[Proliferation and differentiation of olfactory cells in primary culture system]

A primary culture system of olfactory cells derived from newborn mouse was established by coculturing with a feeder layer of brain astrocytes. In this system, the whole lifespan of olfactory cells could be observed in vitro. Neurogenesis occurred from 5 days after plating and coexistence of immature and mature olfactory cells was observed until day 14. After day 15, immature cells were diminished and most of the culture cells appeared differentiated after day 20. The lifespan of differentiated cells was estimated to be 3 to 6 weeks. Cultured cells expressed growth associated protein 43 (GAP43), neurofilament protein (NFP), protein gene product 9.5 (PGP9.5) and olfactory marker protein (OMP). In addition, other round cells were cytokeratin-positive by immunostaining. RT-PCR of growth factor receptors on the coculture cells revealed the expressions of fibroblast growth factor receptor 2 (FGFR2) and FGFR3, both of which could not be detected in the feeder cell layer of astrocytes. FGFR1 and transforming growth factor beta receptor (TGF beta R) were detected both on the coculture and on feeder cells. FGFR4, insulin-like growth factor 2 receptor (IGF2R) and hepatocyte growth factor receptor (HGFR) could not be detected in both samples. Furthermore, basic FGF, a prototypic FGF, was also found in the coculture system and in feeder cells. The present study indicated FGF might affect regulation of proliferation and differentiation of olfactory cells.