JPS6362220B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an adsorbent capable of removing low-density lipoproteins containing a large amount of cholesterol from the blood of hypercholesterolemic patients. Hypercholesterolemia, especially familial hypercholesterolemia, is caused by a genetic defect in low-density lipoprotein receptors in cell membranes, resulting in high blood cholesterol levels, deposition of cholesterol on blood vessel walls, which causes arteriosclerosis, and even myocardial It is a disease with a high mortality rate due to infarction and angina pectoris. Therefore, it is necessary to remove low-density lipoproteins that contain large amounts of cholesterol from the blood of these patients.
Conventionally, methods such as plasma exchange have been implemented, but there are problems in that plasma, which must be replenished daily, is expensive and in short supply. Adsorption methods have the advantage of not requiring fluid replacement if they can selectively remove cholesterol or low-density lipoproteins, but such adsorbents include agarose with immobilized parin (S. Moorjani et al.
Clin.Chim.Acta77 (1977) 21-30.) has been used and has only been reported to be effective. However, the carrier agarose is mechanically weak,
Another problem was that blood coagulation factors were also adsorbed at the same time. Further, when activated carbon, organic porous resin, or ion exchange resin, which have been conventionally used to adsorb and remove waste products and toxic substances in blood, are used, low-density lipoproteins are hardly adsorbed. In view of these circumstances, the present inventors have conducted extensive research and have found that porous glass with a specific average pore diameter selectively reduces low-density lipoproteins (and therefore cholesterol) in plasma. This led to the completion of the present invention. That is, the present invention is a low-density lipoprotein adsorbent characterized by being made of porous glass having an average pore diameter within the range of 700 to 2000 Å (but not having sulfonic acid groups on the surface). The reason why the adsorbent of the present invention selectively adsorbs low-density lipoproteins is not clear, but it is presumed that the silanol groups present on the surface of the porous glass have some kind of interaction with the protein. Since low-density lipoprotein is a seeking protein with a molecular weight of several million, the average pore diameter of porous glass is
It is necessary that the thickness is 700 Å or more, and more preferably 900 Å or more. Low-density lipoproteins are difficult to adsorb to pores smaller than 700 Å, and γ-
Other proteins such as globulin are also adsorbed, which is not preferable. If the average pore diameter exceeds 2000 Å, the physical strength decreases and fine pieces are likely to be formed, which is not preferable. More preferably, the average pore diameter is 1600 Å or less. In order to selectively adsorb proteins, it is preferable that the pore size distribution of the porous glass is narrow, and when the average pore diameter is D, the pore diameter is within the range of 0.8D to 1.2D. Volume ratio is 80% of total pore volume
% or more. In addition, the pore volume of porous glass is 0.3cc/g ~
It is preferably within the range of 2.0cc/g. 0.3
If it is less than cc/g, the protein adsorption capacity will be low and it will not be suitable for the purpose of the invention. If it exceeds 2.0 cc/g, the skeleton becomes weak and minute fragments are likely to occur. Since the porous glass used in the present invention is brought into contact with body fluids such as blood or plasma, the diameter of the particles is preferably within the range of 0.1 mm to 5 mm, and more preferably within the range of 0.2 mm to 2 mm. . If the particle size is smaller than 0.1 mm, the pressure drop in the adsorbent layer will increase, causing problems such as hemolysis. If the particle size is larger than 5 mm, the voids between the particles will become large.
This is not preferable because the adsorption performance decreases. Further, since the present adsorbent is brought into contact with blood, it is preferable to have a spherical external shape in order to increase the safety against blood cell components and to prevent blood clots and the like. Porous glass may be used as it is, but its surface may be coated with a hydrophilic polymer to improve its affinity with blood. A preferred method for coating with the hydrophilic polymer is a method in which porous glass is immersed in a hydrophilic polymer solution and then the solvent is removed. According to this method, the hydrophilic polymer hardly penetrates into the pores of the porous glass, so the silanol groups present on the inner surface of the pores are not covered with the hydrophilic polymer and the functionality is reduced. rare. Further, as the hydrophilic polymer, a polymer containing a crosslinking component is preferable, and it is more preferable to crosslink it by heating after the coating treatment. Examples of hydrophilic polymers include acrylic ester polymers, methacrylic ester polymers, acrylamide polymers, polyvinyl alcohol polymers,
Examples include polyvinylpyrrolidone, cellulose nitrate, and gelatin. The low-density lipoprotein adsorbent made of porous glass of the present invention is usually used by filling a column. The column has a main body having an inlet and an outlet shaped to be easily connected to a blood circuit on both sides of an adsorbent layer, and a space between the adsorbent layer and the inlet and outlet, through which blood, etc. passes, but the adsorbent does not pass through. A column having a filter having a mesh size of 80 to 180 meshes is preferable, but columns having other shapes having substantially the same function can be used for this purpose. As the material of the column, glass, polyethylene, polypropylene, polycarbonate, polystyrene, polymethyl methacrylate, etc. can be used, but polypropylene, polycarbonate, etc., which can be sterilized by autoclaving, are preferable. The filter may be anything as long as it is physiologically inert and has high strength, but one made of polyester is particularly preferred. The adsorbent of the present invention is preferably packed into a column together with water or physiological saline, and the filled column is usually sterilized before use, but autoclave sterilization and gamma ray sterilization are preferred. The adsorbent of the present invention can be brought into contact with whole blood as it is, but it may also be brought into contact with only plasma that has been separated in advance using a plasma separator or the like. The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples. Examples 1 to 2, Comparative Example 1 Porous glass with an average pore diameter of 720 Å (D = 720
Å, 99% of the pore volume with a pore diameter of 0.8D to 1.2D, pore volume of 0.95cc/g, particle size of 0.2mm to 0.5mm)
was used as Example 1, and porous glass with an average pore diameter of 1060 Å (D = 1060 Å, pore diameter 0.8D ~
Percentage of pore volume in 1.2D 81%, pore volume
0.92 cc/g, particle size 0.2 mm to 0.5 mm) was used as Example 2. In addition, porous glass with an average pore diameter of 560 Å (D = 560 Å, 91% of the pore volume with a pore diameter of 0.8 D to 1.2 D, pore volume 0.76 cc/g,
A particle size of 0.2 mm to 0.5 mm) was used as Comparative Example 1.
2 g of each of the above porous glasses was packed into a polypropylene column (with 180 mesh polyester filters at both ends), and 20 ml of rabbit plasma was circulated at 37° C. for 3 hours. The total protein concentration before and after circulation was determined by the Biuret method, and the cholesterol concentration was determined by the ortho-phthalaldehyde method, and the removal rate was calculated (removal rate (%) = (1 - concentration after circulation/concentration before circulation) x 100). Cholesterol rarely exists alone in the blood; most of it exists bound to low-density lipoproteins. Therefore, since the removal rate of cholesterol and the removal rate of low-density lipoprotein are considered to be substantially equal, the concentration of cholesterol was analyzed. As shown in Table 1, the decrease in total protein by the adsorbent of Examples is small, and around 30 to 40% of cholesterol is removed, but in Comparative Example 1, where the average pore diameter is smaller than 700 Å, was large, but the total protein removal rate was also large and the selectivity was low.

