In the clinic, SVF, which contains ADSC, is usually obtained by liposuction of the abdomen or thighs and then centrifuged, digested and washed, etc. It is then mixed with adipose tissue in a certain proportion and transplanted to the recipient area. SVF can also be cultured in vitro to obtain wall-grown ADSC, and the ADSC with good growth status in vitro can be taken for composite transplantation with adipose tissue. Since CAL technology is standardized and easy to automate production, industrialized equipment is now available on the market, which makes the promotion and application of this technology more convenient. First, the application of SVF CAL technology (a) fat suction Studies have found that human abdominal and thigh subcutaneous fat is most rich in ADSC. Therefore, the CAL technique often selects the above two areas as the best choice for fat donor area. In a sterile operating room, after anesthesia is applied by swelling solution to the liposuction site, the fat is suctioned through a 2.5-3mm diameter suction tube in the usual way. The mixture sucked out by the negative pressure liposuction tube contains swelling solution components, adipose tissue, connective tissue, blood cells and other tissue fragments. (ii) SVF preparation The aspirated fat was divided into two parts, one of which was used to extract SVF, and subsequently the extracted SVF was mixed with the other part of the fat and the mixture was used for grafting. Therefore, the process of extracting SVF containing ADSC is a critical step in the CAL technique. The whole separation process usually takes 70-80 min, and the basic process is as follows. 1.Centrifugation Half of the fat obtained by aspiration is centrifuged, by which components such as adipocytes, lipids and blood cells can be separated. After centrifugation, the mixture can be divided into upper, middle and lower three layers: the upper layer, mainly for the fat, which contains triacylglycerol and celiac disease particles, which is the product of the fat cells after crushing; the middle layer, mainly for the purified fat; the lower layer, containing blood cells, plasma, filtrate, etc. At this time, the middle layer is the purified fat. At this point, the middle layer is the purified adipose tissue. One part of the adipose tissue is kept for reserve, and the other part is taken out to continue the following steps to present SVF. 2. Digestion The adipose part is digested with an equal amount of 0.075% sterile collagenase by oscillation (37℃, 30min). 3.Washing The fat fraction and liquid fraction were separated by repeated washing with phosphatebuffersaline (PBS) or saline solution and centrifugation. The fat fraction was discarded and the liquid fraction was retained. Wash with PBS or saline solution and centrifuge. The bottom tangible cell fraction obtained by centrifugation is SVF, which is the cell mixture rich in ADSC, and in addition to ADSC, there are also cells of blood origin, vascular endothelial cells, and so on. (iii) Adipose tissue-SVF complex formation The other half of the fat obtained from aspiration was mixed with the SVF obtained from the treatment and left to stand for 15 min, so that the ADSC were fully adsorbed on the fat. These fats were similar to active biological scaffolds and were reserved as grafts. The isolated cells need to be strictly tested for quantity and quality, and a small portion of SVF can also be extracted for cell culture to verify cell activity. (D) Adipose tissue-SVF complex transplantation Adipose tissue-SVF complex transplantation was performed according to the conventional fat grafting method. Second, the application of ADSC CAL technology (1) The same steps as above to complete fat aspiration, SVF preparation. (2) ADSC culture: inoculate the mixture in the culture container and culture it with cell culture solution, generally using DMEM culture solution containing 10% fetal bovine serum. Change the fluid once every 2-3 d. The more blood cell components contained in SVF can not be adhered to the wall for growth, and can be removed by changing the fluid. The wall-adherent cells continue to be cultured. After the cells have grown to a certain number, a suspension is made and then mixed with the aspirated adipose tissue for application. (3) Adipose tissue-ADSC complex formation: resuspend the adipose tissue, mix the cell suspension with it, and let it stand for 15min, so that ADSC can be fully adsorbed on the fat. (4) Adipose tissue-ADSC complex transplantation: adipose tissue-SVF complex transplantation was performed according to the routine method of fat transplantation.