JP4201313B2 - Toxic substance binding albumin removal system - Google Patents

Description

[0001]
[Industrial application fields]
The present invention provides a harmful substance-bound albumin removal system for removing harmful substances in blood continuously and efficiently from the blood of patients with liver diseases such as chronic or acute hepatitis and liver failure by extracorporeal circulation, and harmful substances The present invention relates to a method for removing harmful substance-bound albumin by a bound albumin removal system.
[0002]
[Prior art]
For the purpose of treating liver diseases such as chronic or acute hepatitis and liver failure, removal of medium and low molecular weight harmful substances in blood, correction of water and electrolyte balance, removal of mediators such as cytokines, harmful effects such as bilirubin bound to albumin Removal of substance-bound albumin or protein synthesis function assistance such as supplementation of blood coagulation factors and albumin is performed.
In other words, extracorporeal circulation treatment methods such as plasma exchange therapy, continuous hemofiltration therapy (CHF), continuous hemofiltration dialysis therapy (CHDF), or adsorption therapy have been implemented, and various extracorporeal circulation systems have been put to practical use. Yes.
[0003]
Continuous hemofiltration therapy (CHF) and continuous hemofiltration dialysis therapy (CHDF) have excellent ability to remove medium and low molecular weight substances having a molecular weight of 1 to 20,000 daltons or less, and are used for the purpose of removing these substances. Recently, for the purpose of removing mediators such as cytokines, CHF and CHDF using a membrane capable of removing a substance having a molecular weight of about 30,000 daltons are also performed. However, the membranes used in these treatments do not allow albumin to pass through, so CHF or CHDF removes almost no toxic substance-bound albumin.
[0004]
Plasma exchange therapy uses a plasma separation membrane to separate and discard the patient's plasma and then administer fresh plasma to remove cytokines and other mediators, remove harmful substance-bound albumin, and supplement blood coagulation factors and albumin. It is intended to assist liver function such as protein synthesis. Although plasma exchange therapy is excellent at removing harmful substance-bound albumin, it requires a large amount of fresh plasma, and it also replaces a lot of plasma to assist liver function. There is a problem that a large amount of expensive plasma is required. Furthermore, there was a drawback that the removal of substances having a molecular weight of 10,000 or less was insufficient.
[0005]
Furthermore, for the purpose of removing medium and low molecular weight substances and removal of mediators such as cytokines, use of an adsorbent made of, for example, a styrene / divinylbenzene copolymer or petroleum pitch-based activated carbon is also known. However, although the adsorbent is suitable for removing a limited number of substances, it is not sufficient for removing a wide range of medium and low molecular weight substances, and the ability to remove mediators and harmful substance-bound albumin is also insufficient. Furthermore, the balance of water and electrolyte cannot be corrected.
[0006]
Molecular Adsorbents Recirculating System (MARS, Terraklin) has been reported as a technology that focuses on the ability of albumin to adsorb toxic substances (Artificial Organs. 23 (4): 319-330,1999 ). The mechanism of action of MARS is explained as follows. That is, in devices such as a dialyzer (artificial kidney) where blood and dialysate come into contact with each other through a membrane, a large amount of albumin is present on the dialysate side, and from harmful substance-adsorbed albumin in blood that comes in contact with the membrane, Only the released harmful substances are moved by the principle of adsorption equilibrium and concentration gradient, and the membrane is moved to re-adsorb to the albumin on the dialysate side. As a result, the amount of harmful substances in the blood is lowered. This method removes only the amount of harmful substances adsorbed on albumin in the blood that is released by adsorption equilibrium, permeates through the membrane, and adsorbs on albumin in the dialysate. Is not good.
[0007]
JP-A-9-507414 describes the removal of protein-bound and medium molecular weight toxins using a hollow fiber membrane and an adsorbent. That is, by contacting the bodily fluid obtained by plasma filtration (plasma is filtered through a membrane) or blood filtration (medium molecular weight molecules (about 300 to about 10,000 molecular weight)) with an adsorbent outside the hollow fiber. It is intended to adsorb and remove protein-bound and medium molecular weight toxins. The hollow fiber membrane used here is capable of filtering plasma or medium molecular weight molecules (about 300 to about 10,000 molecular weight), and it is said that both plasma separation membranes and dialysis membranes can be used. Examples include Plasmaflo AP-05H (cut-off molecular weight of about 1,000,000) and copper ammonium cellulose dialysis membrane.
