INDUCTION OF CELL-PROLIFERATION IN MAMMALIAN INNER-EAR SENSORY EPITHELIA BY TRANSFORMING GROWTH-FACTOR-ALPHA AND EPIDERMAL GROWTH-FACTOR

Regenerative proliferation occurs in the inner-ear sensory epithelia of warm-blooded vertebrates after insult. To determine how this proliferation is controlled in the mature mammalian inner ear, several growth factors were tested for effects on progenitor-cell division in cultured mouse vestibular sensory epithelia. Cell proliferation was induced in the sensory epithelium by transforming growth factor alpha (TGP-alpha) in a dose-dependent manner. Proliferation was also induced by epidermal growth factor (EGF) when supplemented with insulin, but not by EGF alone. These observations suggest that stimulation of the EGF receptors by TGF-alpha binding, or EGF (plus insulin) binding, stimulates cell proliferation in the mature mammalian vestibular sensory epithelium.