Dose-dependent spatiotemporal comparison of cell-assisted lipotransfer between stromal vascular fraction and adipose-derived stromal cells

Autologous fat grafting is widely used in reconstructive and aesthetic surgery, yet long-term retention remains variable. Cell-assisted lipotransfer (CAL) enriches grafts with stromal vascular fraction (SVF) cells or adipose-derived stromal cells (ASCs) to improve graft survival. Their comparative efficacy in graft remodeling remains insufficiently investigated. Human fat tissues supplemented with graded doses of SVF cells or ASCs were grafted into nude mice. Phase I compared dose levels; Phase II evaluated graft remodeling at the optimal dose over time. Graft volume and tissue integrity were assessed using micro-CT and histological analysis. Both SVF and ASC supplementation achieved maximal retention at 10 5 cells ( p < 0.05); higher doses showed no additional benefit. At this dose, SVF cells promoted angiogenesis, showing increased von Willebrand factor⁺ endothelial cells at weeks 1 and 2 ( p < 0.001) and greater CD31⁺ coverage at week 8 ( p = 0.025). ASC treatment supported sustained tissue remodeling, with significantly larger perilipin⁺ adipocyte areas ( p = 0.047) and an elevated M2/M1 macrophage ratio ( p = 0.009). PKH26 tracking revealed transient persistence of SVF cells, while ASCs exhibited durable engraftment accompanied by higher Ki67⁺ cell counts within the grafts ( p < 0.001). SVF cells and ASCs show distinct temporal roles in CAL. Tailored dosing and cell-type selection may optimize clinical fat grafting outcomes.