Specific Features of Stromal Cells Isolated from the Two Layers of Subcutaneous Adipose Tissue: Roles of Their Secretion on Angiogenesis and Neurogenesis

Human-adipose-tissue-derived mesenchymal stromal cells (AD-MSCs) are currently being tested as autologous-cell-based therapies for use in tissue healing and regeneration. Recent studies have also demonstrated that AD-MSC-derived exosomes contribute to tissue repair and peripheral nerve regeneration. Subcutaneous abdominal adipose tissue (AAT) is divided into two layers: the superficial layer (sAAT) and the deep layer (dAAT). However, it is unclear whether there are particular characteristics of each layer in terms of AD-MSC regenerative potential. Using AD-MSCs purified and characterized from three abdominoplasties, we compared their secretomes and exosome functions to identify which layer may be most suitable as a source for cell therapy. Phenotypical analysis of the AD-MSCs containing stromal vascular fraction did not reveal any difference between the two layers. The AD-MSC secretomes showed a very similar pattern of cytokine content and both layers were able to release exosomes with identical characteristics. However, compared to the secretome, the released exosomes showed better biological properties. Interestingly, dAAT exosomes appeared to be more effective on neuromodulation, whereas neither sAAT nor dAAT-derived exosomes had significant effects on endothelial function. It thus appears that AD-MSC-derived exosomes from the two abdominal adipose tissue layers possess different features for cell therapy.