Evaluation of the Expansion and Neuronal Differentiation Potency of Cultured Olfactory Epithelium Progenitor Cells from a Rat Model of Depression

Background: Olfactory impairment has been reported in patients with depression and in rodent models of depression. Olfactory epithelium (OE) is the only peripheral neural tissue connected to the brain that has the potential for self-renewal. We hypothesized the olfactory deficit during depression may be related to the dysfunction of OE progenitor cells. The aim of the present study was therefore to evaluate the expansion and neuronal differentiation potency of cultured OE progenitor cells obtained from a rat model of depression. Methods: Rats were exposed to chronic unpredictable mild stress procedures to establish a depressive-like state. Depressive-like behavior and olfactory sensing function were then evaluated and compared with control rats. Primary OE progenitor cells were cultured in vitro. The proliferation potency and survival of OE progenitor cells were assessed by 5-Ethynyl-2′-deoxyuridine staining and Cell Counting Kit-8 (CCK8), respectively, while cellular apoptosis was measured by flow cytometry. The neuronal differentiation potency of OE progenitor cells was evaluated by measurement of the protein and mRNA level of β-3 tubulin, a marker of neural cells. mRNA expression associated with neural stemness was examined by quantitative reverse transcription polymerase chain reaction (RT-PCR). Results: Depressive-like rats showed decreased olfactory function. OE progenitor cells from depressive-like rats showed reduced cell proliferation/survival and neuronal differentiation potency. Moreover, OE progenitor cells from depressive-like rats showed decreased expression of mRNA related to neural stemness. Conclusions: These results indicate the impaired function of OE progenitor cells may contribute to the olfactory deficit observed during depression. The OE may therefore provide a window for the study of depression.