| Bone defects and fracture non-union are common Othorpeadic clinical problems, affecting as many as millions patients in the world every year, and are difficult to heal using current therapies. Previously, these cases have been treated by surgery, using techniques such as autologous and allogous bone grafting or artificial bone grafting. However, autologous and allogous bone grafts have a number of problems including donor-site problems, danger of transmitting diseases, and the limitations of harvested bone or the weak strength of graft-bone, while artificial bone grafts also have associated problems caused by the use of biomaterials, including immunogenicity, biodegradation or strength limitations. Since the beginning of 1990, it has been reported that bone morphogenetic proteins (BMPs) can induce bone formation in both ectopic and orthotopic sites in vivo. Bone morphogenetic proteins (BMPs) are members of TGF-P family of growth factors possessing strong osteoinducitive properties. Bone morphogenetic proteins-2 (BMP-2) is consideded as the solely BMPs which has the capacity to induce heterotopic bone formation in vivo and promote endochondrial ossification at fracture sites and may thus be potentially useful in accelerating bone repair. Previous studies have demonstrated the clinical utility of these proteins in fracture healing, spinal fusion and prosthetic joint stabilization. However, the ideal approach to deliver BMPs properly remains unknown. Gene therapy to deliver BMPs offers several theoretical advantages over implantation of a recombinant BMP protein, including persistent BMP delivery and eliminating the need for a foreign body carrier.Bone mesenchymal stem cells (MSCs) may provide an alternative for use in cell therapy after pretreatment with BMP-2. Recent research works suggest that the MSCs may be excellent vehicles for cell and gene therapy. MSCs are self-renewing pluripotent progenitor cells that have been isolated from the whole marrow of chick, mouse, rat, rabbit, goat and human. Unlike hematopoietic stem cells, which are difficult to culture, marrow derived MSCs can be conditioned to grow in vitro. In fact, human bone marrow-derived MSCs have been subcultured for as many as 15 passages without losing differentiation potential. Neither cryopreservation nor thawing negatively affects the growth or differentiation of MSC. Most important, marrow-derived cells have the potential to differentiate into bone, cartilage, tendon, muscle, and fat both in vitro and in vivo.Bone regeneration by gene transfer into MSCs has also been reported. These reports have mainly used a retrovirus, or adenovirus vector and plasmid vector carrying human BMP-2, -4, or -7, as the therapeutic gene and these were effective in the formation of new bone. However, the transduction efficiency into MSCs by each vector has not always been reported to be high, e.g. plasmid vector; below 11%, retroviral vector; 18-65%, adenoviral vector; about 20%. Our study is focused on plasmid vector transfection, which is considered having more industrial productive possibility, safer than virus vectors but less studied in the field of bone repair.Bone mesenchymal stem cells (MSCs) consist of inducible (IOPC) and determined osteo-progenitors (DOPC) committed to osteogenesis, the latter having the propensity of form bone cells without any external cues or signals. The inducible osteogenic precursors, on the other hand, do require an inductive signal, such as BMP-2. In order to make the both inducible and determined osteo-progenitors of MSCs commit to bone lesion repairing, we transfected the hBMP-2 gene into MSCs, hopefully this procedure can produce more osteogenic cells lineage, which could contribute to the bone tissue engineering's requirement for MSCs of l*107, and short the time of MSCs culture. In the other hand, we also studied the effect of human and rabbit aging on MSCs culture, that is important to present and further studies, when the MSCs are choosed as cell carrier.1 Construction of recombined eukaryotic e... |
PDF Full Text Request