Reply: Cell-Enriched Fat Grafting Improves Graft Retention in a Porcine Model: A Dose-Response Study of Adipose-Derived Stem Cells versus Stromal Vascular Fraction.

Abstract

Sir: We thank Dr. Choudhery for the interesting perspectives on our work,1 and we appreciate the opportunity to address his comments and elaborate on the results of our study. Dr. Choudhery would like to have seen more adipose-derived stromal cell dosages tested in addition to the six groups that were chosen for our study. While we also would have liked to provide a more detailed dose-response curve, we were limited by how many groups could be fit into the abdominal area of the pigs without risking the grafts influencing each other. Dr. Choudhery seemed puzzled that we did not find a statistically significantly different fat graft volume retention in the stromal vascular fraction–enriched group compared with the adipose-derived stem cell–enriched groups (which contained a much higher adipose-derived stem cell concentration). While we can only speculate as to the reason for this lack of difference, we must also point out that a lack of statistically significant difference in this study does not necessarily mean that there was no difference between the groups. It could just as well be that our study was not statistically powered to detect the actual difference. Also, it is possible that further changes in the fat graft volume could occur later than 4 months after the fat grafting.2 Dr. Choudhery pointed out that the stromal vascular fraction cells were harvested from the neck area, whereas the culture-expanded adipose-derived stem cells originated from the dorsal area. This is true and may have influenced the stromal vascular fraction composition. However, we have previously shown that similar cell compositions and cell counts can be found in the two harvesting areas.3 It was also pointed out by Dr. Choudhery that the first media change should have been performed after 24 hours and that the cells should have been harvested at 70 percent to 90 percent confluence to ensure cell purity and cell viability. The culturing protocol used in this study was validated to ensure cell purity and cell viability with cell marker analysis and differentiation assays in a previous study.4 Once again, we thank Dr. Choudhery for his interest in our study and for emphasizing the need for further randomized trials within the field of cell-enriched fat grafting to ensure its place in clinical practice. DISCLOSURE The authors have no financial interest to disclose in relation to the content of this communication.