In vitro effect of altering potassium concentration in artificial endolymph on apoptosis and ultrastructure features of olfactory bulb neural precursor cells

Abstract

Transplantation of neural stem cells (NSCs) into the cochlea to replace irreversibly damaged sensory epithelia is a potentially valuable remedy for hearing loss. Several mammalian stem cell lines are being successfully transplanted into, or migrated to, the endolymph (EL) fluids environment of the cochlea. However, the survival rate of transplanted cells is relatively low. This study focused on the effect of altering the potassium (K+) concentration of artificial EL on cell survival and apoptosis of olfactory bulb neural precursor cells (OB NPCs) in vitro. OB NPCs were prepared and placed in media for 24h, supplemented either with artificial EL, or artificial EL-like solutions of different K+ concentrations. Survival, apoptotic features and ultrastructural changes in the cells are noted. Artificial EL-like solutions, especially with K+ concentrations of 50mM or more, resulted in a series of necrotic or apoptotic events. Lower K+ concentrations (30mM) decreased apoptosis and necrosis, improving the survival rate of cultured NPCs. Thus, it is conceivable that the external K+ concentration in EL is a key environmental factor to regulate the survival of exogenous stem cells.