In vitro constitution of esophageal muscle tissue with endocyclic and exolongitudinal patterns.

Smooth muscle tissue is the main functional structure of the esophagus and comprises of the endocircular and exolongitudinal muscle layers. To construct a tissue engineered smooth muscle by mimicking the esophageal muscle tissue, we have designed a silicon wafer where a daughter mold was prepared using soft PDMS. The daughter mold was, in turn, casted with poly(ester urethane) (PU) solution to fabricate the tissue scaffolds. The casted PU scaffolds were available in two configurations. Prototype 1 (P1) have microchannels of 100 μm width and discontinuous channel wall with gaps of 30 μm at regular intervals. Prototype 2 (P2) have microchannels of 200 μm width and continuous channel walls. The wall thickness and depth of the microchannels are 30 μm. A tubular scaffold with micropattern P1 in the lumen and micropattern P2 on the exterior was fabricated with the aim of regenerating muscle tissue with endocircular and exolongitudinal muscle architecture. After grafting with natural silk fibroin (SF), the PU micropatterned scaffold demonstrated the ability to promote smooth muscle cell (SMC) growth and differentiation; differentiation is believed to contribute to maintain the contractile function of SMCs. Results from the preliminary in vivo test revealed that the tubular scaffold patterned with microchannels is capable of supporting esophageal muscle regeneration.