ObjectiveTo observe the change of stromal cell-derived factor 1α/cysteine X cysteine receptor 4 (SDF-1α/CXCR4) signaling pathway during the process of axial stress stimulation promoting bone regeneration, and to further explore its mechanism.MethodsA total of 72 male New Zealand white rabbits were selected to prepare the single cortical bone defect in diameter of 8 mm at the proximal end of the right tibia that repaired with deproteinized cancellous bone. All models were randomly divided into 3 groups (n=24). Group A was treated with intraperitoneally injection of PBS; Group B was treated with stress stimulation and intraperitoneally injection of PBS; Group C was treated with stress stimulation and intraperitoneally injection of AMD3100 solution. The X-ray films were taken and Lane-Sandhu scores of bone healing were scored at 2, 4, 8, and 12 weeks after operation, while specimens were harvested for HE staining, immunohistochemical staining of vascular endothelial growth factor (VEGF) and CXCR4, and Western blot (SDF-1α and CXCR4). The bone healing area was scanned by Micro-CT at 12 weeks after operation, and the volume and density of new bone were calculated.ResultsX-ray film showed that the Lane-Sandhu scores of bone healing in group B were significantly higher than those in groups A and C at 4, 8, and 12 weeks after operation (P<0.05). Micro-CT scan showed that the bone defect was repaired in group B and the pulp cavity was re-passed at 12 weeks after operation. The volume and density of new bone were higher in group B than in groups A and C (P<0.05). HE staining showed that the new bone growth in bone defect area and the degradation of scaffolds were faster in group B than in groups A and C after 4 weeks. The immunohistochemical staining showed that the expressions of VEGF and CXCR4 in 3 groups reached the peak at 4 weeks, and group B was higher than groups A and C (P<0.05). Western blot analysis showed that the expressions of SDF-1α and CXCR4 in group B were significantly higher than those in groups A and C at 4 and 8 weeks after operation (P<0.05).ConclusionAxial stress stimulation can promote the expression of SDF-1α in bone defect tissue, activate and regulate the CXCR4 signal collected by marrow mesenchymal stem cells, and accelerate bone regeneration in bone defect area.
ObjectiveTo explored the effect of stromal cell-derived factor 1α (SDF-1α) on promoting the migration ability of rat adipose derived stem cells (rADSCs) by constructed the rADSCs overexpression SDF-1α via adenovirus transfection.MethodsrADSCs were isolated from adipose tissue of 6-week-old SPF Sprague Dawley rats. Morphological observation, multi-directional differentiations (osteogenic, adipogenic, and chondrogenic inductions), and flow cytometry identification were performed. Transwell cell migration experiment was used to observe and screen the optimal concentration of exogenous SDF-1α to optimize the migration ability of rADSCs; the optimal multiplicity of infection (MOI) of rADSCs was screened by observing the cell status and fluorescence expression after transfection. Then the third generation of rADSCs were divided into 4 groups: group A was pure rADSCs; group B was rADSCs co-cultured with SDF-1α at the best concentration; group C was rADSCs infected with recombinant adenovirus-mediated green fluorescent protein (Adv-GFP) with the best MOI; group D was rADSCs infected with Adv-GFP-SDF-1α overexpression adenovirus with the best MOI. Cell counting kit 8 (CCK-8) and Transwell cell migration experiment were preformed to detect and compare the effect of exogenous SDF-1α and SDF-1α overexpression on the proliferation and migration ability of rADSCs.ResultsThe cell morphology, multi-directional differentiations, and flow cytometry identification showed that the cultured cells were rADSCs. After screening, the optimal stimulating concentration of exogenous SDF-1α was 12.5 nmol/L; the optimal MOI of Adv-GFP adenovirus was 200; the optimal MOI of Adv-GFP-SDF-1α overexpression adenovirus was 400. CCK-8 method and Transwell cell migration experiment showed that compared with groups A and C, groups B and D could significantly improve the proliferation and migration of rADSCs (P<0.05); the effect of group D on enhancing the migration of rADSCs was weaker than that of group B, but the effect of promoting the proliferation of rADSCs was stronger than that of group D (P<0.05).ConclusionSDF-1α overexpression modification on rADSCs can significantly promote the proliferation and migration ability, which may be a potential method to optimize the application of ADSCs in tissue regeneration and wound repair.