Abstract

Mechanisms of Extracellular Vesicle Biogenesis that Regulate Wound Healing

Brian Eliceiri, Professor, UC San Diego

Small extracellular vesicles (EVs) are important mediators of intercellular signaling that carry biologically active protein payloads relevant in wound healing.  However, whether EVs are analyzed from wound fluid or other biological fluids, EVs are heterogenous, reflecting in part the release of EVs from different cell types.  To address the central question of EV heterogeneity in parallel with the unmet need for in vivo sources of EVs with low platelet contamination, we have developed a macroporous scaffold for the subcutaneous implantation and subsequent collection of EVs that is applicable for the study of EV activity in any defined mouse model. Using polyvinylalcohol (PVA) sponges as the scaffold, we first show that the rapid infiltration of immune cells of hematopoietic origin is accompanied a substantial and heterogenous population of EVs. Second, we show how single vesicle flow cytometry (vFC) addresses the heterogeneity challenge by quantifying the expression of surface markers that map to specific subpopulations of EVs relevant to cellular origin.  Third, we show how in vitro two-dimensional cell culture, although common, introduces significant bias in EV release that is addressed with the PVA scaffold in vivo model. Together these studies, define a novel model establishing the biochemical basis and biological activity of EVs in the biology of wound healing.