Yes, cell growth is dependent on a wide variety of proteins and differentiation markers found in the cellular environment. Even other cells affect what one cell will do. They affect everything from frequency of cell divisions to density, orientation, and migration. By studying micro-patterning across the substrate (surface of cell growth/ other cells in standard culture) changes in orientation and migration can be predicted. The rest is far more subtle. The process of cell maturity is incredibly sensitive to this environment. A few extra additions to the substrate and it becomes a neuronal cell, a few less and it becomes a muscle cell or any of a multitude of things. Sometimes they transdifferentiate, change from something like a muscle cell into a neuronal cell. There is widespread agreement that transdifferentiation of this sort is dependent on more than just the differentiating cell in question. As a body begins to reach full scale, fewer and fewer of these transdifferentiations occur. Cells replace their own type and density all the time but form and function become relatively constant. A splash in a puddle has a far greater affect on the changes of the whole than a splash of equal magnitude in a lake.
By studying the cell lines the President allowed for federal funding in research, do you feel science will grasp the mechanism and process by which cells differentiate in the stem cell cascade, then apply that to learn how to 'back up' MAPCs and bring them forward as specific tissue donor cells?