Triple-layered cell sheet for tissue-engineering the synovial membrane of the temporomandibular joint

Temporomandibular disorder causes the dysfunction of fibroblast-like synoviocytes (FLSs) which are predominant in the lining layer (LL) of synovial membrane (SM) and responsible for the secretion function of the SM of the temporomandibular joint (TMJ). This study aimed to construct a triple-layered cell sheet (CS) for tissue-engineering the SM.

FLSs were harvested and identified immunocytochemically. A triple-layered CS was fabricated by an original method of combining type I collagen and FLSs. Staining and a transmission electron microscope were used to compare the morphological similarities between the CS and the natural LL. Hyaluronic acid (HA) production and HA synthase 2 (HAS2) gene expression were assessed by ELISA and PCR, respectively. Transplantation of triple-layered CSs into nude mice was performed and examined by staining and immunohistochemical methods.

FLSs expressed vimentin, CD44 and heat shock protein 27. The triple-layered CS possessed a structure similar to natural LL. No tight conjunction was observed between adjacent FLSs. The triple-layered CS secreted HA at a quantity about 3 times that of the single-layered CS. The triple-layered structure induced higher expression of HAS2 in FLSs. No difference in HAS2 expression between the triple-layered CS and natural SM was observed. Multiple-layered FLSs and invasion of host fibroblasts and vessels were observed 2 weeks after transplantation. HAS2 and HA were expressed in surface cells and extracellular matrix, respectively.

FLSs of the TMJ were type B synoviocytes. The triple-layered CS mimicked natural SM morphologically and functionally. The CS survived for 2 weeks in vivo. Therefore, triple-layered CS might be highly competent for tissue-engineered SM.