However, JP 9-507414 attempts to bind a toxin bound to a protein to the adsorbent by a competitive reaction between the protein and the adsorbent. Toxins that bind strongly to proteins and are extremely difficult to dissociate do not substantially bind to the adsorbent and are not removed. Therefore, compared with the conventional method in which the separated plasma is perfused into a container filled with an adsorbent after separating the plasma, there is no change in that the plasma is separated and then brought into contact with the adsorbent. Further, since the adsorbent is perfused, the adsorbent may be damaged by the pump.
[0008]
In the present invention, the harmful substance firmly bound to albumin is to be removed together with albumin, and the loss of proteins other than albumin is minimized when removing the harmful substance bound to albumin. It is intended to use a membrane having albumin permeability.
As described above, in order to treat liver diseases such as hepatitis and liver failure, extracorporeal circulation treatment methods such as plasma exchange therapy, CHF, CHDF, and adsorption therapy have been put into practical use. However, none of these methods yet has a therapeutic system that is excellent in removing medium and low molecular weight substances, correcting water and electrolyte balance, removing mediators such as cytokines, and removing harmful substance-bound albumin. It has not been converted.
[0009]
[Problems to be solved by the invention]
For the purpose of treating liver diseases such as chronic or acute hepatitis and liver failure, the present inventors removed medium and low molecular weight substances, corrected water and electrolyte balance, removed mediators such as cytokines, and bilirubin bound to albumin. Therefore, the present invention aims to provide an extracorporeal circulation treatment system that is excellent in removing harmful substance-bound albumin and that does not consume a large amount of expensive plasma.
[0010]
[Means for Solving the Problems]
A harmful substance-bound albumin removal system for extracorporeal circulation treatment for removing harmful substances in blood for the treatment of liver diseases , characterized by comprising the following means.
1) Means for supplying bodily fluid containing harmful substance-bound albumin to the harmful substance-bound albumin remover 2) Albumin sieving coefficient that allows the passage of harmful substance-bound albumin and leaves a protein higher than albumin is 0.1 or more 0 4 ) Means for removing harmful substance-bound albumin from the body fluid by means of a harmful substance-bound albumin remover mainly comprising a membrane having a sieving coefficient of 0.1 or less for fibrinogen 3) Body fluid from which harmful substance-bound albumin has been removed For supplying albumin to the skin
DETAILED DESCRIPTION OF THE INVENTION
[0012]
(Toxic substance-bound albumin)
The medium and low molecular weight harmful substances referred to in the present invention are those having a molecular weight of about 20,000 to 30,000 daltons, which are observed in blood such as acute or chronic hepatitis and liver failure, and can adversely affect the liver. Refers to a compound. Medium and low molecular weight harmful substances include ammonia, uric acid, creatinine, urea, uremic toxins, hydrophobic amino acids, bilirubin, bile acids, paraquat and other agricultural chemicals or herbicides, barbital and non-barbital hypnotics, and coma substances It can be illustrated.
The harmful substance-bound albumin referred to in the present invention refers to albumin bound with the low-molecular weight harmful substance, and examples thereof include hydrophobic amino acid-bound albumin, bilirubin-bound albumin, and paraquat-bound albumin.
[0013]
(Toxic substance binding albumin removal system)
Hazardous substance-bound albumin system is a means for supplying and mixing anticoagulants with body fluids such as blood and plasma containing harmful substance-bound albumin obtained from patients with liver diseases such as chronic or acute hepatitis and liver failure. For supplying body fluid containing toxic substance-bound albumin remover, removing harmful substance-bound albumin and leaving high molecular weight protein, toxic substance-bound albumin removing means, supplying albumin to body fluid from which harmful substance-bound albumin has been removed Means in this order.
