RU2374843C1 - Method of anticalcium treatment of biological prostheses of heart valves - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to field of medicine, namely to cardio-vascular surgery, and can be used in manufacturing bioprostheses intended for heart valve prosthetics. Essence of invention lies in the following: after conservation with epoxy compound, such as 2-5% solution of ethylene glycol diglycidyl ether, during 2-21 days biomaterial is washed in 0.9% sodium chloride solution and treated with 0.05-1.0% solution of 3-amino-1-oxypropylidene-1,1-diphosphonic acid (DP), prepared on phosphate buffer pH 4.0-8.0. Treatment is carried out at temperature 5-40°C. After treatment biomaterial is washed from non-bound DP and placed into sterilising solution for storage. Application of DP as anticalcium agent gives epoxy-treated biomaterial additional resistance to calcification.

EFFECT: invention ensures increase of treatment efficiency due to reduction of calcium-binding activity of biological prostheses for cardio-vascular surgery.

2 cl, 1 tbl, 1 ex

Description

The invention relates to medicine, namely to cardiovascular surgery, and can be used in the manufacture of bioprostheses intended for prosthetics of heart valves.

A known method of processing vascular xenoprostheses and heart valves, contributing to the reduction of calcium-binding activity of the biomaterial. After washing, the biomaterial is fixed with a 0.625% solution of glutaraldehyde (HA) for 14 days, and then it is processed for 24 hours with carbodiimide in the presence of iminobis- (2-ethylidene) -1,1-diphosphonic acid (USSR copyright certificate No. 1823177, class A61F 2/02, claimed 06/22/1988, published in 1997, BI No. 29).

There is a method of anti-calcium treatment of biomaterial, which consists in treating the biomaterial with a GA solution for 21 days, then with a solution of unstabilized serum albumin with a solution of xidiphone, after which the tissue is washed and immersed in a GA solution, where it is stored until implantation (USSR copyright certificate No. 1568961, class. A01N 1/02, declared December 28, 1987, published in 1990, BI No. 21).

A known method of anticalcium processing of biomaterial used in the manufacture of bioprostheses for cardiovascular surgery. The method consists in pre-treatment of biomaterial stabilized with a solution of HA. After stabilization, the biomaterial is treated with a solution of diphosphonate-containing oligo- and polymers (polyethyleneimine or polyethylene polyamine modified with vinylidene diphosphonic acid), then kefzol solutions prepared on phosphate buffer, serum albumin and heparin. After that, the tissue is washed and stored in the HA until implantation (USSR copyright certificate No. 1785625, class A01N 1/02, filed April 9, 1990, published in 1993, BI No. 1).

The disadvantages of the above methods is the basic preservation of HA, initially increasing the calcium-binding activity of the biomaterial. The modification is carried out in several stages, as a result of which the biomaterial for a long time (≈18-24 h) remains without a preservative solution, and after each stage the biomaterial is washed in distilled water or physiological saline, which can lead to tissue swelling.

As a prototype, a method of anti-calcium treatment of bioprostheses was adopted, consisting in the phased processing of native biomaterial in the preservation process (US patent No. 4553974, NKI 8 / 94.11, filed August 14, 1984, published November 11, 1985). At the first stage, the purified native biomaterial is washed in a 0.9% NaCl solution and placed in a mixture of a 1% solution of sodium dodecyl sulfate and a 1% solution of Triton X-100 for 3 hours, processing is carried out at room temperature (23 -25 ° C). After that, the biomaterial is washed in a 0.9% solution of NaCl or deionized water or in 0.05 M acetate buffer at pH 5.5 and placed for 3.5 hours in a preservation solution of HA. The next step is the processing of the biomaterial with a 1.6% solution of 3-amino-1-hydroxypropylidene-1,1-diphosphonic acid (DF) prepared on 0.05 M acetate buffer, and the biomaterial is preliminarily washed from unbound HA. In this solution, the biomaterial is incubated for 2-3 hours, after which the biomaterial is placed for 12 hours in a GA preservation solution in 0.05 M acetate buffer, and the treatment is repeated 4 times. After the final treatment of DF, the biomaterial is placed for 30 min in a 0.5% solution of Na borohydride at 25 ° C to stabilize the connection of DF with collagen. In conclusion, the biomaterial is washed from unbound Na borohydride and placed in a solution of 0.5% HA or formaldehyde until implantation.

As with the analogues described above, the basic preservation of the biomaterial is carried out by GA, which initially increases the calcium-binding activity of the biomaterial.

