The use of gene-modified bone marrow mesenchymal stem cells for cochlear cell therapy

The aim of this study was to investigate the potential of using bone marrow mesenchymal stem cells (BMSCs) for treatment of inflammation and autoimmune sensorineural hearing loss.

Fifty-five immunized guinea pigs were divided into five groups. Group A received BMSCs expressing IL-4, group B received BMSCs expressing an empty carrier vector, group C received recombinant lentivirus expressing IL-4, group D received recombinant lentivirus expressing an empty carrier vector, and group E received phosphate-buffered saline. Auditory function was monitored using brain stem responses (ABRs) to evaluate the auditory changes. The distribution of implanted BMSCs in the inner ear was estimated using fluorescence microscopy. The distribution and expression of IL-4 gene products in the inner ear were detected via immunohistochemistry.

After transplantation, the ABR III wave threshold decreased significantly in BMSCs expressing exogenous IL-4 group (group A), BMSCs expressing empty carrier vector group (group B), and recombinant lentivirus expressing IL-4 group (group C) (P < 0.001), which means the auditory functions of the experimental guinea pigs were improved. Further statistical analysis revealed that BMSCs expressing exogenous IL-4 group (group A) and BMSCs expressing empty carrier vector group (group B) were able to improve the auditory function more obviously (P < 0.05). Lentivirus-infected BMSCs were able to migrate to the inner ear. Fluorescence-positive BMSCs were scattered in the scala tympani and vestibule.

These results demonstrated that BMSCs expressing exogenous IL-4 successfully migrated into the inner ear in an in vitro study. BMSCs expressing exogenous IL-4 and BMSCs can be used to treat inflammatory injury in autoimmune inner ear diseases.