[0014]
The means for supplying and mixing the anticoagulant into the body fluid as used in the present invention means that the anticoagulant solution stored in the bag, syringe or the like is supplied at a constant flow rate from the supply circuit to the body fluid circulation circuit using a peristaltic pump or syringe pump. It is a means to supply with. The supply method may be either continuous or intermittent. As a means for supplying body fluid containing harmful substance-bound albumin to the harmful substance-bound albumin remover, body fluid is supplied to the remover at a constant flow rate to perform extracorporeal circulation, and a blood pump represented by a roller pump is preferable. Used. In addition, as a means for removing harmful substance-bound albumin, which removes harmful substance-bound albumin and leaves high molecular weight protein, the substance to be removed has a selective separation property, for example, a built-in adsorbent or separation membrane A remover is used. Furthermore, as a means for supplying albumin to a body fluid from which harmful substance-bound albumin has been removed, an albumin solution having a predetermined concentration stored in a bag or the like is supplied from a supply circuit to a body fluid circulation circuit using a peristaltic pump or syringe pump at a constant flow rate. It is a means to supply with.
Here, a means to mix a certain amount of anticoagulant such as citric acid and / or ethylenediaminetetraacetic acid, heparin, nafamostat mesylate into body fluid containing harmful substance-bound albumin by peristatic pump, syringe pump, etc. It is desirable to have it before the means for supplying to the albumin remover or after the means for supplying to the harmful substance-bound albumin remover and before the harmful substance-bound albumin remover.
The harmful substance-bound albumin removal system in the present invention can be used in a form in which harmful substance-bound albumin is separated from blood by filtration or in a form of filtration dialysis.
[0015]
First, the plasma separation method is described. When whole blood is processed using a membrane that meets the performance of the present invention, a significant portion of high molecular weight proteins such as fibrinogen remain in the blood and are returned to the body. However, the medium and low molecular weight harmful substances such as ammonia and the harmful substances adsorbed on albumin pass through the membrane according to the present invention and are discharged out of the blood. Since the inhibition rate of fibrinogen is often not 100%, high molecular weight proteins are also slightly excreted from the blood. That is, in the plasma separation type system according to the present invention, compared to the blood in the body, the discarded plasma contains a large amount of albumin bound to harmful substances and medium and low molecular weight substances below it, and high concentrations such as fibrinogen. Low molecular weight material. High molecular weight proteins that are slightly lost from the blood can be replenished by injecting blood products such as frozen fresh plasma and albumin. Frozen fresh plasma or the like required in the present invention may be a very small amount, and does not require a large amount of expensive plasma unlike plasma exchange therapy. Furthermore, since there may be harmful substances to be removed in the high molecular weight as well as harmful substance-bound albumin, a treatment system superior to CHF and CHDF can be provided.
Next, the usage pattern of filtration dialysis will be described. Continuous slow filtration dialysis (CHDF) performed slowly over 8 to 24 hours or filtration dialysis (HDF) performed in several hours may be used. As the dialysis solution, a dialysis solution used for normal artificial dialysis can be used. Since medium and low molecular weight substances can be efficiently removed by dialysis, the use form of filtration dialysis is more desirable than the plasma separation method in that medium and low molecular weight substances can be efficiently removed simultaneously with harmful substance-bound albumin.
[0016]
(Toxic substance binding albumin remover)
The means for removing the harmful substance-bound albumin with the harmful substance-bound albumin remover needs to remove the harmful substance-bound albumin and the medium and low molecular weight substance and leave the high molecular weight protein. In addition, it is more desirable to supply water and electrolyte at the same time when removing harmful substance-bound albumin.
As the harmful substance-bound albumin remover, a membrane that allows albumin to pass through, a combination of an adsorbent for harmful substance-bound albumin and an adsorbent for medium-low molecular weight substances, and the like can be used. However, it is preferable to carry out filtration or dialysis with a membrane from the viewpoint that harmful substance-bound albumin and medium and low molecular weight substances can be easily removed with a simple system. Furthermore, the method by dialysis using a hollow fiber membrane is most desirable because water / electrolyte can be easily adjusted and excellent removal ability of medium and low molecular weight substances can be obtained without increasing the amount of protein removal.
The most preferable harmful substance-binding albumin remover is exemplified by a space having at least a body fluid inlet and outlet and a harmful substance-bound albumin outlet and communicating with the body fluid inlet and outlet, and a harmful substance-bound albumin outlet. The communication space is divided by a porous film.
The harmful substance-bound albumin remover is preferably sterilized by radiation sterilization such as γ-rays and electron beams, autoclave sterilization, gas sterilization and the like.
[0017]
(Membrane for harmful substance-bound albumin remover)
As the membrane used for the harmful substance-bound albumin remover, either a flat membrane or a hollow fiber membrane can be used. However, a hollow fiber membrane is preferable because a larger surface area can be secured in a limited volume.
