Fat Grafting into Younger Recipients Improves Volume Retention in an Animal Model.

BACKGROUND: Soft-tissue deficits associated with various craniofacial anomalies can be addressed by fat grafting, although outcomes remain unpredictable. Furthermore, consensus does not exist for timing of these procedures. Whereas some advocate approaching soft-tissue reconstruction after the underlying skeletal foundation has been corrected, other studies have suggested that earlier grafting may exploit a younger recipient niche that is more conducive to fat graft survival. As there is a dearth of research investigating effects of recipient age on fat graft volume retention, this study compared the effectiveness of fat grafting in younger versus older animals through a longitudinal, in vivo analysis. METHODS: Human lipoaspirate from three healthy female donors was grafted subcutaneously over the calvaria of immunocompromised mice. Volume retention over 8 weeks was evaluated using micro-computed tomography at three experimental ages: 3 weeks, 6 months, and 1 year. Histologic examination was performed on explanted grafts to evaluate graft health and vascularity. Recipient-site vascularity was also evaluated by confocal microscopy. RESULTS: The greatest retention of fat graft volume was noted in the youngest group compared with both older groups (p < 0.05) at 6 and 8 weeks after grafting. Histologic and immunohistochemical analyses revealed that improved retention in younger groups was associated with greater fat graft integrity and more robust vascularization. CONCLUSION: The authors' study provides evidence that grafting fat into a younger recipient site correlates with improved volume retention over time, suggesting that beginning soft-tissue reconstruction with fat grafting in patients at an earlier age may be preferable to late correction.

Cell-Based Soft Tissue Reconstruction in a Hydrogel Scaffold.

BACKGROUND: Renevia is a hyaluronin-gelatin crosslinked matrix scaffold that has been studied as an alternative to adipose transfer in soft tissue reconstruction. It is designed to emulate the native extracellular matrix environment by supporting stromal vascular fraction (SVF) cell attachment, survival, and proliferation, thus promoting cell-based volume restoration. However, the concentration of incorporated cells for a clinically relevant result has yet to be determined. METHODS: Five experimental groups of seven CD-1 nude immunodeficient mice were given 250 µL grafts of the following composition: 1 million human SVF cells per mL of Renevia scaffold, 6 million human SVF cells per mL scaffold, 12 million human SVF cells per mL scaffold, Renevia scaffold-alone or human adipose tissue-alone. Volumetric analysis was conducted at discrete time points over 16 weeks using 3-dimensional ultrasound, after which time the grafts were explanted for histologic analysis. RESULTS: At the conclusion of the study at week 16, the Renevia scaffold group incorporating the highest concentration of human SVF cells (12 million cells per mL scaffold) had significantly greater volume retention compared with the 2 lower concentrations, scaffold-alone and fat-alone groups. Histology of the 12 million scaffold group revealed abundant adipocyte formation within the scaffold, exceeding that observed in the 6 million, 1 million, and scaffold-alone groups. The 12 million group also demonstrated significantly increased vascularity per CD31 staining. CONCLUSIONS: Stromal vascular fraction cells coupled with Renevia hydrogel scaffold can enhance soft tissue volume reconstruction. In this study, we observed the greatest effect with 12 million cells per mL. From the perspective of volume retention, incorporation of higher concentrations of SVF cells with Renevia may be an alternative to conventional adipose tissue grafting.