RU2709621C1 - Method for obtaining bioresorbable vascular prosthesis of small diameter - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, particularly to tissue replacement therapy and tissue engineering, as well as cardiovascular surgery. Disclosed is a method of producing a bioresorbable vascular prosthesis of a small diameter, modified by fibrinogen. Method involves preliminary preparation of a soluble rod of the required diameter by melting sugar to a homogeneous mass with addition of 10 wt% glycerol to increase rod elasticity. Rods of the required diameter and length are prepared from the obtained melt. After drying in air rods are lowered into a prepared solution of polycaprolactone in chloroform with concentration of 30 mg/ml for 5 seconds. Then the rod is removed from the polymer and left to air-dry for 5 minutes. Procedure for lowering and drying is repeated 3 to 9 times depending on requirements to thickness of walls of the vascular prosthesis, and air-dried for 1 day. Then the vascular prosthesis together with the rod is lowered into a glass with distilled water in volume of 100 ml for 1 day, at the end of which the rod is dissolved, the vessel is washed 3 times in distilled water and allowed to dry in air. Further, the vessel is lowered into a fibrinogen solution with concentration of 0.1 mg/ml with volume of 25 to 30 ml on 1st day, after which the modified vascular prosthesis is removed and washed once in a phosphate-salt buffer pH 7.4 to remove unbound protein, air-dried and sterilized in an ozone chamber for 90 minutes for subsequent implantation of rat into abdominal aorta.

EFFECT: higher efficiency and reliability of vascular prosthesis structure and modification of its polymer walls, which promotes hemocompatibility of the product, as well as simplification and cheapening of the vascular prosthesis for cardiovascular surgery method.

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Description

The invention relates to medicine, in particular to tissue replacement therapy and tissue engineering, as well as cardiovascular surgery. The invention can be used in the manufacture of biodegradable vascular prostheses designed to restore small blood vessels in various pathologies, including by reducing their conductive ability.

Cardiovascular pathologies occupy a leading position among diseases leading to death and persistent disability of a person. A decrease in the conductive ability of blood vessels can paralyze the work of many organs and systems of the body. Approximately 17 million people die from this disease annually worldwide (McAloon et al., 2016). To restore coronary arteries and peripheral vessels, a large number of transplants are needed. As a rule, transplantation of autologous arteries and veins of a patient is used, which ensures histocompatibility of tissues and gives a good survival result. However, this method of treatment is limited by the lack of autologous transplants, caused either by concomitant diseases of the patient, or by the length of fragments of autologous vessels and, in some cases, their poor quality (Tordoir et al., 2015).

Currently, synthetic vascular prostheses based on such polymeric materials as polyethylene terephthalate (PET, Dacron) and polytetrafluoroethylene (PTFE) are used in clinical practice. Polymeric vascular prostheses perform well in cases of replacement of vessels of large diameters, but with small diameters (less than 4 mm) occlusion and stenosis occur (Agaimy et al., 2016). Patency of such vascular prostheses significantly decreases over time, which necessitates repeated surgical intervention (Klinkert et al., 2014; Kreienberg et al., 2002). Also, for the manufacture of vascular prostheses, copolymers based on lactic and glycolic acids are used (Stitzel et al., 2006). Such vessels have a fairly good tensile strength, smooth muscle cells adhere well to them. However, the elastic modulus of these prostheses is 5 GPa, which significantly exceeds the elasticity of native vessels (Mooney et al., 2006). Of great interest are polyurethanes as materials for the manufacture of vascular prostheses (Tanzi et al., 2000). Vessels based on polyurethanes have optimal tensile strength and high elasticity. These materials are one of the few suitable for the manufacture of small diameter vessels (Grasl et al., 2010). Despite the generally accepted belief that polyurethanes are non-degradable polymer materials, they can undergo oxidative, hydrolytic, or enzymatic degradation (Huang et al., 2011). Due to the unstable behavior of vascular prostheses based on polyurethanes, their use in practice is still limited.

