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Khoobehi K. Quanliticatton üI nc^äliiie píbüiites generated in Luet-lotking syringes compared to convenlionaHiposuctionrrachine in relation to adipocyte viability te tat gratlirg, Ptishc and Reconstructive Surgery 2OO9;I23 (suppl S).I34.

Mojallal A. Auxentans C, lequeui C, Braye F. Oainour 0. Influence ot negative pressure when harvestingcell yield ol the stromal-uascular traction. Bimed Mater Eng. 2008^18:193-197,

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is fat graftviability?

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NeDvasculariiationOta tat transplant maybe boosted by addingautologous ADCs.

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All photos credit: Kamran Khoobehi, M.D., F.A.C.S.

31-year-old female patient before (¡eft photos m panels A, B and C) and nine months following (right photos in panels A, B and C> mastopexy, fat grafting and tummy tuck procedures.

AT ASPIRATION using a syringehas not only been a long-acceptedtechnique of harvesting autologousfat in fat grafting procedures, buthas also been widely viewed asatraumatic to the patient's tissues— including the aspirated fat tissue

itself. A recent as-yet unpublished study,presented at the recent 54th Annual Meetingof the Plastic Surgery Research Council,shows that the hand-held syringe techniqueis not as atraumatic as once believed andthat an alternate method using a liposuctiondevice to harvest the fat may, in fact, be moreadvantageous in maintaining fat tissue viability.

A PREMISE IS 'NEEDLED' "The syringe isthe most popular technique used in fat graftingprocedures worldwide and most plastic surgeonsbelieve and accept that the technique is gentleand does not cause any fat cell destruction whenaspirating," study investigator Kamran Khoobehi,M.D., F.A.C.S., clinical associate professor ofsurgery, Division of Plastic and ReconstructiveSurgery, Louisiana State University HealthSciences Center School of Medicine, NewOrleans, Louisiana, tells Cosmetic Surgery Times.

^ ^ ^ ^ L

Dr. Khoobehi

"However, the negative pressureproduced during aspiration canvary greatly from surgeon tosurgeon and the problem Is thatthere is no consistency here,which can make it difficult toguarantee reproducible andconstant results."

Dr. Khoobehi put this long-accepted premiseto the test and conducted a study quantifyingthe negative pressures generated in Luer-Locksyringes and compared them to those generatedfrom a conventional liposuction machine.Negative pressures were measured in vitroand in situ within 1, 3, 5, 10, 30 and 60 ccLuer-Lock syringes, as well as with conventionalliposuction machine at -10, -15 and -30 inchesof Hg. To evaluate the viability of the adipocytesharvested in both procedures, the lipoaspiratesamples from the in situ lipoaspiration wereanalyzed for LDH, triglycéride and G3PD assaysand were stained with fluorescent dyes forimaging using scanning electron and confocallaser electron microscopy.

Results showed that the negative pressure

generated by the liposuction device at low settingwas less than that generated by 10 cc and60 cc syringes. Furthermore, Dr. Khoobehi foundthat there was much less LDH and triglycéridesin the serum at the lower negative pressureswhen using the liposuction device, accordingto the results of the biochemical assays andmicroscopic analyses. Though these parametersare nonspecific for fat cell damage, Dr. Khoobehicontends that if their levels are elevated in theserum, this is an indication of increased adipocytedamage. He adds that the G3PD assay is themost specific for adult, intact living adipocytes,and assay resufts showed that the enzyme uptakewas higher with the liposuction-assisted aspirationtechnique, indicating more intact adipocytes.

"We found that, compared to the syringetechnique, the liposuction device could not onlyharvest the fat much faster, but also proved tobe the less traumatic and a therefore gentlertechnique, which is in stark contrast to the currentconventional wisdom," Dr. Khoobehi explains.

FAT FRAGILITY According to Dr. Khoobehi,on average, a plastic surgeon will pull backabout 5 cc to 6 cc to allow for enough ^

48-year-old témale patient befare (photos A and B) and three months following; a single fat grafting session (photos C and D). Implants were deflated two weeks before fat grafting procedure.

room for the fat cells to be aspirated whenperforming a fat grafting procedure. This willgenerate high negative pressure (more than 550mmHg negative pressure), which is detrimental tothe survival of the fragile fat celts. Additional celldamage may also take place with the industry-invented syringe that contains an already-pulled-back plunger to counter the fatigue that manysurgeons experience as a result of pulling back onthe plunger of the syringe in performing multiplefat grafting procedures on a daily basis.

