Abstract 18365: Bioengineered Silk Conduits Are Effective for Small Diameter Revascularization
Introduction: Currently available synthetic graft materials (ePTFE and Dacron) are inadequate for use for coronary artery bypass surgery, with uniform failure within 12 months. Silk fibroin is a versatile natural polymer with remarkable mechanical properties and tuneable biodegradation that is well tolerated in vivo. Small diameter silk grafts were engineered using electrospinning to obtain a woven mesh of silk nanofibers.
Methods: Our silk materials are uniquely electrospun and subsequently cross-linked using water only, enhancing their biocompatibility. Following optimisation of mechanical properties and endothelialization, silk grafts and ePTFE controls were implanted into the abdominal aorta of rats with explant time points of 3, 6, 12 and 24 weeks (n=4).
Results: In vitro, silk scaffolds enhanced endothelial cell proliferation ~ 5-fold, from day 1 to 6, significantly greater than ePTFE controls (p<0.01, n=14). Silk conduits demonstrated comparable elasticity to rat aorta (5.4±1.6MPa vs 2.1±1.0MPa, n=14 and 2, respectively) and were significantly more elastic than ePTFE (31.9±3.5MPa, p<0.001, n=8). Burst pressures of 849±132.8mmHg (n=6) were achieved with conduits with wall thickness of only 400μm. In vivo, silk conduits were well tolerated up to 24 weeks, showing only low levels of inflammatory cells and neointimal hyperplasia, which was stable by 12 weeks (23.3±0.89% hyperplasia, n=3). Complete re-endothelialization of silk grafts was observed by 12-weeks, in contrast to ePTFE controls which were only partially endothelialized, with exposed ePTFE visible all time points.
Conclusion: We engineered Silk fibroin to have the appropriate mechanical and biological properties for use as a small diameter vascular graft. Ultimately, this may lead to the development of silk-based grafts for small diameter revascularisation, thereby meeting a large unmet need in cardiovascular medicine.
Author Disclosures: E. Filipe: None. M. Santos: None. J. Hung: None. J. Rnjak-Kovacina: None. M.K. Ng: None. S.G. Wise: None.
- © 2016 by American Heart Association, Inc.