Osteogenic effect of crocin in human periodontal ligament stem cells via Wnt/β-catenin signaling

Objectives: Crocin is a major class of medicinal components in saffron. This study aimed to determine whether crocin directly promotes the proliferation and osteogenic differentiation of human periodontal ligament stem cells (PDLSCs) in vitro and in vivo.Materials and Methods: CCK8 cell proliferation assay, reverse transcription quantitative polymerase chain reaction (RT-qPCR), Western blot analysis and Alizarin Red staining were performed in PDLSCs using crocin as a stimulant. DKK1 was used to selectively inhibit Wnt/beta-catenin signaling, and Western blotting was performed to investigate the underlying mechanism. The PDLSCs were mixed with calcium phosphate cement and implanted into nude mice subcutaneously to study the effect of crocin on PDLSC osteogenic differentiation in vivo.Results: The CCK-8 assay showed that crocin did not promote the proliferation of PDLSCs. Treatment with 400 mu M crocin significantly promoted PDLSC mRNA levels of ALP, COL1 and OCN; RUNX2 and BMP2 protein expression; mineralized nodule formation in vitro and in vivo; and ALP activity in tissues in vivo. In addition, crocin significantly promoted the phosphorylation of beta-catenin and cyclin D1. DKK1 inhibits Wnt/beta-catenin activation and partially reverses crocin-mediated promotion of PDLSC osteogenic differentiation.Conclusion: Crocin may contribute to the regeneration of periodontal bone tissue.