Bone Morphogenetic Protein-2 Plasmid Research Articles

Simple and Efficient Gene Therapy for Bone Regeneration

Introduction Therapy using recombinat human bone morphogenetic protein2 (BMP-2) is expected to promote bone healing, and regeneration. The protein is soluble and disperses soon after implantation, so that many researchers have sought the delivery system to retain the protein at the target site. Previous studies using BMP-2 protein or BMP-2 gene expressing viral vectors had required a suitable carrier matrix, expensive bone morphogenetic protein to purify, or antigenic viral vectors. On the other hand, non viral delivery systems do not require an expensive BMP protein, a carrier matrix, or treatment of immunosuppression for general or local. In particular, electroporation is an efficient and simple method. Under these conditions, the combination of plasmid vectors and electroporation has been used for tissue regeneration, considering clinical applications. But, the value of this technique for local tissue regeneration has not yet been fully defined. The aim of our first study was to determine whether gene transfer by transcutaneous electroporation could induce ectopic bone formation in the muscles of rats. It has been generally accepted that BMP-2 can induce osteogenesis in skeletal muscles via endochondral ossification. However, it is not clear how the ossification process occurs after the BMP-2 gene transfer to skeletal muscles in rats using in vivo electroporation. In our second study, we evaluated the ossification process by BMP-2 gene transfer using in vivo electroporation. In this model, the volume of the injected plasmid is restricted to 50 ml, given the surface area the electrodes can cover. Furthermore, any relationship between the plasmid dose and the electrical parameters will affect the efficiency of the gene transfer. As the third study, our trial was designed to improve the method to enhance bone formation at the intrinsic level of the osteoinductive activity. Here, to enhance bone regeneration or repair by BMP gene transfer, we examined the effects on osteoinduction of the direct and simultaneous gene transfer of BMP-2 and BMP-7 expression plasmid vectors into skeletal muscles by electroporation.

Bone regeneration in rats with BMP-4 and VEGF plasmid DNA

Problem: Gene therapy offers a promising new method of bone regeneration. One technique uses bioresorbable polymer scaffolding at the bony defect site that contains plasmid DNA of bone growth factors. Previous studies have demonstrated bone growth using bone morphogenetic protein-4 (BMP-4) plasmid DNA. Research has suggested a synergistic effect of BMP-4 and vascular endothelial growth factor (VEGF) on bone regeneration. The present study aims to confirm bone regeneration with a polymer scaffold containing BMP-4 plasmid DNA in the rat calvarial defect model and to quantify a synergistic effect of BMP-4 and VEGF plasmid DNA in this model. Methods: Calvarial critical-sized defects were created in 100 male Sprague-Dawley rats. The animals were divided into 5 equal groups by treatment: none (negative control); VEGF plasmid DNA; BMP-4 plasmid DNA; VEGF and BMP-4 plasmid DNA; and autograft (positive control). The animals were euthanized at 4 and 8 weeks; calvaria were radiographed and histologically sectioned. Results: Radiomorphometry measured bone growth within the calvarial defects to quantify the bone regeneration effects of BMP-4 and VEGF plasmid DNA alone and in combination. Compared to control groups, significant bone growth was noted in the BMP-4 and BMP-4/VEGF groups, but no bone growth was noted in the VEGF group. No significant difference in bone growth was noted between the BMP-4 and BMP-4/VEGF groups. Microscopy of histologic sections (1 slide/specimen) confirmed the bone growth noted on radiomorphometry. Conclusion: BMP-4 plasmid DNA demonstrates significant bone growth in the rat calvarial defect model. VEGF plasmid DNA alone demonstrates no bone growth. When BMP-4 and VEGF plasmid DNA are combined, no synergistic effect is noted. Significance: Reconstruction of osseous craniofacial defects such as autografting for cleft palate and osteocutaneous free tissue transfer for mandibular defects often requires bone harvest with an associated donor site morbidity. Tissue engineering employing gene therapy for bone regeneration may offer a less morbid alternative. Support: None reported.

Stimulation of new bone formation by direct transfer of osteogenic plasmid genes.

Degradable matrices containing expression plasmid DNA [gene-activated matrices (GAMs)] were implanted into segmental gaps created in the adult rat femur. Implantation of GAMs containing beta-galactosidase or luciferase plasmids led to DNA uptake and functional enzyme expression by repair cells (granulation tissue) growing into the gap. Implantation of a GAM containing either a bone morphogenetic protein-4 plasmid or a plasmid coding for a fragment of parathyroid hormone (amino acids 1-34) resulted in a biological response of new bone filling the gap. Finally, implantation of a two-plasmid GAM encoding bone morphogenetic protein-4 and the parathyroid hormone fragment, which act synergistically in vitro, caused new bone to form faster than with either factor alone. These studies demonstrate for the first time that repair cells (fibroblasts) in bone can be genetically manipulated in vivo. While serving as a useful tool to study the biology of repair fibroblasts and the wound healing response, the GAM technology may also have wide therapeutic utility.