Fat Grafting : A Convenient Way of Body Contouring
"What we are today comes from our thoughts of yesterday, and our present thoughts build our life of tomorrow; our life is the creation of our mind."
Medical Science is a dynamic process of evolution where every day some new scientific discoveries are made. Sometimes on revisiting discarded clinical methods of the past. Sometimes, out of the blue to be established by scientific research. The development of the present from past archives builds a new tomorrow. One which stays has stood the test of time often with modifications to the proposed model.
Fat grafting, fat transfer or lipo-modelling is one such which when revisited from its initial discovery, found a place as a method of body contouring. Only from 1990’s has it been reliably used by Plastic Surgeons efficaciously for enhancement of the aesthetic appearance of the face, breast, hands, feet and buttocks. It involves correction of aesthetic irregularities and grooves. Before we delve into the treatise, it’s worthwhile delving into its history and evolution.
History and Evolution
It came into vogue when Gustav Neuber (1850-1932), a German Plastic Surgeon in 1893 transferred fat to the orbital region from the arm to improve retracted scar from osteomyelitis at the infra-orbital rim. Couple of years later Dr. Viktor Czerny (1842-1916) in 1895 transferred a lipoma to the breast to reconstruct the asymmetry as a result of unilateral partial mastectomy.
Though developed nearly a hundred years back it wasn’t accepted because of its complications due to lack of standardization of fat extraction techniques. The extracted fat was of inconsistent quality leading to poor results.
It was only in 1990’s Dr. Sydney Coleman, a New York City Plastic Surgeon standardized its removal, preparation and injection. Even with artificial implants evolving to better quality ones, natural transplantation is by far the best for reconstruction and aesthetic improvement. Since Dr Coleman’s standardization, it gained popularity. It was weighing its results and complications comparing it with artificial means, be it implants or injections. The popularity soon gathered momentum to the extent of naming fat transfer to the buttocks as Brazilian Butt Lift.
With the advent of liposuction in 1980’s a new vista of fat transfer developed simultaneously to culminate in the standardization by Dr Coleman. Mojallal et al described three phases in the development of autologous fat transfer:
- Open Surgery Period (1889-1977)
A period when en bloc transfer was done without changing the structure of the fatty tissue. It treaded Neuber’s footsteps by implanting small quantities of adipose tissue for correction of adherent scars from osteomyelitis. Though initial results were promising, there was significant rate of graft resorption for bigger volume transplantation.
- Fat Transfer after invention of liposuction (1978-1994)
The invention of liposuction opened a new horizon to the practised fat transfer method. Illouz in 1983 first described the use of impurified lipoaspirate for fat transplant. Ellenbogen in 1986 reported the use of free pearl fat autografts in a variety of atrophic and posttraumatic facial deficits. Fournier followed their trail.
- Post Coleman Technique
This emphasized the importance of free fat cell transfer from the previously practised free transfer of intact adiposa. It involved harvesting fat at low pressures reducing the trauma to the fat cells. Processing the lipoaspirate by the Coleman method involves centrifugation at 3000 rpm for 30 mins in 10ml syringes. The processed harvested fat is separated into three layers. The supernatant one containing lipid is poured off and the lower one containing blood, tissue fluid and injected solution is ejected from the base of the syringe leaving the middle part containing ADSCs, stromal cells, vascular cells, endothelial cells, and mural cells termed the stromal vascular fraction (SVF).
Though many innovative methods were described, inconstancy leading to low retention rates due to partial necrosis, remained. The actual mechanism by which fat grafts survived post-transfer was partly understood. An old, established theory on fat graft survival is one cell survival theory proposed by Peer in the early 1950s. According to it, fat graft survival depends mainly on the transfer of viable adipocytes and the formation of a vascular supply from the recipient site. Initial nutrition through serum imbibition requires the graft to be near to 2 mm of vascularised tissues. Cells in the fat graft that receive early and adequate circulation survive, whereas those far from vascularized source degenerates only to be gradually eliminated. It stresses the need for processing, injection techniques to minimize trauma enabling the transfer of viable adipocytes.
Recently, the host replacement theory has been proposed. It suggests that in ischemic conditions there is early death of transferred adipocytes and their replacement occurs through the activation and regeneration of ADSCs. The final volume retention after fat grafting is largely determined by the rate of successful adipocyte replacement by ADSCs. The results which have utilized ADSC-enriched fat grafts are promising. Better understanding of the role of the cells within SVF and other factors that affect graft survival have led to various advancements recently. Their efforts focussed to improve fat retention, advancements in surgical techniques and clinical applications that harness not only volumetric but also anti-fibrotic, angiogenic, anti-inflammatory and anti-apoptotic effects noted after fat transfer.
Characteristics of Adiposa
Adipose tissue has a central role in aging, metabolism, and homeostasis.
