Is 1, 25-dihydroxyvitamin D_3 an ideal substitute for dexame- thasone for inducing osteogenic differentiation of human adipose tissue-derived stromal cells in vitro?

摘要

Background Human adipose tissue-derived stromal cells (hADSCs) can be induced to differentiate along an osteoblastic lineage under stimulation of dexamethasone (DEX). Recent studies, however, have questioned the efficacy of glucocorticoids such as DEX in mediating the osteogenesis process of skeletal progenitor cells and processed lipoaspirate cells. Is it possible to find a substitute for DEX? Therefore, this study was designed to investigate osteogenic capacity and regulating mechanisms for osteoblastic differentiation of hADSCs by comparing osteogenic media (OM) containing either 1, 25-dihydroxyvitamin D_3 (VD) or DEX and determine if VD was an ideal substitute for DEX as an induction agent for the osteogenesis of hADSCs. Methods Osteogenic differentiation of hADSCs was induced by osteogenic medium (OM) containing either 10 nmol/L VD or 100 nmol/L DEX. Differentiation of hADSCs into osteoblastic lineage was identified by alkaline phosphatase (ALP) staining, von Kossa staining, and reverse transcription-polymerase chain reaction assays for mRNA expression of osteogenesis-related genes such as type Ⅰ collagen (COL Ⅰ), bone sialoprotein (BSP), osteocalcin (OC), bone morphogenetic protein (BMP)-2, BMP-4, BMP-6, BMP-7, runt-related transcription factor 2/core binding factor α1 (Runx2/Cbfa1), osterix (Osx), and LIM mineralization protein-1 (LMP-1). Results von Kossa staining revealed that the differentiated cells induced by both VD and DEX were mineralized in vitro. They also expressed osteoblast-related markers, such as ALP, COL Ⅰ, BSP, and OC. Runx2/Cbfa1, Osx, BMP-6, and LMP-1 were upregulated during VD and DEX-induced hADSC osteoblastic differentiation, but BMP-4, BMP-7 were not. BMP-2 was only expressed in VD-induced differentiated cells. Conclusions VD or DEX-induced hADSCs differentiate toward the osteoblastic lineage in vitro. Runx2/Cbfa1, Osx, BMP-2, BMP-6, and LMP-1 are involved in regulating osteoblastic differentiation of hADSCs, but BMP-4, BMP-7 are not. VD, but not DEX, induces expression of BMP-2 during osteogenic induction of hADSCs. VD is an ideal substitute for DEX for osteogenic induction of hADSCs.