Gene-enhanced tissue engineering: Applications for bone healing using cultured periosteal cells transduced retrovirally with the BMP-7 gene

Periosteum has cell populations, including osteoprogenitor and chondroproge nitor cells, that can be grown in cell culture and form both bone and carti lage under appropriate conditions. The authors have shown previously that c ultured periosteal cells can be used in the tissue engineering of bone, and they demonstrated substantial bone formation in a rabbit cranial defect mo del. In the current study, principles of tissue engineering were combined w ith principles of gene therapy to produce cultured periosteal cells transdu ced retrovirally with the bone morphogenetic protein 7 (BMP-7) gene to be u sed in the treatment of bone defects. Human BMP-7 complementary deoxyribonu cleic acid was generated from a cell line using reverse transcription polym erase chain reaction and cloned into a retroviral vector plasmid. Retrovira l vector particles were then used to transduce New Zealand White rabbit per iosteal cells. Transduced periosteal cells demonstrated substantial product ion of both BMP-7 messenger ribonucleic acid by Northern blot analysis and BMP-7 protein by enzyme-linked immunosorbent assay. These cells were then s eeded into polyglycolic acid (PGA) matrices and used to repair critical-siz e rabbit cranial defects. At 12 weeks, defect sites repaired with BMP-7-tra nsduced periosteal cells/PGA had significantly increased radiographic and h istological evidence of bone repair compared with those defect sites repair ed with negative control-transduced cells/PGA, nontransduced cells/PGA, PGA alone, or unrepaired defects. Thus, this study demonstrates successfully a tissue engineering approach to bone repair using genetically modified cell s.