Yield and growth characteristics of MSCs. Cells per gram of adipose tissue decreases with increased age of the donors (A). CFU assay was performed to enumerate number of cells in SVF that can form colonies. Number of CFUs deceases with age of the donor (B). Proliferative potential is associated with donor age as indicated by number and time for population doublings. Number of population doublings of MSCs decreases (C) while time per population doubling increases (D) with age of the donor. Results are expressed as mean ± standard deviation. MSCs: mesenchymal stem cells, CFU, colony forming unit assay. *P < 0.01 for young AT-MSCs versus aged AT-MSCs.