Construction And Performance Study Of Multi-level Structure Composite Scaffold For Vascular Tissue Engineerin

Nowadays,cardiovascular disease(CVD)is one of the main causes of human death worldwide,which has seriously threatened human life and health.Vascular replacement and reconstruction is the main method of treatment for this disease.In the case of severely diseased vessels,only vascular replacement can be used.One of the sources of replacement is native blood vessels,usually using the great saphenous vein to replace the arterial vessels.However,this method has its limitations.The mechanical properties of venous blood vessels are not as good as those of native arteries,and they are susceptible to their own primary diseases.The second source of replacement is tissue-engineered blood vessels,but most of the grafts still need several months or even longer to reconstruct vascular function after replacement,so its clinical application is also limited.The ideal TEVGs should have both micro-nano hierarchical structures to provide more favorable scaffold conditions for the structural and functional reconstruction of blood vessels.In this paper,two kinds of hierarchical vascular scaffolds were prepared by different methods.The specific research contents are as follows:1.Poly(L-propylene-co-ε-caprolactone)(PLCL)multistage structural scaffolds were prepared by electrostatic spinning and femtosecond laser.SEM and laser confocal results showed that micron-scale microchannels were successfully constructed on nanoscale electrospun fiber membranes.The average widths of the microchannels were 45.79 ± 3.56 μm,66.49 ± 2.39 μm,and 80.25 ± 2.96 μm,and the average depths were 10.57 ± 0.60 μm,18.98 ± 0.84 μm,and 28.37 ± 0.64 μm,in that order.Mechanical experiments showed that the mechanical strength of the scaffolds was better than that of natural arteries.Human umbilical vein cells(HUVEC)and rat thoracic artery smooth muscle cells(A7r5)were inoculated on microchannel fibrous membranes,and on day 5,HUVEC formed lamellae on the nanoscale fibrous membranes with a coverage of 30.53%.A7r5 spread inside the nanoscale fibrous ridges and micrometer channels,especially the Cu 450 group of cells had entered the microchannel under the remelted fibers.In vivo,animal experiments showed that this multistage structured stent infiltrated the tubular wall with a large number of inflammatory cells 3 weeks after implantation.An abundant extracellular matrix was generated in the stent.2.The hierarchical structured vascular scaffolds with nanometer to micron gradient were successfully fabricated by program-controlled electrospinning with variable pushing speed,and the SEM and laser confocal results showed that the gradient film with fiber diameter from 0.79 ± 0.26 μm to 3.41 ± 1.59 μm was successfully fabricated.The mechanical experiments showed that the scaffolds had excellent mechanical properties,and there was no significant loss of mechanical properties in the wet state.HUVEC spread into a lamellar layer on the nanoscale fiber membrane in cytological experiments with 40.53 % coverage by the fifth day.A7r5 had entered the interstices of the micron-sized fibers.In vivo,animal experiments showed that the scaffold structure remained intact one week after implantation and cellular infiltration had occurred in the tubular wall.