Transfer of any tissue from one individual to another within the same species is called homologous transplantation. Thus, kidney, liver, heart etc tissues are routinely being transplanted from one human to another human with the intention that the transplanted tissue survives and functions as a normal tissue. However, the recipient’s immunity fights against the transplanted tissue since these organs are from another individual. Therefore, these patients need to be given immune-suppressing medicines. In such cases, the usage of such medicines (with significant side-effects) to deplete your immunity can be justified so that the function of a vital organ can be maintained.
Theoretically, fat can also be transplanted from one person to another. However, the subsequent survival of this fat will require immune-suppressant medicines. Generally, fat transfer is done for aesthetic purposes and therefore does not justify the use of such medicines. Thus, without immunity suppressing medicines the fat that would be transplanted into another person would simply not survive (rejection process) and may cause certain untoward reactions.
Fat is routinely transferred from one body part to another in the same individual. This is called as autologous fat transfer. This can be done very safely without any rejection process. The technique for autologous fat transfer is now streamlined so that we can achieve better and more reliable results. Generally, sufficient amounts of fat can be harvested successfully from “thin” individuals as well.