Demonstration of the effect of stromal vascular fraction on capsular contracture in a rat model

The most common side effect of silicone prostheses frequently used for breast augmentation is capsular contracture. Approximately 20 percent of patients who undergo breast augmentation undergo surgery again due to capsular contracture in the future. Although its pathophysiology is not fully understood, it is known that capsular contracture occurs due to an excess reaction in the normal inflammation and fibrosis response to an implanted foreign body. A great deal of research has been conducted to date to prevent capsule contracture. Hyaluronic acid injection, nanofat injection, use of anti-inflammatory agents and botox injection are the main ones. In our study, it was thought that stromal vascular fraction (SVF), which is popular in regenerative medicine and is frequently used in plastic surgery with its positive effects on wound healing, scar quality and antiaging properties, may have an effect on capsular contracture due to its known anti-inflammatory properties. 30 Wistar – Albino type rats with an average weight of 240+-25 g were used in the study. Animals will be kept in plexiglass cages and a maximum of 4 animals will be placed in each cage and their care will be provided. Animals were kept in windowless rooms by monitoring temperature (22 ± 2°C) and light (14 hours of light between 07.00-21.00 and 10 hours of darkness between 21.00-07.00). All rats were fed with standard laboratory chow before and during the experiment. The rats were randomly divided into 3 groups: n:10 control, n:10 chemical (enzymatic) svf, and n:10 mechanical (non-enzymatic) svf obtaining group. Cut silicone material of 1.5x1.5 cm2 size was placed in the pouch prepared under the panniculus carnosus muscle of all rats. SVFs obtained from the fat tissue and obtained from the inguinal region of the same experimental group were applied to the same experimental group in the same surgical session. 4 quadrants were determined in the circle drawn around the material, and 0.1 cc of SVF was given to these 4 quadrants in a panniculus carnosus muscle plane to the entire group as a standard. As a result of the 12-week follow-up period, the implant, capsule and back skin were excised as a composite tissue with an appropriate incision made on the back of the euthanized rats, and the capsule tissue and skin were separated by surgical dissection and sent to pathology for histopathological examination. In histopathological examination, inflammation, granulation tissue, angiogenesis, foreign body reaction and fibrosis were evaluated. Control and experimental groups were compared for each parameter. The presence of significant inflammation, the presence of granulation tissue and the rate of angiogenesis in the chemical svf group were significantly (p<0.05) higher than the control and mechanical svf groups. No significant (p>0.05) difference could be shown between the control and mechanical svf groups in terms of the presence of significant inflammation, the presence of granulation tissue and the angiogenesis rate. There were similar results in all three groups in terms of fibrosis and foreign body reaction. The intense presence of inflammation, granulation tissue and angiogenesis in the chemical svf group can be considered as the reaction of the host tissue to collagenase. We think that the SVF obtained by chemical method may be effective in wound healing by increasing angiogenesis and granulation, but it is disadvantageous in preventing capsular contracture because it increases inflammation compared to the mechanical method. The collagenase used in the chemical extraction method may have caused a reaction in the host tissue, resulting in increased inflammation. No significant difference in inflammation in the mechanical svf group compared to the control group may be due to the fact that the stem cells in the stromal vascular fraction are negatively affected by the implant environment, which is already in hypoxic conditions, during retention as a graft. According to these results, we demonstrated that applying enzymatic or non-enzymatic SVF around the implant alone will not prevent capsular contracture. However, despite periprosthetic hypoxia, there will be living cells within the svf, just like the fat graft. Studies aim to increase these cells can be planned in the future. Our study has been a pioneer in this sense.