Enhanced osteoinduction by mesenchymal stem cells transfected with a fiber-mutant adenoviral BMP2 gene

Bone regeneration therapy using mesenchymal stem cells (MSCs) is beginning to come into clinical use. To overcome the difficulty of healing large bone defects, we previously reported the efficacy of using rat mesenchymal stem cells (rMSCs) carrying a modified adenoviral vector (Adv-F/RGD) with an RGD-containing peptide in the HI loop of the fiber knob domain of adenovirus type 5 (Ad5).

Firstly, we evaluated the transduction efficiency of Adv-F/RGD into bone-marrow-derived human MSCs (hMSCs) using a beta-galactosidase chemiluminescent assay. Next, we evaluated whether the vector AxCAhBMP2-F/RGD carrying the human bone morphogenetic protein 2 (BMP2) gene could enhance the osteogenic activity of hMSCs in vitro and in vivo (in an ectopic model). In the ectopic model, transduced hMSCs, hMSCs in the presence of recombinant human BMP2 (rhBMP2) or hMSCs alone were implanted into a subcutaneous site of nude mice. We also applied this vector system to an orthotopic model (large bone defect model) using rMSCs.

The transduction efficiency of Adv-F/RGD into hMSCs was increased 10-fold over the vector containing the wild-type fiber (Adv-F/wt), as assessed by a beta-galactosidase chemiluminescent assay. AxCAhBMP2-F/RGD increased the osteogenic activity of hMSCs in vitro. In the ectopic model, AxCAhBMP2-F/RGD-transduced hMSCs were found to induce new bone at 1 week after transplantation, and a greater quantity of new bone was formed than in other groups. Similarly, AxCAhBMP2-F/RGD-transduced rMSCs induced a greater quantity of new bone than other groups (AxCAhBMP2-F/wt-transduced rMSCs, rMSCs in the presence of rhBMP2, rMSCs alone, or scaffolds alone) in the orthotopic model.

These data suggest that Adv-F/RGD is useful for introducing foreign genes into MSCs and that it will be a powerful gene therapy tool for bone regeneration and other tissue-engineering applications.