"My research has shown that negative pressuresexceeding -260 mmHg cause cell damage and,therefore, I do not advocate the use of thesespecial syringes as they can create high negativepressures ranging from -450 mmHg to -550mmHg," Dr. Khoobehi notes.

TOWARDS STANDARDIZED OUTCOMESLiposuction Via device. Dr. Khoobehi holds,offers the possibility of producing a standardizednegative pressure that is applied to the fat cellsupon aspiration. Dr. Khoobehi believes that thistechnique not only removes the human error factorof pulling back too hard on the plunger and creatingtoo much negative pressure, but also addresses thehand fatigue factor for the surgeons who performmany of these procedures every day. He adds thatthe syringe technique, pioneered by Sydney R.Coleman, M.D., can take about an hour to aspirateapproximately 100 cc fat whereas the liposuctiondevice is three times faster, taking only 20 minutesfor 100 cc fat, he estimates. "We believe thatthe liposuction technique allows any surgeon tobe able to harvest the fat in a timely, predictable,reproducible and less traumatic fashion so that theprocedure would not change from patient to patient.This could likely lead to more uniform aestheticresults," Dr. Khoobehi says,

Dr. Coleman

Dr. Khoobehi is currently conducting a fat grafting

study including over 120 patients exclusively using

the liposuction aspiration technique and finds

that harvesting the fat using the lower pressure

of the liposuction approach also results in less

bruising when compared to the syringe technique.

According to Dr. Khoobehi, plastic surgeons should

look at both techniques and decide for themselves

which technique is superior.

A SYRINGE SPECIALIST According toSydney R. Coleman, M.D., Tribeca Plastic

Surgery, New York, New York,if the plunger of the syringe isgently pulled back upon aspiration"as careful plastic surgeons who[perform fat grafting proceduresdo," the negative pressure createdwill not unduly damage theadipocytes. Typically, the surgeon

will need to pull back about 5 cc to 6 cc on theplunger to get the suction going and then revertback to 1 cc to 2 cc. However, Dr. Colemanallows that some surgeons may pull back on theplunger too much when using syringe suctioning.For the last 20 years. Dr. Coleman has beenusing the hand-held syringe technique to aspiratefat and has consistently achieved excellentcosmetic results in his fat grafting patientswithout any issues concerning the destructionof the adipocytes as a result of the aspirationtechnique. "The enzyme levels of the fat in fatgrafting procedures often usually reflect thepresence of the fat itself but do not pay attentionto stem cells or primitive cells, which I, as well asleading plastic surgeons around the world, believeto be one of the most important constituentsof the aspirate," Dr. Coleman explains. "In myopinion, the cellular part of the aspirate is moreimportant than the iipid-filled adipocytes."

Dr. Coleman concurs that if the plunger of a 10cc or 60 cc syringe is pulled back all the way,the resultant negative pressure is much higherthan that of a liposuction device set at its lowestsetting. He also discourages the use of specialsyringes in which the plunger is already pulledback until such devices are graduated. However,he says, if the plunger is pulled back slowly andgently, the negative pressures created are muchlower and basically, nontraumatic to the fat cells.And in terms of "productivity," the amount ofadipocytes a surgeon can harvest depends entirelyon the donor sites. Dr. Coleman notes that patientswith a higher BMI can have 800 cc or moreharvested in an hour.

"I have tried the liposuction aspiration techniqueand found that, at low settings, the techniqueis not only too slow but also not as efficient ascarefully aspirating by hand using a hand-heldsyringe," Dr. Coleman contends. "Furthermore,the liposuction technique allows the aspirate to beexposed to the air for longer periods of time, whichis not good."

S T E M C E L L BOOST? In terms of boosting falgraft viability. Dr. Khoobehi tells CSrthat currently,there is no scientific data that conclusively supportsthe idea that the mixing of stem cells with the fataspirate will help the aspirated fat cells survive orbe an advantage in achieving superior fat graftingresults.

In further exploration of the possible viabilityadvantage stem cells may present, Frenchplastic surgeon Alain-Aii Mojallal, M.D., assistantprofessor of the Department of Plastic Surgery atthe University of Lyon, France, recently conducteda study (submitted for publication) on fat culturingwith and without the addition of adipose-derived

Results showed that the negative pressure generated by the liposuction device atlow setting was less than that generated by 10 cc and 60 cc syringes."

