OECs CONDITIONED MEDIUM (OECs-CM) REDUCED OXYGEN DEPRIVATION-MEDIATED DAMAGE BY REGULATION OF CONNEXIN 43 GAP JUNCTION (GJ) COMMUNICATION

Olfactory Ensheathing Cells (OECs), a special population of glial cells, are able to synthesise several trophic factors exerting a neuroprotective action and promoting growth and functional recovery both in vivo and in vitro models. In the present work, we investigated the neuroprotective effects of OECs Conditioned Medium (OECs-CM) on an in vitro model of hypoxic injury on a neuron-like cell line, human SH-SY5Y neuroblastoma cells. We focus our attention on the role of Connexins (Cxs) in this process. Many evidences proved a dynamic expression of Cxs, the core proteins of Gap Junctions (GJs) and Hemichannels (HCs), during injury and stress conditions. Is still unclear if up- or down- regulation of such structures helps cells to survive or, on the contrary, contribute to their killing. Here we found that (OECs-CM)-mediated neuroprotection reduced Cx43 levels compared to unconditioned hypoxic cultures. We investigated the role of Cx43-HCs and Cx43-GJs in hypoxic-reoxygenation injury using Carbenoxolone (unselective GJs inhibitor), Ioxynil Octanoato (selective Cx43-GJs inhibitor) and Gap19 (selective Cx43-HCs inhibitor) and, it has been found that Cx43- GJs and Cx43-HCs inhibitors are able to protect SH-SY5Y and allow to these culture to overcome the injury. Our findings support the hypothesis that both OECs-CM and the inhibition of Cx43-GJs and Cx43-HCs offer a neuroprotective effect reducing cell-to-cell and cell-to-extracellular environment communication Cx43-mediated.