COSMETIC
Influences of Centrifugation on Cells andTissues in Liposuction Aspirates: Optimized
Centrifugation for Lipotransfer and Cell Isolation
Masakazu Kurita, M.D.
Daisuke Matsumoto, M.D.
Tomokuni Shigeura, M.S.
Katsujiro Sato, M.D.
Koichi Gonda, M.D.
Kiyonori Harii, M.D.
Kotaro Yoshimura, M.D.
Tokyo and Yokohama, Japan

Background: Although injective autologous fat transplantation is one of themost attractive options for soft-tissue augmentation, problems such as unpredictability and fibrosis resulting from fat necrosis limit its universal acceptance.
Centrifugation is one of most common methods for overcoming these difficulties. This study was performed to investigate quantitatively the effects of centrifugation on liposuction aspirates to optimize centrifugal conditions for fat
transplantation and isolation of adipose-derived stem cells.
Methods: Liposuction aspirates, obtained from eight healthy female donors,
were either not centrifuged or centrifuged at 400, 700, 1200, 3000, or 4200 g for
3 minutes. The volumes of the oil, adipose, and fluid portions and numbers ofblood cells and adipose-derived cells in each portion were examined. The
processed adipose tissues (1 ml) were injected into athymic mice, and grafts were
harvested and weighed at 4 weeks. Morphologic alterations were observed using
light and scanning electron microscopy.
Results: Centrifugation concentrated adipose tissues and adipose-derived stem
cells in the adipose portion and partly removed red blood cells from the adipose
portion. Centrifugation at more than 3000 g significantly damaged adiposederived stem cells. Centrifugation enhanced graft take per 1 ml centrifugedadipose but reduced calculated graft take per 1 ml adipose before centrifugation.
Conclusions: Excessive centrifugation can destroy adipocytes and adiposederived stem cells, but appropriate centrifugation concentrates them, resulting in enhanced graft take. The authors tentatively recommend 1200 g
as an optimized centrifugal force for obtaining good short- and long-term
results in adipose transplantation. (Plast. Reconstr. Surg. 121: 1033, 2008.)

S

oft-tissue augmentation by autologous fat
transplantation is an attractive therapy, butsome problems remain, including the low
survival rate of transplanted adipose tissue andformation of calcifications. To overcome these
difficulties, a number of technical improvements in harvesting, processing, and injection
were reported.1–9 Among these, we focused on
centrifugation of liposuction aspirates. Centrifugation is also an important process for isolating adipose-derived stem cells from liposuction aspirates.

Centrifugation, which has been used in processing lipoaspirates since the 1980s,10 is now
widely used to concentrate aspirated fat and to
remove oil, fluid, and blood products. Various
views and ideas regarding centrifugation of lipoaspirates have been reported,1,3,5,7–9,11–13 and thecurrent consensus is as follows. Centrifugation
concentrates adipocytes3,5,7,8 and separates themfrom substances that may degrade adipocytes,
such as blood cells, lipids, proteases, andlipases,3,5,8 but does not enhance immediate fat

From the Department of Plastic Surgery, University of Tokyo
School of Medicine; Department of Plastic Surgery, Kyorin
University School of Medicine; and Division of Research andDevelopment, Biomaster, Inc.
Received for publication May 24, 2006; accepted August 25,
2006.
Copyright ©2008 by the American Society of Plastic Surgeons
DOI: 10.1097/01.prs.0000299384.53131.87

Disclosures: A centrifugation device (Lipokit;
Medikan Corp., Seoul, Korea) and syringes madespecific for the device (Medikan Corp.) were provided to authors for research purposes by the company.

