Study On The Construction And Function Of Smooth Muscle Tissue For Esophageal Tissue Engineering

Smooth muscle is an unstriated muscle tissue. It is an important part of many organs in humanbody, such as alimentary canal, respiratory organs and blood vessel etc. It contracts and relaxesunder some inducing stimuli and factors to assist the main functions of these organs. Therefore,smooth muscle tissue engineering was proposed during the reconstitution of those tissue or/andorgans. Smooth muscle tissue is the main functional architecture of esophagus with endo-circularand exo-longitudinal muscle bi-layers. The research of esophageal smooth muscle has a vitalsignificance in esophageal tissue engineering.This research aimed at the scaffold fabrication towards guiding the regeneration of smoothmuscle tissue with endo-circular and exo-longitudinal muscle architecture. Firstly, We we designeda silicon wafer with a predetermined pattern, by which a soft PDMS sheet was copied. and was Itwas used as a daughter mould to prepare a polyurethane scaffold, on which there are channels with100μm width and hollow discontinuous intervals with30μm width and depth spaced by a30μmgap (P1), or channels with200μm width intermitted by a hollow interval of30μm width anddepth (P2). Using poly(ester urethane)(PU) as the substrate material, a tubular scaffold with P1patterned lumen and P2patterned outer face was fabricated aiming at constituting a muscle tissuewith endo-circular and exo-longitudinal bi-layers like esophageal muscle structure. After graftedwith natural silk fibroin (SF), the scaffold was seeded by primary esophageal smooth muscle cells(SMC) originated from healthy adult rabbit. The results of HE staining, mitochondrial activity,immunohistochemistry and immumofluorescence assay verified that it was verified that thescaffold with specific micro-channel grafted with natural silk fibroin (SF) exhibits a good supportto promote smooth muscle cell (SMC) growth, and differentiation, which is believed to contributeto maintain SMC’s contractile function.As literature reported, micro-channel enhanced SMCs to organize into aligned patterns due tothe narrow space. Therefore, we fabricated a scaffold with patterns of200μm channels intermittedby a wall interval of30μm width and height (P3, concave channel), too. After grafted with SF, thecytocompatibility and the biocompatibility of the scaffold was evaluated in vitro and in vivo,respectively.It was verified that scaffold with concave micro-channel had favorable biocompatibility invivo and was capable to support esophageal muscle regeneration. Scaffold grafted with natural silk fibroin or gelatin was implanted subcutaneously in rabbit. Regenerate tissues around scaffold wereexamined by frozen section examination and HE stain. Results demonstrated the biocompatibilityin vivo of the scaffold. We dissected the neck of healthy adult rabbit to get the physical location ofesophagus. Then small pieces of muscle tissue was cut off and patched with a slice of scaffold withendo-circular and exo-longitudinal micro-channel. The same way, the whole circle of muscle layer2mm width was cut off and substituted by a circle of scaffold with endo-circular and exo-longitudinal micro-channel. Experimental rabbits can survive and eat normally. The induction ofscaffold with micro-channel on smooth muscle tissue regeneration was verified by frozen sectionexamination, HE stain, immunofluorescence stain.