Stem cell transplantation in noise induced hearing loss

ObjectiveTo investigate efficacy of bone marrow stem cell implantation in rehabilitation of noise induced hearing loss in rats.Materials and methodsHearing loss was induced in male rats by a continuous wide-band noise (8-16 kHz/120 dB/120 min). Ten microliter of stem cell containing solution was injected by a Hamilton syringe with 30G needle through the round window membrane. Hearing status was examined by, distortion product otoacoustic emissions using DP-OAE. Animals were studied in 4 different groups: (1) Normal hearing animals, undergoing sham surgery (no injection done, only round window membrane ruptured and sealed). (2) Deaf animals, undergoing sham surgery. (3) Deaf animals undergoing surgery and injection of solvent (artificial perilymph). (4) Deaf animals undergoing surgery and injection of artificial perilymph containing BMSCs.ResultsDP-Gram in rat with normal hearing undergoing sham surgery show that procedure has neither negative impact on normal cochlear nor on deaf cochleas. No significant difference (p = 0.25) between ears excludes artificial perilymph as a confounding factor. There is no significant difference between ears in animals receiving BMSCs.ConclusionsImplanted cells with normal histologic structures have no physiologic function and hearing rehabilitation. Further studies by monitoring the survival of these cells with histologic and appropriate biomarkers will help to investigate differentiation process of these cells.