www.PRSJournal.com

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Plastic and Reconstructive Surgery • March 2008
tissue viability.9 Centrifugation may enhance thetotal amount of transplanted fat,11 although excessive centrifugal force may damage intact
adipocytes.7,9,13,14
Undifferentiated stromal cells present in adipose tissue recently became a focus. Stromal vascular fractions isolated from liposuction aspirates
contain multiple cell populations,15,16 one ofwhich has been identified as adipose-derived stem
cells.17 Adipose-derived stem cells can differentiate into various lineages forming adipose, bone,cartilage, neuronal, and vasculature tissues. Our
recent research18 showed that both the fatty andfluid portions of liposuction aspirates contain a significant amount of adipose-derived stem cells, andwe characterized freshly isolated adipose-derived stem cells as CD31–CD34⫹CD45–CD90⫹
CD105–CD146– cells. The presence of adipose-derived stem cells has clinical implications for autologous fat transfer because adipose-derived stem
cells may contribute to neoangiogenesis in theacute phase by acting as endothelial progenitor
cells19 or angiogenic-factor-releasing cells.20 Adipose-derived stem cells are known to secreteangiogenic factors such as vascular endothelial
growth factor and hepatocyte growth factor under hypoxic conditions20 and to contribute toincreased capillary density and blood flow.19 In
addition, they can affect long-term survival oftransplanted adipose by acting as preadipocytes.
We have recognized positive effects of centrifugation on fat transfer in our clinical experience,but the force-dependent influences of centrifugation on liposuction aspirates have not been wellstudied thus far. The purposes of this study were
(1) to determine the anatomical and physiologic
alterations of cell and tissue components in liposuction aspirates during the centrifugation process, and (2) to optimize centrifugation parameters for autologous lipotransfer and isolation of
adipose-derived stem cells.

MATERIALS AND METHODS
Centrifugation of Liposuction Aspirates
Liposuction aspirates were obtained from surgery performed on the abdomen or thigh regionsof eight healthy female donors aged 21 to 38 years
with informed consent approved by our institutional review board. Infiltration of saline (tumescent solution), liposuction, and subsequent centrifugation of syringes were conducted using asingle combined machine (Lipokit; Medikan
Corp., Seoul, Korea) (Fig. 1, above). Liposuction
aspirates were divided and poured into disposable

1034

Fig. 1. Centrifugation of liposuction aspirates. (Above) A machine for centrifugation used in this study. (Below) A disposable
sterilized syringe (50 ml) with a filter piston. By centrifugation, oil
was shifted onto the piston (arrow).

sterilized syringes (50 ml) with a filter piston(Medikan). The filter piston was specifically designed for separation of the oil from the otherportions by centrifugation (Fig. 1, below). Afterbeing placed upright for 10 minutes, specimens
were divided into two portions: a floating adipose
portion and a denser fluid portion. Syringes wereallotted to six groups (two syringes each) and centrifuged at 0, 400, 800, 1200, 3000, or 4200 g bymeans of the Lipokit for 3 minutes. After centrifugation, specimens were divided into three portions; oil (top), adipose (middle), and fluid (bottom) (Fig. 2). The volume and weight of eachportion were measured before and after centrifugation, and the specific gravity [weight (ingrams)/volume (in milliliters)] of the adipose
portion was calculated. The volume of the oil
portion was measured by aspirating the oil on
the filter piston with a 10-ml syringe, and thoseVolume 121, Number 3 • Influence of Centrifugation on Cells
Isolation, Culture, and Counting of
Adipose-Derived Stem Cells from the Adipose
and Fluid Portions
Adipose-derived stem cells were isolated separately from the adipose and fluid portions ofliposuction aspirates as described before.18 The
cells were cultured on 100-mm gelatin-coateddishes with M-199 medium containing 10% fetal
bovine serum, 100 IU penicillin, 100 mg/ml streptomycin, 5 ng/ml heparin, and 2 ␮g/ml acidic
fibroblast growth factor, at 37°C, in a humid atmosphere of air and 5% carbon dioxide. Afterbeing cultured for 7 days, cell counts were performed using a NucleoCounter (Chemometec,
Denmark).

Fig. 2. The adipose and fluid portions of liposuction aspirates
were clearly separated by 3 minutes of centrifugation and stayed
below the piston after that.

of the adipose and fluid portions were measured
by reading a scale on the centrifugation syringe(50 ml).
Counting of Blood Cells and Adipose-Derived
Stem Cells
Although blood cells are thought to disturb
engraftment of injected adipose and to be partly
extracted by centrifugation, there are no reliabledata on the extent of blood cell clearance by centrifugation. Adipose portion tissues before andafter centrifugation were digested at 37°C for 30
minutes on a shaker with an equal volume of
0.075% collagenase. Mature adipocytes and connective tissues were separated from pellets by centrifugation (400 g for 10 minutes). The pellet was
resuspended in phosphate-buffered saline andpassed through a 100-␮m mesh filter (Millipore,
Billerica, Mass.). Fluid portions (3 ml each) before
and after centrifugation were centrifuged (400 g
for 10 minutes), and the pellets were resuspended and passed through a 100-␮m mesh filter. Numbers of red blood cells and nucleatedcells in adipose and fluid portions were counted
separately with CellTec (Nihon Koden, Tokyo,
Japan). Nucleated cells counted corresponded
to the total of white blood cells, adipose-derived
stem cells, and other adipose-derived cells suchas endothelial cells.

