| How to fabricate a kind of small-diameter vascular scaffold to mimic the structure and function of the native extracellular matrix(ECM) of blood vessel is of great interest and difficult point in the vascular tissue engineering and regenerative medicine research all the time.An ideal small-diameter vascular graft should have excellent mechanical properties and appropriate degradation speed,but also have good cell compatibility,antithrombogenicity and could induce the growth of blood vessel cells and promote the reconstruction of vascular tissue.Electrospinning is an efficient technology for fabricating ultra-fine fibers.Many natural biological and polymer materials can be fabricated into ultra-fine single fibers or core-shell fibers by this method,and the vascular grafts which are composed of those kinds of fibers have high surface area to volume ratio, high porosity and three-dimensional network structure which make better mimesis of the natural skeleton structure of vascular tissue compared with the conventional scaffolds.In the construction of functional vascular graft,core-shell structure of ultra-fine fibers can be used as drug delivery system which is conducive to the reconstruction of vascular tissue,and providing lasting and effective promotion for blood vessel tissue reconstruction.In order to obtain good mechanical properties,biocompatibility,and durable antithrombogenicity and promotion of vascular endothelial cell growth of small -diameter vascular graft,this research focus on the fabrication of meticulous vascular scaffold which the inner was composed of core-shell P(LLA-CL)/Heparin fibers by coaxial electrospinning and the elastic electrospun P(LLA-CL)(50:50) fibers as the outer part through the rotational Stainless steel bar as the fiber receiver.By SEM,TEM,the test of mechanical properties and heparin sustained-release,demonstrated systematically the morphology of the P(LLA-CL) / Heparin film and tubular graft shape,the size distribution of fiber diameter,mechanical properties of vascular graft and heparin-release behavior for the core-shell P(LLA-CL)/Heparin ultra-fine fibers.For evaluating systematically the biocompatibility and the performance of anticoagulant and promotion of endothelial cell growth of P(LLA-CL)/Heparin as the inner of P(LLA-CL) vascular graft,we set pure electrospun P(LLA-CL) graft and endothelialization P(LLA-CL) graft by autologous endothelial cells as the controls in the dogs of Beagle.By the analysis of the blood patency rate in the prosthesis of femoral artery and the HE staining result of the implanted vascular grafts,giving a reasonable evaluation for the small-diameter vascular graft of assembling vascular graft in the application of blood vessel tissue reconstruction.At the final this research,for the construction of a middle-fine structure of vascular graft,and mimic the structure of natural blood vessel tissue skeleton,we try to fabricate array hydrophobic P(LLA-CL)/Fe3O4 ultra-fine fiber by magnetic-assisted electrospinning,through the analysis of the result of SEM,TEM and MTT tests of EC adhesion and proliferation,demonstrated systematically the orientation rate of P(LLA-CL)/Fe3O4 fibers,the dispersion and distribution of Fe3O4 magnetic nanoparticles and the fiber biocompatibility.It provides an initial reference for the construction of the middle layer of vascular graft which should have a certain orientation fibers in the skeleton.The results show:the heparin control-release of P(LLA-CL)/ Heparin core-shell fibers assembling small-diameter tubular scaffold has good mechanical properties,and the high concentration pre-release of heparin effectively prevent the post-thrombotic after the graft transplantation in the first week and the sustained-release heparin in a low concentration effectively promoted the migration of endothelial cells.It is a valuable researching achievement for the development of fabrication of small-caliber vascular graft in blood vessel tissue engineering.By magnetic-assisted electrospinning,well aligned P(LLA-CL)/Fe3O4 ultra-fine fibers were obtained by ellectrospinning under the influence of extra magnetic field,the fiber alignment disposition goes along with magnetic lines of force.And the fiber has an excellent biocompatibility. |
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