Currently, much attention is paid to poly (ε-caprolactone) (PC). PC slowly degrades in the body by hydrolysis of ester bonds to form ε-hydroxycaproic acid. PC degradation products are completely processed by body cells. The mechanical properties, namely, the value of the elasticity of prostheses based on PC, are close to the elasticity of native vessels (Nair et al., 2011). It has also been demonstrated that PK-based vessels withstand fairly high blood pressure (McClure et al., 2011).

Various methods of manufacturing vessels are offered in the modern literature. For example, a method for producing vessels by cross-linking non-woven polymer matrices is known (Mooney et al., 1996). Rectangles (1.3 × 3.0 cm) of a non-woven mesh of polyglycolide-based fibers are wrapped around a Teflon cylinder (outer diameter = 3.0 mm) to form a tube, and two overlapping ends are manually fastened to form a seam. Teflon cylinders are rotated at 20 rpm using a stirrer (Caframo, Wiarton, Ontario, Canada). Solutions of poly (L, L-lactide) and a copolymer based on lactic and glycolic acids in chloroform at a concentration of 1-15 mass. %, sprayed at a distance of 15 cm on a rotating mesh based on polyglycolide. After spraying, the vessels are lyophilized to remove residual solvent and removed from the Teflon cylinder. Dentures are sterilized under the influence of ethylene oxide for 24 hours, followed by degassing for 24 hours.

One of the disadvantages of this method of obtaining a vascular prosthesis is the presence of a suture in the vessel, as well as the need to remove the prosthesis from the Teflon cylinder, which often leads to damage to the product itself and a violation of the topology of the inner wall of the vessel.

To obtain vessels, a combination of leaching and extrusion methods is used (Widmer et al., 1996). A copolymer based on D, L of lactic and glycolic acids, as well as a homopolymer based on L, L - lactic acid, are dissolved in methylene chloride, and then crystals of sodium chloride are added in various proportions. The resulting dispersion is cast into molds and dried until the solvent is completely removed. The dried composite based on polymer and salt, containing bound salt particles together with a polymer matrix, is crushed into particles with a diameter of not more than 5 mm and placed in a piston extruder. Then, the composite (polymer / salt) heated to a certain temperature is extruded under pressure. Extrusion produces vessels with an inner diameter of 1.6 mm and an outer diameter of 3.2 mm. Vascular prostheses are cooled, then kept in water for 24 hours until the salt is completely dissolved and dried in vacuum.

The disadvantages of this method of producing vessels based on copolymers of lactic and glycolic acids, as well as a homopolymer based on lactic acid, are their rather large thickness, low elasticity and strength, due to the used properties of polymers, which impede normal functioning in physiological conditions.

A known method of forming a vascular prosthesis by electrospinning, which uses a mixture of polymers and proteins, including polycaprolactone (patent RU 2572333 C1, publ. 2016.01.10). Initially, a mixture of a synthetic polymer (polycaprolactone (PCL), polybutylene terephthalate (PBTF), polylactide-co-glycolide, nylon) and protein (gelatin, elastin, fibronectin) in hexafluoroisopropanol 1.0-10 is applied to a metal electrode-collector of a selected diameter by electrospinning, 0% of the required volume of the solution of the composition. Then the obtained prosthesis layer is impregnated with 1.0-5.0% aqueous protein solution at the rate of 1-25 μl / cm ² . Next, the remaining volume of the solution of the composition (using electrospinning) is applied to the formed inner layer of the prosthesis and an external layer of the vessel prosthesis is formed, which comprises 90-99% of the given wall thickness of the vessel prosthesis.

The disadvantage of this method of vessel preparation is the need to remove the formed vessel from the collector electrode, which also often leads to deformation of the product and the inability to control the structure of the inner vessel wall, which is responsible for cell adhesion and thrombosis. Insufficient hemocompatibility of such prostheses will contribute to thrombosis.