Fat Transplantation to Nude MiceTo examine the influences of centrifugation
on engraftment of adipose tissue, lipoaspirates obtained from a single donor were divided into six
graft materials using centrifugations at 0, 400, 700,
1200, 3000, and 4200 g. Six milliliters of eachmaterial was injected into the backs of six 5-weekold nude mice using an 18-gauge needle, with 1 ml
injected per mouse. The same experiment was
repeated twice using lipoaspirates from another
donor. Consequently, a total of 72 mice were used
as recipients of human fat transplantation. Animals were killed 4 weeks after fat transplantation,and transplanted grafts were measured for weight.
Harvested samples were fixed and processed for histology (see below). To estimate the net efficacy oftransplantation per volume of adipose portion before centrifugation, a calculation was performed
with the following hypothetical equation: Putative
graft take of 1 ml uncentrifuged adipose ⫽ (graft
take of 1 ml centrifuged adipose) ⫻ (volume of
adipose portion after centrifugation)/(volume of
adipose portion before centrifugation).
Scanning Electron Microscopic Study
Adipose samples were fixed with paraformaldehyde and 2.5% glutaraldehyde in 0.2 M cacodylate buffer for 1 week at room temperature, andfixed in 1% osmium tetroxide. After dehydration,
they were dried with a supercritical point carbon
dioxide dryer (HCP-2; Hitachi, Tokyo, Japan),sputter-coated with platinum/palladium, and examined with a scanning electron microscope(S3500N; Hitachi). Light microscopic examination of hematoxylin and eosin–stained slides was
also performed.

1035

Plastic and Reconstructive Surgery • March 2008
Statistical Analyses
Results were expressed as mean ⫾ SE. Pairedt tests were performed to evaluate the differences
between centrifugal conditions, and no correction
was made for multiple comparisons. Statistical significance was defined as p ⬍ 0.05.

RESULTS
Gross Effects of Centrifugation on the Adipose
Portion of Liposuction Aspirates
A total of 78 syringes containing liposuction
aspirates were centrifuged with six different centrifugal forces. With increased centrifugal force,the volumes of the oil and fluid portions increased, and the volume of the adipose portion
decreased. Although there was no significant difference between 3000 g and 4200 g, volumes of oil,adipose, and fluids altered significantly with increased centrifugal forces (Fig. 3, above). For 48
samples, the specific gravity of the adipose portion
was measured; it did not change significantly except for a decrease between control and 400 g (Fig.
3, below). On scanning electron microscopic observation, the adipose portion was observed asclusters of spherically shaped adipose cells. Adipocyte size was not remarkably altered with increased centrifugal forces. In all samples, including uncentrifuged controls, clusters of adipocytes
were partially ruptured. The degree of ruptured
adipocyte clusters seemed to vary among donor
subjects, but no remarkable difference was seen
between the samples processed with different centrifugal forces from the same subject (Fig. 4).
Effects of Centrifugation on Numbers of Red
Blood Cells, Adipose-Derived Stem Cells, andNucleated Cells
Numbers of red blood cells, adipose-derived
stem cells, and nucleated cells in the adipose andfluid portions were counted separately using 48
samples. Although the total number of red blood
cells in the adipose and fluid portions did notchange significantly based on centrifugal forces(Fig. 5, above), red blood cells shifted significantly
from the adipose portion to the fluid portion at all
different centrifugal forces. In addition, a significant difference was seen between 400 g and 700
g but not between 700 g and more than 1200 g (Fig.
6, above). Total numbers of nucleated cells, which
included white blood cells, adipose-derived stem
cells, and other adipose-derived cells, did notchange significantly by centrifugation; nor were
there statistically significant shifts in numbers of
nucleated cells detected for any centrifugal

1036

Fig. 3. (Above) Columns on the left, middle, and right demonstrate the volumetric proportions of the oil, adipose, and fluid
portions, respectively, under each centrifugal condition. Statistical analysis was performed with paired t tests between groups.
Green, orange, and red bars indicate statistical significances in theoil, adipose, and fluid portions, respectively. The significance levels are indicated with the number of asterisks (*p ⬍ 0.05; **p ⬍0.01; ***p ⬍ 0.001). A significant volume reduction in the adipose
portion was observed not only between uncentrifuged and centrifuged samples but also between different centrifugal forces.
The fluid and oil portions significantly increased in volume ina centrifugal force– dependent manner. Data representmeans ⫾ SE. (Below) Specific gravity of the adipose portion
tends to decrease with increased centrifugal force, but thedifferences were not statistically significant. Data representmeans ⫾ SE.

