Yield of Human Adipose-derived Adult Stem Cells from Liposuction Aspirates

Background: Primary cultures of isolated human adipose-derived adult stem (ADAS) cells are multipotent and differentiate in vitro along the adipocyte, chondrocyte, neuronal, osteoblast, and skeletal muscle pathways.

Methods: We examined the ADAS cell yield per unit volume of liposuction tissue, and their surface protein phenotype by flow cytometry. Adipogenesis was assessed by Oil Red O staining and ELISA analysis of leptin secretion.

Results: The donor population was 87.5% female (n=18) with a mean age (+/-SD) of 44+/-10 years and body mass index (BMI) of 24.9+/-2.7. The mean cell yield was 404 000+/-206 000 cells per milliliter of lipoaspirate (n=18). Linear regression analysis of the cells derived from the female donors demonstrated a significant negative correlation between the number of cells obtained per milliliter of lipoaspirate with the BMI but not the age of the donor. The undifferentiated ADAS cells were homogeneously positive for the cell-surface markers CD10, CD13, CD29, CD44, CD49e, CD59, CD90, and HLA-ABC, and homogeneously negative for the cell surface markers CD11b, CD45, and HLA-DR. The absence of the panhematopoietic marker, CD45, indicates that the ADAS cells do not derive from circulating BM hematopoietic stem cells. Adipocyte differentiation led to a 5.1-fold increase in Oil Red O staining, and a 196-fold increase in leptin secretion levels. Culture of the cells in the presence of antibiotic and fungizone did not alter the undifferentiated ADAS cell immunophenotype based on flow cytometry, or their adipocyte differentiation based on leptin secretion.

Discussion: The ability to isolate a consistently homogeneous population of undifferentiated adult stem cells from adipose tissue of multiple donors supports their potential utility in future tissue-engineering applications.