Long Noncoding RNA GAS5 Contained in Exosomes Derived from Human Adipose Stem Cells Promotes Repair and Modulates Inflammation in a Chronic Dermal Wound Healing Model

SIMPLE SUMMARY: Wounds due to cuts, lacerations, or surgical incisions undergo healing through a highly regulated process. Occasionally, the skin is unable to heal in a timely manner, leading to chronic wounds and related sequelae, such as scarring, risk of infections on open wounds, and—as a growing body of evidence attests—psychological impact on the individual. In addition, certain diseases, such as diabetes, obesity, and cancer, are characterized by an ongoing state of very low-grade inflammation. This underlying inflammation substantially hinders wound healing. To improve the outcome of chronic wounds, we harvested the potential of exosomes (nanovesicles) secreted from human adipose stem cells. We demonstrate that exosomes are efficiently taken up by skin cells and promote healing by significantly accelerating wound closure time. To understand the mechanism by which exosomes promote wound healing, we identified an RNA called GAS5 that is a driver of the regenerative properties of exosomes. Additionally, we identified the inflammation pathways that are regulated by GAS5 to promote the healing of wounds. Such a determination is essential to move exosome therapy into the clinic. In conclusion, our results demonstrate that exosomes harvested from human adipose stem cells accelerate the healing of chronic recalcitrant wounds and thus have a tremendous therapeutic potential in wound healing. ABSTRACT: Chronic recalcitrant wounds result from delayed or slowed healing processes. Underlying inflammation is a substantial risk factor for impaired dermal wound healing and often leads to chronic wound-related sequelae. Human adipose stem cells (hASCs) have shown tremendous potential in regenerative medicine. The goal of this project was to improve the outcome of chronic wounds by harvesting the exosomes from hASCs for therapeutic intervention. The results demonstrate that long noncoding RNA GAS5 is highly enriched in hASC exosomes and, further, that GAS5 is central to promoting wound repair in vitro. To evaluate the outcome of wound healing in a chronic low-grade inflammatory environment, lipopolysaccharide-treated HDF cells were evaluated for their response to hASC exosome treatment. Ingenuity pathway analysis identified inflammation pathways and genes affected by exosomes in a GAS5-dependent manner. Using siRNA to deplete GAS5 in HDF, the results demonstrated that Toll-like receptor 7 (TLR7) expression levels were regulated by GAS5. Importantly, the results demonstrate that GAS5 regulates inflammatory pathway genes in a chronic inflammation environment. The results presented here demonstrate that hASC exosomes are a viable therapeutic that accelerate the healing of chronic recalcitrant wounds.