**3. Treatment/surgical technique**

The surgical protocol should always include a complete medical history and an analysis of the degree of deformity to estimate the volume to be replaced. Also, photographic controls to assess its evolution in the medium and long term. Informed consent must be obtained.

Before starting the procedure, a tracing is made on the preoperative images to better estimate the required volume, the mini-approaches necessary for its application, and a projection of the desired result.

The lower abdomen of each patient is evaluated as the donor area of choice. Other areas may be the lower back and thighs since, in pediatric patients, the availability of abdominal fat may be limited.

An oral dose of cephalexin is indicated the day before surgery and will continue for 4 days after. In pediatric patients, the procedure is performed under general anesthesia.

#### **3.1 Tumescence and fat aspiration**

The lower abdomen is infiltrated with a tumescent solution (0.25 mg of epinephrine in 250 mL saline solution) to perform fat aspiration. The ratio of infiltration is 1 mL of solution per 1 mL of harvested fat. We perform fat collection using a blunt-tipped #20 1-mm sharpened holes cannula 10 cm long and 2.5 mm in diameter attached to a 10-mL Luer-lock syringe. According to the areas to be treated and their degree of deformity, the average number of syringes usually collected is 2 to 3. In adults, for facial esthetics, it varies from 3 to 6.

#### **3.2 Fat processing technique and isolation of ASCs**

The extracted fat is separated into two samples, one is used for the isolation of ASCs, and the other will be enriched with the ASCs. The second sample is processed according to the Coleman protocol [12]. The isolation of the ASCs is carried out according to the technique described by Yoshimura [20]. It is important to point out that, in our beginning, the protocol for obtaining and isolating stem cells was in accordance with what was previously described. We currently treat fat in a simple way. In this way, we obtain 3 types of fat grafts: Mini-fat grafts (where adipocytes provide an average of 85% of the cell volume), Micro-fat grafts (average volume 50%), and Nano-fat grafts (virtually no adipocytes and a higher cell concentration of elements of the stromal vascular fraction), very similar to that described by Tonnard et al., however, with some variants [29].

Once the fat has been collected with 10 ml syringes for mini-grafts, it is centrifuged for 1 min at 3000 rpm, and the infranatant fluid (composed mainly of tumescence fluid, blood, detritus, free fatty acids, etc.) is eliminated. We then connect a 2.5 mm diameter female-to-female transfer device at one end of the syringe, and on the other end, we connect 1 and 3 mL Luer lock syringes, ready to be filled and injected.

For micro-grafts, the centrifugation and obtention process is similar. Afterward, the syringes are connected to another 10 ml Luer lock connector through the transfer device and are passed to the empty syringe "round trip" 5 times. The product is centrifuged again for 1 min at 3000 rpm, the infranatant is eliminated, and the cell conglomerate is transferred to 1- and 3-mL syringes ready to be injected.

Mini and micro-fat injections are performed with short and long malleable fine cannulas, 1.5 to 2 mm in diameter. The process to obtain nano-fat is also similar to the previous one, with the difference that the fat is emulsified by making 30 "round trip" passes, with a 1.5 mm transfer. The syringes are then centrifuged for 1 min at 3000 rpm. Injections are performed with short and long, fine malleable cannulas, 1.5 to 2 mm in diameter.

Logically, we use mini-graft and micro-graft for volumetric increases. In nano-grafts, adipocytes are practically destroyed; therefore, they do not provide volume, and it has been shown that they have a higher concentration of ACSs with a vast potential for cell regeneration [30]. We use them to enrich the mini and micro-graft, and for injection into the subcutaneous and intradermal stratum (with 23-to-27-gauge needles) and to improve the inherent characteristics of the skin such *The Versatility of Autologous Fat Transplantation in Abnormalities... DOI: http://dx.doi.org/10.5772/intechopen.97015*

**Figure 1.**

*Intraoperative view of the lipoinjection of adipose stem cells. (A) Glabellar approach. (B) Temporal approach (behind the hairline).*

as shine and texture due to the thickening of the dermis, moisturizing, and better contraction quality. It even better unifies the natural tone of the skin. All this provides a more youthful appearance of facial expression. We have recently also used nano-grafts to improve the appearance of tear trough, dark circles of the eyelids, and camouflage scars in general.

## **3.3 Volumetric lipoinjection technique**

We use 3-mL syringes and a 2-mm blunt-tipped cannula for lipoinjection. The micro-approaches to be made will depend on the area to be injected. We make these incisions initially with a 22-gauge needle. The area to which we will have access should be considered when performing our approaches to achieve a uniform "fanshaped" distribution of the entire area to be lipoinjected and keep the cannula tip in mind (**Figure 1**).

The final step consists of manual manipulation and remodeling of the injected fat, and in some cases, removal of excess grafted fat through the entry site. We use a 6–0 nylon suture to close the micro-approaches and 4–0 nylon for the scalp. The sutures are removed on the 4th or 5th postoperative day.
