Trials in breast growth (and re-growth in the case of breast cancer survivors recovering from mastectomies, lumpectomies and quadrantectomies) have been promising. Since the tissues induce the formation of blood vessels, the regenerative cells link the blood supply to the fat cells they're traveling with, presenting a much lower risk of reabsorption than the injection of fat cells alone. In 2007, a cosmetic surgeon in Japan began a human study and reported that patients injected with the stem-cell-loaded fat solution grew an average of 4 centimeters in breast circumference while the tissue remained soft and natural.