Objective To investigate the effects of crocin on regulating the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK) signaling pathway in lipopolysaccharide (LPS)-induced inflammatory injury and osteogenic differentiation of human dental pulp stem cells (hDPSCs).

Methods The hDPSCs were divided into blank group, crocin-alone treatment group, LPS group, low-concentration crocin group, high-concentration crocin group, and high-concentration crocin+ERK/MAPK inhibitor group, and were treated with corresponding methods respectively. Cell proliferation was detected using the CCK-8 assay. Alkaline phosphatase (ALP) activity was measured using an ALP activity detection kit. Mineralized nodule formation was detected by alizarin red S staining.The expression of inflammatory cytokines interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α) was detected by enzyme-linked immunosorbent assay (ELISA). The expression of osteogenic differentiation-related factors Runt-related transcription factor 2 (RUNX2), osteocalcin (OCN), osteopontin (OPN), and ERK/MAPK pathway proteins was detected by Western blot.

Results Compared with the LPS group, the proliferation ability, ALP activity, and mineralized nodule formation ability of hDPSCs in the low- and high-concentration crocin groups were enhanced. The expression levels of IL-1β, IL-6 and TNF-α were decreased, while the protein expressions of RUNX2, in the high-concentration crocin group were more significant than those in the low-concentration crocin group (P < 0.05). Compared with the high-concentration crocin group, the high-concentration crocin+ERK/MAPK inhibitor group could reverse the effects of high-concentration crocin on hDPSC proliferation, inflammatory injury, and osteogenic differentiation (P < 0.05).

Conclusion Crocin may promote the proliferation of LPS-induced hDPSCs, alleviate inflammatory injury, and promote osteogenic differentiation by activating the ERK/MAPK signaling pathway.