WO2006012885A1 - Filter system for treating liquids containing particles using membrane isolation and adsorption - Google Patents

Abstract

The invention relates to a filtration and adsorption system that combines the characteristics of membrane filtration with those of particle-assisted adsorption in a sealed housing.

Description

Filter system for the membrane-separated, adsorptive treatment of particle-containing liquids

description

The invention relates to a filter system for the membrane-separated, adsorptive treatment of particle-containing liquids. The field of application of the invention is medicine, in particular direct blood treatment.

For the purpose of supporting the healing of diseases, medicament-active substances have been administered for millennia. Another possibility of therapeutical influencing is the removal of harmful substances from the blood by extracorporeal blood treatment. The starting point for this development is the classic bloodletting, which for more than two thousand years was a standard therapy for certain diseases. New materials and technologies, as well as the findings of blood group research enabled the introduction of hemodialysis in clinical application more than 50 years ago and led to the blood exchange therapy, which was later replaced by the plasma exchange. Unspecificity, cost and risk of infection limit the use of the plasma exchange.

Hemofiltration, hemodiafiltration, double filtration and plasma adsorption are milestones in the application of extra-corporeal therapeutic methods (or therapeutical apheresis). With plasma adsorption, it was possible for the first time to remove substances from the blood which are larger than albumin. Non-specific or specific factors are used for the binding of high-molecular substances in the flowing blood or plasma.

Electrostatic or hydrophobic interactions between the matrix and blood components routinely remove LDL, beta2-microglobulin, endotoxins, immunoglobulins, and circulating immune complexes from the blood. The specific affinity of protein A for the Fc receptor of IgG allowed the development of immunoadsorbers used for the depletion of IgG for the treatment of eg severe forms of rheumatoid arthritis (Prosorba®). Specific recognition sequences (antibodies, peptides) make it possible to remove clearly defined specificities from blood. They are used, inter alia, for the elimination of LDL (Therasorb®, LDL Lipopak®), Lp (a) (Lp (a) Lipopak®), acetylcholine receptor antibody (MedisorbaMG®), anti-ß1 adrenergic antibodies (Corafin ®) or inflammatory mediators (EP 1163004).

The use of patient-specific, dissociated immune complex constituents as ligands for a patient-specific immunoadsorner (DE 19538641) is a special form on the path of increasingly targeted and personalized therapy.

In all continuous apheresis procedures, blood is continuously withdrawn from a peripheral vein or a central venous catheter by means of a blood pump, usually with a blood flow of 60-120 ml / min in an extracorporeal circulation, and retransfused via another peripheral vein after removal of the pathogen. The provision of this intermittent extracorporeal blood circulation is subject to conditions similar to extracorporeal hemodialysis.

Most apheresis procedures require a primary separation of plasma and blood cells prior to actual plasma treatment. This primary separation can be carried out either by centrifugal plasma separation or by filtration plasma separation. Both methods have advantages and disadvantages that must be taken into consideration. Essentially, the filtration plasma separation is easier to handle and results in a platelet-free plasma. The disadvantage is the formation of a secondary membrane in the plasma filter, which limits the filtration efficiency over time. By contrast, a virtually unlimited amount of plasma can be obtained continuously by means of the centrifugation plasma separation. Disadvantageously, the low platelet contamination of the plasma can affect the secondary separation.

The filtrate flow in the primary separation is usually about 30% of the blood flow (plasma flow about 20-30 ml / min). Depending on the indication, usually one to two times the plasma volume of the patient is treated. In the treatment of one or two patient plasma volumes (assumption of a one-compartment model without re-distribution, synthesis or catabolism), theoretically a maximum can be achieved per treatment Reduction of the pathogen to 37% and 14% of the initial value can be achieved. However, these values are usually not realized in practice.

Non-selective plasmapheresis (plasma exchange)

In the case of unspectacular plasma exchange, the plasma in the extracorporeal circulation is separated from the blood cells by means of a membrane plasma separator or a centrifuge, the entire plasma is discarded and isovolemically substituted by an electrolyte solution plus human albumin or fresh plasma. The substitution solution is combined with the separated blood cells and re-infused into the patient. The advantage of the unselective plasma exchange lies in the simple structure of the extracorporeal circulation, the general applicability of the method for all apheresis zu¬ accessible pathogens, the effectiveness of not exactly known pathogen structure (eg in acetylcholine receptor negative myasthenia gravis) and the relatively low extracorporeal volume. Disadvantages are the immunoglobulin and coagulation factor depletion, the risk of incompatibility of the substituted foreign protein and a hyperoncotic substitution and the potential risk of infection in the transmission of pathogens with the substitution solution.