Volume 121, Number 3 • Influence of Centrifugation on Cells

Fig. 4. Scanning electron microscopic photographs of representative uncentrifuged and centrifuged samples derived from a single
donor. Clusters of spherically shaped adipocytes and intermittently dispersed ruptured cells were observed, regardless of centrifugal
forces [left, control (uncentrifuged); center, 1200 g; right, 4200 g). Magnified photographs show that there are adipocytes that were
not morphologically altered even in samples centrifuged at 4200 g (below, right). Scale bar ⫽ 200 ␮m (above) and 50 ␮m (below).

force (data not shown). The total number ofadipose-derived stem cells remained consistent
up to 1200 g, whereas the number of adiposederived stem cells decreased significantly at
more than 3000 g (Fig. 5, below). Unlike red
blood cells, adipose-derived stem cells did not
shift significantly between the adipose and fluid
portions (Fig. 6, below).
Adipose Graft Survival of In Vivo Experimental
Models
The results of the transplantation of uncentrifuged or centrifuged adipose using 72 nude
mice revealed that centrifugation significantly enhanced the proportion of graft survival (Fig. 7,
above). Significance was detected not only between
control and all centrifugal forces, but also between
increased centrifugal forces, although resultsfrom centrifugation at 3000 g were superior tothose from 4200 g (Fig. 7, above).
Centrifugation made the original volume of
fat compact, and thus 1 ml of uncentrifuged fat
and 1 ml of centrifuged fat differed originally infat volume. If we have a sufficient volume of aspirated fat, we conclude that centrifugation canenhance the graft take. In contrast, if we tried toobtain the largest adipose graft by using 1 ml ofuncentrifuged adipose alone, it could be concluded by virtual calculation that the uncentrifuged graft would be better than any centrifuged
grafts (Fig. 7, below).
Under microscopic observation, no remarkable difference was observed in cell integrity or
structure among samples centrifuged at different
forces. Even in samples centrifuged with a maximum force of 4200 g, adipocytes survived well 4
weeks after transplantation.

DISCUSSION
Concentration of the Graft
Although various authors have recommended
performing precentrifugation of fat grafts, many
reports described centrifugal force using rpm (revolutions per minute) units.1,3,5,8,21–24 Working centrifugal forces with the same rpm value can differ
in terms of radius of centrifugation. For example,
centrifugation at 3000 rpm with either a 12- or
18-cm radius of gyration is equivalent to 1207 or
1811 g, respectively. Thus, it is hard to compare
our results with those from other previous reportsthat used rpm.
Our study showed that 3 minutes of centrifugation compacts aspirated fat and partly excludes
oil, water, and blood cells, but not adipose-derived

1037

Plastic and Reconstructive Surgery • March 2008

Fig. 5. Total numbers of red blood cells and adipose-derived
stem cells in the adipose and fluid portions of liposuction aspirates before and after centrifugation. Proportions of total (adipose and fluid portions) cell count at each centrifugal condition
compared to control are presented. Significance was analyzed
using paired t tests for groups. Data represent means ⫾ SE (*p ⬍0.05; **p ⬍ 0.01; ***p ⬍ 0.001). (Above) Total numbers of red
blood cells did not change significantly by centrifugation. (Below)
Total number of adipose-derived stem cells showed no remarkable alteration after centrifugation up to 1200 g, but a significant
decrease was observed between control and samples centrifuged at 3000 and 4200 g.

stem cells. Consequently, adipose tissue, extracellular matrix, and adipose-derived stem cells areconcentrated by centrifugation, likely contributing to a boost in the graft take.25,26 The degrees ofconcentration and exclusion tended to be elevated with increased centrifugal force.
Damage to Adipocytes
Boschert et al.7 reported that the quantity ofoil increased because of adipocyte destruction
when specimens were centrifuged at more than
100 g and thus concluded that centrifugation at
greater than 100 g was not appropriate for autol-