A known method for producing vascular prostheses based on PC (Gupta et al., 2012), which is the closest in technical essence to the proposed invention and therefore is selected as a prototype. In this method, polycaprolactone (with a weight average molecular weight of 80,000) is dissolved in chloroform in three different concentrations of 2.5, 5 and 7.5 mass. % The sodium chloride salt is ground in a ball mill (Retsch PM 100, Germany) for 2 hours. Particle size is measured by a particle size analyzer (Brookhaven, USA) after dispersion in acetone. The average particle size was 1.8 μm. Salt in an amount of from 33 to 75 mass. % is added to the polymer solution with constant stirring. A glass rod with a diameter of 5 mm was placed manually in a polymer solution for 5 s, then removed and dried in air. The polymer coated glass rods are left overnight in distilled water with slight stirring (200 rpm) to dissolve the sodium chloride salt. After dissolving the salt, the polymer tubes are removed from the glass rods, dried in air and under vacuum.

The disadvantage of this method is the inefficiency of the vascular prosthesis, which represents a tube with a porous and partially destroyed internal wall made of PC when removed from the rod and the low hemocompatibility of the prosthesis itself, due to the properties of the material to sorb blood proteins with subsequent formation of a blood clot.

These disadvantages are due to the fact that the use of glass rods in the formation of polymer vessels does not allow to control and regulate the structure and topology of the inner wall of the vessel, and, therefore, provide the necessary and sufficient number of cells attached to the surface of the prosthesis. Along with this, the absence of a modification that increases the hemocompatibility of the vascular prosthesis will lead to rapid thrombosis of the implant.

Our invention is devoid of these drawbacks due to the implementation of the production of polymeric vascular prostheses using soluble rods and the modification of the vessel with substances that increase the hemocompatibility of the vascular prosthesis.

The technical result of the invention is to increase the efficiency and reliability of the structure of the vascular prosthesis and the modification of its polymer walls, which contributes to the hemocompatibility of the product, the invention has several advantages, which are mainly due to the fact that:

- the use of a soluble rod, on which the polymer solution is applied, avoids damage to the vascular prosthesis during its removal from the rod;

- obtaining a vascular prosthesis with an inner wall having an adjustable and controlled structure that provides the optimal number of adherent cells;

- an increase in the hemocompatibility of the vascular prosthesis due to its modification with fibrinogen.

The technical result is achieved by the fact that in the known method for producing a polymer prosthesis intended for the restoration of vessels of various diameters, which includes known and common features of the claimed new method, dissolve polycaprolactone in an organic solvent, mix it with salt, immerse the glass rod in the resulting suspension, drying in air, washing in distilled water, removing from a glass rod, drying in air and under vacuum, in the proposed method a polymeric vascular prosthesis is obtained, and a soluble rod of the desired diameter is first obtained by melting sugar to a homogeneous mass with the addition of 10 mass% glycerol to increase the elasticity of the rod, rods of the required diameter and length are prepared from the obtained melt, after drying in air, the rods are lowered into a previously prepared polycaprolactone solution in chloroform with a concentration of 30 mg / ml for 5 seconds, then the rod is removed from the polymer and allowed to air dry for 5 minutes, the procedure is omitted washing and drying is repeated from 3 to 9 times, depending on the wall thickness requirements of the vascular prosthesis, dried in air for 1 day, then the vascular prosthesis together with the stem is lowered into a glass of distilled water with a volume of 100 ml for 1 day, after which the core dissolves, the vessel is washed 3 times in distilled water and allowed to air dry, then immersed in a 0.1 mg / ml fibrinogen solution with a volume of 25 to 30 ml for 1 day, after which the modified vascular prosthesis is removed and it is crushed 1 time in phosphate-buffered saline pH = 7.4 to remove unbound protein, dried in air and sterilized in an ozone chamber for 90 minutes for subsequent implantation in the rat abdominal aorta. At the same time, in the process of creation, the structure of the walls of the polymeric vascular prosthesis is assessed using scanning electron microscopy, the mechanical characteristics of the vessel are assessed using a universal bursting machine, its biocompatibility is assessed using a confocal microscope after plating and culturing smooth muscle rabbit cells on its surface. The claimed method was tested in laboratory conditions on the basis of the Federal State Budgetary Institution of Science of the Institute of Cytology of the Russian Academy of Sciences of St. Petersburg. The results of the studies are illustrated by the following examples.

