Functional effects of adult human olfactory stem cells on early-onset sensorineural hearing loss.

Transplantation of exogenous stem cells has been proposed as a treatment to prevent or reverse sensorineural hearing loss. Here, we investigate the effects of transplantation of adult human olfactory mucosa-derived stem cells on auditory function in A/J mice, a strain exhibiting early-onset progressive sensorineural hearing loss. Recent evidence indicates that these stem cells exhibit multipotency in transplantation settings and may represent a subtype of mesenchymal stem cell. Olfactory stem cells were injected into the cochleae of A/J mice via a lateral wall cochleostomy during the time period in which hearing loss first becomes apparent. Changes in auditory function were assessed 1 month after transplantation and compared against animals that received sham injections. Hearing threshold levels in stem cell-transplanted mice were found to be significantly lower than those of sham-injected mice (p < .05) for both click and pure tone stimuli. Transplanted cells survived within the perilymphatic compartments but did not integrate into cochlear tissues. These results indicate that transplantation of adult human olfactory mucosa-derived stem cells can help preserve auditory function during early-onset progressive sensorineural hearing loss.

Effect of epithelial stem cell transplantation on noise-induced hearing loss in adult mice.

Noise trauma in mammals can result in damage to multiple epithelial cochlear cell types, producing permanent hearing loss. Here we investigate whether epithelial stem cell transplantation can ameliorate noise-induced hearing loss in mice. Epithelial stem/progenitor cells isolated from adult mouse tongue displayed extensive proliferation in vitro as well as positive immunolabelling for the epithelial stem cell marker p63. To examine the functional effects of cochlear transplantation of these cells, mice were exposed to noise trauma and the cells were transplanted via a lateral wall cochleostomy 2 days post-trauma. Changes in auditory function were assessed by determining auditory brainstem response (ABR) threshold shifts 4 weeks after stem cell transplantation or sham surgery. Stem/progenitor cell transplantation resulted in a significantly reduced permanent ABR threshold shift for click stimuli compared to sham-injected mice, as corroborated using two distinct analyses. Cell fate analyses revealed stem/progenitor cell survival and integration into suprastrial regions of the spiral ligament. These results suggest that transplantation of adult epithelial stem/progenitor cells can attenuate the ototoxic effects of noise trauma in a mammalian model of noise-induced hearing loss.