Research Of Silk Fibroin-based Vascular Tissue Engineering Scaffold Materials

Long-distance vascular injury(LDVJ,≥ 10 mm)caused by violent invasion or cardiovascular disease has always been an important issue for human health.At present,vascular tissue engineering is considered to be an effective method to treat LDVJ.Silk fibroin(SF)is an excellent scaffold material for tissue engineering.However,pure silk fibroin is challenging to meet the treatment requirements of LDVJ.The preparation of composite scaffolds with good mechanical properties,matching biodegradability and enhanced vascular repairing effects is an important subject in the field of biomedical engineering.Here we used SF as the basic material for constructing vascular tissue engineering scaffolds.Polycaprolactone(PCL)and polydextrose sorbitol carboxymethyl ether(PSC)-coated iron oxide nanoparticles(γ-Fe2O3@PSC,MNPs)were applied to improve the performance of SF,and the related mechanisms were discussed.The main research contents include the following parts:(1)The polycaprolactone(PCL)/SF composite microfiber scaffold was prepared by an improved electrospinning method.PCL can significantly improve the mechanical properties of the scaffolds.Compared with pure silk fibroin,in vitro co-culture with human umbilical vein endothelial cells(HUVECs)and in vivo subcutaneous transplantation experiments on rabbit backs proved that the new composite microfiber scaffold could effectively inhibit cell infiltration and inflammation compared with pure silk fibroin.In addition,due to PCL doping in the scaffold,the prepared scaffold also showed good structural stability in vivo.The PCL/SF composite microfiber scaffold was an effective candidate for vascular tissue engineering applications.(2)The magnetic silk fibroin scaffold(MSFC)containing different concentrations of magnetic nanoparticles(MNPs)was prepared by freeze-drying.Compared with pure SF stent,MSFC has better crystallinity,magneto-caloric performance and mechanical properties.At the same time,MNPs can delay the degradation of the scaffold by forming hydrogen bonds between SF and MNPs and inhibiting hydrolase activity through complexing with tyrosine.Cell and animal experiments have shown that MSFCs have good biocompatibility and can promote the growth of vascular endothelial cells(VECs).(3)In order to better repair LDVJ,based on the above MSFCs,palmitoylphosphatidylcholine(DPPC)and polyvinyl alcohol(PVA)were further compounded to construct a functional magnetic scaffold with temperature control switch.The radial support force of the functional scaffold is about5 times higher than that of the pure SF scaffold.And the degradation of the scaffolds were also delayed,which is beneficial to maintaining the structural integrity of the scaffold during long-term transplantation.At the same time,the phase transition effect of DPPC can effectively regulate the release of MNPs through magnetothermal heating,which could induce the migration of macrophages,and up-regulate the expression of vascular repair-related factors,and promote the regeneration and repair of blood vessels.It can be used as an effective candidate material for repairing LDVJ.