Background: Glucocorticoid has been used extensively in clinical applications, because of its several pharmacologic actions, which include immunosuppression, anti-inflammation, anti-shock, and relief of asthma. However, the long-term or high-dose application of glucocorticoid can induce adverse effects such as osteoporosis, which is known in this case as glucocorticoid-induced osteoporosis (GIOP). It is a secondary osteoporosis that results in easy fracturing, and even disability. Therefore it became a thorny issue.
Methods: The rat model of glucocorticoid-induced osteoporosis (GIOP) was replicated to isolate BMSCs. Rats were assigned into four groups: normal, normal induction, GIOP, and GIOP induction. The growth cycle was monitored by using flow cytometry. Osteogenic differentiation was compared by using alkaline phosphatase (ALP) staining with a modified calcium cobalt method. The quantitative detection of osteoprotegerin and the receptor activator of nuclear factor kappa-B ligand (RANKL) was conducted by using enzyme-linked immunoassay. Finally, renal Klotho mRNA expression was assessed by using RT-PCR.
Results: BMSC proliferation was reduced in GIOP rats. The ALP-positive expression of normal BMSCs to the osteogenic induction solution was stronger than that of BMSCs from GIOP rats (P < 0.01). Osteoprotegerin expression was significantly higher in the normal induction group than in the normal, GIOP (P < 0.01), and GIOP induction groups (P < 0.05). RANKL expression was significantly higher in the normal induction group than in the other groups (P < 0.01) and significantly higher in the normal group than in the GIOP and GIOP induction groups (P < 0.01). RT-PCR analysis showed that renal Klotho mRNA expression was significantly reduced in the GIOP group compared with the normal group (P < 0.01).
Conclusion: BMSC proliferation, osteogenic differentiation, and reactive activity to an osteogenic inductor were reduced in GIOP rats. Klotho mRNA expression decreased during GIOP induction.