In Vitro Survival of Human Mesenchymal Stem Cells is Enhanced in Artificial Endolymph with Moderately High Concentrations of Potassium

While mesenchymal stem cells (MSCs) are promising candidates for inner ear hair cell regeneration, to date, there have been no convincing reports indicating whether MSCs can survive in the cochlea for more than a few weeks, as the high levels of potassium (K+) in the endolymph (EL) are thought to be toxic to transplanted stem cells. For conditioning the EL for MSC transplantation, we conducted this in vitro study to examine the effects of artificial EL with altered K+ concentration levels, in the range of 5–153.8 mM, on proliferation, apoptosis, and morphological changes in MSCs derived from various human tissues. Our findings demonstrate that altering the K+ concentration in artificial EL could significantly influence the survival of MSCs in vitro. We discovered that K+ concentrations of 55–130 mM in artificial EL could enhance the survival of MSCs in vitro. However, MSCs exhibited reduced proliferation regardless of K+ concentration.