There are various obstacles to using stem cells for cell therapy that must be overcome. One obstacle is that the proper source of stem cells must be used. The procedure of identifying, isolating, and producing the correct stem cell is a laborious process. Once stem cells are isolated, the proper conditions must be made so that cells are able to differentiate into specialized cells specific to that type of therapy. This process requires a lot of testing. Another obstacle is that the cells must be transported to the right part of the body, which requires the body to not reject the stem cells by being able to function with normal cells. The body’s immune system may have to be suppressed to reduce any immune reaction by the stem cells. An additional obstacle is that adult stem cells are very small in number in each tissue, making them hard to identify and purify. They also cannot be grown for extended periods of time in culture. Additionally, there are currently no tools or technology that can be used to produce large amounts of stem cells in culture.