Methods of reprogramming cells to a less differentiated state

A method for reprogramming a cell to a less differentiated state, comprising:

• (a) culturing a differentiated cell with a reprogramming medium;
• (b) transfecting the cell with one or more synthetic RNA molecules, wherein the one or more synthetic RNA molecules include at least one RNA molecule encoding one or more reprogramming factors and wherein the transfecting results in the cell expressing the one or more reprogramming factors;
• and
• (c) repeating step (b) at least twice during 5 consecutive days, wherein the amount of one or more synthetic RNA molecules transfected in one or more later transfections is greater than the amount transfected in one or more earlier transfections, to result in the cell being reprogrammed to a less differentiated state,
• wherein steps (a)-(c) are performed without using feeder cells and occur in the presence of a feeder cell conditioned medium.