Transient receptor potential melastatin 4 channel is required for rat dental pulp stem cell proliferation and...

Investigate the role of the transient receptor potential melastatin 4 (TRPM4) channel in rat dental pulp stem cell (DPSC) proliferation and survival.

Immunofluorescence and FACS analysis were used to detect the stem cell marker CD90. Alizarin Red S and Oil Red O staining were used to identify osteoblast and adipocyte differentiation, respectively. To characterize TRPM4, patch-clamp recordings were obtained from single cells in the whole-cell configuration mode. The significance of TRPM4 for proliferation and survival was examined with 9-phenanthrol, a TRPM4 inhibitor during a 96-hour period of culture. Real-time Ca²⁺ imaging analysis with Fura-2AM was used to investigate the impact of TRPM4 on intracellular Ca²⁺ signals.

DPSCs were CD90-positive and differentiated into osteoblasts. Patch-clamp recordings revealed currents typical of TRPM4 that were Ca²⁺ -activated, voltage-dependent and Na⁺ -conducting. Inhibition of TRPM4 resulted in a significant reduction in the cell population after a 96-hr period of culture and transformed the biphasic pattern of intracellular Ca²⁺ signalling into sustained oscillations.

Rat DPSCs have stem cell characteristics and functional TRPM4 channels that are required for proliferation and survival. These data suggest that the shape and frequency of intracellular Ca²⁺ signals may mediate stem cell proliferation and survival.