Role of Stem Cells in Treatment of Sensorineural Hearing Loss

Abstract Background More than 5% of the world population lives with a hearing impairment. The main factors responsible for hearing degeneration are ototoxic drugs, aging, continued exposure to excessive noise and infections. The pool of adult stem cells in the inner ear drops dramatically after birth, and therefore an endogenous cellular source for regeneration is absent. Objectives The purpose of this study is to evaluate the role of mesenchymal stem cells in the treatment of severe to profound sensorineural hearing loss as regarding permanent regeneration of the auditory hair cells. Materials and Methods It is a prospective study which was performed in the period of May 2019 till December 2019 and encountered 40 adult male guinea pigs, aged 6 to 8 weeks (body weight 250-500 gram). 30 guinea pigs had been subjected to right side intratympanic injection of Garamycin sulphate to induce sensorineural hearing loss then the 30 animals were subdivided after that into 2 groups; Group A (15 animals) were treated by mesenchymal stem cells implantation in right inner ear cochlea and group B (15 animals) left untreated and the remaining 10 guinea pigs; Group C left normally as a control group. Results As respect to histopathological examination, 100% of animals in group B (n = 15) expressed severe degenerative changes in the peripheral organs. The outer hair cells showed severe destruction with individual loss of the inner hair cells. Also the supporting cells of Corti’s organ presented severe necrosis which was more relevant in the basal turns. We used the bone marrow differentiated MSCs to evaluate their potency in regeneration of the damaged and lost sensorineural elements in gentamicin injured cochlea. In group A (n = 15) 9 out of 15 (60%) expressed profound regeneration and 4 out of 15 (26.66%) expressed early regenerative changes, while 2 animals (13.33%) expressed less degenerative changes which impacted by gentamicin. Conclusion Stem cell transplantation is a promising approach for hearing loss therapy. The choice of stem cell type for transplantation plays a crucial role in the outcome. MSCs are multipotent cells that can be isolated from adult bone marrow and can be induced to differentiate into a variety of tissues in vitro and in vivo.