Studies in Fat Grafting

Abstract

Background Cell-assisted lipotransfer has shown much promise as a technique to improve fat graft take. However, the concentration of stromal vascular fraction cells required to optimally enhance fat graft retention remains unknown. Methods Human lipoaspirate was processed for both fat transfer and harvest of stromal vascular fraction (SVF) cells. Cells were then mixed back with fat at varying concentrations ranging from 10,000 to 10 million cells per 200 µl of fat. Fat graft volume retention was assessed via CT scanning over 8 weeks, and then fat grafts were explanted and compared histologically for overall architecture and vascularity. Results Maximum fat graft retention was seen at a concentration of 10,000 cells per 200 µl of fat. The addition of higher number of cells negatively impacted fat graft retention, with supplementation of 10 million cells producing the lowest final volumes, lower than fat alone. Interestingly, fat grafts supplemented with 10,000 cells showed significantly increased vascularity and decreased inflammation, while fat grafts supplemented with 10 million cells showed significant lipodegeneration compared to fat alone Conclusions Our study demonstrates dose dependence in the number of SVF cells that can be added to a fat graft to enhance retention. While cell-assisted lipotransfer may help promote graft survival, this effect may need to be balanced with the increased metabolic load of added cells that may compete with adipocytes for nutrients during the post-graft period.

Cell-Assisted Lipotransfer Improves Volume Retention in Irradiated Recipient Sites and Rescues Radiation-Induced Skin Changes

“…Lipoaspirate was obtained from two healthy female donors, ages 45 and 49 years. ASCs were harvested from half of the lipoaspirate while the other half was processed for grafting by centrifugation [13, 14]. For CAL, 250,000 supplemental cells were added in a small volume (20 μ l) to a larger volume of fat (5 ml).…”

“…For CAL, 250,000 supplemental cells were added in a small volume (20 μ l) to a larger volume of fat (5 ml). Fat (200 μ l), with or without supplemental cells (10,000 cells per graft), was then injected beneath the scalp of age-matched irradiated and non-irradiated mice [7, 14–16]. This well-established mouse model facilitates in vivo study of human grafts with minimal immunological reaction.…”

Oxygen and nutrient delivery in tissue engineering: Approaches to graft vascularization

“…Beyond the cell type, selecting an appropriate ratio of endothelial cells within the graft is also critical. The ratio of vascular cells to tissue-specific cells in a tissue construct has been investigated and confirmed the notion that using too many endothelial cells actually decreases graft neovascularization, likely due to a higher metabolic load and increased competition for nutrients (Paik et al, 2015). At current, no unified accepted ratio has been reported, partially at depends greatly on tissue type and graft size.…”

Application of adipose-derived stromal cells in fat grafting: Basic science and literature review

“…Therefore, based on the hypothesis that enrichment with ADSCs increases fat graft viability, the use of ex vivo expanded ADSC-enriched fat grafts in a similar way is expected to lead to far more reliable and predictable results than those achieved by the minor fraction of ADSCs observed in SVF and without the need for overcorrection. Undeniably, the high residual volume of >80% in a previous human randomised controlled clinical trial ( 68 ) is encouraging with respect to the potential use of enriched fat grafts in reconstructive surgery following ex vivo expansion of collagenase-processed ADSCs used for CAL.…”

“…Paik et al ( 68 ) in 2015 used that same xenografting murine model (nude mouse) to try and determine the optimal SVF cell concentration. Results demonstrated a dose-dependence in the number of SVF cells that may be added to a fat graft to enhance retention by comparing fat grafts with and without SVF supplementation.…”