Polymeric heart valves seem to be an attractive alternative to mechanical and biological prostheses as they are more durable, due to the superior properties of novel polymers, and have the biocompatibility and hemodynamics comparable to tissue substitutes. This study reports a comprehensive assessment of a nanocomposite based on the functionalised graphene oxide and poly(carbonate-urea)urethane with the trade name “Hastalex” in comparison with GORE-TEX, a commercial polymer routinely used for cardiovascular medical devices. Experimental data have proved that GORE-TEX has a 2.5-fold (longitudinal direction) and 3.5-fold (transverse direction) lower ultimate tensile strength in comparison with Hastalex (p < 0.05). The contact angles of Hastalex surfaces (85.2 ± 1.1°) significantly (p < 0.05) are lower than those of GORE-TEX (127.1 ± 6.8°). The highest number of viable cells Ea.hy 926 is on the Hastalex surface exceeding 7.5-fold when compared with the GORE-TEX surface (p < 0.001). The platelet deformation index for GORE-TEX is 2-fold higher than that of Hastalex polymer (p < 0.05). Calcium content is greater for GORE-TEX (8.4 mg/g) in comparison with Hastalex (0.55 mg/g). The results of this study have proven that Hastalex meets the main standards required for manufacturing artificial heart valves and has superior mechanical, hemocompatibility and calcific resistance properties in comparison with GORE-TEX.
We have previously developed a polycaprolactone (PCL) vascular graft with incorporated vascular endothelial growth factor (VEGF). Functioning of the PCL/VEGF graft in rat circulatory system over 1, 3 and 6 months after implantation into abdominal aorta was tested. Graft patency and formation of vascular wall elements were assessed histologically and by immunofluorescence staining for von Willebrand factor, CD31, CD34, and collagens I and IV and DAPI staining. Local application of VEGF promoted endothelialization and improved patency of the graft. The wall of the PCL/VEGF graft underwent remodeling due to active cellular infiltration and the extracellular matrix deposition.
Background. Tissue-engineered vascular grafts can be reinforced by a biostable or biodegradable polymer sheath. A combination of electrospinning, routinely used for fabrication of biodegradable tubular grafts, and the layer-by-layer coating allows forming a polymeric sheath ensuring long-term integrity and high biocompatibility of the vascular grafts after the implantation. Aim To evaluate mechanical properties and in vivo performance of biodegradable small-diameter vascular grafts with a reinforcing sheath.Methods. Tubular grafts (4 mm diameter) were fabricated from poly(3-hydroxybutyrate-co3-hydroxyvalerate) and poly(ε-caprolactone) by emulsion electrospinning with the incorporation of vascular endothelial growth factor (VEGF) into the inner third of the graft and basic fibroblast growth factor (bFGF) along with stromal cell-derived factor-1α (SDF-1α) into the outer two thirds of the graft wall. Poly(ε-caprolactone) sheath was formed by the layer-by-layer coating. Upon graft fabrication, scanning electron microscopy was performed to assess the grafts’ surface, tensile testing allowed evaluating mechanical properties. The samples were implanted into the ovine carotid artery (n = 5 animals) for 12 months with the subsequent histological examination.Results. Sintering temperature of 160°C during the extrusion allowed effective and delicate merging of poly(ε-caprolactone) coating with the outer surface of the poly(3hydroxybutyrate-co-3-hydroxyvalerate)/poly(ε-caprolactone) tubular graft. The thickness of poly(ε-caprolactone) fiber was 380–400 μm, the increment of the reinforcing filament was 1 mm. The reinforcing sheath led to a 3-fold increase in durability and elastic modulus of the vascular grafts. At the 12-months follow-up, the grafts reported retained integrity. No signs of inflammation or calcification were found.Conclusion. The poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and poly(ε-caprolactone) vascular grafts with hierarchically incorporated growth factors and the reinforced poly(ε-caprolactone) spiral sheath demonstrated improved mechanical properties while retaining integrity and high biocompatibility after the long-term implantation into the ovine carotid artery.
