Embryonic salivary gland mesenchyme (eSGM) secretes various growth factors (bioactives) that support the proper growth and differentiation of salivary gland epithelium. Therefore, eSGM cells can be used as feeder cells for in vitro-cultured artificial salivary gland if their survival and bioactivity are properly maintained. As eSGM is encapsulated in a hyaluronan (HA)-rich developmental milieu, we hypothesized that mimicking this environment in vitro via surface immobilization of HA might enhance survival and bioactivity of eSGM. In this study, various HA derivatives, conjugated with catechol (HA-CA), thiol (HA-SH), or amine (HA-EDA) moieties, respectively, were screened for their efficacy of culturing eSGM-derived feeder cells in vitro. Among these HA derivatives, HA-CA showed the highest surface coating efficiency and growth enhancement effect on the embryonic submandibular gland. In addition, the HA-CA coating enhanced the production of growth factors EGF and FGF7, but not FGF10. These effects were maintained when eSGM cells isolated from the embryonic salivary gland were re-seeded to develop the feeder layer cells. CD44s (a major HA receptor) in eSGM cells were clustered at the cell membrane, and enhanced EGF expression was detected only in CD44 cluster-positive cells, suggesting that membrane clustering of CD44 is the key mechanism for the increased expression of EGF.
Keywords: CD44; branching morphogenesis; catechol; feeder cell; hyaluronan; mesenchyme; salivary gland; tissue engineering.