Efficacy and Safety of a Nanofat-seeded Biological Scaffold in Healing Lower Limb Surgical Defects

Large full-thickness skin defects, such as those resulting from trauma, large and giant congenital nevi, disfiguring scars, or tumor resection remain major clinical problems to patients and physicians. Skin flaps and grafts represent the current standard of care (SOC), but often present limitations associated with surgical morbidity and donor site availability. To overcome these limitations, cultured epidermal autografts consisting of keratinocytes were developed to provide enough autologous skin. However, the routine use of these cultured epidermal autografts was hampered by its high risk of recurrent wound opening, long-term fragility, and increased rates of scar contractures. Tissue-engineered dermal skin substitutes containing complex dermal layers have also been developed to produce large, near-natural skin substitutes. They promote healing and avoid scar contracture; however, the healing times are long as they lack the active cellular and paracrine components of healing, and they often need a second delayed surgical procedure, a split-thickness skin graft, to obtain complete epithelization. The term "nanofat grafting" was first used by Tonnard et al. and constitutes a rich reservoir of regenerative precursor cells (including stromal vascular fraction cells, among which adipose-derived stem cells) with pro-angiogenic capabilities. The many proprieties of nanofat and the stromal vascular fraction in regenerative and aesthetic surgery are just being discovered. In particular, numerous in vitro and in vivo studies have demonstrated the ability of these cells to differentiate into various skin cell lineages. Moreover, they are recognized as a powerful source for tissue regeneration because of their capability to secrete paracrine factors, initiating tissue repair and accelerating wound closure by skin regeneration instead of fibrotic scar formation. Few anecdotal reports have documented the efficacy of the stromal vascular fraction in acute as well as chronic wounds. However, no observation has explored the efficacy of nanofat in healing surgical defects. Of note, nanofat is substantially easier, faster, and remarkably less expensive to obtain when compared to the mechanically- or enzymatically-isolated stromal vascular fraction. At present, there is a noticeable lack of randomized-controlled evidence in the international literature. Thus, this would represent the most comprehensive and the first randomized, controlled experience documenting the use of nanofat for wound healing.