The most preferred embodiment of the invention is described in Example 1. Within the spirit and scope of the invention, other variants of a method for preparing a polymeric vascular prosthesis are possible, covered by the claims.

Example 1

In the particular case of the invention, a polymeric vascular prosthesis is obtained to repair damaged or lost vessels. Pre-get the rod of the required diameter and length. To do this, sugar is melted to a homogeneous mass with the addition of 10 mass% glycerol to increase the elasticity of the core. From the obtained melt, rods of the required diameter and length are prepared, and then dried in air. To obtain a polymer solution, poly (ε-caprolactone) with a molecular weight of 80 kDa (Sigma, USA) is dissolved in chloroform (Vecton, Russia) to a final concentration of polymer solution of 30 mg / ml. The prepared sugar rod is lowered for 5 seconds into the polymer solution, then removed and left to air dry for 5 minutes. The procedure of lowering and drying is repeated from 3 to 9 times, depending on the requirements for the thickness of the walls of the vascular prosthesis. The vascular prosthesis is dried in air for 1 day, then, together with the stem, it is lowered into a glass of 100 ml of distilled water for 1 day, after which the stem is dissolved, the vessel is washed 3 times in distilled water and allowed to air dry. The thickness of the walls of the vascular prosthesis is measured using a micrometer (MK-50-1, China). The results of measuring the wall thickness of vascular prostheses, depending on the number of layers applied, are presented in Table 1. The structure of the inner and outer layers of the polymeric vascular prosthesis is evaluated using a scanning electron microscope (Jeol JSM-35C, Japan). The results of scanning electron microscopy of a polymeric vascular prosthesis obtained by applying three layers are presented in Fig. 1 (enlarged 2000x). In fig. 1d, the smooth surface of the inner layer of the vascular prosthesis based on polycaprolactone is visible.

Fig. 1 Scanning electron microscopy of vascular prostheses.

a - the appearance of the vascular prosthesis;

b - end and in - lateral section of the vascular prosthesis;

g - structure of the inner wall of the vascular prosthesis.

The mechanical tensile properties of samples of polymeric vascular prostheses based on PC were determined using a universal testing machine (Instron 5943, USA). The test results are presented in table 1.

As follows from the table. 1, a polymeric vascular prosthesis in the form of 3 and 6 layers show similar mechanical properties: strength is about 17 MPa, elongation at break is 600%, and the initial modulus of elasticity is 220 MPa. The scatter of values is within the measurement error. The vascular prosthesis in the form of 9 layers in the initial state has strength values higher by 35%, elastic modulus - by 23% and elongation at break - by 42%.

Polycaprolactone is a hydrophobic polymer, on which blood proteins are well absorbed, which leads to a decrease in the lumen of blood vessels and the formation of blood clots. To increase the hemocompatibility of the polymeric vascular prosthesis, its inner wall was treated with 0.1 ml / ml fibrinogen solution for 1 day. After this time, the vascular prosthesis was washed 1 time in phosphate-buffered saline pH 7.4 to remove unbound protein, then dried in air and sterilized in an ozone chamber for 90 minutes. The finished vascular prosthesis is implanted in the rat abdominal aorta (Fig. 2).