Or. Mojallal

stem cells. In the study, Dr. Mojaüal madea component fat culture and observed

that, if mature adipocytesare isolated without anystem cells or extracellularmatrix, a total failure

of the graft resulted.However, if a culture of

stem cells and matrix wasmade without any matureadipocytes, a differentiation of stem cells

into mature adipocytes resulted. Therefore,according to Dr. Mojaltal, stem cells and

the extracellular matrix are the keys to

successful fat grafting.

Dr. Khoobehi's finds Dr. Mojallal'sconclusion reasonable. "I have not exploredin-depth the use of stem cell technologyin fat grafting procedures," Dr. Khoobehinotes. "But logically, if you traumatizethe tissue less, you are not going toseparate the stem cells from their nativeenvironment. Possibly the reason I amachieving positive aesthetic results in mypatients is because perhaps the stem cellsand the adipocytes are less disturbed ordamaged with the liposuction technique."

MORE STUDIES WARRANTEDAccording to Dr. Khoobehi, the questionremains as to whether less damaged fatcells ultimately translate into less damagedstem cells and whether this has animpact on the final aesthetic outcome, anaspect of fat grafting technique he thinksmerits further exploration in comparativestudies. Dr. Mojallal explains that matureadipocytes, adipose-derived stem cellsand extracellular matrix are the threecomponents that contribute to successfulfat grafting results, and each of thesecomponents has to be in sufficient qualityand quantity.

Recently, Dr. Mojallal conducted a smallthree-patient study evaluating the influenceof pressure on the yield of stroma I-vascularfraction {SVF) cells in relation to the goldstandard hand-held syringe aspirationtechnique. Using a 3 mm cannula. Dr.Mojallal compared several different aspirationtechniques including a 10 mL syringe{Coleman technique), wail suction and apump alone or power-assisted aspirationregulated to -350 mmHg, then -700 mmHg.Study patients were 36, 4-3 and 58 years ofage without associated pathologies and witha BMI under 30. The cannula width, donorsite Ctrochanter region) and volume harvestedwere identical.

Results showed that using a pressure of

-350 mmHg — power-assisted or not— was superior to that obtained at -700mmHg (likely due to the small samplesize) and significantly superior to thehand-held syringe aspiration technique.At -350 mmHg, the use of power-assistedliposuction showed better results for twoout of three patients when compared tonon-power-assisted liposuction. Resultsalso showed that the yield of stem ceilsfrom the SVF per mL of adipose tissue was2.8 times greater than that yielded whenusing a syringe. Dr. Mojallai found that, forall of the techniques tested, the cells werecapable of proliferation and acquired thesame morphology.

DOES DAMAGE MATTER? "I thinkthat more cells are damaged when usingthe 3 mm cannulas and manual syringeaspiration techniques," says Dr, Mojallal."However, it makes no difference in theend because you still have enough viableadipose cells to perform the fat grafting."

Stem cells are a critical part of the aspirateand may ultimately play a role in achievingmore superior aesthetic results in fatgrafting procedures. Using lower negativepressures when harvesting fat tissue canavoid damage to the stem cell portion of theaspirate. However, the damage to the stemcell portion can likely only play a role whenthe overall yield of fat tissue aspirate is low.

"The cells that have been damagedduring harvesting are eliminated aftercentrifugation anyway," adds Dr. Mojallai,"The damaged adipocytes, and thereforealso some SVF cells, are less importantparticularly when large amounts ofadipose tissue are harvested. Regardlessof the harvesting technique used, theoverall yield of normal and healthy cellsmay be lower due to a portion of thecells that are lost through damage, butstilt enough to complete fat graftingprocedures without compromisingaesthetic outcomes."

However, negative pressure is not the onlyfactor that can influence cell yield. Dr.Mojallal continues. Any trauma to the fattissue — as well as its exposure to air — isas important as a low negative pressure.And therein lies the problem in his view.There is no low-pressure fat harvestingdevice available on the market that doesnot harvest the fat without trauma orexposure to air and, according to Dr.Mojallal, all the devices that use a filter,damage the cells more than the manualColeman technique.

DEMANDING PROOF Dr. Khoobehi believes that plasticsurgeons need to take the initiative and claim exploration of thisand other cosmetic procedures to remain the frontrunners inthe aesthetic field, lest this area of science fall into the handsof other specialties vying for position. "We need to approach ourprocedures and techniques not only by hearsay and word-of-mouthbut also need to back up our methodology with proven techniquesand solid basic science," Dr. Khoobehi stresses. "This liposuctiontechnique study coutd be one step towards a more scientific fashionof approaching fat grafting." <•

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