1038

Fig. 6. Shift of red blood cells and adipose-derived stem cells
between the adipose and fluid portions by centrifugation. Proportions of cell numbers contained in adipose and fluid portions before and after centrifugation are presented. Significance was analyzed using paired t tests between groups. Data
represent means ⫾ SE (*p ⬍ 0.05; **p ⬍ 0.01; ***p ⬍ 0.001).
(Above) Percentages of red blood cell count contained in the
adipose and fluid portions. Red blood cells shifted significantly from the adipose portion to the fluid portion at all different centrifugal forces compared with control. In addition,
significance was seen between 400 g and 700 g, but not between 700 g and more than 1200 g, suggesting that centrifugation at 700 g is enough and that more than 700 g may not benecessary for red blood cell extraction from aspirated adipose.
(Below) Percentage of adipose-derived stem cell count contained in the adipose and fluid portions. Adipose-derived
stem cells did not shift significantly between the adipose andfluid portions at any level of centrifugal force.

Volume 121, Number 3 • Influence of Centrifugation on Cells
ogous fat transplantation. However, the results ofour fat graft experiments indicate that centrifugation with more than 100 g centrifugal force cansurely be used in aspirated fat transplantation.
Our results showed that the oil volume increased with increased centrifugal forces, but histologic findings did not clearly demonstrate destruction of adipocytes. Based on our microscopic
observations, the degree of adipocyte destruction
differed among patients but showed only minor
differences between different centrifugal forces.
Scanning electron microscopic observation
showed that remnant oil was seen in the adipose
portion even after 3 minutes of centrifugation.
Thus, we suggest that the increase in the oil portion does not necessarily mean an increase of adipocyte destruction by centrifugation but may
rather mean an increase in separation of oil fromthe adipose portion.

Fig. 7. Transplantation of uncentrifuged and centrifuged adipose tissue lipoaspirates obtained from a single donor were divided into six graft materials using centrifugation at 0, 400, 700,
1200, 3000, and 4200 g. Six milliliters of each material was injected into the backs of six 5-week-old nude mice using an 18gauge needle, with 1 ml injected per mouse. The same experiment was repeated twice using lipoaspirates from another
donor. The surviving adipose tissues were harvested 4 weeks
later. Significance was analyzed with paired t tests between
groups. Data represent means ⫾ SE (*p ⬍ 0.05; **p ⬍ 0.01; ***p ⬍0.001). (Above) Weights of transplanted adipose tissues. With
centrifugation at 1200 g or more, transplanted adipose tissue wassignificantly greater in weight than uncentrifuged control. Centrifugation significantly contributed to obtaining a better graft
take at least in short-term observations, although centrifugation
at 4200 g might be excessive compared with 3000 g. (Below) Calculated putative graft take per volume of uncentrifuged adipose. Values were calculated as follows. Putative graft take of 1 ml uncentrifuged adipose ⫽ (graft take of 1 ml centrifuged adipose) ⫻ (volumeof adipose portion after centrifugation)/(volume of adipose portion
before centrifugation). Based on these putative calculations, if there
was a limited volume of aspirated adipose, graft take would be bestwhen it was not centrifuged before transplantation.

Damage and Distribution of Blood Cells andAdipose-Derived Stem Cells
Our results are mostly in accordance with theview previously reported that centrifugation separates fat cells from lipid, blood cells, water, andwater-soluble ingredients such as proteases andlipases.3,5,7,8 To our knowledge, there have been noreports examining quantitatively the effects ofcentrifugation on blood cells and adipose-derived
stem cells in liposuction aspirates. Although centrifugation induced a slight shift of red blood cells
from the adipose portion to the fluid portion without change in total numbers of red blood cells, thevolume of the adipose portion was compacted toa greater extent than the shift of blood cells, andthus these blood cells were slightly concentrated
in the adipose portion. Although a previous author indicated that the presence of blood in theinjected fat stimulates macrophage activity to remove the fat cells,5 the actual effect of the bloodin the graft has not clearly been elucidated. Thusfar, we cannot determine whether a decrease of
number and increase of concentration of red
blood cells and white blood cells is advantageousor disadvantageous in fat grafting.
In contrast, the results indicated that adiposederived stem cell yield after 1 week of culture wasalmost consistent up to 3000 g and decreased atmore than 3000 g. In addition, it was shown that
adipose-derived stem cells did not shift between
the adipose and fluid portions by centrifugation,
likely because adipose-derived stem cells contained in the adipose portion are resident in orstrongly adhered to the adipose tissues. Accord-1039

