Objective To investigate the effects of miR-34a on proliferation and osteogenic differentiation of human periodontal stem cells.Methods Twenty healthy teeth that needed to be extracted for orthodontic treatment were collected.Human periodontal stem cells(hPDLSCs)were isolated and cultured in vitro,and miR-34a mimetics were constructed and transfected into hPDLSCs.The experimental groups were subsequently categorized into the mimics group(miR-34a overexpression group)and the mimics-NC group(control group without load).The transfection efficiency was assessed using real-time fluorescence quantitative PCR(qRT-PCR),while CCK-8 assays were used to evaluate the proliferation capacity of hPDLSCs post-transfection.Osteogenic differentiation of miR-34a-transfected hPDLSCs was induced,with samples being collected at day 0 and day 14 after the osteogenic induction.The expression level of Runx2-associated transcription factor 2(Runx2)was quantified via qRT-PCR,protein levels of Runx2-associated proteins were analyzed through Western blot,and mineralized nodule formation was examined using alizarin red staining.Results The expression level of miR-34a in the mimics group was significantly higher than that in the mimics-NC group(P<0.05).There was no significant difference in the value-added rate between the mimics group and the mimics-NC group on days 1～5(P>0.05),and the value-added rate between the mimics group and the mimics-NC group was significantly lower than that between the mimics-NC group and the mimics-NC group on days 5～11,and the difference was statistically significant.After the osteogenic induction,the mRNA expression level of Runx2 in the mimics group was higher than that in the mimics-NC group(P<0.05),and the expression level of Runx2 protein in the mimics group was also higher than that in the mimics-NC group(P<0.05),and there were more mineralized nodules in the mimics group than in the mimics-NC group after 14 days of osteogenic induction.Conclusion Under in vitro conditions,miR-34a inhibits the proliferative activity of hPDLSCs and promotes the osteogenic differentiation of human periodontal ligament stem cells.