In vitro and in vivo induction of bone formation based on adeno-associated virus-mediated BMP-7 gene therapy using human adipose-derived mesenchymal stem cells.

Aim: To determine whether adeno-associated virus (AAV)-2-mediated, bone morphogenetic protein (BMP)-7-expressing human adipose-derived mesenchymal stem cells (ADMS) cells would induce bone formation in vitro and in vivo.

Methods: ADMS cells were harvested from patients undergoing selective suction-assisted lipectomy and transduced with AAV carrying the human BMP-7 gene. Non-transduced cells and cells transduced with AAV serotype 2 carrying the enhanced green fluorescence protein gene served as controls. ADMS cells were qualitatively assessed for the production of BMP-7 and osteocalcin, and subjected to alkaline phosphatase (ALP) and Chinalizarin staining. A total of 2.5 x 10(6) cells mixed with type I collagen were implanted into the hind limb of severe combined immune-deficient (SCID) mice and subjected to a histological analysis 3 weeks post implantation.

Results: Transfection of the ADMS cells achieved an efficiency of 99% at d 7. Transduction with AAV2-BMP-7 induced the expression of BMP-7 until d 56, which was markedly increased by d 7. The cells were positively stained for ALP. Osteocalcin production and matrix mineralization further confirmed that these cells differentiated into osteoblasts and induced bone formation in vitro. A histological examination demonstrated that implantation of BMP-7-expressing ADMS cells could induce new bone formation in vivo.

Conclusion: The present in vitro and in vivo study demonstrated that human ADMS cells would be a promising source of autologous mesenchymal stem cells for BMP gene therapy and tissue engineering.