The main disadvantage of the proposed processing method is that the modification of the biomaterial begins before the completion of the full cross-linking of collagen. Reactive collagen groups form bonds with an anticalcium agent, which entails the formation of fewer cross-links in collagen and, as a result, leads to disruption of the biomaterial crosslinking process. The disadvantages of this method can also include technological difficulties, consisting in the multi-stage processing of biomaterial using additional reagents such as a solution of sodium dodecyl sulfate, Triton X-10 and Na borohydride. The modification process takes more than 2 days, which is not technologically advanced.

The technical result of the invention is to increase the processing efficiency by reducing the calcium-binding activity of biological prostheses for cardiovascular surgery when treated with epoxy compounds, for example, ethylene glycol diglycidyl ether (DEE).

A method is proposed for anticalcium treatment of biological prostheses of heart valves, including the washing, stabilization and modification of the material with subsequent storage in a sterilizing solution.

The difference of the proposed method is that after washing the native tissue, it is stabilized with a 2-5% solution of epoxy compounds until complete stabilization, and the modification is carried out after completion of the stabilization process by placing after washing in 0.05-1.0% a solution of a diphosphonate containing an amino group in the structure for 3-5 hours at a temperature of 18-25 ° C, followed by washing and storage in a sterilizing solution. The use of a modifying solution with a concentration in the range of 0.05-1.0% is due to the fact that when using a concentration below 0.05%, an anti-calcium effect is not achieved, and the use of a solution with a concentration above 1.0% is not technologically advanced. Another advantage of this method is the ease of processing, which consists in the absence of additional reagents. When processing the proposed method, the biomaterial is without a preservative solution for no more than 6 hours, which minimizes the risk of destructive changes in the biomaterial such as edema, loosening and fragmentation of collagen fibers.

The following is an example implementation of the proposed method.

The native tissue prepared by existing selection procedures is washed with a 0.9% NaCl solution, then placed in a 2-5% DEE solution for stabilization. After 2-21 days of preservation, the biomaterial is washed in a 0.9% NaCl solution for 1 h with a three-fold change of solution and placed for modification, for example, in a solution of 3-amino-1-hydroxypropylidene-1,1-diphosphonic acid (DF) prepared on phosphate buffer at pH 4.0-8.0 for 4 hours at room temperature. After this time, the bioprosthesis is washed from unbound DF in a 0.9% NaCl solution for 40 minutes with a two-time change of the solution and placed in a sterilizing solution for storage, for example, in 0.01-2.0% 2-bromo-2- nitropropane-1,3 diol.

Evaluation of the effectiveness of anti-calcium treatment was carried out using a standard model of accelerated calcification by subcutaneous implantation of the test material to Vistar rats followed by a quantitative analysis of the calcium content in the tissue. We examined the valves of the aortic complex of pigs and cattle pericardium, processed according to the proposed method. The implanted biomaterial was extracted on days 60 and 90.

The results of the study demonstrated the anti-calcium effectiveness of the proposed method. Throughout the study, the level of calcium in the biomaterial processed according to the proposed method remained at the metabolic level (table).

Table The amount of calcium, mg / g of tissue 60 days 90 days Swine Aortic Valve Valves Canned by DEE 6.22 ± 0.37 7.35 ± 0.12 Flaps of the aortic valve of a pig, canned DEE, processed by the proposed method 0.65 ± 0.06 0.88 ± 0.06 Pericardial cattle, canned DEE 4.88 ± 0.27 6.11 ± 0.21 Pericardial cattle, canned DEE, processed by the proposed method 0.75 ± 0.2 0.68 ± 0.08

When processing the proposed method, the amount of 3-amino-1-hydroxypropylidene-1,1-diphosphonic acid immobilized on the biomaterial was 2.8 μg / mg of tissue. This amount of DF is sufficient to reduce the calcium-binding activity of the epoxy-treated biomaterial by 84-89%.

Claims (2)

1. The method of anticalcium treatment of biological prostheses of heart valves, including the washing, stabilization and modification of biomaterial followed by storage in a sterilizing solution, characterized in that after washing the native tissue, stabilize it with a 2-5% solution of epoxy compounds until complete stabilization, and modification is carried out after completion of the stabilization process by placing after washing in a 0.05-1.0% solution of diphosphonate containing an amino group in the structure for 3-5 hours at a temperature of 18-25 ° C, followed by by washing and storing in a sterilizing solution. 2. The method according to claim 1, characterized in that the washing is carried out with a 0.9% solution of NaCl with its repeated change during each washing process.