Mechanically Isolated Stromal Vascular Fraction by Nanofat Emulsification Techniques
We would like to discuss two points that have not been addressed by the authors. First, in our opinion, it would be really interesting to determine whether the adipose-derived stromal cells (CD45−/CD31−/CD34+) isolated by these two free enzymatic extraction methods are “classic” adipose-derived stromal cells. Indeed, adipose-derived stromal cells are characterized by different criteria,3 such as their ability to form colony-forming unit-fibroblast cells, the ability to differentiate into various cell types derived from the mesodermal lineage (bone, cartilage, and adipose tissue), and the presence of mesenchymal markers (CD105, CD73, and CD90), which were not assayed by the authors.
Moreover, we demonstrated that the stromal vascular fraction obtained after emulsification of the fat with the nanofat technique, described by Tonnard and Verpaele, contains functional adipose-derived stromal cells.4 Indeed, adipose-derived stromal cells isolated with this technique present all the criteria described below and are functional with immunosuppressive properties characterized by the capability to decrease the proliferation of human T cells. Functional adipose-derived stromal cells, through secretion of paracrine factors, can modulate inflammation and can favor angiogenesis, two factors that play an essential role in tissue regeneration.5
In conclusion, all changes in the technique of mechanical extraction of stromal vascular fraction cells can modify cell composition and may alter cell properties. Therefore, stromal vascular fraction isolated with new mechanical techniques has to be tested in vitro to demonstrate the presence of adipose-derived stromal cells. Moreover, the presence of functional adipose-derived stromal cells has to be determined so that the use of this new technique in the operating room can be judged and validated and the best regenerative mechanical technique can be chosen.