Derived from mesenchyme it provides greatest volumetric contribution to the connective tissue matrix (CTM) making it the largest endocrine organ in the body. A complex one is composed of adipocyte matrices interleaved with collagen fibres, stromal cells, adipose-derived stem cells (ADSC) and neurovascular structures. Nearly 85% of it, is in the subcutaneous fat, the rest 15% in the visceral fat. It’s the largest reservoir of adult stem cells. It plays a vital role in a variety of physiological processes like lipid storage, cushioning of organs, metabolic homeostasis, immune regulation, and angiogenesis. Its major physiologic contributions are energy storage, thermoregulation, secretion of adipokines thereby playing a critical role in the confining process by caloric restriction pathway. This increases longevity by reduced caloric intake. Its excess resulting in obesity is associated with significant metabolic derangements like changes in insulin metabolism, triglyceride and cholesterol storage, with their subsequent impact on related end-organ function, affecting longevity. Initially thought to be composed solely of white adipose tissue (WAT), now its known to be composed of brown adipose tissue (BAT) which contains a high concentration of mitochondria resulting in it being excessively metabolically active. Known for its role in thermogenesis, its presence initially thought to be in new-borns, with the 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) it’s now known to be in adults too. It might account for 1% of the adult fat. Its high metabolic activity might play a protective role in metabolism affecting the ageing process. Uncoupling protein UCP-1 is the BAT-specific expression distinguishing it from WAT.
Adipose-Derived Stem Cells
The discovery of Adipose-Derived Stem Cells (ADSC) brought a new dimension to soft tissue regeneration and stem cell research. It’s a type of mesenchymal stem cell with the ability to differentiate into a multitude of tissues with angiogenic potential via endothelial neovascularization.
Its isolation involves four steps:
- Harvest of harvest of lipoaspirate or excised fat
- Processing it in collagenase solution
- Centrifugation to separate the stromal vascular fraction containing the stem cells
- Culture and expansion of the isolated stem cell line after flow cytometry analysis
It has a high degree of regenerative potential. It can be used for multiple types of neovascularized tissue reconstructions only after definition of its growth and differentiation at the molecular level.
Stem cells are classified by its ability to undergo multiple divisions without differentiation into varied lineages. The totipotent embryonic ones are derived from the inner cell mass of the blastocyst. The adult ones are multipotent. ADSC can differentiate into multiple cell types, including adipocytes, cardiomyocytes, chondrocytes, endothelial cells, myocytes, neuronal-like cells, and osteoblasts. Of late, CD 34+/CD45– cells have been proposed to have the most adipogenic potential. Its potential to differentiate into endothelial cells form the key to neovascularization of the soft tissue for reconstruction.
Larger fat grafts have limited diffusion of nutrients and oxygen from inadequate vascular networks whereas ones processed for fat transfer are capable of neovascularization ensuring its survival in the recipient zone.
When to Consider Fat Transfer?
Whilst there could be many instances where fat could be transferred, discretion is crucial when trying to bypass traditional methods. With new developments of injectables, caution is vital where to use it with an eye on the long-term results. It might not be the best option considering longevity. Some of the areas where it has been used can be summarised as:
- Facial areas that are creased and shrunk
- As a permanent substitute for temporary fillers
- Improve body contouring
- Scar revision including those of acne scars
- Correction of hemifacial atrophy
- Lip Augmentation
- Adjuvants in face lift where surgeon is not adequately trained for extended SMAS and endoscopic brow lift. It often helps correcting periorbital region, malar region, marionette lines, pre-jowl sulcus
- Rejuvenating hands
- In facial rejuvenation
- Facial contour correction in atrophic regions as Romberg syndrome or Treacher-Collins syndrome
- Breast Reconstruction as in micromastia, tuberous breast deformities, Poland syndrome or mastectomy. Though reconstruction by TRAM flap has now replaced latissimus dorsi flap, those practicing the old technique need some other form of augmentation. Fat transfer can replace the use of prosthesis.
Sometimes the fat transfer is an easier option to conventional surgery especially to those not familiar with the surgical techniques. Only experience and expertise could filter the absolute indications from relative ones.
I am sceptical about the Brazilian Butt Lift, though it has been extensively used. Buttock Augmentation with an implant, a procedure selectively used might not be a best method with prosthesis, inconvenience outweighing its use. Free tissue transfer poses the question whether such an extensive surgery is warranted for a relatively less important cosmetic procedure. In Brazilian Butt Lift, instead of using an implant or free tissue transfer, fat from abdomen or the thighs is used to enhance the fullness of the buttocks giving it a natural feel which is equally possible by a free tissue transfer. However, its risk outweighs its use in cosmetic surgery. There is a tenfold risk of death due to pulmonary embolism. In addition, it causes cellulitis and lumpy scars.
