Enhanced osteogenic activity of mesenchymal stem cells and co-modified BMP-2 and bFGF genes

We co-modified rat mesenchymal stem cells (rMSCs) with bone morphogenetic protein-2 (BMP-2) and basic fibroblast growth factor (bFGF) genes, and then evaluated their osteogenic activity in vitro and evaluated ectopic bone formation in vivo.

Nude mice (male, 20±2 g) were randomly divided into 2 groups: a control group (n=30) and a transfection group (n=30). In the control group, rMSCs+scaffold was implanted into the intramuscular pocket in the left femur, and BMP-2 gene modified rMSCs+scaffold was implanted into the intramuscular pocket in the right femur. In the transfection group, bFGF gene modified rMSCs+scaffold was implanted into the left femur, and BMP-2+bFGF gene modified rMSCs+scaffold was implanted into the right femur. Under anesthesia, an 8-mm incision was made over the lateral aspect of each femur and cell-scaffold composite was implanted into an intramuscular pocket created by blunt dissection. Samples taken at 3 months were stained. Sections were counterstained with hematoxylin. The relative capillary density was estimated by counting the capillary number and measuring the length of the capillaries in the defined area after image digitization.

Comparison with the BMP-2 group and bFGF group, the proliferation of the BMP-2+bFGF group was obviously enhanced (p<0.01). The modification could promote alkaline phosphatase activity in endochylema of MSCs in BMP-2+bFGF group. Osteocalcin secretion had obviously improved in the BMP-2+bFGF group compared with the BMP-2 group and the bFGF group (p<0.01). Histologic analysis of the stages of bone formation showed a more obvious scaffold substitution progress in the BMP-2+bFGF group.

Co-modification of rMSCs with BMP-2 and bFGF genes can promote the in vitro osteogenic activity of rMSCs and in vivo ectopic bone formation.