[rusculture]

What exactly do you mean when you say "and they can be fairly well manipulated" in your answer for #2.
By this do you mean that the lab adds chemicals to alter the cells to make them into another type of cell?

A pluripotent stem cell has the ability to form any cell type in your body. To do this the stem cells need chemical signals (cytokines, growth factors, induction agents, etc.) to tell the stem cells what to do. Your body makes the appropriate signals depending on which organ or tissue is nearby and is of need of repair. Scientists have discovered the composition of some of those signals. In culture with the stem cells, the scientists have used different "cocktails" of these chemical signals to form different cell types from the stem cells. My own lab has been able to create 65 separate cell types from cultures of pluripotent stem cells using different "cocktails" of various agents.

How safe are these chemicals?

The chemicals are safe when used appropriately. Usually for human use, only purified chemicals or human-derived signals are used. This makes sure that the procedure is safe for human use.

What happens if they don't alter or manipulate the cells?

The scientists usually know the correct "cocktails" of chemicals to use to get the desired effect from the cells, when the cells are grown outside the body "in culture" first. However, in my laboratory, we have discovered that the body knows a lot more than we do with respect to using the appropriate signals at the proper time to make the appropriate cell types to heal damaged tissue. Therefore, we put in naive pluripotent stem cells, that have never seen any exogenous agents, and the body uses those cells that way it wants to to get very good healing responses.

Dr. Young