Growth factors, added at the precise time and concentration to in vitro cultures are essential to control cell proliferation and differentiation. When added to a culture vessel, however, the concentrations of these signaling proteins rapidly decline, altering both levels of individual growth factors and the ratio of factors for cell signaling. When growth factors are replenished by exchanging the medium, concentrations peak, resulting in an ebb and flow of growth factor levels resulting in mixed signaling that can lead the…