Defining extracellular vesicle release, uptake, and function in wound healing

Small extracellular vesicles (EVs) are released by cells and deliver biologically active payloads important in the intercellular signaling that coordinates the response of multiple cell types in cutaneous wound healing. Here we focus on the use of EV reporters to address cell type specificity and central questions regarding EV source cells, target cells, heterogeneity, payload, and activity using a combination of molecular approaches to address some of the barriers to translation in the use of engineered EVs. We identify a role for EVs released by resident macrophages present in adipose tissue and dermis to stimulate proliferation of overlying basal layer of keratinocytes. For these studies we use an allograft model, where donor EVs are harvested from subcutaneous implants, then purified for transplantation into the wound bed of recipient mice with a defined impaired wound healing phenotype. We demonstrate that EVs isolated from diabetic obese mice decreased keratinocyte proliferation and delayed wound closure, and that EVs loaded with specific miRNAs like miR-425-5p increased proliferation and accelerated wound closure. Utilizing a CD9-GFP reporter system, we show that fibroblasts uptake macrophage-derived EVs. In this work, we show that cell type-specific approaches can be used to unravel the biochemical activity of EVs in the complex microenvironment of the wound bed and form the basis for developing targeted pro-reparative EV payloads. To investigate the expression of different cell type markers with sequencing between wildtype and diabetic derived extracellular vesicles.