For the latter reasons, unselective plasma exchange is today only used if no selective method is available (eg in the case of TIT, chylomicronaemia, antibody-negative myasthenia gravis).

Membrane plasma separators consist of hollow fiber modules with synthetic membranes (eg polyethylene or polysulfone). The surface is between 0.2-0.5 m ² , the pore size 0.2-0.5 microns. To monitor the extracorporeal circuit, specially developed devices are used for this purpose; Alternatively, the use of devices for hemoperfusion or hemofiltration is possible.

Selective plasmapheresis

In selective plasmapheresis, the plasma separated by a plasma filter (primary separation) in a secondary circuit is purified either by a further filtration process (secondary separation) or by adsorption (immunological or physical). sikochemically) or by precipitation the pathogen is removed and the purified plasma is returned to the patient. Selective plasmapheresis requires special devices that monitor both the extracorporeal blood circulation and the secondary circulation.

1. Double Filtration (Cascade Filtration, Membrane Differential Filtration)

This method uses after separation of the plasma in a secondary circuit, a second filter smaller pore size (cut-off 25-40 nm). The aim is to recover albumin as quantitatively as possible, while retaining the higher molecular weight pathogenic protein in the secondary filter, which operates in the so-called "dead-end" mode (closure of the distal outlet of the distal outlet of the hollow fibers) spatial molecular conformation), it is only suitable for the removal of high-molecular pathogens such as IgM, LDL, fibrinogen or a-2-macroglobulin, therefore indications are eg hyperviscosity syndrome, M. Wadenström, cryoglobulinemia and hypercholesterolaemia Treatment of microcirculation disorders is referred to as Rheophere se.

Advantages of this method compared to the unselective plasma exchange are that no substitution solution is required and the selective removal of especially the rheologically active proteins is possible without causing disturbances of the hemostasis. Disadvantages are the limited capacity of the secondary filter due to possible blockage of the hollow fibers at very high initial values as well as possible, depending on the method different immunoglobulin losses.

2. Immunoadsorption

By immunoadsorption is meant clinically the binding of immunologically active moieties to eg immobilized amino acids, peptides or proteins. The methods based on adsorption either remove specific protein classes or specifically pathogenic antibodies. In terms of process technology, conversely, LDL binding to anti-apoprotein B antibodies is also referred to as LDL immunoadsorption. 2.1 Elimination of lipoproteins

The Liposorber® system (Kaneka, Osaka, Hospal, Planegg) is based on the adsorption of LDL and Lp (a) from the plasma on dextran sulfate / cellulose (DSC). The mechanism is based on an electrostatic interaction of the negatively charged sulfate groups of the dextran sulfate with the positively charged apo B of the two o. G. Li popols. HDL, immunoglobulins and albumin are adsorbed only to a slight extent.

In HELP® apheresis (heparin-induced extracorporeal LDL precipitation, disposable product, Braun, Melsungen), LDL, Lp (a) and fibrinogen are precipitated from the plasma at an acidic pH of 5.12 by means of heparin in an extracorporeal circulation and filtered off.

2.2 Elimination of immunoglobulins

Immunosorba® system (Fresenius HemoCare, St. Wendel) used as a ligand staphylococcal protein A with Sepharose as a carrier.

Prosorba® system (Fresenius HemoCare, St. Wendel) used as a ligand staphylococcal protein A with a silica matrix as a carrier

Globaffin® (Fresenius HemoCare, St. Wendel) immobilizes the synthetic peptide GAM® as a ligand on Sepharose CL-4B. The binding properties correspond to those of protein A.

Coraffin® (Fresenius HemoCare, St. Wendel) specifically removes autoantibodies to the ß1-adrenergic receptor of the heart muscle. This is an indi¬ cation-specific process.

