A Novel Thin Film Nitinol/Silk Endograft for Treating Small-Caliber Vascular Diseases
Methods: In all tests conducted in this study, 6μm-thick sputter-deposited superelastic thin film nitinol and 10μm-thick electrospun/cast silk samples were used. Both high-pressure bonding technique and direct electrospun deposition were used to fabricate composite materials. Platelet adhesion studies compared all materials tested in order to quantitatively assess hemocompatibility. In vitro dynamic flow test using fresh whole blood examined the formed
thrombi both qualitatively and quantitatively. Cell adhesion and growth studies using a 48hr time point were also performed looking at vascular smooth and endothelial cell attachment and proliferation on all tested biomaterials. Samples were evaluated using fluorescent microscopy and scanning electron microscopy.
Results: This study demonstrated clear evidence of non-thrombogenic surface on thin film nitinol and silk. The hemocompatible surface-treated thin film nitinol demonstrated the number of adherent platelets in the range of 0-3 with a mean value of 1±0.5 platelets per mm2 (n=3). The electrospun thin silk material also demonstrated a significant low number of adherent platelets (similar numbers of TFN) compared to other conventional graft materials, for example, ePTFE and Dacron polyester showed 71±21 and 41±17 platelets per mm2.
Conclusion: A novel composite endograft was manufactured using thin layers of nitinol and silk, and tested in vitro. This new composite material was shown to be appropriate for the small artery stent graft due to its unique biocompatible characteristics from both think film nitinol and silk materials.