Embryonal stem cells can today be grown outside the body, and have the potential to develop into any type of cells.

Adult stem cells exist in the brain, in the skin and in the bone marrow.

Cell therapy and tissue engineering encompass a broad range of technologies that use living cells and biological substitutes for living tissues to restore, maintain or improve the function of tissues and organs. Many of these technologies and procedures rely on media and other products to culture cells and tissues outside the body.