Transient Production of Bone Morphogenetic Protein 2 by Allogeneic Transplanted Transduced Cells Induces Bone Formation

Abstract

The aim of this study was to evaluate the use of transplantation of genetically modified allogeneic cells as a method to induce bone formation. In this study, we infected a murine osteoprogenitor cell line with a retroviral vector containing the human bone morphogenic protein 2 (BMP2) gene. Transduced cells exhibited more alkaline phosphatase activity than cells treated with any of the tested doses of recombinant human BMP2 protein (rhBMP2). The transduced cells were suspended in a collagen solution and injected into the quadriceps muscle in immunocompetent outbred mice. Radiographic and histological examinations demonstrate abundant ectopic bone formation in 85% of the transplanted animals (n = 13). PCR and Southern blot analysis for the puromycin resistance gene revealed that the transplanted cells were detectable for up to 1 week, but not at later time points. None of the animals developed tumors. Our results suggest that allogeneic BMP2-expressing transduced cells may have therapeutic potential for enhancing new bone formation. This model also provides a simple, inexpensive, and sensitive assay for evaluating in vivo the osteoinductive potentials of secreted proteins without the requirement of protein purification or the use of immunodeficient animals.

Osteoinduction by ex vivo adenovirus-mediated BMP2 delivery is independent of cell type

“…The cells, once transduced with Ad-BMP2 act primarily as a source of local BMP2, regardless of their osteogenic potential. Similarly, Engstrand et al 7 have recently demonstrated that retrovirally transduced W20-17 cells, a mouse bone marrow cell line, showed significant bone formation; however, the cells were rapidly cleared even in the presence of a collagen carrier.…”

“…[1][2][3][4][5][6][7][8] Localized delivery of cells transduced ex vivo with adenoviral vectors encoding bone morphogenetic proteins (BMPs) has proven successful in induction of new bone formation in hetero-and orthotopic locations. Although safe and efficacious gene-based bone induction systems have yet to be developed, the adenoviral delivery of BMP offers the potential of rapidly achieving local effective concentrations of the protein to induce bone formation.…”

Ex vivo gene therapy with stromal cells transduced with a retroviral vector containing the BMP4 gene completely heals critical size calvarial defect in rats

“…Although there are several studies which have shown evidence for skeletal regeneration in vivo using ex vivo modified stromal cells, myoblasts, or fibroblasts, 10,15,16,22,24,25 our study is unique in that it provides quantitative data on the extent of healing by valid bone density measurements. Furthermore, our data demonstrate that the healing of a critical calvarial defect is dependent on the time of exposure, as well as the number of BMP4-expressing stromal cells implanted.…”

Bone regeneration in critical size defects by cell-mediated BMP-2 gene transfer: a comparison of adenoviral vectors and liposomes

“…Regional gene transfer may therefore provide a viable alternative to protein therapy. Recently, different gene therapy approaches to bone regeneration have been studied, suggesting the use of viral vectors such as adenoviruses [10][11][12][13][14][15][16][17] and retroviruses 18,19 as carriers of BMP-2 cDNA. Adenoviruses, although highly immunogenic and at higher doses toxic to several tissues, are generally considered as the most efficient gene transfer vehicles.…”