Electrospun sulfated silk fibroin nanofibrous scaffolds for vascular tissue engineering

One of the major downfalls of tissue-engineered small-diameter vascular grafts is the inability to obtain a confluent endothelium on the lumenal surface. Loosely attached endothelial cells (ECs) are easily separated from the vessel wall when exposed to the in vivo vascular system. Thus any denuded areas on the lumenal surface of vascular grafts may lead to thrombus formation via platelet deposition and activation. If the denuded areas could express anticoagulant activity until the endothelial cell lining is fully achieved, it may greatly improve the chances of successful vascular reconstruction. In this study, we fabricate sulfated silk fibroin nanofibrous scaffolds (S-silk scaffolds) and assess the anticoagulant activity and cytocompatibility of S-silk scaffolds in vitro in order to improve the antithrombogenicity and get some insights into its potential use for vascular tissue engineering. Sulfated silk fibroin was prepared by reaction with chlorosulphonic acid in pyridine, and then was developed to form an S-silk scaffold by electrospinning technique. FTIR analyses identified the successful incorporation of sulfate groups in silk fibroin molecules. It was found that the anticoagulant activity of S-silk scaffolds was significantly enhanced compared with silk fibroin nanofibrous scaffolds (Silk scaffolds). Vascular cells, including ECs and smooth muscle cells (SMCs), demonstrated strong attachment to S-silk scaffolds and proliferated well with higher expression of some phenotype-related marker genes and proteins. Overall, the data in this study suggest the suitability of S-silk scaffolds used along with vascular cells for the development of tissue-engineered vascular grafts.