Plastic and Reconstructive Surgery • March 2008
ingly, centrifugation simply enhanced the densityof adipose-derived stem cells as a result of compaction of the adipose portion. Condensation of
adipose-derived stem cells in fat graft may be beneficial for enhancing the fat graft survival rate forthe reasons discussed below.
Graft Survival
We propose that the aspirated fat graft takes
were grossly influenced by the balance of the negative effects of destruction and the positive effectsof condensation by centrifugation. Our results revealed that the short-term survival rate of aspirated
adipose graft per volumetric unit after centrifugation increased with centrifugal forces up to 3000
g. Condensation of the graft material and adiposederived stem cells is thought to dominantly contribute to this enhancement.
However, it was also shown by a virtual calculation that surviving fat graft per volumetric unit
before centrifugation decreased by intervention
with centrifugation. Surviving fat graft decreased
at 400 g but did not decrease further with increased centrifugal forces; this outcome may imply
that the decrease at 400 g could have resulted fromdestruction of adipocytes located especially in the
superficial layers of adipose fragments and that
adipocytes in the inner layers may be protectedfrom mechanical injuries by the destroyed superficially located adipocytes.
Histologic findings of transplanted fat wereconsistent with previous reports,5,27 which foundthat centrifuged graft samples were similar to uncentrifuged ones. Even samples centrifuged at4200 g showed no remarkable differences in histology from controls after transplantation. It isthus suggested that once adipocytes succeed in
avoiding critical damage during centrifugation,
there will be no difference in the structural qualityof adipocytes between centrifuged and uncentrifuged samples.
Our results of graft take with or without centrifugation indicate a clinical application for selective use of centrifugation. If there has only beena restricted amount of adipose (though it would
be very rare), centrifugation might not have been
the best approach from the standpoint of the mosteffective use of restricted graft material. For example, by using 10 ml of uncentrifuged adipose
tissue, we would have a 6.4-ml augmentation (64percent survival) if we transplanted the adipose
without centrifugation. However, if we centrifuged the 10 ml of adipose at 1200 g, we would
obtain centrifuged and condensed adipose, with a1040

volume of 7.2 ml. After transplanting the 7.2 ml ofcentrifuged fat, we would have a 5.9-ml augmentation (82 percent survival). However, in most clinical cases, we can harvest a sufficient volume of
aspirated fat, and in such cases, we should centrifuge aspirated fat before grafting to obtain thebest augmentation effects. For example, by harvesting 13.8 ml of adipose tissue, we could transplant 10 ml of adipose centrifuged at 1200 g andachieve an 8.2-ml augmentation.
We suggest that adipose-derived stem cells andother adipose-derived cells are crucial for graft
survivability in both the short and long term. Our
recent report26 revealed that aspirated fat is relatively adipose-derived stem cell deficient compared with excised whole fat, which contains
large vessels and nerves, unlike aspirated fat,and that adipose-derived stem cells can survive
and reside between adipocytes or in the connective tissues of surviving adipose tissue after
transplantation. The relative deficiency of adipose-derived stem cells may be the reason forthe lessened survival rate of aspirated fat after
transplantation compared with excised fat reported by two previous experimental studies.28,29
Condensation of adipose-derived stem cells by
centrifugation may mean conversion of relatively stem-cell– deficient adipose to relatively
stem-cell–rich adipose. This adipose-derived
stem cell condensation may enhance the fat
graft take26 and prevent long-term atrophy oftransplanted adipose by working as tissue-specific progenitors.25,26
Excessive centrifugation can destroy adipocytes and adipose-derived stem cells. Centrifugation, however, plays a beneficial role in concentrating adipocytes, extracellular matrix, andadipose-derived stem cells, and in partially excluding red blood cells. Extracellular matrix should
maintain its volume after transplantation, at leastin the short term, and exclusion of red blood cells
from graft materials may contribute to a better
survival rate of transplanted adipose.
The oil portion increased only after centrifugation at 400 g. Red blood cells were shifted at
400 g. The adipose-derived stem cell-to-adipocyte
ratio, which may influence long-term atrophy ofgrafted adipose, was suggested to be relatively improved by centrifugation, but adipose-derived
stem cells were damaged at 3000 g. Graft takes ofcentrifuged adipose were best at 3000 g. Considered together, these data lead us tentatively torecommend 1200 g as an optimized centrifugal
force among the tested centrifugal forces for obtaining good short- and long-term results in adi-Volume 121, Number 3 • Influence of Centrifugation on Cells
pose transplantation. Although our conclusionthat selective centrifugation with relatively highcentrifugal force may be beneficial for graft survival contradicts the views or recommendations ofrecent authors,7,9,12 it is similar to the 1286 g recommended by Coleman based on abundant clinicalexperience.13 Further investigation is necessary to
elucidate the net efficacy of centrifugation on graft
survival in clinical settings because the gross takeof transplanted tissue will be clinically influenced
by various factors associated with harvesting, processing, and transplanting adipose tissues.
Kotaro Yoshimura, M.D.
Department of Plastic Surgery
University of Tokyo School of Medicine
7-3-1 Hongo, Bunkyo-Ku
Tokyo 113-8655, Japan
yoshimura-pla@h.u-tokyo.ac.jp

