Cultured olfactory ensheathing cells express nerve growth factor, brain-derived neurotrophic factor, glia cell line-derived neurotrophic factor and their receptors

In the primary olfactory pathway axons of olfactory neurons (ONs) are accom panied by ensheathing cells (ECs) as the fibres course towards the olfactor y bulb. Ensheathing cells are thought to play an important role in promotin g and guiding olfactory axons to their appropriate target. In recent years, studies have shown that transplants of ECs into lesions in the central ner vous system (CNS) are able to stimulate the growth of axons and in some cas es restore functional connections. In an attempt to identify a possible mec hanism underlying EC support for olfactory nerve growth and CNS axonal rege neration, this study investigated the production of growth factors and expr ession of corresponding receptors by these cells. Three techniques immunohi stochemistry, enzyme linked immunosorbent assay (ELISA) and reverse transcr iptase-polymerase chain reaction (RT-PCR) were used to assess growth factor expression in cultured ECs. Immunohistochemistry showed that ECs expressed nerve growth factor (NGF), brain derived neurotrophic factor (BDNF) and gl ial cell-line derived neurotrophic factor (GDNF). ELISA confirmed the intra cellular presence of NGF and BDNF and showed that, compared to BDNF, about seven times as much NGF was secreted by ECs. RT-PCR analysis demonstrated e xpression of mRNA for NGF, BDNF, GDNF and neurturin (NTN). In addition, ECs also expressed the receptors trkB, GFR alpha -1 and GFR alpha -2. The resu lts of the experiments show that ECs express a number of growth factors and that BDNF in particular could act both in a paracrine and autocrine manner . (C) 2001 Elsevier Science B.V. All rights reserved.