Fig. 2 Implantation of a vascular prosthesis into the abdominal aorta of a rat,

a - formation of an aortic defect;

b - sewing on a vascular prosthesis;

c - a vascular prosthesis sewn to the aorta (the junction is indicated by arrows).

After 1 month, histological studies of biopsy specimens are performed. The results of histological studies are presented in Fig. 3.

Fig. 3 Fragment of the abdominal aorta after implantation of a polymeric vascular prosthesis. Hemotoxylin and eosin stain. 100x magnification.

a - control - aortic lumen outside the anastomosis, intima and media of a typical structure;

b - vascular prosthesis with histiocyte infiltration;

c - anastomosis of the aorta and prosthesis.

The aortic wall outside the anastomosis is endothelized; a typical histological structure of intima and media is observed, with adventitia edema (Fig. 3, a).

A polymeric vascular prosthesis 5 mm long, stitched to the aortic wall, is represented by an amorphous eosinophilic fine-grained pink-colored substrate; from the side of the lumen (in the part adjacent to the aorta) it is covered with endothelium 0.35-0.5 mm from the proximal end of the aorta and 0.15- 0.35 mm from the distal end of the aorta; in the rest, without endothelium, with single microthrombi from erythrocytes, a small number of lymphocytes and neutrophils (Fig. 3, b). On the part of adipose tissue in the scaffold, focal histiocyte infiltration with a diameter of 12 μm to 75 μm, the cytoplasm of which contains a small granular pink scaffold substrate (Fig. 3, c).

Example 2

In this embodiment of the invention, the biocompatibility of the vascular prosthesis is increased by plating and culturing smooth muscle cells. A vascular prosthesis based on polycaprolactone is preliminarily obtained. For this, sugar rods with a diameter of 1 mm are prepared. To obtain a polymer solution, poly (ε-caprolactone) with a molecular weight of 80 kDa (Sigma, USA) is dissolved in chloroform (Vecton, Russia) to a final concentration of 30 mg / ml. The prepared sugar rod is lowered for 5 seconds, then removed from the polymer solution and left to air dry for 5 minutes, the lowering and drying procedure is repeated 3 to 9 times, depending on the requirements for the thickness of the walls of the vascular prosthesis. The vascular prosthesis is dried in air for 1 day, then, together with the rod, it is lowered into a glass of distilled water with a volume of 100 ml for 1 day, after which time the rod is dissolved, the vessel is washed 3 times in distilled water and left to air dry. The vascular prosthesis is treated with 0.1 mg / ml fibrinogen solution for 1 day. After the specified time, the vascular prosthesis is washed 1 time in phosphate-buffered saline pH 7.4 to remove unbound protein, dried in air and sterilized in an ozone chamber for 90 minutes.

Smooth muscle cells are obtained from rat aorta. The cultivation of smooth muscle cells on such a modified vascular prosthesis is as follows. A suspension of the obtained cells in an amount of 200 thousand per 1 cm ² is applied to a modified vascular prosthesis and cultured for 3 days in a mixture of α-DMEM media (Biolot, Russia), with the addition of 10% FBS (Gibco, USA), 5 μg / ml insulin, 5 μg / ml hydrocortisone.

Then, the attachment, spreading and growth of smooth muscle cells on a modified vascular prosthesis is assessed. Cells are fixed and stained with DAPI (Vectashield, USA) to detect nuclei and antibodies to smooth muscle actin (clone 1A4, DAKO, Germany). Stained preparations are analyzed using a confocal microscope (Olympus IX83, Germany). The research results are presented in Fig. 4.

Fig. 4 Confocal microscopy of smooth muscle cells cultured in a modified vascular prosthesis. Scale, 100 μm

a - vascular prosthesis (transmitted light);

b - nuclei (blue, DAPI), smooth muscle actin (green);

in - combined image.

In fig. 4 shows that on the inner wall of the vessel the cells form an interconnected network.