ACKNOWLEDGMENT

This study was supported by grants-in-aid (contract no. B2-16390507) from the Japanese Ministry of
Education, Culture, Sports, Science, and Technology
Contract.
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24. Ramon, Y., Shoshani, O., Peled, I. J., et al. Enhancing the takeof injected adipose tissue by a simple method for concentrating fat cells. Plast. Reconstr. Surg. 115: 197, 2005.
25. Masuda, T., Furue, M., and Matsuda, T. Novel strategy for soft
tissue augmentation based on transplantation of fragmented
omentum and preadipocytes. Tissue Eng. 10: 1672, 2004.
26. Matsumoto, D., Sato, K., Gonda, K., et al. Cell-assisted lipotransfer (CAL): Supportive use of human adipose-derived
cells for soft tissue augmentation with lipoinjection. TissueEng. 12: 3375, 2006.
27. Carpaneda, C. A., and Ribeiro, M. T. Study of the histologic
alterations and viability of the adipose graft in humans. Aesthetic Plast. Surg. 17: 43, 1993.
28. Kononas, T. C., Bucky, L. P., Hurley, C., and May, J. W., Jr.
The fate of suctioned and surgically removed fat after reimplantation for soft-tissue augmentation: A volumetric andhistologic study in the rabbit. Plast. Reconstr. Surg. 91: 763,
1993.
29. Fagrell, D., Enestrom, S., Berggren, A., and Kniola, B. Fat
cylinder transplantation: An experimental comparative studyof three different kinds of fat transplants. Plast. Reconstr. Surg.
98: 90, 1996.

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DISCUSSION
Influences of Centrifugation on Cells and Tissues in
Liposuction Aspirates: Optimized Centrifugation for
Lipotransfer and Cell Isolation
Charles L. Puckett, M.D.
Steven L. Henry, M.D.
Columbia, Mo.

T

he authors present a sophisticated and somewhat complex analysis of the role of centrifugation in fat grafting. This study addresses a numberof aspects regarding the value of centrifugationand probably needs to be read more than oncefor one to extract and evaluate all of the information. The methods used are sound and thediscussion is particularly germane to the reader’s interpretation.
As with any good research, for each answeredquestion several additional ones are raised, but
this study does provide several interesting answers.
Optimizing fat transfer has been an ongoing interest of ours, and clearly this article sheds additional light on the subject. The authors have analyzed cell viability after centrifugation at a varietyof g forces. These data have been compared withours and with those of other contributors.1–3 Recent interest in the role of adipose-derived stem
cells and their potentially positive effects on fat
graft take are explored and some important points
are made. Since our work was published and presented, the interest in adipose-derived stem cells
has clearly increased. This has been fostered by thetheoretical potential of adipose-derived stem cells
to enhance neoangiogenesis and, by inference,
also enhance adipocyte viability and graft take.
The authors used fat from female liposuction
patients and indicated that the sources were abdominal and thigh fatty deposits. No subsequent
analysis as to any differences in these sources wasmade and therefore no information can begleaned in terms of site designation and its potential role in fat graft survival.
Beyond the identification of viable cells, theauthors have pursued short-term cell culture survival and proliferation and longer term survival intransplantation to the athymic nude mousemodel, assessed at 4 weeks. The authors conclude
that although excessive centrifugation can destroy

