Olfactory Ensheathing Cells (OECs) are special types of glial cells showing an exceptional plasticity, and support olfactory neurogenesis. They secrete growth factors and adhesion molecules, inhibit inflammatory reaction and promote neurite regeneration. Because of these features, OECs transplantation is supposed to be one of the most promising methods for nerve injuries. Here, we characterized the NOBEC (Neonatal Olfactory Bulb Ensheathing Cells) line obtained from primary cells dissociated from rat neonatal olfactory bulb (OB) and immortalized by retroviral transduction of SV40 large T antigen. Light and electron microscopy investigation showed that NOBECs are a homogeneous cell population both at structural and ultrastructural level. RT-PCR, Western blotting and immunocytochemistry releaved that NOBECs express several markers such as S100, GFAP, calponin, nestin, vimentin, p75NGFR, NRG1 and ErbB1-2-3 receptors while they are negative for ErbB4. Moreover, we examined the expression of neuronal markers, such as PGP 9.5 and MAP-2, by immunocytochemistry in NOBECs grown in different conditions. PGP 9.5 and MAP-2 immunoreactivity was low or absent in the presence of serum independently of the addition of growth factors (NFG or bFGF or GDNF). In contrast, in serum-free medium NOBECs exhibited a moderate and strong PGP 9.5 or MAP-2 signal in the absence and the presence of growth factors, respectively. These results suggest that serum might contain molecules which inhibit the expression of neuronal markers induced by growth factors. Yet, NOBECs exhibit a high proliferation and migration basal activity and can be transduced with vectors carrying GFP and NRG1 cDNA. Functional stimulation by means of NRG1-III-beta3 overexpression through viral transduction induced a significant increase in cell proliferation rate while it had no effect on cell migration. It could be concluded that in general the NOBEC cell line exhibits glial features both morphologically and functionally; however, under certain in vitro condition NOBECs show the expression of neuronal markers. Our results suggest that NOBECs might be considered for cell transplantation in the injured nervous system. This work was supported by grants from Regione Piemonte and Compagnia di San Paolo.
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