The in vitro and in vivo biocompatibility evaluation of electrospun recombinant spider silk protein/PCL/gelatin for small caliber vascular tissue engineering scaffolds

Recombinant spider silk protein (pNSR32) and gelatin (Gt) were demonstrated to enhance cytocompatibility of electrospun pNSR32/PCL/Gt scaffold. However, its potential pro-inflammatory effects and interactions with tissue and blood are unknown. In this study, the physicochemical properties and in vitro and in vivo biocompatibility of such scaffolds were evaluated. The results showed that the pNSR32/PCL/Gt scaffold possessed larger average fiber diameters, wider fiber diameter distribution and faster degradation rate than that of pNSR32/PCL and PCL scaffolds. The addition of pNSR32 and Gt had little influence on the hemolysis and plasma re-calcification time, but prolonged kinetic clotting time and reduced the platelet adhesion. The Il-6 and Tnf-α mRNA expression levels were up-regulated in macrophages seeded on the PCL and pNSR32/PCL scaffolds. The lowest release of IL-6 and TNF-α appeared in the pNSR32/PCL/Gt scaffold. Histological results revealed that the PCL and pNSR32/PCL scaffolds elicited severe host tissue responses after implantation, while prominent ingrowth of host cells were observed in the pNSR32/PCL and pNSR32/PCL/Gt scaffolds. The comet assay and bone marrow micronucleus test demonstrated that the pNSR32/PCL/Gt scaffold did not increase the frequency of DNA damage or bone marrow micronucleus. In short, this study confirmed that the pNSR32/PCL/Gt scaffold exhibited better blood and tissue compatibility than pNSR32/PCL and PCL scaffolds. No induction of genotoxicity and inflammatory factor releases makes the pNSR32/PCL/Gt scaffold a good candidate for engineering small diameter vascular tissue.