In the Ig Therasorb® process (Miltenyi Biotec, Teterow), polyclonal anti-human immunoglobulin sheep antibodies are immobilized on Sepharose CL-4B.

The Immusorba® system (ASAHI / Diamed, Cologne) uses non-reusable adsorbers based on tryptophan (TR-350L) or phenylalanine ligands (PH-350L), which are bound to a polyvinylethanol gel matrix. 3. cryofiltration

In cryofiltration (Asahi Medical, Tokyo, Diamed, Cologne), the separated plasma is cooled to 4 ° C. in a membrane differential filtration method to precipitate cryoglobulins and, after separation of the precipitates, with the aid of a cry - ofilters reinfused after reheating to body temperature.

Vollblutapherese

In the case of whole blood apheresis, harmful substances in the extracorporeal circulation are removed more or less selectively from the blood by means of adsorbing substances (activated carbon, exchange resins), which are in granulated form in an adsorber cartridge. It is similar to activated charcoal haemoperfusion, which is used in intensive care in a series of intoxications. The size of the adsorber cartridge must ensure a sufficient exchange surface and contact time of the adsorbent.

Direct adsorption of LDL and Lp (a) from whole blood is possible using the DALI® system (direct adsorption of lipoproteins from Fresenius HemoCare, St. Wendel). The disposable adsorption cartridges consist of negatively charged polyacrylate ligands immobilized on polyacrylamide and electrostatically binding the atherogenic lipoproteins.

Filtration and adsorption processes can be combined in different ways. Matson, et al. (US 6,287,516) describes a hemofiltration system consisting of a blood filter with downstream adsorber. The ultrafiltrate from the filter (exclusion MW # 50,000 daltons) is pumped via a tubing system into an adsorber unit where the sepsis mediators are bound. The ultrafiltrate thus treated can be combined with the primary filtered blood by another pump-tube valve system and reinfused into the patient. However, it has hitherto not been possible to combine the advantages of membranes (emit no particles, pore size freely selectable, inexpensive) with those of adsorption by means of particles (large variations in terms of substance classes, size, surface area, activation and coupling of ligands). The object of the invention is to provide a whole blood treatment unit which is characterized by a simple system structure. This is to blood flow (up to 160 ml / min) and shorter treatment times can be achieved

The object of the invention is to combine in this treatment unit, the advantages of membranes and particles and to achieve the elimination of pumps and additional hose connections.

The object is achieved by a filter system for the simultaneous separation and adsorptive treatment of particle-containing liquids (Figure 1). It consists of a housing in which

Hollow fiber membranes are arranged so that the inlet and outlet openings for the liquids are outside the housing and the

Space between the hollow fiber membranes and the wall of the housing for filling with microparticles which are larger than the pore diameter of the hollow fiber membranes is determined, wherein before the Austrittsöff¬ tion - is a sieve which has a pore diameter of 20-500 microns.

It is essential that the particle-containing liquid to be adsorbed be separated by filters having a pore size smaller than the particle diameter into a particle-free, extra-luminal and particle-containing intra-luminal phase. It is also essential that the housing simultaneously serves for receiving the adsorber material, the adsorber material consisting of particles having a diameter greater than the pore diameter of the membrane.

The object of the invention is achieved in that, in a self-contained housing made of biocompatible material, known plasma filters (membrane filters) are used. Hollow tubes) are arranged with the usual pore diameter of 0.2 to 0.5 microns. The membrane material used may be cellulose derivatives or synthetic materials such as polysulfones or polyamides. At the same time, the housing serves as a receptacle for the functionalized particles. Polysulfone, polyacrylonitrile, polymethyl methacrylate, polyvinyl alcohol, polyamides, polycarbonates and cellulose derivatives can be used as material for the particles. Introduced into the flowing blood, the plasma passes the membrane according to the pressure gradient and the pore size. Outside the membrane, the plasma now flows through the adsorber gel, consisting of unspecific or specifically functionalized micro-particles having a diameter above the pore diameter of the membrane. The plasma, which has been purified so specifically by certain bioactive substances, is combined in the housing with the intra-luminal plasma filter blood stream and reinfused into the patient as purified whole blood. A system of filters prevents micro-particles from entering the bloodstream. The filter system according to the invention is suitable for material separations of all kinds from liquid (extra-luminal) phases, where the particle-containing (intra-luminal) phase is to be further used in a closed system after reintroduction of the liquid phase treated according to the invention.