The fractionation ability of the membrane requires that the sieving coefficient of albumin is 0.05 or more from the point that harmful substance-bound albumin can be removed. Further, if the sieving coefficient of albumin is too high, protein loss increases, and it becomes necessary to supply a larger amount of albumin preparation, which is not preferable. The preferred albumin sieving coefficient is 0.8 or less, more preferably 0.6 or less.
Most preferably, a certain amount of harmful substance-bound albumin can be stably removed during extracorporeal circulation while maintaining the ability to remove medium and low molecular weight substances, the ability to adjust water and electrolytes, and keeping the loss of total protein low. From the point that can be done, the albumin sieving coefficient is 0.1 or more and 0.4 or less.
[0018]
It is therapeutically undesirable to filter out proteins of higher molecular weight than albumin, such as fibrinogen. A preferable membrane needs to be 0.6 or less when expressed by a sieving coefficient of fibrinogen, and the smaller the better. Most preferably, it is 0.1 or less. The fibrinogen listed here (molecular weight 340 kDa) is considered to be an indicator of membrane performance in a group of proteins thought to have been lost more than necessary in the conventional mass plasma exchange method. In addition to fibrinogen, von Willebrand factor (1,000 kDa), factor VIII (1,200 kDa), high molecular weight kininogen (110 kDa), factor XI (160 kDa), factor XIII fibrin stabilizing factor (320 kDa) should also be used as indicators. Can do. However, the number of blocking rates varies slightly depending on which index is used.
Examples of the membrane material include polysulfone, ethylene vinyl alcohol, cellulose diacetate, cellulose triacetate, and polyacrylonitrile. However, any material can be used as long as it has a preferable albumin sieving coefficient and is stable against sterilization. However, it is not limited to these.
[0019]
(Albumin supply method)
As the harmful substance-bound albumin is removed, it is necessary to replenish albumin. As albumin to be supplemented, preparation albumin is preferable because it is easily available. Albumin can be obtained in a solution state or a lyophilized state, but when it is replenished into the body, it is in a solution state. In consideration of immunogenicity, human albumin is desirable. Formulated albumin is obtained at the same time as the separation of components other than albumin from plasma, so it is considerably less expensive than frozen fresh plasma. Furthermore, since a method for mass production of human albumin by genetic engineering has been developed and put into practical use in recent years, albumin may become cheaper when this preparation is commercialized.
Of course, albumin can be extracted from human blood at the treatment site and used.
As for the supply of albumin, it is only necessary to supply an amount necessary for treatment with respect to the amount of the harmful substance-bound albumin removed, and it may be supplied continuously or intermittently. Examples of the supply method include a method of continuously or intermittently adding / mixing an albumin solution from a replenishment circuit to body fluid that has passed through a harmful substance-bound albumin remover, and removal of harmful substance-bound albumin with a harmful substance-bound albumin remover. In this case, there is a method of dialysis using a solution in which albumin is dissolved in a physiological electrolyte solution such as a dialysis solution. Alternatively, it may be supplemented separately into the body continuously or intermittently.
[0020]
(Function)
Mediators such as toxic substance-bound albumin, medium and low molecular weight substances, and cytokines can be easily and efficiently removed from body fluids of liver diseases such as chronic or acute hepatitis and liver failure, and water and electrolyte balance can be corrected. An excellent extracorporeal circulation treatment system that can be provided can be provided.
[0021]
[Example 1]
A cascade flow EC20W (Asahi Medical Co., Ltd.) was used as the harmful substance-binding albumin remover 6 to construct a CHDF blood circulation system as shown in FIG. This remover incorporates a hollow fiber membrane made of an ethylene / vinyl alcohol copolymer having an inner diameter of 175 μm and a film thickness of 40 μm, and has an effective membrane area of 2.0 m ² .
[0022]
As model blood containing harmful substance-bound albumin, bovine blood containing bilirubin-bound albumin was prepared. That is, bilirubin was dissolved in a bovine albumin solution at a high pH in advance, and then a neutral pH solution was prepared. Heparin (Novo heparin, 1 ml of this heparin contains 1000 units of heparin. Manufactured by Novo Nordisk A / S) ) Was added to bovine whole blood containing 5 units / ml, and bovine whole blood having a total bilirubin concentration of 15.7 mg / dL was used as model blood.
