Study Of SVF-gel Promoting Wound Healing In Diabetic Mice

Objective: Chronic wound is a difficult disease to treat in clinic.It can be seen in diabetic foot venous ulcer bedsore and deep trauma.At present,there is still a lack of effective treatment for chronic wounds in clinical practice,and the difficulty of repair lies in less neovascularization than normal wounds,insufficient local blood supply of wounds,and persistent inflammatory factors.With the breakthroughs in stem cell technology,adipose stem cells are considered to be the most suitable wound repair stem cells because they are easier to obtain than other adult stem cells,have abundant reserves,have fewer complications,and are less involved in ethical issues.They can secrete a variety of angiogenic growth factors after re-injection.however,directing injection of stem cells into the lesion site leads to lower cell survival.Secondly,the preparation process of SVF/ADSCs is complex,time consuming and cost consuming,so it is not feasible to use SVF/ADSCs widely in clinic.Furthermore,collagenase added during SVF/ADSCs extraction and heterogeneous serum added during culture may contaminate ADSCs and cause immune rejection.Therefore,it is particularly important to find an efficient,economical and safe method to deal with the above problems in the field of clinical treatment research.Svf-gel is destroyed by adipocytes,and large amounts of lipids are separated out by high speed centrifugation to obtain a complex rich in adipocyte stem cells and extracellular matrix(ECM).ECM can provide extracellular scaffolds for ADSCs,protect adipose stem cells from phagocytosis by macrophages,and enable them to give better play to regeneration.Therefore,it is speculated that svf-gel has a better effect of promoting wound healing than pure SVF suspension.In this study,svf-gel was locally transplanted into the chronic wound model to observe and evaluate the effect of its treatment on chronic wound.Methods: Firstly,SVF-gel model was prepared and whether it contained adipose stem cells was verified.Secondly,we established a chronic wound model in diabetic rats,and at the same time,svf-gel and SVF suspension were locally transplanted to the wound surface of rats,and wound healing was observed by taking photos andcalculating the wound healing rate at each time point in each group.Specimens were collected,and HE staining was performed to observe the histopathological status of wound in each group,and the number of wound neovascularization in each group was calculated by immunohistochemical stainingWestern blotting was used to detect VEGF protein expression in wound granulation tissue of diabetic rats at day 14.To further explore the possible mechanism of SVF-gel promoting wound regeneration Results:1.Svf-gel successfully prepared is a kind of substance similar to hyaluronic acid gel.About 1ml svf-gel can be obtained from 10 ml structural fat.2.Comparison of wound healing rate: the wound healing rate of the svf-gel group was significantly better than that of the other two groups on 3d,7d,10 d and14d.These results suggest that SVF-gel has a better effect on promoting healing of chronic wounds.3.Results of HE staining: on the 14 th day,there were a large number of inflammatory cells infiltrating and fibroblasts in the wound surface of the control group,and the cells were arranged,with fewer new blood vessels,loose granulation tissue structure,and incomplete reepithelialization.Compared with the SVF suspension group,the infiltration of inflammatory cells was reduced in the svf-gel group,the number of dermal capillaries was significantly increased,the degree of re-epithelialization was obvious,and the granulation tissue structure was dense..Compared with the control group,the SVF suspension group had less inflammatory cell infiltration,more collagen fibers and capillaries,and more complete reepithelialization,but it was inferior to the SVF-gel group4.Immunohistochemical staining results: 10 days after treatment,there were new angiogenesis perpendicular to the wound in the granulation tissue of the three groups.The number of new blood vessels in the two groups of svf-gel and SVF suspension was more than that in the normal saline control group.Some new blood vessels had no obvious lumen structure,and only a single endothelial cell was found in the vascular fault.After 14 days,the number of blood vessels in the wound increased significantly compared with 10 days.In both svf-gel group and SVFsuspension group,there were more neovascularization with mature lumen in the wound surface,while there were fewer in normal saline group.5.VEGF protein expression in wound tissue of each group at day 10 was detected by western blotting: VEGF protein expression in svf-gel group was significantly higher than that in SVF suspension group and control group,with statistically significant difference(p<0.05).VEGF protein expression in SVF suspension was also significantly higher than that in control group,with statistically significant difference(p<0.05)Conclusion: SVF-gel is a new type of injectable product from fat source,which can obtain highly concentrated fat stem cells and extracellular matrix(ECM)from fat aspirate by simple physical methods.We applied svf-gel to chronic wounds of rats,and compared with the simple SVF suspension,it has a better effect of promoting wound healing.It mainly induces the formation of new blood vessels in chronic wounds by secreting more VEGF,and at the same time,it can also regulate the inflammatory reaction inside the wound which is difficult to heal and accelerate the formation of re-epithelialization.