Example 3

In this embodiment of the invention, a vascular prosthesis with an internal impermeable wall and an external porous is obtained. Pre-get the core based on sugar of the required diameter and length. To obtain a polymer solution, poly (ε-caprolactone) with a molecular weight of 80 kDa (Sigma, USA) is dissolved in chloroform (Vecton, Russia) to a final concentration of 30 mg / ml. The prepared sugar rod is lowered for 5 seconds, then removed from the polymer solution and left to air dry for 5 minutes, the lowering and drying procedure is repeated 3 times. A solution is also prepared to obtain a porous layer. Poly (ε-caprolactone) with a molecular weight of 80 kDa (Sigma, USA) is dissolved in chloroform (Vecton, Russia) to a final concentration of 30 mg / ml, sodium chloride salt is added in an amount of 30 wt%. The particle size of the salt varies in the range of 150-200 microns. The mixture is thoroughly mixed. A pre-prepared core with a continuous layer based on poly (ε-caprolactone) is lowered into the mixture for 5 seconds, then removed from the polymer solution and allowed to air dry for 5 minutes, the lowering and drying procedure is repeated 3 times. The vascular prosthesis is dried in air for 1 day, then, together with the rod, it is lowered into a glass of 100 ml of distilled water for 1 day, after which the rod is dissolved, the vessel is washed 3 times in distilled and left to air dry. The structure of the outer layer of the polymeric vascular prosthesis was evaluated using a scanning electron microscope (Jeol JSM-35C, Japan). The results of scanning electron microscopy of a polymeric vascular prosthesis are presented in Fig. 5. In fig. 5a, the porous surface of the outer layer of the vascular prosthesis based on polycaprolactone is visible.

Fig. 5 Scanning electron microscopy of the outer layer of the vascular prosthesis. 2000x magnification.

a - structure of the outer layer of the vascular prosthesis;

a is a lateral section of a vascular prosthesis.

Bibliography

Stepanova A.O., Chernonosova B.C., Popova I.V., Karpenko A.A., Pokushalov E.A., Karaskov A.M., Laktionov P.P., Vlasov V.V. A method of manufacturing prosthetic vessels of small diameter vessels with low porosity, RF Patent 2572333, patent publication: 01/10/2016

Agaimy A., Ben-Izhak O., Lorey T., Scharpf M., Rubin B.P. 2016. Angiosarcoma arising in association with vascular Dacron grafts and orthopedic joint prostheses: clinicopathologic, immunohistochemical, and molecular study. Ann. Diagn. Pathol. 21: 21-28.

Grasl S., Bergmeister H., Stoiber M., Schima H., Weigel G. 2010. Electrospun polyurethane vascular grafts: In vitro mechanical behavior and endothelial adhesion molecule expression. J. Biomed. Mater. Res. A. 93 (2): 716-723.

Gupta B., Patra S. Ray A. 2012. Preparation of porous polycaprolactone tubular matrix by salt leaching process. J. of Appl. Polymer Sc. 126 (5): 1505-1510.

Huang C., Chen R., Ke Q., Morsi Y., Zhang K., Mo X. 2011. Electrospun collagen-chitosan-TPU nanofibrous scaffolds for tissue engineered tubular grafts. Colloids Surf. In Biointerfaces. 82 (2): 307-315.

Klinkert P., Post P.N., Breslau P.J., van Bockel J.H. 2004. Saphenous vein versus PTFE for above-knee femoropopliteal bypass: a review of the literature. Eur. J. Vase. Endovasc. Surg. 27: 357-362.

Kreienberg P.V., Darling R.C., Chang B.B., Champagne B.J., Paty P.S., Roddy S.P., Lloyd W.E., Ozsvath K.J., Shah D.M. 2002. Early results of a prospective randomized trial of spliced vein versus polytetrafluoroethylene graft with a distal vein cuff for limb-threatening ischemia. J. Vasc. Surg. 35: 299-305.

