While I have been aware some of the functions of fat cells probably since High School and knew what it looked like since seeing my mother cook as a child, recent attention to fat cells has produced some great advances. We know that fat cells store energy and that they definitely take up space, but we now know that they do so much more.
First, not all fat cells are the same. There are white fat cells that are mainly storage units. These cells have one big body of lipid. The brown fat cells, in contrast, are metabolically active, contain multiple smaller fat compartments and can produce heat. The higher the percentage of cells that are brown, the less likely the person is to be overweight.
Fat also contains some “stem cells” which have the potential to develop into other types of cell. See below.
Because white fat is the variety that creates unwanted fullness in parts of the body, plastic surgeons work with fat has mostly involved removing that fat, often through liposuction. That is a safe and highly effective way to remove fat and improve body contour in the trunk, extremities and neck areas.
As time has gone by, however, surgeons have noted that some of the changes of aging, especially in the face, are related to a decrease in the fat deposits and to a change in their distribution. We have also known for a relatively long time, that fat can be grafted from one body area to another, much like skin can be grafted. This depends of moving live cells from place to place in such a way that they can re-attach to blood supply and stay alive and functional. With those two facts, plastic surgeons have been using fat as a live, permanent, self-renewing “filler” to help with facial rejuvenation. When fat grafts take, they provide volume that stays, in contrast to fillers like Restylane® or Juvederm® which are, by their nature, temporary. Fat grafting technique is routinely applied to eyelids, cheeks, lips, mouth, temporal areas and combinations of those areas.
Anecdotally, surgeons also believe that fat grafting can improve the quality of tissue, perhaps through some stem cell effect, which may have to do with improving the blood supply to the areas where they are placed. This reportedly appears as an improvement in the quality of the skin in the face. Stem cells are cells in the body that have not “differentiated” completely into one cell type or another, and they can subsequently differentiate into various cell types as necessary, with some specific limitations. Not all stem cells, including those found in fat, can differentiate into all cell types.
In other areas, especially the breast, fat cells have been used for reconstruction of smaller deformities caused by disease and treatment. In breasts where cancer has been treated with radiation, the fat cells seem to allow some recovery from the damage caused by the radiation, so the breast may regain some better blood supply, in addition to improved shape and volume. There are some surgeons who are investigating the augmentation of the breasts with fat as well, but this is not a routine procedure and merits further study.
As a cautionary note, there are advertisements on the web for “stem cell facelifts” which are not well-studied at this point. Fat unquestionably has been used to great benefit in facial rejuvenation, but the “stem cell” component of this therapy requires greater study to find out what is really happening.