Fat as a filler material has many advantages, while the disadvantage is that it is partially absorbed and partially apoptotic before it becomes viable. Today, we will introduce what issues need attention before the fat cells become viable in the filler area. 1. Selection of the donor area There is no significant difference in the survival rate of fat grafting in the abdomen or non-abdominal area. However, the fat in the lower abdomen and inner thighs may be concentrated to more fat-derived stem cells than other areas. The choice of donor area depends on: the availability of easy and safe access, patient preference and the amount of fat required. 2. Swelling solution Swelling solution consists of local anesthetic drugs and vasoconstrictors diluted in a large amount of fluid, which reduces pain and bleeding, and facilitates liposuction. Some studies have shown that local anesthetic drugs, may alter the survival rate of isolated fat precursor cells. However, there does not seem to be an adverse effect on grafting in terms of the dose used and the transient exposure of fat to anesthetics. There were no significant differences between commonly used anesthetic drugs, except for epinephrine + ativan. 3. Liposuction cannula selection There is no significant difference in terms of fat cell viability, and the size of the transplanted fat tissue. And a larger liposuction cannula diameter enhances cell viability. However, most of these studies used a dry suction technique without swelling anesthesia. 4, Liposuction Methods of liposuction include hand-held syringe suction, vacuum-assisted, hydrodynamic, or ultrasound-assisted liposuction. There is no evidence to suggest which liposuction method is superior to other liposuction techniques. Even though some studies have shown that cell viability and fat cell function vary between separation methods. For example: the use of low-pressure suction technique improves fat cell viability and reduces fibrosis. 5. Fat processing techniques Fat grafts were processed by: centrifugation, filtration, washing and gauze tumbling methods. After evaluation of all data, no one technique was found to be significantly superior to the others. There is a high degree of inconsistency in the results due to the inconsistent results of animal and human studies. Some studies refer to the fact that the use of centrifugal techniques with centrifugal force greater than 3000 rpm (1200 g) causes more fat cell damage. 6, fat injection Can be injected in multiple channels, multiple tissue planes and multiple directions, each channel with a small amount of injection. Currently, there appears to be a lack of scientific basis for performing overcorrection to obtain better graft survival. The grafted area should be avoided with elastic bandages or massage.