This involves three essential steps:
- Removal of Fat
- Preparation of the Lipoaspirate
- Fat injection
The Coleman Technique is the one widely practised. It involves the use of a 10ml syringe with gentle hand-applied negative pressure for harvesting. The syringe is centrifuged for 2 or 3 minutes at 3000 rpm (800 g). The supernatant one containing lipid is poured off. The lower one containing blood, tissue fluid, cellular debris and injected solution is ejected from the base of the syringe leaving the middle part containing the cellular fraction composed of adipocytes and stromal vascular cells, is then transferred to 1ml syringes for injection. Injection into the recipient site is done using very small aliquots (0.1 ml) via small tunnels through recipient tissue allowing direct communication with recipient tissue for graft neovascularization.
Of late, to bypass centrifuge many commercial lipoaspirate preparation techniques have evolved like LipiVage (Genesis Biosystems, Lewisville, Texas), PureGraft (Cytori Therapeutics, San Diego, California) and Viafill (Lipose Corp, Maitland, Florida).
Several factors act as potential significant contributors to the viability of grafted fat like injected cell viability, cell type (stem cells vs adipocytes), and exclusion of noxious factors from the prepared graft. However, there is still controversy on this issue with varied suggestions for its improvement.
- Bruising settles in 3 weeks. Till then could be masked by cosmetic camouflage
- Swelling treated by cold pack and compress
- Drainage of liposuction cocktail over 24 hours
- Swelling (especially the lips if treated)
Of the several described note may be taken of those crucial critical ones
- Haematoma under skin
- Fat necrosis
- Fat Embolism
- Hypertrophic Scars
- Excessive Haemorrhage
- Skin pigment changes
- A-V fistula
- Penile Augmentation
Where do we go from here?
With its inconsistency of 25 to 30% resorption Coleman’s technique remains an area for further developments. Focus is to improve retention of transplanted fat
- Platelet Rich Plasma (PRP)
Platelet rich plasma (PRP), a concentrate of platelets in plasma by centrifuge of whole blood has been found to improve graft take. The platelet alpha granules have growth factors which promote wound healing by angiogenesis and production of extracellular matrix products. Thee growth factors contain platelet-derived growth factor, Transforming Growth Factor-B (TGF-B), Vascular Endothelial Growth Factor (VEGF), Epithelial Growth Factor (EGF), Insulin-like Growth Factor, Fibroblast Growth Factor and Platelet-derived Angiogenesis Factor.
As the transplanted fat survives by imbibition and neovascularization, PRP at the time of grafting could increase the graft take.
- Stromal Vascular Fraction (SVF)
Stromal vascular fraction (SVF) discussed earlier is highly rich Adipose-Derived Stem Cells (ADSC) and growth factors. Presence in mesenchymal stem cells is the most abundant source of stem cells as high as 5000 ADSC per gram of fat.
- Hypoxic Preconditioning
Hypoxic preconditioning by recipient sites conditioned to hypoxia before transfer increases expression of angiogenic growth factors such as vascular endothelial growth factor and decreases tissue hypoxia. How certain areas could be selectively subjected to hypoxia remains a million-dollar question.
- Hyperbaric Oxygen
Hyperbaric oxygen (HBO) has been known to improve wound healing. Oxygen could be a tool to improve fat grafting and stem cell outcomes.
- Tissue Engineering of Scaffolds
The basic principle is to hold the 3D structure of the tissue to be created. It should be biodegradable but hold its shape till host cellular infiltration has occurred. It shouldn’t elicit an immune or hyper inflammatory response, should be easy to use and inexpensive. There are two types of scaffolds –synthetic and biologic.
Major problems are with its degradation prior to transfer to the host tissue. To give a construct structural stability. Polylactic acid (PLA), polyglycolic acid, polyethylene terephthalate, polylactic-co-glycolic acid, polyethylene glycol, polytetrafluoroethylene and polyethylene have been tried to that effect. If these scaffolds are impregnated with ADSC, they could well act as carriers until neo-adipogenesis could occur.
Biologic scaffolds resemble the extracellular matrix (ECM). Biologic ones like collagen, gelatine, Matrigel, chitosan, alginates, decellularized human placenta and hyaluronic acids have been used.
Though now, a mainstream procedure in aesthetic and reconstructive surgery, it has challenges which needs sorting out. Unpredictable graft take often to 25% loss poses a major problem even with improved techniques. Others include recipient site complications (cysts, fat necrosis, calcifications), donor site complications (contour abnormalities from aggressive harvest) and insufficient donor sites (children, thin patients). Of the several advances, Platelet Rich Plasma (PRP) has been promising. Its use as an adjunct in facial rejuvenation procedures have been rewarding. Stromal Vascular Fraction (SVF) likewise definitely improves graft survival. Recent findings also indicate fat to improve scar contracture and the skin quality of burn scars, presumably due to the regenerative effects of Adipose-Derived Stem Cells (ADSC). It also improves intractable neuropathic pain after severe burns and the quality of radiated tissue after radiation.
Hopefully more progress would be made to overcome the drawbacks. In future a standardization could be reached as regards its reliability. Until then, experience and expertise must be judiciously used in its application so that it doesn’t fall into disrepute by its indiscreet use.