| Background and ObjectiveThe valve exchanging operation is the main method of treating end-stage valvular heart disease. With the development of the man-made heart valve, the life quality of the patients were highly improved. There are two types of heart valve Prostheses in use: mechanical valve and bioprosthetic valve. Though it has been proved that all these valves are effective and has been shown to significantly alter the course of valvular disease, they are still far from an ideal one. Mechanical valves are associated with a significant risk of thrombo-embolism and require life-long anticoagulation. Bioprosthetic valves do not need life-long anticoagulation, but they are far less durable and are subject to progressive tissue deterioration. Homograft valves also have a limited resources and durability. None of available valve replacements has the capacity for growth and repair, so to produce an ideal heart valve prostheses is the current target in the field of valve surgery.The establish and development of tissue engineering provides a new idea for man-made heart valves. The conception of TEHV is to use expanded and isolated autologous cells seeded onto appropriate carrier structures-the scaffolds, then is implanted into recipients after a certain time culturing in vitro. The cells start to develop a neo-matrix, while the scafold material is bio-degrading, ultimatelyrendering a completely autologous functional and living heart valve, providing theability to grow, repair, remodel, and avoiding coagulation. Therefore, it is an optimal heart valve including adequate mechanical function, durability, excellent haemodynamic performance, as well as the absence of immunogenic and/or inflammatory reactions. So tissue engineering heart valve ( TEHV ) is believed to be the ideal heart valve prosthesis.The success of tissue engineered heart valves ( TEHV ) is dependent on three main issues: ( a ) seeded cells ( b ) matrix-scafold ( c ) cell implants on scaffold. The scaffold is the base of the TEHV, which determines the three-dimensional shape and serves as an initial guiding structure for cell attachment and tissue developments.on the other hand, it should has enough mechanical strength to bear the stress of blood stream. In this study , we use four methods to decellularize the porcine heart valves.For comparison investigation and investigate the results of cells extraction, the change of biomechanical properties and the immunogenicity of decelluarized porcine aortic valves also researched.MethodsPart 1: the establish of decellularized porcine heart valves, a: Fresh adult porcine hearts were obtained from abattoir within 15 minutes after abataged and valve leaflets were dissected free from the wall of valves, b: The leaflets were divided into five groups at random according to different decellularization reagents : groupI ( fresh valve ); groupII ( Triton X-100, trypsin, RNase and Dnase, EDTA ); group III ( trypsin, RNase and DNase, EDTA, DCA ); group IV ( trypsin, DCA, EDTA ) ; groupV ( SDS ); c: The leaflets were decellularized and then preserved at 4℃.Part 2: The evaluation of decellularization. Specimens were observed grossly, under Haematoxylin-eosin was performed to confirm the removal of cell, Transmission electron microscope was used to observe the integrity of collagen and elastin. Also the thickness ,water content, shrinkage temperature and DNA contents of the Specimens were observed compared with that of fresh valves .Results(1) The basic disposition of the porcine valves decellularized by trypsin and decontaminants was maintained.(2) The cells were removed effectively from porcine thoracic aortas by groupII ( Triton X-100, trypsin, RNase and Dnase, EDTA ) and group III( trypsin, RNase and DNase, EDTA, DCA).(3) GroupIV ( trypsin, DCA,EDTA ), groupV ( SDS ) were failed for porcine thoracic aortas decellularization. (4) Major structural compenents of porcine thoracic aorta valves decelluarized by groupIII( trypsin, RNase and DNase, EDTA, DCA )had been maintained, the collagen and elastin were kept intact.ConclusionsPorcine aortic valve can be successfully decellularised with retention of near normal structure and mechanical properties by combination use of trypsin, Rnase, Dnase, EDTA, and DCA.
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