Objectives: To confirm if a population of stem cells that can differentiate along the osteoblastic lineage could be isolated from human adipose tissue and to determine if the regulating factors that are normally responsible for bone formation and development also play roles for its osteogenesis.
Methods: Adipose tissues of heathy adults were obtained by liposuction. Human adipose tissue-derived stromal cells(hADSCs) were isolated from these adipose tissues. hADSCs were maintained and passaged in DMEM containing 10% FBS. Osteogenic differentiation of hADSCs was induced by osteogenic medium(OM) containing 100nM dexamethasone(DEX) and 10 mM b-glycerophosphate(b-GP) and 200mM of ascorbic acid(AA). The differentiation of hADSCs into osteoblastic lineage was identified by alkaline phosphatase(ALP) staining, von Kossa staining and RT-PCR assays for mRNA expression of osteogenesis related genes like type I Collagen, bone sialoprotein(BSP), osteocalcin(OC), bone mophogenetic protein-2(BMP-2), bone mophogenetic protein-4(BMP-4), bone mophogenetic protein-6(BMP-6), bone mophogenetic protein-7(BMP-7), Core binding factor a1(Cbfa1), osterix(Osx), LIM mineralization Proteins(LMPs).
Results: hADSCs can differentiate along osteoblastic lineage induced by osteogenic medium containing DEX, b-GP, and AA. Not only can the differentiated cells be mineralized in vitro, but also they can express osteoblast related markers such as ALP, type I Collagen, BSP, and OC. The transcription factors Cbfa1 and Osx, growth factor BMP-6, and intracellular regulating factor LMP-1 were upregulated during the osteoblastic differentiation of hADSCs, but the expression of BMP-2, BMP-4, BMP-7, LMP-2 or 3 were not turned on during the whole induction course.
Conclusions: hADSCs are capable of differentiating toward the osteoblastic lineage in vitro. Cbfa1, Osx, BMP-6, LMP-1 are associated with the regulation of osteoblastic differentiation of hADSCs.