Carbon monoxide releasing molecule‑3 promotes the osteogenic differentiation of rat bone marrow mesenchymal stem cells by releasing carbon monoxide

Stem cell‑based therapies are promising strategies to stimulate bone regeneration. Carbon monoxide releasing molecule‑3 (CORM‑3) exhibits multiple regulatory effects in a number of cells by releasing carbon monoxide (CO). The present study aimed to investigate the influence of CORM‑3 on the osteogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs). BMSCs were divided into five groups: A CORM‑3‑osteogenic group, in which cells were pretreated with CORM‑3 and subjected to osteogenic differentiation induction using osteogenic medium; an osteogenic group, in which cells were cultured in osteogenic medium; a degassed CORM‑3‑osteogenic group, in which cells were pretreated with degassed CORM‑3 and subjected to osteogenic differentiation induction; a CORM‑3 group, in which cells were cultured in control medium containing CORM‑3; and a control group, in which cells were cultured in control medium alone. The osteo‑specific mRNA and protein expression of runt‑related transcription factor 2 (Runx2), osteocalcin (OCN) and osteopontin (OPN) were assessed using reverse transcription‑quantitative polymerase chain reaction and western blot analysis. Alkaline phosphatase (ALP) activity was also examined and mineralization was detected using alizarin red staining. Levels of Runx2, OCN and OPN mRNA and protein in the CORM‑3‑osteogenic group were significantly increased compared with the osteogenic group (P<0.05), with the exception of OCN protein levels on day 3. The mRNA and protein expression of Runx2, OCN and OPN in the degassed CORM‑3‑osteogenic and osteogenic groups were similar. In addition, the mRNA and protein expression of Runx2, OCN and OPN in the CORM‑3 and control group were similar. ALP activity in the CORM‑3‑osteogenic group was increased from day 3 and remained significantly higher compared with all other groups on days 3, 5 and 7 (P<0.05). Additionally, the results indicated that the optical density value of alizarin red staining in the CORM‑3‑osteogenic group was significantly increased compared with the other groups (P<0.05). Therefore, the present study demonstrated that CORM‑3 may promote the osteogenic differentiation of BMSCs by releasing CO.