Current surgical procedures for the treatment of diseased peripheral small diameter (<6mm) blood vessel relies on replacement with autologous graft. Limitations are usually faced off with this strategy due to prior vein harvesting and diseased autograft. Herein, we propose the use of patterned silk films as vascular graft biomaterial and combined conventional template based approach with cell sheet engineering. Highly explored mulberry silk (B. mori) is compared with the non-mulberry silk (P. ricini and A. assama). Films were physically characterized and checked for cellular compatibility. Non-mulberry silk films presented superior characteristics in terms of thermal stability, proteolytic degradation, cellular proliferation (1.1-1.3 folds higher than mulberry silk) and alignment of vascular cells. Immunogenicity of films was assessed in vitro by looking into macrophage response in terms of TNF-α secretion. It was 40.79-51.4% lesser as compared to positive control after 7 days. In vivo subcutaneous implantation of films in mice showed minimal fibrosis and inflammation after 28 days validating the material suitability. All three vascular cells, viz. endothelial cells (ECs), smooth muscle cells (SMCs) and fibroblasts were co-cultured in multi-layered tubular construct. Pattern induced alignment favoured functional contractile phenotype of SMCs (a major challenge) and they strongly expressed contractile markers calponin and α-SMA. Moreover, the expression of elastin in SMCs and punctuated pattern of vWF in ECs layer further assures the potential candidature of silk films. Burst strength of tubular construct ranged between 915-1260 mmHg, sufficiently higher than the physiological pressure making it mechanically competent. Conclusively, we successfully bioengineered a multilayer vascular conduit similar to native vessel with optimal mechanical properties that would be adequate for in vivo transplantation.
