OBJECTIVETo investigate the protective role of brain-derived neurotrophic factor (BDNF) gene transfected bone-marrow mesenchymal stem cells (BMSC) on cochlear spiral ganglion cells (SGC) impaired by aminoglycoside antibiotics (AmAn).

METHODSThe differentiation of BMSC transfected by BDNF gene (BDNF-BMSC) were detected with immunohistochemical examination of Nestin, neuron-specific enolase (NSE), and glial fibrillary acid protein (GFAP) antibody in vitro. BDNF gene transfected BMSC were transplanted into the cochleae of guinea pigs deafened by amikacin, while the control groups were designed in which artificial perilymphatic fluid (APF), BMSC or BDNF gene was injected into cochleae alone. The cochleae were obtained on the week 1, 2 and 4 after injection, respectively, paraffin-embedded, and cut in a paramodiolar plane subsequently. The histopathological changes of cochleae were observed, the density of SGC was calculated by staining with HE, and the corresponding optical density (COD) was calculated with immunohistochemical staining using NSE antibody. And the protective role of various groups on the cochlear SGC were compared.

RESULTSThe positive staining rate of BDNF gene transfected BMSC with Nestin, NSE and GFAP antibody were all higher than that of BMSC in vitro (P < 0.01). After transplantation into cochleae, the differences of SGC density and COD among various groups were all significant on the same time points (P < 0.05). The SGC density and COD of the BDNF gene transfected BMSC group were the highest. The SGC density and COD of various groups on week 4 were all obviously decreased than those on week 1 and 2 (P < 0.05).

CONCLUSIONAmAn-induced SGC damage could be depressed by BMSC, BDNF gene or BDNF gene transfected BMSC transplantation into cochleae, while BDNF gene transfected BMSC showed the best protective role.