Mechanisms for treating ischemic wounds with human adipocyte derived stem cell exosomes

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This research will develop an innovative therapy to promote tissue regeneration and reverse the consequences of recalcitrant wound healing. It is particularly relevant to our Veteran population that suffers the consequences of injury and aging. The $5 billion global market for “advanced wound care” is anticipated to triple in the next ten years. We have a rapidly growing cohort of older veterans with diabetes, a new cohort of wounded warriors with injuries that include non-healing ulcers from spinal cord injury, multiple traumatic injuries and burns. Hence Veteran populations are at risk for a staggering number of chronic wounds. We propose to use a secreted nanovesicle from adipose derived stem cells (human ADSC). Adipose tissue is an abundant and renewable source of stem cells. Human ADSC release trophic factors that stimulate endogenous repair mechanisms in wounds, and they have immunomodulatory effects, responding to the microenvironment. They have been shown to heal wounds. However, hADSC research is flawed by the lack of standardization and delivery methods. Our goal is to harness the promise of stem cell regenerative secreted factors to heal wounds. We have identified a wound healing treatment using conditioned media (CM) collected from hADSC in culture. We recognize that CM contains exosomes secreted by hADSC, and the factors within the exosomes act in a paracrine manner. In addition to lipids and proteins, exosomes contain various species of RNA. One type, long non- coding RNA, is of particular interest in that it is only secreted by stem cells. Once cells start to differentiate to lineages such as bone and adipocytes, it is retained for a nuclear function. The secreted long non-coding RNA that we find in exosomes is MALAT1. It functions in wound healing, and we predict that exosomes rich in MALAT1 will be able to heal a variety of wounds. We hypothesize that MALAT probably derepresses genes for migration, proliferation, and angiogenesis via its interaction with microRNAs. We will examine how exosomes function in vitro in a human dermal fibroblast wound healing assay. We will use a rat ischemic wound model for examining how exosomes function in vivo. Both of these models will let us optimize the number and concentrations of exosomes that allow for wound closure and modulation of angiogenesis. We propose improvements to hADSC that will allow for collection of more exosomes. Exosomes are more stable than stem cells for wound applications. They can be stored in low temperatures, applied topically and be made available to wounds in emergency rooms and for home use. This project is the first step in making hADSC exosomes a clinical reality for wound repair and tissue regeneration.