Delayed Postconditioning with External Volume Expansion Improves Survival of Adipose Tissue Grafts in a Murine Model

Background: External volume expansion improves the survival of adipose tissue grafts by preoperatively conditioning (“preconditioning”) tissues that will receive the graft. External volume expansion’s mechanisms of action (induction of angiogenesis and of adipogenesis) could improve graft survival also when applied postoperatively (“postconditioning”). Methods: Fifty-six 8-week-old athymic (nu/nu) mice received dorsal subcutaneous grafts of human lipoaspirate (0.3 ml each) bilaterally before undergoing external volume expansion (left dorsum) or no treatment (right dorsum, controls). External volume expansion was started either on the same day of (immediate group), 2 days after (early group), or 1 week after surgery (delayed group). At follow-up, grafts were analyzed for tissue survival, remodeling, adipogenesis, and angiogenesis using histology. The authors subsequently assessed the effects of the delayed application of external volume expansion adopting a foam-shaped interface to deliver the treatment. Results: At 28-day follow-up, delayed postconditioning with external volume expansion significantly improved the survival of grafts (18 percent) compared with controls (viable graft thickness ratio, 58 ± 15 percent versus 49 ± 13 percent) and increased the density of blood vessels within the graft (63 percent; blood vessels per 10× magnification field, 44 ± 12 versus 27 ± 11). Other groups did not experience significant changes. Adoption of external volume expansion with a foam-shaped interface similarly improved outcomes and further reduced fibrosis within the grafts. Conclusions: Postoperative delayed application of external volume expansion modestly improves the survival of adipose tissue grafts by inducing adipogenesis and angiogenesis. Use of a foam-shaped interface decreases the fibrosis induced in the grafts.