Stem Cell Enhanced Fat Grafting to Buttocks

Type I

2:1 or high projection ratio, adequate volume, good projection, but excess of supragluteal, paralumbar, and subgluteal fat

Type II

Lower than 2:1 projection ratio, enough volume and latero-lateral projection but little anteroposterior projection; appearance of wide hips with relatively flat buttocks

Type III

2:1 or slightly lower projection ratio, lumbosacral hyperlordosis

Type VI

Lower than 2:1 projection ratio and lack of both projection and volume; usually have athletic build, thin, or at ideal weight, with lack of volume and projection

Type V

Older women with “senile buttocks” characterized by hypertrophy of skin, fat, and muscle, and ptosis of tissue

Another classification system is based on pelvic height and four different frame types:

(i)

Round

(ii)

Square

(iii)

A shape

(iv)

V shape

The shapes are based on lines connecting the outermost projection at the superior iliac crest to the outermost projection at the trochanteric inferior region to the central point of the gluteus represents the approximate mean point between the first two points.

Roberts et al. [3] uses a third method to evaluate the derriere. The waist-to-hip ratio (WHR) is defined as the ratio of the circumference of the waist at its narrowest to the circumference of the thighs at the level of the maximum prominence of the buttocks. The authors concluded that attractive, youthful buttocks have a WHR of ~0.7. In addition, he found several buttock characteristics that appealed to ethnic groups:

(a)

Smooth inward sweep of the lumbosacral area and waist

(b)

A feminine cleavage as the buttocks separate superiorly and inferiorly

(c)

Maximum prominence in the mid to upper buttock (or at the junction of medial and central thirds of the buttocks in cross section)

(d)

Minimal infragluteal crease without ptosis

(e)

Sacral dimples may be present in an attractive youthful buttock but are not a determinant of an attractive buttock

(f)

“Universally” perceived ideal buttocks are 1.4 times the circumference of the waist, which is consistent cross-culturally and throughout history

43.4 Adipose-Derived Stem Cells and Current Clinical Applications

The idea behind stem cell enhanced fat grafting is to improve graft take. The clinical use of adipose-derived stem cells in the form of autologous stromal vascular fraction cells or noncultured adipose-derived regenerative cells is rapidly growing in all fields of medicine including cosmetic surgery. Currently no automated device for separating adipose stem cells is approved for human use in the United States. Most commonly, clinical-grade collagenase and centrifugation is used to separate and concentrate an array of precursor regenerative cells including adipose-derived mesenchymal stem cells found in the harvested fat. A cell pellet containing these cells, termed the stromal vascular fraction, is formed with centrifugation [4]. The cells are usually added in to the harvested fat that is prepared for injection.

The stromal vascular fraction contains multiple cell types, including circulating blood cells, fibroblasts, pericytes, endothelial cells, and adipose-derived stem cells [5]. Adipose-derived stem cells secrete a large variety of high level of cytokines which have angiogenic, anti-inflammatory, and antioxidative effects, such as vascular endothelial growth factor, hepatocyte growth factor, platelet derived growth factor, and basic fibroblast growth factor [6]. They also possess immunomodulatory properties, such as immunosuppressive effects in the control of the graft-versus-host disease and autoimmune disease and in inducing immune tolerance as well [7, 8]. Adipose-derived mesenchymal stem cells are multipotent cells that are capable of differentiating into multiple cell lineages, such as adipogenic, osteogenic, chondrogenic, and neurogenic cell lines [9].

