The effect of TRPM7 suppression on the proliferation, migration and osteogenic differentiation of human dental pulp stem cells

Abstract

Aim: To investigate the role of the Ca(2+) -Mg(2+) ion channel TRPM7 in the proliferation, migration and osteogenic differentiation of human dental pulp stem cells (hDPSCs).

Methodology: Immunohistochemistry was used to localize expression of TRPM7 in human dental pulp tissues and in cultured hDPSCs. Isolated hDPSCs were infected with recombinant lentiviruses expressing short hairpin RNA (shRNA) specific for TRPM7, or control shRNA, in order to suppress TRPM7 mRNA expression and investigate its functional role. The proliferation of the shRNA-infected hDPSCs was evaluated using both an MTT assay to measure viable cell numbers and cell cycle analysis. Cell migration was assessed using a transwell assay. The dynamic mRNA expression of TRPM7 during osteogenic differentiation of hDPSCs and the effect of shRNA specific for TRPM7 on hDPSC osteogenic differentiation were evaluated by real-time PCR.

Results: TRPM7 expression was widespread in human dental pulp tissue and was detected mainly in the cytomembrane and cytoplasm of hDPSCs. Suppression of TRPM7 inhibited both the proliferation and the migratory capacity of hDPSCs. TRPM7 mRNA expression was elevated during osteogenic differentiation of hDPSCs. TRPM7-specific shRNA inhibited osteogenic differentiation of hDPSCs, with downregulated mRNA expression of the osteogenic markers alkaline phosphatase (ALP), dentine sialophosphoprotein (DSPP), bone sialoprotein (BSP), runt-related transcription factor (RUNX2) and osterix (OSX).

Conclusions: TRPM7 was involved in the regulation of hDPSC proliferation, migration and osteogenic differentiation and may play a role in the dental pulp repair process.

Keywords: TRPM7; human dental pulp stem cells; migration; osteogenic differentiation; proliferation.