Effects of hepatocyte growth factor (HGF) and activin A on the morphogenesis of rat submandibular gland-derived epithelial cells in serum-free collagen gel culture

To study the mechanisms of morphogenesis in salivary gland regeneration, we have established the RSMG-1 cell line derived from submandibular gland (SMG) of 10-week-old Wistar female rats in serum-free culture. Our finding that RSMG-1 cells originated from duct cells was based on morphology and immunohistochemical results. In three-dimensional serum-free collagen gel culture, HGF induced branching morphogenesis of RSMG-1 cells. Histological examination revealed that HGF-induced branching structure exhibited well-formed lumina. This morphology closely resembles that found in vivo. The cells also expressed activin A. Exogenously added activin A at a high concentration reduced HGF-induced branching morphogenesis. These findings suggest that the morphogenesis of the salivary gland is modulated by HGF and activin A. Our results show that the RSMG-1 cell line may be useful in studies of salivary gland regeneration.