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Ghosh et al. Plast Aesthet Res 2024;11:50 https://dx.doi.org/10.20517/2347-9264.2024.70 Page 3 of 11

assisted liposuction (PAL), as well as alternative processing techniques, as effective ways for obtaining viable
fat [28,29] . PAL and ultrasound-assisted liposuction (UAL) have also been found to collect equivalent amounts
of ASCs to SAL [30,31] . Additionally, the use of a 2-mm diameter multiperforated microcannula and lower
suction pressures have been shown to increase ASC yield in isolation [32-34] .

Similarly, with cell-supplementation such as CAL, the optimal technique is yet to be determined. In a
standard approach, fat is typically harvested via liposuction to ensure an adequate quantity of ASCs. It is
then washed with sterile phosphate-buffered saline (PBS), digested with collagenase, centrifuged, and
resuspended [27,35] . Depending on the quantity of ASCs, the sample can then be used directly or expanded in
culture to ensure adequate sample size. Several products have come on the market to help facilitate and
automate the process of enzymatic isolation. Aronowitz et al. compared four of these products - the Multi-
Station (PNC International, Gyeonggi-do, Republic of Korea), the Cha-Station (CHA Biotech, Kangnamgu,
Republic of Korea), the Lipokit with MaxStem (Medi-Khan, West Hollywood, Calif.), and the Celution 800/
[36]
CRS System (Cytori Therapeutics, Inc., San Diego, Calif.) - in their efficiency in isolating SVF in vitro .
They found the latter to yield a significantly higher concentration of SVF and endothelial cells, with
minimal residual collagenase activity.

However, the safety of enzymatic digestion with the potential for residual collagenase in SVF samples has
been questioned, and purely mechanical means of SVF have been described as well [37,38] . Tiryaki et al.
describe a three-step process of manual isolation utilizing initial processing through different sizes of
microblades, incubation and centrifugation, and resuspension of the SVF pellet after discarding supernatant
[39]
material . They compared their methods to traditional enzymatic processing, and though the latter had a
higher SVF cell concentration, mechanical digestion had equal cell viability and higher stem cell surface
markers. Therefore, mechanical digestion may provide a faster and cheaper means of SVF isolation.

Large-scale studies examining the clinical implications of these findings remain limited. Domenis et al.
compared the enzymatic Celution and Lipokit systems to the mechanical Fastem (CORIOS Soc. Coop, San
Giuliano Milanese MI, Italy) system . While the mechanical system had less potential for multipotency in
[40]
vitro, there was no difference in clinical fat retention at 12 months when comparing the three methods. A
similarly designed study by Gentile et al. focused mostly on clinical outcomes and found the enzymatic
Celution systems to be superior in terms of isolating SVF and maintaining volume . A more recent study
[41]
published by this group prospectively compared fat grafting enhanced with SVF either isolated
enzymatically or mechanically (via filtration alone, centrifugation alone, or filtration and centrifugation)
and found that filtration was the most efficient mechanical method of isolation leading to the highest fat
retention at 1-year follow-up, though this was still superseded by enzymatic isolation .
[42]
The difference in ASCs from different anatomical fat deposits has also been of recent interest. Di Taranto et
al. examined the differences between superficial and deep abdominal adipose tissue from female donors and
found the superficial layer of fat had higher ASC concentration and increased multipotency when
[43]
isolated . Faustini et al., studying SVF concentration differences in males versus females, found the
abdomen to be the best fat harvest site in males, whereas they did not find any significant anatomical
[44]
difference in SVF yield in females from different fat deposits . In contrast, Tsekouras et al. found a
significantly higher yield of ASCs from the inner and outer thigh compared to the abdomen, while Grasys et
al. found the opposite [45,46] . One of the most comprehensive studies regarding harvest technique and
anatomical site of harvest was conducted by Iyyanki et al. in 2015 . In this study, fat was harvested from
[47]
the abdomen, flank, or axilla using liposuction, direct excision or the Coleman technique with or without
centrifugation. They found that direct excision led to the highest SVF and ASC concentration while