TRANSDUCING MURINE EMBRYONIC STEM CELLS TO MESODERM LINEAGE

With so many deaths around the world being due to cardiovascular disease, there is great demand for an unlimited supply of cells for application in regenerative medicine. However, the control of directing pluripotent cells into mesoderm lineage which gives rise to cardiac muscle cells remains poor. Here in this work, the synergistic effect of chemical and mechanical signaling in driving cells towards mesoderm germ-layer was investigated. Transgenic reporter mouse embryonic stem cells were used in this study. The reporter cell line shows the cellular endogenous activity of pluripotency gene Oct3/4 with green fluorescent protein (GFP) while also reporting mesoderm-specific gene, Brachyury, activity with DsRed fluorescent protein. To promote adhesion of mouse embryonic stem cells and to initiate integrin-based mechanical signaling, the extracellular matrix protein fibronectin was used. In the presence of fibronectin and a small molecule called leukemia inhibitory factor (LIF), which is known to maintain pluripotency and self-renewal, mouse embryonic stem cells responded by exhibiting expressions of both GFP and DsRed. To further promote differentiation and to increase mechanical signaling, Notch signaling was activated by presenting cells with fibronectin and DLL1 protein. The differentiation was found to have a pronounced effect in the presence of fibronectin and DLL1 protein together with the withdrawal of LIF. This is a proof-of-concept that mechanical signaling together with synergistic chemical signaling can drive pluripotent cells towards mesoderm lineage. Future studies with human pluripotent stem cells may transduce cells towards mesoderm and finally towards cardiac fate. Collectively, this study shows the importance of chemical, but also the importance of mechanical signaling to transduce cells to mesoderm