In vitro construction and in vivo regeneration of esophageal bilamellar muscle tissue.

In order to induce esophageal muscle cells' orientation, the silicon wafer with prototype 1 and prototype 2 was designed. Prototype 1 has micro-channels of 200 µm width and 30 µm depth with 30 µm wide wall as the interval. Prototype 2 has channels of 100 µm width and 30 µm depth with a discontinuous wall which has 30 µm gap for each 100 µm channel. The poly(ester urethane) scaffolds with pattern prototype 1 and prototype 2 were fabricated using solution casting method and abbreviated as PU1 and PU2, respectively. Silk fibroin was grafted individually on PU1 and PU2 surface (PU1-SF, PU2-SF) using our previous protocol, aiming at improving scaffolds' biocompatibility. The primary esophageal smooth muscle cell was seeded to evaluate the scaffolds' cytocompatibility in vitro. Characterizations like MTT assay, immunocytochemistry, scanning electron microscope, and Western blotting were applied. After that, poly(ester urethane) scaffolds with double patterns, prototype 1 on the exterior, and prototype 2 in the lumen were implanted into the rabbit esophagous to test the regeneration of the muscle tissue. Results from these preliminary tests showed that the growth and differentiation of primary smooth muscle cells were promoted, but also the muscle tissue with endocircular and exolongitudinal architecture was in regenerating, against non-constitution in the animals without the patterned scaffold or with poly(ester urethane) plane membrane at the defaulted sites. This micro-channel pattern together with silk fibroin grafting and vascular endothelial growth factor coating greatly promoted the regeneration of esophageal muscle with normal histological structure.