The recent Nobel prize awarded for stem cell research was a good choice. The prize is split evenly between a British researcher, (Gurdon) best known for Dolly the sheep (cloning) and a Japanese researcher (Yamanaka) who discovered how to induce stem cells from ordinary skin cells.
It is the latter achievement that should not escape our notice. All cells contain a full complement of human DNA, a set of chromosomes (in duplicate) that contains the information for the entire human being. How clever of nature to make it such that only a small portion of the genome is turned on at any one time; so a brain cell can be a brain cell and a liver cell a liver cell etc. It is not totally obvious why this type of redundancy evolved, but there you have it. The instruction set for the human is copied and copied and copied throughout life.
It is highly likely that many diseases occur as a result of all this copying, with its associated errors. But more on that at another time. As far as treatment of disease goes, the race now is to unlock the potential of stem cells to treat disease. This could be accomplished in a variety of ways. To do this, it is important to understand just what factors cause the stem cells to become…brain, liver…kidney…etc. This is referred to as “differentiation”. Differentiation could be controlled by chemical signals, such as growth factors, or by the local environment itself. One of the challenges of microfracture, for example, has been to induce stem cells from bone marrow to “become” cartilage. As discussed elsewhere, this sometimes works and sometime does not.
Ongoing studies with stem cells for such conditions as stroke or peripheral vascular disease may rely upon lack of tissue oxygen as a trigger. One option for stem cell therapy is to anticipate that the stem cells will actually grow into and become the damaged tissue; or, they could simply secrete various growth factors and chemicals of their own and induce other cells to heal. It is this phenomenon that Dr. Yamanaka demonstrated when he provided a “cocktail’ of four growth factors that cause skin cells to become stem cells. The stem cells then can be differentiated into other tissues, given the right environment.
The bottom line is that human tissue is somewhat plastic, or changeable, and to some extent it can be modified throughout life. If we can better understand this process new methods for treating disease will soon be in the offing.