Effects of Dexamethasone Withdrawal on Proliferation and Differentiation of Mesenchymal Stem Cells

Song, In Hwan; Kim, Joo Young; Sung, Eon Gi; Kim, Seong Yong

Abstract

With potential of differentiation into many different lineages, mesenchymal stem cells have been candidate on cell therapy for recovery of injured body. Dexamethasone plays important role in mesenchymal stem cells differentiation and can derived into osteoblast, chondrocytes, adipocytes, and fibroblasts in vitro. There has been many studies on effect of dexamethasone for differentiation of MSCs with continuous exposure, but little work on the effect for deprivation during this progress. This result will be an important guild line for evaluation of transplanted MSCs after pretreatment with dexamethasone. In this study, dexamethasone was deprived by weekly withdrawal schedule in the process of differentiation induction by dexamethasone. During this period, expression of APase was evaluated as mark of osteoblast differentiation and number of BrdU incorporated cells were counted as index of proliferation. APase level of one or two week exposure groups decreased immediately after deprivation of dexamethasone and approached to control level at 4~5 week but three or four week exposure groups reached peak level at 3th week then decreased but still remained higher level than other groups. Dexamethasone exposure groups showed the trend of decreased in mitotic activity compared to control, but there were significant increase in mitosis after deprivation of dexamethasone. This pattern prominent in 6, 9, 12, 15 day exposure groups. These results showed that the effect of dexamethasone derived MSCs differentiation into osteoblasts is faint without full enough exposure and the period should be more than three weeks.