Biodegradable Polyvinyl Alcohol Vascular Stents: Structural Model and Mechanical and Biological Property Evaluation

This study proposes structural models of biodegradable vascular stents. One, two, or three plies of biodegradable polyvinyl alcohol (PVA) yarns are combined and twisted with twist factors of 2, 3, 4, 5, and 6 to form one-, two-, and three-ply PVA twisted yarns. The braided, warp-knitted, and weft-knitted PVA vascular stents are composed of PVA twisted yarns by using a braider, a warp knitting machine, and a weft knitting machine. The formation and mechanical properties of PVA vascular stents are evaluated, and the biological properties are examined in terms of biocompatibility through in vitro assay and subcutaneous embedding using in vivo assay. Test results indicate that the compression strength of PVA vascular stents is improved when using PVA twisted yarns containing a high number of plies and twist factor. Specifically, weft-knitted PVA vascular stents exhibit the optimal compression strength. PVA vascular stents treated with chemical cross-linking show weight loss lower than 3% after immersion in PBS solution for 30 days. Moreover, the antibacterial test and cell culture results suggest that PVA vascular stents are nontoxic and biocompatible. Subcutaneous embedding results show that PVA vascular stents retain intact formation when subcutaneously embedded in vivo for 28 days, indicating their good biological property. PVA vascular stents are suitable candidates for tissue engineering applications.