43.5 Open vs. Closed System Fat Grafting

In the past, fat grafting was fraught with poor outcome and complications because of the techniques used to harvest, prepare, and inject the fat. In the old open system, the harvested fat was poured out into a sieve or a gauze sponge in the open air, was rinsed, and then, using a spoon, was scooped and placed into syringes for injection. Today, a closed system is used in which the harvested fat is drawn into a syringe and prepared in the syringe system without exposing the fat to the open air. We now know that the exposure of the fat cells to atmospheric oxygen levels is detrimental to the fat. In vivo, adipose tissue oxygen concentrations are typically less than 3 %; thus, adipose-derived stem cells reside in relatively oxygen-deficient sites in the body. Low-oxygen tension is an important component of the stem cell niche, and hypoxia provides a conducive environment for the maintenance of stem cell properties [10]. Adipose-derived stem cell function is enhanced by hypoxia through upregulating secretion of growth factors which enhance the skin’s regenerative potential [11, 12].

A closed system provides for a low-oxygen environment that is more analogous to the physiologic conditions of the adipose tissues. This system also provides for improved adipose-derived stem cell viability, decreased postoperative infection rate, less tissue manipulation, enhanced augmentation trough improved graft take, and therefore better patient satisfaction [13].

43.6 Consultation

43.6.1 Understanding Patient’s Desires

Patients who seek gluteal augmentation generally desire more gluteal projection. In the medical consultation before the procedure, it is vital to set a realistic expectation to have a successful outcome in the eyes of the patient. The most common complaint of patients after gluteal augmentation surgery, as in breast augmentation, is that the augmentation is not large enough. There is no single standard procedure that fits all expectations. The consultation should include a discussion of the combination procedure of lipoharvesting, liposuction, stromal vascular fraction isolation, and regenerative cell enhanced fat grafting.

43.6.2 Examining the Gluteus and Its Frame

The ideal buttock form is achieved when there is a balanced proportion with the rest of the body. Systematic and aesthetic analysis should be performed before the procedure. First the buttock itself needs to be evaluated for volume, shape, and skin laxity. Then the frame of the buttocks needs to be evaluated for lipocontouring. The relationship and proportion between height and width of the gluteus to the bone frame should be analyzed for symmetry and deformities and ratios. Successful buttock augmentation requires sufficient quantities of fat tissues in the donor sites for graft injection into the buttocks and proportioned and contoured frame that defines the borders of the buttocks.

43.7 Preoperative Preparation

Patients are instructed to suspend any medications or supplements with anticoagulant effects such as aspirin, NSAID, and fish oil for at least 2 weeks prior to the procedure.

The clinical examination is performed with the patient standing up and rotating 360°.

Photos are taken from different angles (posterior and oblique, lateral, frontal and oblique). Areas both to be harvested from and injected to are examined and analyzed.

Plan to harvest about 30 % more than the estimated amount of fat needed for grafting. This “extra” fat is needed to ensure there is enough viable fat to graft as about 10–20 % of the collected fat may become damaged in harvesting and free oil is released. Also some of the fat will be processed to separate out the regenerative cells in order to enrich the adipose tissues destined to be injected into the buttocks for tissue grafting.

Markings are made to indicate the areas to be lipoaspirated and areas to be fat grafted. All markings are made when the patient is in the standing position.

Presurgical marking to create the frame around the buttocks. Proper 3-D proportion is essential to buttock enhancement. Contouring the lower back and lateral thighs will define the buttocks and create the appearance of more projection. Excess fat in the lower back tends to make the buttocks appear long and flat and on the lateral thighs wide and flat.

Prepare the patient circumferentially with povidone-iodine while standing.

Positioning the patient: If the patient is undergoing general anesthesia, the patient is intubated in the supine position and then turned to the prone position. Under local anesthesia, the patient is placed on the operative table in the prone position. For the lateral thighs, the patient is turned on the lateral position.

Place a gauze pad soaked in povidone-iodine over the anal area.

10.

Place warming blanket under patient and warm air blanket over patient wherever possible.

11.

Under general anesthesia, use sequential compression devices for the prevention of venous thrombosis.

12.

Antibiotic prophylaxis: In healthy patients undergoing local anesthesia, I generally do not give antibiotics. Patients with indications for antibiotic prophylaxis, such as diabetics, patients with implants, the immunosuppressed, and those undergoing general anesthesia, should be given appropriate antibiotics.