Abstract
OBJECTIVE: To investigate the effects of adipose-derived stem cells (ADSCs) and endothelial cells (ECs) on the survival and neovascularization of fat tissue transplants. METHODS: The ADSCs were isolated by collagenase digestion from the adipose tissues voluntarily donated by the patients undergoing mastectomy, and subcultured. The passage 3 ADSCs were used for subsequent experiments. The residual fat tissues were used to prepare fat particles (FPs). The human umbilical vein endothelial cells (HUVECs) were used as ECs for subsequent experiments. Eighty healthy male nude mice, aged 4-6 weeks, were randomly divided into 4 groups ( n=20). The mice were received subcutaneous injection at the dorsum of 1 mL FPs+0.3 mL normal saline (NS) in control group, 1 mL FPs+2×10 (6) ECs+0.3 mL NS in ECs group, 1 mL FPs+2×10 (6) ADSCs+0.3 mL NS in ADSCs group, and 1 mL FPs+1×10 (6) ECs+1×10 (6) ADSCs+0.3 NS in ADSCs+ECs group. General observations of the injection sites were performed, and the survival of the mice was recorded. At 2, 4, 8, and 12 weeks after injection, grafted fat tissues were firstly assessed by ultrasonography, then they were collected for volume measurement (water displacement method) and histology observation (HE staining and immunofluorescence staining). RESULTS: All mice survived until the end of experiment. At each time point, no significant difference was noted between groups in ultrasonography assay. There was no significant blood flow signal in the grafted fat tissues, or cysts, calcification, solid occupying in recipient area. Generally, the volume of grafted fat tissues decreased with time in all groups. Specifically, the volumes of grafted fat tissues were larger in ADSCs group and ADSCs+ECs group than that in control group and ECs group ( P<0.05) at each time point, and in ADSCs group than in ADSCs+ECs group ( P<0.05) at 8 and 12 weeks. HE staining showed that all groups had similar tendencies in general histology changes, and remodeling in ADSCs group was the fastest than in the other groups. By immunofluorescence staining for neovascularization, the new vessels in all groups were increasing with time. The vessel densities were higher in ECs group, ADSCs group, and ADSCs+ECs group than in control group ( P<0.05) at each time point, in ADSCs group than in ECs group and ADSCs+ECs group ( P<0.05) at 4 weeks, in ADSCs group and ADSCs+ECs group than in ECs group ( P<0.05) at 8 and 12 weeks. CONCLUSION: ADSCs can significantly increase the survival of transplanted fat tissue, which may be related to promoting the neovascularization.