeneous medium with poor cohesion between the layers. In a particular embodiment, the coated copolymer is subjected to an ionizing treatment. This treatment makes it possible to chemically and therefore optimally bind the copolymer to the filtration medium.

  It is immobilized by UV, beta, gamma radiation or by a high-frequency cold plasma technique with an argon-type neutral gas (Ar RFGD: Argon Radio Frequency Glow Discharge). The leukocyte removal medium is formed from a material selected from the group consisting of polyethylene, polyurethane, polypropylene, polybutylene terephthalate or polyethylene terephthalate.

  These materials contained in the filtration unit have the advantage of having a good grafting surface for the hydrophobic part of the copolymer, in particular polybutylene terephthalate.

  In one embodiment of the invention, the average pore diameter of the leukocyte removal medium is between 3 and 15 μm. The average pore diameter of the leukocyte removal medium after coating remains substantially the same.

  The leukocyte removal medium may be in the form of a woven fabric, a knit fabric or a nonwoven fabric.

  The leukocyte removal medium is formed of at least one fibrous layer. For example, the diameter of the fibers is between 0.3 and 7 μm, with an average of between 1 and 3 μm. In particular, the fibrous layer is a nonwoven.

  The coated porous element 5 further comprises a pre-filter and / or a post-filter which are in the form of at least one non-woven layer and which are respectively disposed on the upstream side and the downstream side of the leukocyte depletion.

  These pre and post filters are identical or different and can be coated with the same coating copolymer as the leukocyte removal medium.

  In particular, said pre-filter and / or post-filter are formed based on polybutylene terephthalate.

  According to a second aspect of the invention, the filtration unit 1 is included in a bag system for the deleucocytation of a biological fluid and is connectable.

  A pouch system 6 for the removal of leukocytes from a biological fluid such as blood or a blood component is described below.

  According to FIG. 2, the bag system 6 comprises a bag for collecting the filtrate 7, connected via a tubing 8 and at an inlet orifice 9 to an outlet port 4 of a unit filtration 1 as described above.

  In addition, the bag system comprises a pipe 10 connected to the inlet port 3 of the filtration unit 1.

  In use, a pouch containing the fluid to be filtered is connected to the tubing 10, for example by means of a sterile connector 11 provided on the tubing 10 opposite the filtration unit 1. The fluid to be gravity filtered is passed through the filtration unit 1 and the reduced leucocyte filtered fluid is collected in the filtrate collection bag 7.

  According to a third aspect of the invention, the filtration unit is integrated in a so-called closed bag system, allowing the collection of whole blood and its subsequent treatment to remove leukocytes from whole blood or one of its components.

  For this purpose, the bag system comprises: a bag for collecting the biological fluid, said bag being connected, via a tubing and at an outlet orifice, to an inlet port of a filtration unit according to the invention; and - a filtrate collection bag, said bag being connected, via a tubing and at an inlet port, to an outlet port of said filtration unit. Three embodiments of a filtration unit according to the invention are given below.

  Example 1 A filtration unit 1 as shown in Figure 1 comprising a porous member consisting of: - two layers of PET nonwoven pre-filter having a porosity of 45-50 μm, - 20 layers of nonwoven of average pore size PBT equal to 8-9 μm, - a non-woven PET post-filter layer having a porosity of 45-50 μm.

  The nonwoven of PBT undergoes a surface treatment with Poloxamer 338 under the following operating conditions: padding coating after passage in a solvent bath (solvent mixture comprising water, acetone and ethanol) with a Poloxamer concentration of 2 %. - Drying in an oven.

  The percentage of coating obtained on the media is 3.2%.

  The use of a goniometer makes it possible to determine, with the sessile drop method or the captive drop method, the surface energy of the coated porous element and the polar and dispersive components of said energy.

  The polar component obtained is 35 mN / m and the dispersive component obtained is 14 mN / m. A pool of platelet concentrates is formed in the pocket of a bag system as shown in Figure 2, and then the pool is passed into the filtration unit described above. The platelet recovery rate is between 84 and 96% and the leucocyte depletion rate is greater than 3 log.

  Example 2 A filtration unit 1 as shown in Figure 1 comprising a porous element made of the same material as in Example 1.

  The nonwoven of PBT is surface-treated with Poloxamer 338 under the following operating conditions: padding coating after passage through a solvent bath (solvent mixture comprising water, acetone and ethanol) with a Poloxamer concentration of 4%. - Drying in an oven.

  The percentage of coating obtained on the media is 6.5%.

  The polar component obtained is 36 mN / m and the dispersive component obtained is 14 mN / m.