4 L of the model blood was pooled in the blood reservoir 1 and circulated by the blood pump 2 at a flow rate of 100 ml / min for 12 hours. At the same time, a physiological saline solution of heparin (same as above) was continuously supplied at a rate of 500 units / hour from the remover inlet side circuit 7 using the syringe pump 3. The dialysate 9 was Subrad-B (manufactured by Fuso Pharmaceutical Co., Ltd.), the dialysate supply pump 4 was set at a flow rate of 500 ml / hour, and the dialysate drainage pump 5 was set at a flow rate of 800 ml / hour. That is, the amount of gradual water from the remover was set to 300 ml / hour. The albumin was supplied by dissolving 20% human albumin preparation (manufactured by Japan Red Cross) in Subrad-B to a concentration of 1.38 mg / dL as albumin replacement solution 10 and supplying a flow rate of 300 ml / Supplied by time.
The total bilirubin concentration and albumin concentration, which are harmful substances, were measured on plasma obtained by collecting whole blood from the blood reservoir 1 over time and centrifuging it. The total bilirubin concentration was measured by the alkaline azobilirubin method using bilirubin BII test Wako (manufactured by Wako Pure Chemical Industries), and the albumin concentration was measured by the BCG method using albumin B test Wako (manufactured by Wako Pure Chemical Industries, Ltd.). Sampling time was set to before the start of circulation (0 hour), 6 hours after circulation, and 12 hours.
[0023]
Before the start of circulation (0 hour), the total bilirubin concentration in the blood was 15.7 mg / dL and the albumin concentration was 4.6 mg / dL. Although the total bilirubin concentration in the blood at 6 hours of circulation decreased to 9.99 mg / dL, the albumin concentration was 4.5 mg / dL, and the original concentration was maintained. Furthermore, at the 12th hour of circulation, the total bilirubin concentration in the blood decreased to 8.96 mg / dL and was almost half that before the start, but the albumin concentration was 4.6 mg / dL, and the original concentration was maintained. It was.
[0024]
【The invention's effect】
The extracorporeal circulation system of the present invention is excellent in removal of medium and low molecular weight substances, correction of water and electrolyte balance, removal of mediators such as cytokines, removal of harmful substance-bound albumin such as bilirubin bound to albumin, and expensive plasma. Is an extracorporeal circulatory treatment system that does not consume a large amount of water, and can be effectively used for treatment of liver diseases such as chronic or acute hepatitis and liver failure.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a first embodiment.
[Explanation of symbols]
1. Blood reservoir 2. 2. Blood pump 3. Syringe pump 4. Dialysate supply pump Dialysate drainage pump 6. 6. Toxic substance binding albumin remover Remover input side circuit 8. 8. Remover output side circuit Dialysate 10. Albumin solution

Claims (4)

A harmful substance-bound albumin removal system for extracorporeal circulation treatment for removing harmful substances in blood for the treatment of liver diseases, comprising the following means.
1) Means for supplying bodily fluid containing harmful substance-bound albumin to the harmful substance-bound albumin remover 2) Albumin sieving coefficient that allows the passage of harmful substance-bound albumin and leaves a protein higher than albumin is 0.1 or more 0 4) Means for removing harmful substance-bound albumin from the body fluid by means of a harmful substance-bound albumin remover mainly comprising a membrane having a sieving coefficient of 0.1 or less for fibrinogen 3) Body fluid from which harmful substance-bound albumin has been removed For supplying albumin to food   The system for removing harmful substance-bound albumin for removing harmful substances in blood for treating liver diseases according to claim 1, further comprising means for supplying water and electrolyte to the harmful substance-bound albumin remover. .   3. A harmful substance for removing harmful substances in blood for the treatment of liver disease according to claim 1 or 2, wherein the harmful substance-bound albumin remover simultaneously removes medium and low molecular weight substances together with harmful substance-bound albumin. Substance-bound albumin removal system.   The harmful substance-bound albumin remover has at least a body fluid inlet and outlet and a harmful substance-bound albumin outlet, and the body fluid inlet and outlet and the harmful substance-bound albumin outlet are separated by a porous membrane. A harmful substance-bound albumin removal system for removing harmful substances in blood for the treatment of liver diseases according to any one of claims 1 to 3.

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