Comparison Of Angiogenic Potency Between Bone Marrow Derived Mesenchymal Stem Cells And Vascular Smooth Muscle Cells In A Rat Model Of Hindlimb Ischemia

Introduction: Cell-based therapy to induce angiogenesis has been developed as a novel potential therapeutic strategy for peripheral vascular disease. Both mesenchymal stem cells (MSCs) and vascular smooth muscle cells (VSMCs) were reported to have the ability to secrete several angiogenic factors and contribute to vessel formation. In the present study, we compared the angiogenic potency of the two cell types in a rat model of hindlimb ischemia.Methods: Rat mesenchymal stem cells (MSCs) were isolated from whole marrow cells by density gradient centrifugation and vascular smooth muscle cells (VSMCs) were obtained by digesting media of rat thoracic aortic. The effect of condition media on human umbilical vein endothelial cells (HUVECs) or VSMCs migration and proliferation was detected by Transwell migration assay and MTT assay. In addition, two type of cells were cultured in erum starvation and hypoxia condition to compare the survival ratio. The left femoral artery and its branches were excised in a rat to create a model of hindlimb ischemia. These rats were randomized divided into three groups: MSCs group, VSMCs group and control group, which received equal numbers of MSCs or VSMCs (2.5×106cells/rat) or the same volume of phosphate buffered saline (PBS) by intramuscular injection respectively. Three weeks after cell transplantation, capillary density was measured by alkaline phosphatase staining. The capillary density was evaluated by the capillary/muscle fiber ratio. T lymphocyte alloreactivity after allogeneic cell transplantation was detected by immunostaining with anti-CD3 monoclonal antibody. The levels of VEGF and HGF in the ischemic muscles were also detected.Results: MSCs- or VSMCs- condition media enhanced proliferation and migration of HUVECs and VSMCs. The tolerance to hypoxia stimulus of two cell types was similar. The adjusted capillary density was significantly higher in the MSCs group than that of VSMCs group and control group (2.49±0.154 vs. 1.8±0.146, P<0.05), while VSMC injection also increased the number of capillaries compared to the controls (1.8±0.146 vs. 1.42±0.066, P<0.05).The immunofluorescence analysis observed the similar results with alkaline phosphatase staining. Immune rejection response was not obvious in both cell transplantation groups. The expression of VEGF and HGF in the MSCs group was higher than in the VSMCs group.Conclusions: VSMCs or MSCs as a candidate cell for the treatment of limb ischemia is effective and safe, while MSCs transplantation caused significantly greater angiogenesis in ischemia tissue than VSMCs transplantation.