Superior retention of aged fat graft by supplementing young adipose-derived stromal cells in a murine model.

Background: In 2021, a meta-analysis showed fat graft retention varied from 26 to 83%. In a retrospective study including patients with Parry-Romberg syndrome, the younger age group had higher satisfaction scores (3.8 vs. 3.0) after fat grafting. Cell-assisted lipotransfer (CAL) could be an alternative to overcome the instability of volume loss; however, no study investigated its effect on old recipients.

Methods: In an in vitro study, adipose-derived stromal cells (ASCs) from aged and young (52- and 8-weeks old) DsRed B6 mice were characterized by proliferation rates as percentages of Ki-67-positive cells. 68-week-old wild type B6 mice received 150 µL of green fluorescent protein fat (from 69-week-old B6 mice) mixed with saline, 3 x 105 aged or young DsRed ASCs (N, A, and Y groups, respectively) on the scalp (n = 6/group). After 8 weeks, graft volumes were evaluated using micro-computed tomography. Vessel densities were tracked by percentages of CD31 using immunofluorescence staining.

Results: Young ASCs showed higher proliferation than the aged (47.1% and 26.2%, respectively, p < 0.05). The Y group showed the highest graft retention (median: N = 41.0%, A = 52.2%, Y = 65.2%, p < 0.05) and percentage of blood vessels (median: N = 27.7%, A = 43.5%, Y = 54.7%, p < 0.05) among the three groups.

Conclusions: CAL is effective with old recipients; higher effect was observed by supplementation with younger ASCs due to higher angiogenesis stimulation. However, this is autologous grafting model, further validation of safety, toxicity, and allogenic grafting is required.

Clinical relevance statement: The results suggest that it is clinically possible to conduct CAL for old adults using autologous ASCs. However, further validation of using allogenic ASCs from young donors to improve graft retention in old adults is required.