hBMP-7 induces the differentiation of adipose-derived mesenchymal stem cells into osteoblast-like cells.

The aim of this study was to investigate the differentiation potential of adipose-derived mesenchymal stem cells (ADMSCs) into osteoblasts by human bone morphogenetic protein-7 (hBMP-7) induction. ADMSCs were isolated from the subcutaneous adipose tissue of a rabbit, and then transfected with the pcDNA3.1 vector alone and pcDNA3.1-hBMP-7 (hBMP-7), respectively. Untransfected ADMSCs were used as the control group. After transfection, the morphology and green fluorescent protein (GFP) fluorescence intensity of ADMSCs were observed by fluorescent microscopy. The 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide assay was performed to detect the growth of ADMSCs at 1, 3, and 5 days, respectively. Transmission electron microscopy was performed to observe the ultrastructural morphology of ADMSCs. In addition, ADMSCs were stained with quinalizarin and toluidine blue to reflect the content of osteoblasts and chondrocytes, respectively. Finally, the expression of collagen I and osteocalcin in ADMSCs was detected by western blot. ADMSCs were successfully isolated. Obvious GFP fluorescence and high expression of hBMP-7 demonstrated the successful transfection of hBMP-7. Specific morphological characters with a metabolically active ultrastructure were exhibited on the ADMSCs transfected with hBMP- 7. In addition, the growth rate of ADMSCs transfected with hBMP-7 was significantly higher than that of the cells in the vector and control groups. Successfully induced osteoblast-like cells were identified by an obvious erythrine area and high expression of collagen I and osteocalcin in ADMSCs transfected with hBMP-7. Thus, ADMSCs can be successfully differentiated into osteoblast-like cells by hBMP-7 induction in vitro.

Adeno-associated virus-mediated BMP-7 and SOX9 in vitro co-transfection of human degenerative intervertebral disc cells.

Bone morphogenetic protein-7 (BMP-7) and SOX9 are important transcription factors in chondrogenesis. In this study, we examined the biological function of the adeno-associated virus (AAV)-mediated BMP-7 and SOX9 double gene in vitro co-transfection of nucleus pulposus cells of human degenerative intervertebral disc. Human intervertebral disc nucleus pulposus cells were cultured in vitro and subcultured for 5 generations. Using rAAV-BMP-7 and rAAV-SOX9 AAV2-type AAV viruses, the cells were divided into 4 groups: blank normal, BMP-7 transfection, SOX9 transfection, and BMP-7 and SOX9 co-transfection. After 48 h, expression of type II collagen and its mRNA in nucleus pulposus cells was determined. The expression of type II collagen in BMP-7 transfection, SOX9 transfection, and co-transfection groups was up-regulated to varying degrees compared to the blank control group. The type II collagen mRNA level expression in the co-transfection group was significantly higher than in other groups (P < 0.05). AAV-mediated BMP-7 and SOX9 in vitro co-transfection can promote the synthesis of type II collagen in nucleus pulposus cells in the human degenerative intervertebral disc. Double-gene therapy has a synergistic effect in the treatment of intervertebral disc degeneration.

Expression, purification, bioactivity, and partial characterization of a recombinant human bone morphogenetic protein-7 produced in human 293T cells.

Bone morphogenetic protein-7 (BMP-7) is a secreted multifunctional growth factor of the TGF-beta superfamily, which is predominantly known for its osteoinductive properties and emerging potential for treatment of kidney diseases. The mature 34-38 kDa disulfide-linked homodimer protein plays a key role in the differentiation of mesenchymal cells into bone and cartilage. In this study, the full-length sequence of hBMP-7 was amplified and, then, cloned, expressed, and purified from the conditioned medium of 293T cells stably transfected with a lentiviral vector. The mature protein dimer form was properly secreted and recognized by anti-BMP-7 antibodies, and the protein was shown to be glycosilated by treatment with exoglycosidase, followed by western blotting. Moreover, the activity of the purified protein was demonstrated both in vitro, by alkaline phosphatase activity in C2C12 cells, and in vivo by induction of ectopic bone formation in Balb/c Nude mice after 21 days, respectively. This recombinant protein platform may be very useful for expression of different human cytokines and other proteins for medical applications.

Effects of low-level laser therapy on human osteoblastic cells grown on titanium.

The aim of this study was to investigate the effects of low-level laser therapy (LLLT) by using gallium aluminum arsenide (GaAlAs) diode laser on human osteoblastic cells grown on titanium (Ti). Osteoblastic cells were obtained by enzymatic digestion of human alveolar bone and cultured on Ti discs for up to 17 days. Cells were exposed to LLLT at 3 J/cm2 (wavelength of 780 nm) at days 3 and 7 and non-irradiated cultures were used as control. LLLT treatment did not influence culture growth, ALP activity, and mineralized matrix formation. Analysis of cultures by epifluorescence microscopy revealed an area without cells in LLLT treated cultures, which was repopulated latter with proliferative and less differentiated cells. Gene expression of ALP, OC, BSP, and BMP-7 was higher in LLLT treated cultures, while Runx2, OPN, and OPG were lower. These results indicate that LLLT modulates cell responses in a complex way stimulating osteoblastic differentiation, which suggests possible benefits on implant osseointegration despite a transient deleterious effect immediately after laser irradiation.