The Role of Mechanically Isolated Stromal Vascular Fraction on Epithelial Proliferation during Burn Healing

Abstract

Background: Burn healing consists of four stages, homeostasis, inflammation, proliferation, and remodeling. Burn treatment aims to avoid infection, enhance tissue recovery, and prevent scarring. Recently, regenerative therapy shifted from using fat that contains mesenchymal stem cells to using various types of cells isolated from fat tissue called Stromal Vascular Fraction (SVF). It can be isolated either enzymatically, using collagenase, or mechanically, using emulsification of fat and filtration of cells. Previous research showed that both enzymatical and mechanical isolation of SVF can enhance neovascularization, re-epithelization and reduce inflammation. However, the mechanism behind its therapeutic effect needs to be explored. This study aims to investigate the role of mechanical isolation of SVF on the re-epithelization stage of deep-partial thickness burn in Wistar rats. Methods: Eighteen Wistar rats were used in this experiment. Three rats were used for fat isolation. After burn induction, fifteen rats were grouped randomly as follows: the control group (5 rats) received intradermal injection of 1 mL saline, Silver Sulfadiazine (SSD) Cream group (5 rats) was treated with the cream, and the SVF group (5 rats) received intradermal injection of (1 × 10⁶ cells/mL). All rats were euthanized at day 32 post-treatment. Morphological and histological examination for re-epithelization, measuring epithelial thickness and Ki-67 immunostaining was compared between all groups. Results: Wound contraction and re-epithelization were completed in all experimental groups. However, the epithelial thickness of the epidermis was higher in the SVF group than in the SSD group (p = 0.034). Ki-67 staining was higher in the SVF group than in the SSD group (p = 0.025). Conclusion: Mechanically-isolated SVF showed a positive effect on re-epithelization by increasing cell proliferation via the activation of Ki-67 thus increasing the epidermis thickness in a regulated way.