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.

Wound healing progresses through four phases: hemostasis, inflammation, proliferation, and remodeling. Wounds may become chronic if this process is disrupted. The use of small extracellular vesicle (sEV; EVs < 200 nm) exosomes (exo; ~40–120 nm) derived from human adipose stem cells (hASCs) as a treatment for wounds is well studied. The cargo of these exosomes is of great interest as this accelerates wound healing. Our previous studies identified lncRNAs GAS5 and MALAT1 as packaged and enriched in hASC exosomes. In this study, we use a rat model to examine the effects on wound healing when hASC exosomes are depleted of GAS5 and MALAT1. Rats were wounded and wounds were treated with 100 μg hASC_exo or hASC_exo-G-M every 2 days for 1 week. qPCR was completed to evaluate the molecular effects of depletion of GAS5 and MALAT1 from hASC_exo. RNAseq was performed on wound tissue to evaluate the molecular mechanisms changed by hASC_exo-G-M in wound healing. While hASC_exo-G-M significantly improved wound healing rate compared to control wounds, healing occurred slower than in wounds treated with hASC_exo that were not depleted of GAS5 and MALAT1. Overall, this study reveals that molecular functions associated with healing are reduced in the absence of GAS5 and MALAT1, highlighting the importance of these lncRNAs.

Human intraperitoneal omental adipose tissue, part of the visceral adipose depots, surrounds the abdominal organs and has functions distinct from the subcutaneous adipose depots. In the clinical setting, it is observed that the omentum is beneficial to combat internal sources of inflammation, oxidative stress, and injury-related stress. However, the molecular mechanisms involved in these functions are not fully understood. We previously demonstrated that adipose stem cells derived from human omental adipose tissue (om-hASCs) secrete exosomes (exos). We and others have extensively evaluated the subcutaneous adipose depot-derived exosomes; however, the role of adipose stem cells derived from the human omental depot (om-hASCs) remains less known. In this study, we postulated that exosomes from om-hASCs (om-hASCexos) drive the repair ability of the omentum to heal organs after internal injury and insults. First, we characterized the om-hASCexos using a proteomic analysis which identified the distinct cargo. Using in vitro injury models, we show that om-hASCexos significantly improve cell migration and proliferation, while decreasing oxidative stress and inflammation. To study acute in vivo healing, a rat wound model was evaluated. Om-hASCexos significantly improved the healing rate of injuries. RNAseq revealed that om-hASCexo treatment acts upon pathways associated with lipid and fatty acid metabolism, apoptosis, immune response, and cell differentiation. The pathway analysis indicated that om-hASCexos significantly regulate the expression of Clec5a and Trem1 in the immune response pathway. Overall, we demonstrate the singular properties of om-hASCexos that are distinct from other sources of hASC. Thus, this study provides an understanding of the unique ability of the omental adipose depot to combat internal injuries.