Characteristics of Adipose Tissue-Derived Mesenchymal Stem Cells.

Background: The aim of this study was to examine the differentiation potentials and characteristics of adipose tissue-derived stem cells (ASCs) in other to evaluate for the ASCs to be used as alternative cell sources of mesenchymal stem cells.

Methods: ASCs were isolated from lipo-aspirated adipose tissues by treatment of collagenase A and cultured in a Dulbecco’s Modified Eagle’s Medium (DMEM). To know the characteristics of ASCs, the expression of cell surface antigens was analyzed by flow cytometry, and the proliferation potentials were estimated by colony forming abilities or capacities of population doubling. The differentiation potentials into adipocytes or osteoblasts were confirmed by accumulation of neutral lipid vacuoles stained with Oil-red O and expression of alkaline phosphatases.

Results: When the nucleated cells were isolated by collagenase treatment after lipo-aspiration, the mean cell yield was about 3.1 X 10⁶ or 1.2 X 10⁶ cells per gram of lipo-aspirate (n=8) processed at 3 or 21 hours, respectively. But cells processed at 21 hours were able to form more colonies than those at 3 hours. Flowcytometric analysis showed that Adipose tissue-derived stem cells (ASCs) have a marker expression that is similar to that of bone marrow stromal cells (BMSCs). ASCs expressed CD44, CD73, CD90, and CD105 and were absent for CD14, CD31 and CD45 expression. When primary cells were plated at 50 or 1000 cells/cm² on 6-well plates, cumulative population doublings were about 50 times until passage 7 or 13 (approximately 130 days), respectively, and ASCs expanded to 10¹⁸ cells. ASCs were multipotent, differentiating to the adipocyte and osteoblast lineages. ASCs did not provoke in vitro alloreactivity of incompatable lymphocytes and, moreover, suppressed mixed lymphocyte reaction (MLR) and lymphocyte proliferative response to mitogen.

Conclusion: Our results suggested that ASCs have highly proliferative potentials, multiple differentiation potentials, and immunosuppressive properties like BMSCs. Therefore, ASCs-based reconstructive therapy could employ allogeneic cells and because of their immunosuppressive properties, ASCs could be an alternative source of BMSCs to treat allogeneic conflicts.