It is also useful for the treatment of blood in an extracorporeal circulation, i.a.

- to deplete substances causing or maintaining disease states by their presence, and

- For the treatment of diseases that are triggered or maintained by disorders of the innate and / or acquired immune system.

The invention will be explained in more detail by an embodiment. Exemplary embodiment a) Material and methods:

- 31 citrated blood of bovine origin were admixed with 1, 5 μg of recombinant human IL6 and pumped in a closed circuit via the device shown in FIG. 2 (parameter s.u.)

- The experimentally used device for the removal of antigens from whole blood consists of a hollow-fiber plasma separator (A), the lower Gehäus¬ part by an inserted cylinder (B), in which the Adsorbergel surrounds the hollow fibers has been replaced. The blood plasma released by the transmembrane pressure must pass through the adsorber and is thereby freed of the target substances.

The plasma separation module consisted of a 0.4 m ² hollow fiber filter (A).

The adsorber vessel contained 60 ml Sepharose, to which 5 mg IgY (vitellin antibodies from the eggs of chickens inoculated with IL6) were covalently bound per ml Sepharose.

The binding capacity of the adsorber was 72 μg IL6.

- The blood flow rate was set to about 120 ml / min.

- A plasma flow of 20-25 ml / min could be realized.

- After a total plasma flow of 1, 5 I, the adsorption was stopped and the IL6 concentration in the blood determined (human IL6 ELISA, Milenia Biotec).

b) Results:

- The module can be operated easily. The treated amount of plasma was 1, 5 I.

- Hemolysis was not observed.

The initial IL6 concentration of 500 pg / ml was lowered to 200 pg / ml during the 60 min adsorption period. This corresponds to a depletion of 60% in a single pass of the total plasma volume through the adsorber according to the device shown in Fig. 1.

Claims

claims 1. Filter system for the membrane-separated and adsorptive treatment of particle-containing liquids, consisting of - a housing in which Hollow fiber membranes are arranged so that the inlet and outlet openings for the liquids are outside the reaction vessel and the space between the hollow fiber membranes and the Gehäuserück¬ wall for filling with microparticles which are larger than the pore diameter of the hollow fiber membrane, determined In front of the outlet opening there is a sieve which has a pore diameter of 20-500 μm. 2. Filter system according to claim 1, that the particle-containing liquid to be adsorptively treated are separated by filters having a pore size smaller than the particle diameter into a particle-free, extra-luminal and particle-containing intra-luminal phase. 3. Filter system according to claims 1 and 2, characterized in that the phase separation is carried out by suitable hollow-fiber membranes. 4. Filter system according to claims 1 to 3, characterized in that the hollow-fiber membranes are embedded in a housing which consists of one or more compartments. 5. Filter system according to claims 1 to 4, characterized in that the housing also serves to receive the adsorbent material. 6. Filter system according to claims 1 to 5, characterized in that the adsorbent material consists of particles having a diameter greater than the pore diameter of the membrane. 7. Filter system according to claims 1 to 6, characterized in that the Adsorberpartikel nonspecific or specifically functionalized. 8. Filter system according to claims 1 to 7, characterized in that proteins are used for specific functionalization that specifically bind a target substance. 9. Filter system according to claims 1 to 8, characterized in that the extra-luminal phase with the adsorbent material comes into direct contact and the target substances are nonspecifically or specifically bound to the adsorber. 10. Filter system according to claims 1 to 9, characterized in that the depleted of the target substances extra-luminal phase is combined with the intra luminalen phase. 11.Use of the filter system according to claims 1 to 10 for Stoffabtren¬ voltages of all kinds from liquid (extra-luminal) phases where the particle-containing (intra-luminal) phase is to be used in a closed system after re-feeding the liquid phase treated according to the invention , 12. Use of the filter system according to claim 11 for the treatment of blood in ei¬ nem extracorporeal circulation. 13. Use of the filter system according to claim 11 for the depletion of substances that cause or maintain their presence, disease states. 4. Use of the filter system according to claims 11 to 12 for the treatment of diseases that are triggered or maintained by disorders of the innate and / or acquired immune system.