Rapid differentiation of human dental pulp stem cells to neuron-like cells by high K⁺ stimulation

As human-origin cells, human dental pulp stem cells (hDPSCs) are thought to be potentially useful for biological and medical experiments. They are easily obtained from lost primary teeth or extracted wisdom teeth, and they are mesenchymal stem cells that are known to differentiate into osteoblasts, chondrocytes, and adipocytes. Although hDPSCs originate from neural crest cells, it is difficult to induce hDPSCs to differentiate into neuron-like cells. To facilitate their differentiation into neuron-like cells, we evaluated various differentiation conditions. Activation of K⁺ channels is thought to regulate the intracellular Ca²⁺ concentration, allowing for manipulation of the cell cycle to induce the differentiation of hDPSCs. Therefore, in addition to a conventional neural cell differentiation protocol, we activated K⁺ channels in hDPSCs. Immunocyto-chemistry and real-time PCR revealed that applying a combination of 3 stimuli (high K⁺ solution, epigenetic reprogramming solution, and neural differentiation solution) to hDPSCs increased their expression of neuronal markers, such as β3-tubulin, postsynaptic density protein 95, and nestin within 5 days, which led to their rapid differentiation into neuron-like cells. Our findings indicate that epigenetic reprogramming along with cell cycle regulation by stimulation with high K⁺ accelerated the differentiation of hDPSCs into neuron-like cells. Therefore, hDPSCs can be used in various ways as neuron-like cells by manipulating their cell cycle.