Micro/Nanobubble-Assisted Lipotransfer: In Vivo Evidence of Improved Graft Outcomes

Retention rates of lipotransfer remain variable, with the underlying cause associated with tissue oxygenation and blood supply barriers. One promising new method of improving tissue oxygenation is micro/nanobubbles (MNBs), which are small gas bubbles (<100 μm) generated within a saline solution. MNBs are stable and carry a significant amount of oxygen, and because of their negatively charged surface characteristics, they are an ideal oxygen-delivery solution. Thus, we hypothesize that washing/oxygenating lipoaspirate tissue prior to transplantation in a micro/nanobubble saline solution will improve graft survival and quality compared to a saline control.

Human lipoaspirate samples obtained from healthy donors were washed with an oxygenated MNB or saline wash. These samples were then injected into the dorsum of sixteen 6-week-old male BALB/c mice, where each mouse received one saline and one MNB-washed graft. At 2-, 4-, 8-, and 12-week time points, the explants were harvested and weighed, and gas pycnometry was performed to assess graft volume. The tissues were also subjected to hematoxylin and eosin (HE) staining and immunohistochemistry to detect perilipin and blood vessels (CD31). These stains, as well as adipocyte count and area quantifications, were analyzed using ImageJ.

HE staining revealed that the control group demonstrated notable adipocyte hypertrophy, while MNB-washed samples had evident adipocyte hyperplasia. This observation was confirmed by an analysis of variance (ANOVA), which showed that the control group had a larger average graft mass and volume (P < 0.01). MNB-washed grafts also exhibited significantly greater adipocyte counts and smaller adipocytes (P < 0.001). Perilipin staining was also greater in the MNB group at the 2- and 4-week time point indicating improved de novo adipogenesis following implantation. Lastly, CD31 staining revealed a significantly greater core vessel density and angiogenesis at the 4-week and 12-week time points (P < 0.01).

Our study demonstrates that MNBs enhance tissue quality as indicated by a significant increase in de novo adipogenesis, higher vessel density, and decreased adipocyte hypertrophy. Additional studies are needed to evaluate the clinical effectiveness. Nevertheless, incorporating MNBs into procedures holds great promise in tackling the ongoing challenge of inconsistent outcomes in lipotransfer.