Adipose-Derived Stem/Stromal Cells, Stromal Vascular Fraction, and Microfragmented Adipose Tissue

Adipose tissue has become one of the main foci in the development of regenerative therapeutic strategies due to the easy harvesting procedure and fewer ethical concerns compared to other sources of stem/stromal cells. To date, the adipose tissue has been used for regenerative purposes either as the source of (1) adipose-derived cells (ASCs), that is, plastic-adherent culture-expanded cells, or of (2) adipose tissue-derived products obtained at the point of care known as stromal vascular fraction (SVF) or microfragmented adipose tissue (microfat). The application of both methods has been reported to be successful in different preclinical and clinical scenarios, especially for the treatment of musculoskeletal conditions. Currently, ASCs, SVF, or microfat is delivered with two approaches. The first one relies on the seeding of cells/SVF or microfat on a support (scaffold), and it is typically used in association with surgery for the treatment of focal defects; the second approach consists in the direct injection of these adipose-derived products to damaged sites, and it is meant to treat wider areas of degeneration. In this case, the direct cell differentiation mechanism is not the main responsible for the benefits observed after cell transplantation, but rather the therapeutic effect is related to the secretion of soluble factors (secretome) and their interactions with resident cells through paracrine mechanisms. Many controversial points still animate the debate on the most effective harvest and processing procedures composition, cell concentration, dose, and delivery strategy. In this chapter, we discuss the different adipose-derived products (ASCs, SVF, and microfat), their phenotype, rationale, therapeutic potential, and available evidence based on the most relevant in vitro and preclinical findings.