Healing Of An Ulnar Defect Using RhBMP-2 Releasing Calcium Sulfate-rhBMP-2 Scaffolds In Association With Mesenchymal Stem Cell (MSC) Sheet

Background:Bone defects induced by high energy-wounds were more and mere popular with the economic development of our contry, and the incidence of the bone defects after the treatment of the bone infection, bone tumor and some anamorphosis deseases, which would make the patents or their family endure large burdens. Autograft is considered the gold standard for filling bone defects, however, it has the shortcomings such as donor site morbidity and donor shortage. As to allograft, immunologic response and endemic risk can not be ignored. These difficulties have resulted in the search for alternative bone graft substitutes. In recent years, the regenerative medicine or tissue engineering provide the possibility of successfully repairing and restoring the function in damaged or diseased tissues, which is based on three factors:scaffolds; cells and growth factors.Objective:The aim of this research is to assessing the efficency of the rhBMP-2-calcium sulfate coated by the MSCs cell sheets in the long bone defects models. Methods:Firstly, MSCs was cultured from the 8 weeks-male-rabbits; secondly, the osteogenic differentiation of MSCs cultured on rhBMP-2 loaded CS was investigated; thirdly, the defects were treated with CS (group A), rhBMP-2 loaded CS (group B), MSC sheet wrapped CS (group C) and MSC sheet wrapped rhBMP-2 loaded CS (group D).Results:The ALP of MSCs cultured on rhBMP-2-loaded CS was significantly higher than on CS both at 7 and 14 days (p<0.05). The defects treated with MSC sheet wrapped rhBMP-2-loaded-CS showed significantly higher scores by X-ray analysis and more bone formation determined by both histology and micro-computer tomography than other three groups after 4 and 8 weeks (p<0.05). There was no significant difference in X-ray score and bone formation between group B and C, both significantly higher than group A (p<0.05).Conclusions:MSC sheet wrapped rhBMP-2 loaded CS may be an effective approach to promote repair of segmental bone defects and have great potential for repairing large segmental bone defects in clinic.