Enriching fat grafts with stem cells improves outcomes

Image: PD 

1. Enriching fat grafts with adipose-derived stem cells improved fat graft outcomes by increasing tissue survival while decreasing necrosis and fibrosis, without serious complications. 

Evidence Rating Level: 1 (Excellent)      

Study Rundown: Autologous fat grafting is an increasingly common technique for treatment of multiple indications including breast reconstruction, treatment of burn scars and congenital or post-traumatic malformations. Benefits include biocompatibility, non-immunogenicity, and ready availability, while a current major obstacle remains unpredictability in success and, often, low graft survival. Animal studies have suggested that fat grafts enriched with ex-vivo expanded adipose-derived stem cells (ASCs) may not be as prone to graft failure, though no trials to date have addressed this technique in humans.

This study was a triple-blinded randomized control trial with a matched comparison of ASC-enriched fat grafts and non-enriched control fat grafts. After four months, residual volumes of ASC-enriched grafts were significantly greater than those of the control grafts, with less necrosis and fibrosis. Autologous fat grafting with ASCs appears to be a valuable method of improving initial outcomes with few if any procedural complications. However, the size of this study was small. Further, 2 of the original 13 patients were excluded because their ASC isolates became microbially contaminated and were discarded. As the technique is further assessed in later clinical trials and possibly commercialized, a vital concern is if increased laboratory throughput is associated with increased risk of complications secondary to microbial or chemical contamination.

Click to read the study in Lancet

Click to read the associated comment in Lancet

Relevant Reading: Supplementation of fat grafts with adipose-derived regenerative cells improves long-term graft retention

Lead author Dr Stig-Frederik Trojahn Kølle, MD speaks to 2 Minute Medicine: 

“These promising results add significantly to the prospect of stem cell use in clinical settings and show that ASC graft enrichment could render lipofilling a reliable procedure, since the resorption rate, quality of tissue, and safety can be predicted.”

In-Depth [randomized trial]: This study was a triple-blinded randomized controlled trial conducted at one clinical site. 13 patients received subcutaneous lipoinjections in each upper arm – with one side receiving adipose-derived stem cell (ASC) enriched fat graft and the other receiving an unenriched control fat graft .Patients were followed for 121 days.

The primary outcome was residual volume by MRI imaging, and secondary outcomes included histologic assessment of adipose tissue distribution, newly formed connective tissue, necrosis, and transplant vascular density, as well as safety and feasibility. ASC-enriched fat graft residual volumes were 80.9% (95% CI 76.6 to 85.2) of the initial volume, versus 16.3% (11.1 to 21.4) for the control fat grafts – a difference of 64.6% (57.1 to 72.1, p < 0.0001). Histologic examination showed statistically significant increase in new connective tissue formation, decrease in fibrosis, decrease in necrosis, but no difference in vascular density. No major procedural complications were reported. Of the 13 patients originally randomized, 10 were included for analysis – 1 patient was excluded due to a minor procedural complication required reversal of the lipoinjection, 2 patients were excluded when the growth media used for the ASC expansions was found to be contaminated and the ASCs were discarded. No bias or confounding was reported, though this was a single center study, and the sample size was small. Results may become variable in other clinical sites and with large-scale clinical testing.

By Philip Hewes and Mimmie Kwong

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