[Table] Example 3, Comparative Examples 2 to 5 The same porous glass used in Example 2 was used as Example 3, and XAD-4 (D =280Å,
Percentage of pore volume with pore diameter between 0.8D and 1.2D16
%, pore volume 0.65 cc/g, average particle size 0.6 mm) was used as Comparative Example 2, and ,
Comparative Example 3 was XAD-8 (D = 360 Å, pore diameter 0.8 D).
~1.2% of pore volume at D, pore volume 0.57
cc/g, average particle size 0.8 mm) was used as Comparative Example 4. In addition, an ion exchange resin Dowex 1×4 (CI type) manufactured by Dow Chemical Company was used as Comparative Example 5. 1 g of each of the above porous materials was packed into a polypropylene column, and 10 ml of human plasma was circulated at 37°C for 90 minutes.
Total protein removal rate and cholesterol removal rate (ie, low-density lipoprotein removal rate) were measured using the methods described above. As shown in Table 2, cholesterol is hardly removed when organic porous resins or ion exchange resins are used.

【table】

Claims (1)

[Claims] 1. A low-density lipoprotein adsorbent characterized by being made of porous glass having an average pore diameter within the range of 700 Å to 2000 Å (but not having sulfonic acid groups on the surface). 2. The low-density lipoprotein adsorbent according to claim 1, wherein the average pore diameter is within the range of 900 Å to 1600 Å. 3 The pore volume of the porous glass is 0.3cc/g or more,
The low-density lipoprotein adsorbent according to any one of claims 1 and 2, which has a content of 2.0 cc/g or less. 4. The low-density lipoprotein adsorbent according to any one of claims 1 to 3, wherein the particle diameter of the porous glass is within the range of 0.1 mm to 5 mm. 5 The porous glass is a porous glass in which the volume of pores with a pore diameter within the range of 0.8D to 1.2D accounts for 80% or more of the total pore volume, where the average pore diameter is D. A low-density lipoprotein adsorbent according to any one of claims 1 to 4.