  The same procedure is followed and the results obtained are similar to those of Example 1.

  Example 3 A filtration unit 1 as shown in Figure 1 comprising a porous element made of the same material as in Example 1.

  The non-woven PBT is surface-treated with Poloxamer 338 under the following operating conditions: padding coating after passage in a solvent bath (solvent mixture comprising water, acetone and ethanol) with a Poloxamer concentration of 1%. - Drying in an oven. 355 The percentage of coating obtained on the media is 2.6%.

  The polar component obtained is 44 mN / m and the dispersive component obtained is 16 mN / m.

  The same procedure is followed and the results obtained are similar to those of Example 1.

Claims (19)

  A filter unit (1) for a biological fluid such as blood or a blood component, of the type comprising an outer shell (2) provided with at least one inlet port (3) and at least one outlet port (4), the shell (2) enclosing a porous coated element (5) interposed between said orifices (3,4), wherein the porous element comprises an adsorption-depleting and / or filtration of leukocytes and the coating is based on a copolymer capable of allowing the passage of blood platelets through said medium, said copolymer having the general formula: HO (CH 2 CH 2 O) a (X) b (CH 2 CH 2 O) CH, in which : - (X) b is a hydrophobic polymer block; and - a, b, and c are each an integer greater than or equal to 2; said unit being characterized in that the coated porous element has a surface energy whose polar component is between 30 and 50 mN / m and the dispersive component is between 8 mN / m and 30 mN / m.   2. Filtration unit according to claim 1, characterized in that the coated porous element has a surface energy whose polar component is between 35 and 45 mN / m and the dispersive component is between 13 mN / m and 20 m / m. mN / m.   3. Filtration unit according to claim 1 or 2, characterized in that X is a group -CpH2pO- where p is an integer greater than or equal to 3.   4. Filtration unit according to any one of claims 1 to 3, characterized in that X is the group -CH (CH3) CH2O-.   5. Filtration unit according to claim 4, characterized in that the copolymer has a molar mass of between 2000 and 18000.   6. Filtration unit according to any one of claims 1 to 5, characterized in that a = c. 15 30   7. Filtration unit according to claim 6, characterized in that the copolymer comprises a percentage of -CH2CH2O- between 45 and 86% by weight of the number-average molar mass of the copolymer. s   8. Filtration unit according to any one of claims 1 to 7, characterized in that the leukocyte removal medium is coated with a copolymer mass equal to at most 8% of the mass of said medium.   9. Filter unit according to any one of claims 1 to 8, characterized in that the coated copolymer is subjected to an ionizing treatment.   10. Filtration unit according to any one of claims 1 to 9, characterized in that the average pore diameter of the leukocyte removal medium is between 3 and 15 pm.   11. Filtration unit according to any one of claims 1 to 10, characterized in that the leukocyte removal medium is formed of at least one fibrous layer. 20   12. Filtration unit according to claim 11, characterized in that said fibrous layer is a nonwoven.   13. Filter unit according to claim 11 or 12, characterized in that the diameter of the fibers is between 0.3 and 7 μm, with an average of between 1 and 3 μm.   14. Filtration unit according to any one of claims 1 to 13, characterized in that the leukocyte removal medium is formed based on polybutylene terephthalate.   15. Filtration unit according to any one of claims 1 to 14, characterized in that the porous element further comprises a pre-filter and / or a post-filter which are made in the form of at least one layer of nonwoven and which are arranged respectively upstream side and downstream side of leukocyte removal medium.   16. Filtration unit according to claim 15, characterized in that said pre-filter and / or post-filter are coated with the same coating copolymer as the leukocyte removal medium.   17. Filtration unit according to claim 15 or 16, characterized in that said pre-filter and / or post-filter are formed based on polybutylene terephthalate. i0   18. Bag system (6) for the leukocyte depletion of a biological fluid such as blood or a blood component, characterized in that it comprises: - a connector (11) intended to be connected to a collection bag containing the biological fluid, said connector being connected via tubing (10) to an inlet (3) of a filtration unit (1) according to any one of claims 1 to 17; and - a collection bag (7) of the filtrate, said pocket being connected, via a pipe (8) and at an inlet (9), to an outlet (4) of the filtration unit (1). 20   19. A bag system for the leukocyte deleuction of a biological fluid such as blood or a blood component, characterized in that it comprises: a bag for collecting the biological fluid, said bag being connected, via tubing and at an outlet port at an inlet of a filter unit according to any one of claims 1 to 17; and - a filtrate collection bag, said bag being connected, via a tubing and at an inlet port, to an outlet port of said filtration unit. 30