Construction and performance evaluation of Hep/silk-PLCL composite nanofiber small-caliber artificial blood vessel graft

To meet the growing clinical demand for small-caliber blood vessel grafts to treat cardiovascular diseases, it is necessary to develop safe and long-term unobstructed grafts. In this study, a biodegradable graft made of composite nanofibers is introduced. A composite nanofiber core-shell structure was prepared by a combination of conjugate electrospinning and freeze-dry technology. The core fiber was poly(l-lactide-co-caprolactone) (PLCL)-based and the core fibers were coated with heparin/silk gel, which acted as a shell layer. This special structure in which the core layer was made of synthetic materials and the shell layer was made of natural materials took advantage of these two different materials. The core PLCL nanofibers provided mechanical support during vascular reconstruction, and the shell heparin/silk gel layer enhanced the biocompatibility of the grafts. Moreover, the release of heparin in the early stage after transplantation could regulate the microenvironment and inhibit the proliferation of intima. All of the graft materials were biodegradable and safe biomaterials, and the degradation of the graft provided space for the growth of regenerated tissue in the late stage of transplantation. Animal experiments showed that the graft remained unobstructed for more than eight months in vivo. In addition, the regenerated vascular tissue provided a similar function to that of autogenous vascular tissue when the graft was highly degraded. Thus, the proposed method produced a graft that could maintain long-term patency in vivo and remodel vascular tissue successfully.