McAloon C.J., Boylan L.M., Hamborg T., Stallard N., Osman F., Lim P.V., Hayat S.A. 2016. The changing face of cardiovascular disease 2000-2012: An analysis of the world health organization global health estimates data. Int. J. Cardiol. 224: 256-264.

McClure M.J., Sell S.A., Ayres C.E., Simpson D.G., Bowlin G.L. 2009. Electrospinning-aligned and random polydioxanone-polycaprolactone-silk fibroin-blended scaffolds: geometry for a vascular matrix. Biomed. Mater. 4 (5): 055010.

Mooney D.J., Mazzoni C. L., Breuer C., McNamara K., Hern D., Vacanti J.P., Langer R. 1996. Stabilized polyglycolic acid fiber-based tubes for tissue engineering. Biomaterials. 17 (2): 115-124.

Mooney D.J., Organ G., Vacanti J.P., Longer R. 1994. Design and fabrication of biodegradable polymer devices to engineer tubular tissues. Cell Transplant. 3 (2): 203-210.

Nair L.S., Laurencin C.T. 2007. Biodegradable polymers as biomaterials. Prog. Polym. Sci. 32: 762-798.

Stitzel JI, Liu J., Lee SJ, Komura M., Berry J., Soker S., Lim G., Van Dyke M., Czerw R., Yoo JJ, Atala A. 2006. Controlled fabrication of a biological vascular substitute . Biomaterials. 27: 1088-1094.

Tordoir J.H.M., Bode A.S., van Loon M.M. 2015. Preferred strategy for hemodialysis access creation in elderly patients. Eur. J. Vase. Endovasc. Surg. 49 (6): 738-743

Tanzi M.C., Fare S., Petrini P. 2000. In vitro stability of polyether and polycarbonate urethanes. J. Biomater. Appl. 14: 325-348.

Widmer M.S., Gupta P.K., Lu L., Meszlenyi R.K., Evans G.R., Brandt K., Savel T., Gurlek A., Patrick C.W., Mikos A.G. 1998. Manufacture of porous biodegradable polymer conduits by an extrusion process for guided tissue regeneration. Biomaterials. 19 (21): 1945-1955.

Claims (4)

1. A method of obtaining a polymer prosthesis intended for the restoration of vessels of various diameters, including the preliminary preparation of a soluble core of the desired diameter by melting sugar to a homogeneous mass with the addition of 10 mass. % glycerol to increase the elasticity of the rod, rods of the required diameter and length are prepared from the obtained melt, after drying in air, the rods are lowered into a pre-prepared solution of polycaprolactone in chloroform with a concentration of 30 mg / ml for 5 sec, then the rod is removed from the polymer and allowed to air dry within 5 min, the lowering and drying procedure is repeated from 3 to 9 times depending on the requirements for the thickness of the walls of the vascular prosthesis, dried in air for 1 day, then the vascular prosthesis together those with the rod are lowered into a glass of distilled water with a volume of 100 ml for 1 day, after which the rod is dissolved, the vessel is washed 3 times in distilled water and allowed to air dry, then it is lowered into a fibrinogen solution with a concentration of 0.1 mg / ml from 25 to 30 ml for 1 day, after which the modified vascular prosthesis is removed and washed 1 time in phosphate-buffered saline pH 7.4 to remove unbound protein, dried in air and sterilized in an ozone chamber for 90 minutes for subsequent implantation into the rat abdominal aorta. 2. The method according to p. 1, characterized in that the structure of the inner and outer walls of the vessel is evaluated using scanning electron microscopy. 3. The method according to p. 1, characterized in that the mechanical properties of the tensile samples of polymeric vascular prostheses based on polycaprolactone are determined using a universal testing machine. 4. The method according to p. 1, characterized in that hemocompatibility of the polymeric vascular prosthesis modified by fibrinogen is evaluated after its implantation in the abdominal aorta of experimental animals.

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