Biomaterial testing for covered stent membranes: evaluating thrombosis and restenosis potential

Covered stents may be able to prevent both thrombosis and restenosis, but new mechanically suitable and biocompatible materials are needed before this treatment option can become a reality. Hydrophilic polyvinyl alcohol (PVA) cryogels have desirable mechanical properties for covered stent membranes and may be able to provide a physical barrier to restenosis with low thrombogenicity. An in vitro flow loop with porcine blood was used to compare thrombus formation on different blood-contacting biomaterials. PVA cryogels were found to maintain blood flow with low thrombogenicity and were significantly less thrombogenic than polyester (p < 0.05). The ability to prevent hyperplasic in-growth was evaluated using a modified Boyden chamber cellular migration assay. PVA cryogel membranes used as a physical barrier were found to nearly eliminate cellular migration (p < 0.05) without cellular toxicity. Overall, this article demonstrates pivotal feasibility results for a covered stent membrane material that could prevent restenosis by means of a hydrogel barrier with low thrombogenicity.