Small Molecule GSK-3 Inhibitors Safely Promote the Proliferation and Viability of Human Dental Pulp Stem Cells—In Vitro

Small molecules have demonstrated promising results as successful alternatives to growth factors. In this study, focus was drawn to CHIR99021 and tideglusib as GSK-3 inhibitors known for their anti-inflammatory and regenerative potential. The effect of both tideglusib and CHIR99021 on the proliferation, viability, and stemness of human dental pulp stem cells (hDPSCs) was investigated to assess their possible role in regenerative dentistry. Briefly, hDPSCs were isolated from sound premolars extracted for orthodontic purposes. Cytotoxicity and proliferation assessment were performed via cell counting kit-8 followed by flow cytometric analysis of apoptotic marker ANNEXIN V. The effect of both small molecules on the stemness of hDPSCs was analyzed by qRT-PCR. Both tideglusib and CHIR99021 were proven to be safe on hDPSCs. The tideglusib concentration that resulted in higher viable cells was 100 nM, while the concentration for CHIR99021 was 5 nM. Both small molecules successfully induced cellular proliferation and demonstrated minimal expression of ANNEXIN V, indicative of the absence of cellular apoptosis and further confirming their positive effect on proliferation. Finally, both small molecules enhanced stemness markers expression as evidenced by qRT-PCR, which, again, highlighted the positive effect of both tideglusib and CHIR99021 on safely promoting the proliferation of hDPSCs while maintaining their stemness.