| Objectives: The traditional PRP-assisted fat transplantation strategy is the simultaneous transplantation of autologous fat and PRP,but the effect is not stable [1].Studies have shown that the process of angiogenesis in transplanted fat has a unique spatial and temporal [2].Spatially,the implanted adipose tissue can be divided into a survival zone,a regeneration zone and a necrotic zone from the periphery to the center,and the blood vessel gradually grows into the internal necrotic zone from the peripheral survival zone;in time,the blood vessel is transplanted 7 It began to gradually regenerate around the day and reached its peak on the 28 th day [3].Therefore,the reasons for the instability of traditional mixed transplantation include: 1.The angiogenic factor(VEGF)contained in PRP has been consumed before angiogenesis,and the cytokine(IL-1,which regulates macrophage activity).IL-6,G-CSF)is consumed before the regulation of macrophages to regulate the inflammatory response;2.Within one week after fat transplantation,it is the acute phase of tissue transplantation inflammatory response,and the local release of inflammatory factors affects the promotion of PRP.Angiogenesis;3,PRP and transplanted adipose tissue mixing uneven,making PRP not uniform,failed to achieve the highest utilization of PRP.Therefore,after the acute inflammatory reaction period after fat transplantation,accurate injection of PRP in the transplanted fat center can better exert its promoting angiogenesis,and further increase the volume retention rate of transplanted fat is worthy of discussion.Therefore,the purpose of this thesis includes: to explore the feasibility of delaying the injection of PRP to promote angiogenesis and increase the fat volume retention rate in fat transplantation;and to explore its mechanism.Methods: 24 nude mice were divided into 3 groups: blank group(0.35 m L fat mixed with 0.15 m L saline),single step group(0.35 m L fat mixed with 0.15 m LPRP),two-step group(0.35 mL fat(day 0)+ 0.075 mL PRP(day 7)+ 0.075 mL PRP(day 14)).The adipose tissue was transplanted on both sides of the back of the nude mice.After 6 weeks and 14 weeks,the mass,volume and volume retention of the transplanted fat were analyzed to evaluate the statistical difference.After 14 weeks,the histology and immunohistochemistry were performed simultaneously.Staining was performed to analyze the integrity of adipose tissue,the number of new blood vessels,fat cell regeneration,and macrophage infiltration.Results: The results of the 6th week showed: the quality between the three groups(blank group: 168±22.86,single step group: 159±39.62,two-step group: 186±186±24.7),volume(blank group: 0.165±0.022,single step)Group: 0.159±0.034,two-step group: 0.147±0.067),volume retention rate(blank group: 47.14±6.2%,single-step group: 45.428±9.7%,two-step group: 42±19%),no statistical difference The 14 th week showed that the quality of the two-step group was the highest(blank group: 87.5±4.509,single step group: 106±3.403,two-step group: 136±3.605),and the two-step group had the highest volume(blank group: 0.0855±0.0045),single step group: 0.10475 ± 0.0034,two-step group: 0.1336 ± 0.004),the two-step group has the highest volume retention rate(blank group: 24.44 ± 1.2%,single-step group: 29.928 ± 0.972%,two-step group: 38.190 ± 1.15%),and the fat retention rate of the two-step group was significantly higher than that of the single-step group(single step group: 29.928 ± 0.972%,two-step group: 38.190 ± 1.15%);HE staining results showed adipose tissue integrity of the two-step group Highest;CD31 staining showed the highest number of new blood vessels located in the center of the fat graft in the two-step group(blank: 8.5 ± 1.29;single step 11.75±1.7078;two-step group: 21±3.6055),peripherin staining showed that the number of new fat cells(pre-adipocytes)in the two-step group was higher than that in the single-step group(two-step group: 130/field;single-step group: 10)/Field of view;Mac2/CD206 staining showed that the macrophage infiltration in the two-step group was lighter than that in the single-step group,and the inflammatory infiltration in the blank group was the heaviest.Conclusions: 1.Delayed injection of PRP improves lipid transfer by promoting angiogenesis in the central region of the transplanted fat.The volume retention rate of the fat;2,delayed injection of PRP can promote the repair of inflammatory response,accelerate tissue remodeling,and promote the regeneration of adipocytes in the central region of the transplanted fat. |
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