Gene therapy for bone formation: In vitro and in vivo osteogenic activity of an adenovirus expressing BMP7

Abstract

Bone morphogenetic proteins (BMPs) are well-established agents for inducing orthotopic and ectopic bone formation. However, their clinical usefulness as regenerative agents may be limited by a short in vivo half-life and low specific activity. BMP gene therapy is an alternative route for exploiting the bone-inductive activity of this class of molecules. To test the feasibility of this approach, we examined the osteogenic activity of AdCMV-BMP7, an adenovirus containing BMP7 cDNA under control of the CMV promoter that was constructed using Cre/lox recombination (Hardy et al. [1997] J. Virol. 71:1842-1849). Adenovirus vectors were shown to readily infect a wide variety of cell types in vitro including osteoblasts, fibroblasts, and myoblasts. COS7 cells transduced with AdCMV-BMP7 produced high levels of BMP-7 (approximately 0.5 microg/10(6) cells). Furthermore, transduction of C2C12 murine myoblast cells with AdCMVBMP-7 suppressed the muscle phenotype and induced in vitro osteoblast differentiation. To test its in vivo biological activity, AdCMV-BMP7 was mixed with a bovine bone-derived collagen carrier (10(8) plaque-forming units virus/site) and was implanted into mouse muscle and dermal pouches. In both cases, an ossicle containing cortical and trabecular bone and a clearly defined marrow cavity formed at the site of virus implantation within 4 weeks. These data demonstrate that AdCMV-BMP7 transduced cells produce biologically active BMP-7 both in vitro and in vivo and show that gene therapy by direct viral transduction using a virus/matrix implant may be a viable route for stimulating bone regeneration.

Bone tissue engineering: A review in bone biomimetics and drug delivery strategies

“…Therefore, gene therapy is an alternative route for exploiting the boneinductive activity of this class of molecules. 173 In gene therapy, genes coding for the production of specific proteins are delivered to cells via a virus vector (i.e., retrovirus, adenovirus, adeno-associated virus, herpesvirus), or via non-viral delivery (i.e., naked DNA, oligonucleotides, lipoplexes). The most effective delivery system depends on the application.…”

Characterization of the distinct orthotopic bone-forming activity of 14 BMPs using recombinant adenovirus-mediated gene delivery

“…[25][26][27] In addition to the direct application of recombinant BMP proteins, numerous reports have confirmed the ability of adenoviral or retroviral vector-mediated gene transfer of several BMPs to induce bone formation in animal models. 18,20,21,23,[28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] Although a plethora of studies have demonstrated the ability of several BMPs, mostly BMP-2 and BMP-7, to promote osteogenesis, it is unclear whether or not BMPs other than those currently being tested in clinical trials are more potent stimulators of new bone formation. Thus, it is important to conduct a comprehensive comparative analysis of the in vivo osteogenic activity of all BMPs.…”

Osteogenic potential of five different recombinant human bone morphogenetic protein adenoviral vectors in the rat

“…The BMP viral vectors include recombinant adenovirus, retrovirus and baculovirus. 13,[28][29][30][31][32][33] Gysin et al 34 demonstrated that recombinant BMP-4 retrovirus-transduced stromal cells embedded in a gelatin matrix could heal critical size defects in calvariae of syngeneic rats. Gelatin matrices without cells and with untransduced stromal cells were the two control groups.…”

“…In both locations, an ossicle containing cortical and trabecular bone and a clearly defined marrow cavity formed at the site of virus implantation within 4 weeks. 32 Recombinant BMP-9 adenoviruses, which include both first-generation and helper-dependent adenoviral vectors, induced the ectopic bone formation in both athymic nude rats and Sprague-Dawley rats. 11,13,39 Since different BMP adenoviral vector doses and different animal models were used in previous studies, it remains unclear which BMP vector has the highest potential to stimulate bone formation.…”