Failures in fracture healing are mainly caused by a lack of neovascularization. We have previously demonstrated that G-CSF-mobilized peripheral blood (GM-PB) CD34+ cells, an endothelial progenitor enriched cell population, contributed to fracture healing via vasculogenesis and osteogenesis. We postulated the hypothesis that local transplantation of culture expanded bone marrow (cEx-BM) CD34+ cells could exhibit therapeutic potential for fracture healing. BM CD34+ cells were cultured in specific medium with 5 growth factors for 1week. A reproducible model of femoral fracture was created in nude rats with periosteum cauterization, which leads to nonunion at 8 weeks post-fracture. Rats received local administration of the following cells or PBS alone(1)cEx-BM, (2)BM, (3)GM-PB CD34+ cells or (4)PBS.Introduction
Materials
CXC chemokine receptor 4 (CXCR4) is a specific receptor for stromal-derived-factor 1 (SDF-1). SDF-1/CXCR4 interaction contributes to the regulation of endotherial progenitor cell (EPC) recruitment in ischemic tissues. The purpose of this study is to investigate the mechanistic function of CXCR4 on EPCs for bone fracture healing. We made CXCR4 gene knockout mice using the Cre/loxP system. A reproducible model of femoral fracture was created in both Tie2-Cre CXCR4 knockout mice (CXCR4KO) and wild type mice (control). To evaluate gain function of the SDF-1/CXCR4 pathway, we set three groups of the SDF-1 intraperitoneally injected group, wild type group, and SDF-1 injected CXCR4 KO group.Introduction
Materials and methods
The therapeutic potential of hematopoietic stem cells for fracture healing has been demonstrated with mechanistic insight of vasculogenesis and osteogenesis enhancement. Lnk has recently been proved an essential inhibitory signaling molecule in SCF-c-Kit signaling pathway for stem cell self-renewal demonstrating enhanced hematopoietic and osteogenic reconstitution in Lnk-deficient mice. We investigated the hypothesis that down regulation of Lnk enhances regenerative response via vasculogenesis and osteogenesis in fracture healing. A reproducible model of femoral fracture was created in mice. Immediately after fracture creation, mice received local administration of the following materials with AteloGene, 10μM (1)Lnk siRNA, (2)control siRNA.Introduction
Methods
We have observed damage to the labrum as a result of repetitive acetabular impingement in non-dysplastic hips, in which the femoral neck appears to abut against the acetabular labrum and a non-spherical femoral head to press against the labrum and adjacent cartilage. In both mechanisms anatomical variations of the proximal femur may be a factor. We have measured the orientation of the femoral neck and the offset of the head at various circumferential positions, using MRI data from volunteers with no osteoarthritic changes on standard radiographs. Compared with the control subjects, paired for gender and age, patients showed a significant reduction in mean femoral anteversion and mean head-neck offset on the anterior aspect of the neck. This was consistent with the site of symptomatic impingement in flexion and internal rotation, and with lesions of the adjacent rim. Furthermore, when stratified for gender and age, and compared with the control group, the mean femoral head-neck offset was significantly reduced in the lateral-to-anterior aspect of the neck for young men, and in the anterolateral-to-anterior aspect of the neck for older women. For patients suspected of having impingement of the rim, anatomical variations in the proximal femur should be considered as a possible cause.
