Mesenchymal Stem Cells: The Promotion of Endodermal-Induction Using Activin A

ABSTRACT

PURPOSE: The most important consideration for therapy using MSCs is the differentiation of the target organ's cell type. For in-vitro hepatogenic differentiation of MSCs, the main focus is efficient induction of the MSCs into the endoderm stage. Activin A, which is a signaling molecule that is similar to Nodal, promotes the induction of definitive endoderm from both ESs and MSCs. The protocols for induction into definitive endoderm have shown different efficiency and reproducibility depending on the researchers or the sources of the MSCs. Thus, a study on the various conditions of Activin A is needed to efficiently differentiate MSCs into the definitive endoderm lineage of MSCs. METHODS: MSCs were isolated from human adipose tissues and these were cultured in MCM (MSCs Culture Medium) on a human fibronectin coated plate. At 70~80% confluence, the MSCs were harvested and cultured in MCM supplemented with Activin A, at a 50 ng/mL concentration, and FGF4. The expression of the genes related with MSCs or primitive endoderm were analyzed by RT-PCR. The changes of cell morphology for differentiation were also observed by a light microscope & a SEM. RESULTS: The expression of genes related with primitive foregut endoderm was seen in the groups that were treated with a higher concentration of Activin A. The morphology of the cells that differentiated into definitive endoderm were not different from those of the undifferentiated MSCs. The expression of genes related with functional primitive hepatocytes was seen in the early phase during hepatic differentiation. The cell morphology was changed to a similar cuboidal form in a time-dependent manner. CONCLUSION: Activin A promotes a more rapid induction of definitive endoderm. It also makes an efficient condition for the differentiation into primitive foregut endoderm at a higher concentration.