adipocytes and adipose-derived stem cells, appropriate centrifugation (lower g forces) increased
the population of not only viable adipocytes but
also adipose-derived stem cells, and resulted inenhanced early graft take. They have settled on an
optimum centrifugation of 1200 g.
The authors also paid attention to the presence of red blood cells in the concentrated adipocyte portion of their specimens. They make thetheoretical point that the presence of red blood
cells may negatively affect cell take and viability, as
their presence may stimulate macrophage activity
that could destroy fat cells. They report the interesting finding that centrifugation did not decrease
the number of adipose-derived stem cells but did
result in the removal of some red blood cells,
presumably into the fluid layer. They specificallynote that the short-term survival rate of aspirated
adipose graft (per volumetric unit after centrifugation) increased with centrifugation. They conclude that selective use of centrifugation has probable value in enhancing the viable adipocyte
population, with no diminution in the number ofadipose-derived stem cells. They mention, referencing one of their earlier studies, that the presence of reduced numbers of adipose-derived stem
cells in aspirated fat grafts compared with whole
fat transplants may be the explanation for the
relatively lower survival rate of aspirated fat after
transplantation.
Our personal conclusions from this study
would be in concert. Appropriate centrifugation(50 to 1200 g) can provide a more generous concentration of viable fat cells without sacrifice ofadipose-derived stem cells while reducing the concentration of potentially detrimental red blood
cells. The authors made no mention of the sampling area of the adipose layer, but our work

From the Division of Plastic Surgery, University of Missouri.
Received for publication September 29, 2006.
Copyright ©2008 by the American Society of Plastic Surgeons
DOI: 10.1097/01.prs.0000299385.55282.6f

Disclosure: Neither author has any financial interests in any of the products, drugs, or devices
mentioned in this article.

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www.PRSJournal.com

Volume 121, Number 3 • Discussion
clearly demonstrated a higher concentration of
viable adipocytes in the lowest segment of the fat
layer.2 Of parallel interest, Rohrich et al.4 showed
no increase in adipocyte viability after centrifugation at 500 g when compared with uncentrifuged
specimens. This would be countered by their (Rohrich et al.) lack of indication of the layer from
where the sample was taken—that is, top, middle,
or lower layer—and the use of higher g force (500g) in contrast to our recommendation of 50 g.
Another point made by the authors might benefit from additional interpretation. They observed
good cell viability even with higher g centrifugation (4200 g). Our interpretation of this observation would be that although centrifugation may
result in more lysis of cells, it does not appear tocompromise the viability of the remaining intact
cells in the aliquot of the centrifuged specimen.
The authors make the subtle point that centrifugation may not be appropriate in patients with
impoverished sources of transplantable fat cells.
However, this is a problem rarely encountered in
Americans.
We believe that the authors have made theirpoints well and have analyzed these data accurately and in detail. We also believe that the appreciation of the valuable role of adipose-derived
stem cells in graft survival is at play here. It continues to be apparent to us that appropriate cen-trifugation, which we interpret to be lower g forces
and for short periods of time, can contribute toimproved fat graft transfer success and ultimately
to its reliable use as the best (potentially permanent) method of soft-tissue augmentation. We applaud the authors’ efforts to further define therole of centrifugation in aspirated fat grafts andfeel that there are several valuable “take-home”
messages in this article.
Charles L. Puckett, M.D.
Division of Plastic Surgery
University of Missouri
One Hospital Drive, M349
Columbia, Mo. 65212
puckettc@health.missouri.edu

REFERENCES
1. Boschert, M. T., Beckert, B. W., Puckett, C. L., and Concannon, M. J. Analysis of lipocyte viability after liposuction. Plast.
Reconstr. Surg. 109: 761, 2002.
2. Puckett, C. L., and Beckert, B. W. In search of improved fat
transfer viability: A quantitative analysis of the role of centrifugation and harvest site (Discussion). Plast. Reconstr. Surg. 113:
396, 2004.
3. Butterwick, K. J. Lipoaugmentation for aging hands: A comparison of the longevity and aesthetic results of centrifugedversus noncentrifuged fat. Dermatol. Surg. 28: 987, 2002.
4. Rohrich, R. J., Sorokin, E. S., and Brown, S. A. In search of
improved fat transfer viability: A quantitative analysis of therole of centrifugation and harvest site. Plast. Reconstr. Surg.
113: 391, 2004.

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