Comparison of the effect of crocin and crocetin, two major compounds extracted from saffron, on osteogenic differentiation of mesenchymal stem cells

Background: Mesenchymal stem cells (MSCs) can be considered as an effective tool for bone regeneration. It is variable to find new agents with low cytotoxicity and high efficiency for induction of MSCs into osteoblasts. In the present study, the ability of crocin and crocetin, extracted from saffron, to induce cell differentiation of rat bone marrow-derived mesenchymal stem cells (rat BM-MSCs) into osteoblasts was compared. Methods: Bone marrow cells were isolated from rat's femurs and tibias. Cytotoxic effect of crocin and crocetin was assayed using MTT test and IC50 was calculated from the results. Osteogenic ability of crocin and crocetin at non-toxic concentrations has been evaluated and compared to osteogenic standard medium after 7 and 21 days, using alizarin red (ALZ) staining and alkaline phosphatase (ALP) activity. Furthermore, ALP mRNA expression has been analyzed by real time RT-PCR. Results: Crocetin showed more cytotoxic effect on stem cells compared to crocin. Non-toxic concentrations (12.5, 25 and 50 mu M) were selected for other experiments. Crocin and crocetin (25 mu M) increased ALZ intensity (4.2 +/- 0.12 and 3.8 +/- 0.16 folds, respectively), ALP activity (46.4 +/- 5.8 and 43.2 +/- 1.9 folds, respectively) and ALP mRNA expression (14.27 +/- 1.98 and 8.4 +/- 1.17 folds, respectively) in MSCs after day 21 compared to negative control. Although, crocin was more effective than crocetin, but this difference was not significant. Conclusion: According to these findings, crocin and crocetin could effectively enhance osteogenic differentiation of MSCs and can be considered as safe therapeutic agents in clinical applications.