Aim. To evaluate the potential utility of fibrin matrices containing 10, 20, and 25 mg/ml of fibrinogen (fibrin-10, fibrin-20, and fibrin-30, respectively) in vascular tissue engineering (VTE). Materials and Methods. Fibrinogen was isolated using the method of ethanol cryoprecipitation and polymerized using a solution of thrombin and CaCl2. The fibrin structure was studied in a scanning electron microscope, and the physical and mechanical properties of the material were tested on a Zwick/Roell test machine. The metabolic activity of endothelial cells (EC) on the fibrin surface was evaluated by the MTT assay, and the viability of fibroblasts in the thickness of fibrin and possibility for migration by in fluorescent and light microscopy. Percent of fibrin shrinkage was determined from the difference in the sample volumes before and after removal of moisture. Results. The fiber diameter did not differ among all fibrin samples, but the pore diameter in fibrin-30 was smaller than those in fibrin-10 and fibrin-20. A possibility for migration of fibroblasts into the depth of the fibrin matrix and preservation of 97-100% viability of cells at a depth 5 mm was confirmed. The metabolic activity of EC on the surface of fibrin-20 and fibrin-30 exceeded that on collagen, fibronectin, and fibrin-10. All fibrin samples shrank in volume to 95.5-99.5%, and the highest shrinkage was seen in fibrin-10. The physical and mechanical properties of fibrin were inferior to those of human A. mammaria by a factor of 10. Conclusion. Fibrin with fibrinogen concentrations of 20 and 30 mg/ml maintains a high metabolic and proliferative activity of EC on the surface and also a high viability of fibroblasts in the matrix. Its availability, ease of preparation, and a number of other favorable properties make fibrin a promising material for VTE. However, the problem of insufficient strength requires further investigations.
1 Федеральное государственное бюджетное научное учреждение «Научно-исследовательский институт комплексных проблем сердечно-сосудистых заболеваний, Кемерово, Россия 2 Институт биохимии и физиологии микроорганизмов им. Г. К. Скрябина РАН, Пущино, Московская обл., Россия В статье представлены результаты гистологического исследования местной реакции тканей при подкожной имплантации биополимерных матриксов на основе полиоксиалканоатов и мультипотентных мезенхимальных стромальных клеток. Показано, что имплантированный материал не вызывает отторжения и острой воспалительной реакции. Вокруг имплантированных материалов формируется соединительнотканная капсула. Наблюдается активная инфильтрация имплантированного материала клетками и ва-скуляризация. Имплантированные матриксы подвергаются медленной биодеструкции. Наличие мультипотентных мезенхимальных стромальных клеток на поверхности матриксов замедляет скорость резорбции полимера.Ключевые слова: полигидрокибутират, полигидроксибутировалерат, мультипотентсные мезенхимальные стромальные клетки, биодеградация, биосовместимость. the article presents the findings of histological analysis of local tissue response to subcutaneous implantation of polyhydroxyalkanoatebased scaffolds and scaffolds with multipotent mesenchymal stromal cells. there were no rejection and acute inflammatory response of the implanted biopolymeric materials. the connective tissue capsule has formed around the implanted materials. Active cell infiltration of the implanted material and its vascularization have been observed. the implanted scaffolds undergo slow biodegradation. the presence of multipotent mesenchymal stromal cells on the scaffold surface slows down the resorption rate of the polymer. RESORPTION RATE OF POLYHYDROXYALKANOATE-BASED SCAFFOLDS AND SCAFFOLDS WITH MULTIPOTENT MESENCHYMAL STROMAL CELLSKey words: polyhydroxybutyrate, polyhydroxybutyrovalerate, multipotent mesenchymal stromal cells, biodegradation, biocompatibility. ВведениеНаиболее перспективной задачей современной медицины считается развитие тканевой инжене-рии как одного из направлений регенеративной ме-дицины [10]. При этом приоритетным направлени-ем является разработка биоинженерных каркасов и биоматериалов, применение которых позволило бы решать как этические, так и иммунологические проблемы трансплантологии. Для создания орга-нов и тканей используются каркасы или матриксы (биологические или искусственные), клетки (ауто-, алло-, ксеногенные), биореакторы и биоактивные молекулы [4,9]. В последние годы на рынке изде-лий медицинского назначения появляется большое число материалов, используемых в хирургической практике, различающихся по химической природе и входящих в их состав лекарственных веществ и композиционных материалов: материал -клет-ка. На сегодняшний день материалами для изго-товления скаффолдов являются несколько типов полимеров, на основе которых ведутся разработки по созданию матриц для тканевой инженерии [2]. Основными критериями биологически совмести-мой матрицы должны быть: отсутствие цитоток-сичности, поддержание...
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