Elementary Research Of G-CSF And SCF On The Prevention And Cure Of Osteonecrosis Through Mobilizating, Recruiting And Regulating Autologus Bone Marrow Derived Stem Cells

Partâ… Experimental osteonecrosis induced by a combination of low-doselipopolysaccharide and high-dose methylprednisolone in rabbitsObjective The pathogenetic mechanisms involved in steroid-inducedosteonecrosis are poorly understood. Appropriate experimental models of thehuman disease are indispensable to the understanding of successful treatmentmodalities for osteonecrosis. In the present experiment we devised a novelrabbit model of steroid-induced osteonecrosis by use of LPS and MPS toinvestigate the development of osteonecrosis.Materials and Methods 38 rabbits were assigned into the treatment groupcontrol group. In treatment group, two injections of 10μg/kg body weight ofLPS were given intravenously, and then three injections of 20 mg/kg bodyweight of MPS were given intramuscularly, at a time interval of 24 h(L-LPS× 2 + H-MPS×3). Tissue assessments were performed on proximal third anddistal condyles of femora and humeri obtained 6 weeks after theadministration of LPS and MPS. MRI of these regions and intraosseouspressure of proximal femur were obtained at 0 and 6 weeks. Otherassessments included serum plasminogen activator/inhibitor ratio, cholesterollevel, LDL/HDL ratio, and triglyceride levels at various time points.Results 6 weeks after last injection of MPS ,MRI findings showed irregularlow signal on T₁-weighted images and irregular low or high signal onT₂-weighted image in 73.3%(22/30) rabbits. Histologically, 90% of the rabbits(27/30) in the treatment group developed ON 6 weeks after last injection ofMPS. Other results included bone marrow fat cell enlargement , a rise inintraosseous pressure, coagulation abnormalities and hyperlipidaemia.Conclusions On the whole, this is a novel modified animal model of steroidassociated osteonecrosis and it would be useful for elucidating thepathogenesis of steroid associated osteonecrosis and developing preventiveand therapeutic strategies. Partâ…¡Effects of granulocyte colony-stimulating factor and stem cell factor,alone and in combination, on the biological behaviours of bonemarrow mesenchymal stem cellsObjective The effects of granulocyte colony-stimulating factor (G-CSF) andstem cell factor (SCF) on the proliferation and osteogenic differentiationcapacity of bone marrow mesenchymal stem cells (MSCs) were studied in theexperiment.Materials and Methods Bone marrow MSCs were collected from rabbitssuccessfully, and treated with various concentrations of G-CSF, SCF or acombination of the two. Flow cytometric analyse, MTT test, CFU-F assay,and alkaline phosphatase (ALP) activity measurement were employed.Results: The results of flow cytometry showed that immunophenotype of thecells were CD29⁺/CD45^-,CD105⁺/CD34^-,CD90⁺/HLADR^- MSCs wereshown to constitutively express low levels of c-kit which could be enhancedby SCF. G-CSF and SCF had an obvious facilitative effect on the proliferationof MSCs in a dose-dependent fashion. In addition, G-CSF and SCF would beeffective in reversibly preventing their differentiation, as showed by thedecrease of ALP activity, leading to self-renewal rather than differentiative cell divisions. The effects of G-CSF were superior to SCF. And cells in thegroup treated with combination of G-CSF and SCF showed more powerfuleffects than the groups treated with G-CS, SCF, or none of the two.Conclusion: On the whole, these studies demonstrated that MSCs responsedto G-CSF, SCF, and to G-CSF plus SCF in a manner that suppresseddifferentiation, and promotes proliferation and self-renewal, and support theview that these factors could act synergistically.Partâ…¢A Combination of Granulocyte Colony- Stimulating Factor and Stem CellFactor Ameliorates Steroid-associated Osteonecrosis in RabbitsObjective Bone marrow-derived stem cell (BMSC) has been highlighted forthe treatment of osteonecrosis before collapse of the femoral head. In the study,the potential of G-CSF/SCF- mobilized BMSCs to repair steroid-associatedosteonecrosis were assessed in rabbits.Materials and Methods Osteonecrosis was induced by low-dose lipopolysaccharide and subsequent pulsed high-dose methylprednisolone.Rabbits in the treated group were subjected to subcutaneous injections ofG-CSF at a dose of 100μg/kg and SCF at a dose of 25μg/kg per day for 5days; and rabbits in the control group were given saline. Blood samples werecollected and serum osteocalcin was detected by ELISA. Radiological analysiswas performed by Magnetic Resonance Imaging. Then bilateral femora andhumeri were harvested and processed to paraffin sections and hard tissuesections for immunohistochemical, histologic and histomorphometric analysis.Results The mean number of leukocytes and the relative numbers ofmononuclear cell significantly increased after mobilization. All rabbitsdisplayed a marked increase in OCN protein expression in response toG-CSF/SCF. MRI scans showed reactive interface between the necrotic andreparative zones after G-CSF/SCF administration. Quantitative analysisshowed that new vessel and vessel density in the treatment group was 3.3-foldand 2.6-fold grater than the control group, respectively. The histologic andhistomorphometric analysis revealed that the new bone volume wassignificantly higher in the G-SCF/SCF group than in control group at 4 weeks.Conclusion G-CSF/SCF -induced mobilization of BMSC in the necrotic focimay represent a promising strategy for promoting functional bone repair of theearly-stage osteonecrosis.