Adipose-derived stem cells combined with a demineralized cancellous bone substrate for bone regeneration.

Mesenchymal stem cells (MSCs) isolated from cadaveric adipose tissue can be obtained in large quantities, and have been reported in the literature to be capable of inducing bone formation in vivo and ex vivo.( 1-6 ) The hypothesis tested whether a demineralized cancellous bone matrix (DCBM) can provide an effective substrate for selection and retention of stem cells derived from the stromal vascular fraction (SVF) of adipose. Human cadaveric adipose tissue was recovered from a donor and digested. The resulting SVF-containing MSCs were seeded onto the demineralized bone allografts, after which the nonadherent cells were washed off. The MSCs were characterized using a flow cytometer and tri-lineage differentiation (osteogenesis, chondrogenesis, and adipogenesis) in vitro. The stem cell-seeded allografts were also characterized for cell number, adherence to the DCBM, osteogenic activity (alkaline phosphatase and Alizarin Red staining), and bone morphorgenic protein (BMP) quantity. Flow cytometry identified a mean total of 7.2% MSCs in SVF and 87.2% MSCs after culture. The stem cells showed the capability of differentiating into bone, cartilage, and fat. On the 21 stem cell-seeded bone allografts, there were consistent, attached, viable cells (100,744±22,762 cells/cube). An assessment of donor age, gender, and body mass index revealed no significant differences in cell numbers. Enzyme-linked immunosorbent assay revealed the presence of BMP-2 and BMP-7. In conclusion, this bone graft contains three key elements for bone regeneration: adhered osteogenic stem cells, 3D osteoconductive bone scaffold, and osteoinductive BMP signal. It therefore has the potential to be effective for bone regeneration.