title: Induction of primitive streak and mesendoderm formation in monolayer hESC culture by activation of TGF-β signaling pathway by Activin B.
abstract: Human embryonic stem cells (hESCs) have the ability to differentiate into all human cells, however controlling the differentiation has always been a challenge. In the present study we have investigated the direct differentiation of hESCs on MEFs by using TGF-β signaling pathway activators Activin A and Activin B. Activation of the TGF-β pathway with Activin B in low serum highly induced primitive streak and mesendoderm formation after 24 h, which included up-regulation of SOX 17 and BRACHYURY protein and gene expression. Continuous stimulation with Activin B in 2% serum further induced mesendoderm formation by increased gene expression of Brachyury, SOX17, MEOX and FOX at the same time we found down-regulation of neuroectodermal marker genes. Further, by stimulating the mesodermal cells by BMP-2 we succeeded to induce mesenchymal like cells with high expression of mesenchymal markers including; MEOX, FOX, RUNX2, COL1 and OSTEOPONTIN. In conclusion we have directed the differentiation of hESCs as monolayer to primitive streak like cells with Activin B and further into pure mesoderm and mesenchymal like cells by BMP-2.
authors.affiliation: Stem Cell Unit, Department of Anatomy, College of Medicine, King Saud University and King Khalid University Hospital, Riyadh, Saudi Arabia.
authors.forename: Amer
authors.initials: A
authors.lastname: Mahmood
authors.affiliation: Stem Cell Unit, Department of Anatomy, College of Medicine, King Saud University and King Khalid University Hospital, Riyadh, Saudi Arabia.
authors.forename: Abdullah
authors.initials: A
authors.lastname: Aldahmash
keywords: Differentiation; Human embryonic stem cells; Mesenchymal; Mesendoderm; TGF-β pathway