Current Stem Cell Research Stem cell technology is becoming increasingly relevent to clinical gerontology. Stems cells are unique in that they are capable of becoming many types of other cells. A young embryo is comprised of a very high concentration of stem cells which, as the embryo develops, become specialized cells in a process called differentiation. In this process, a stem cell in the brain might differentiate to become a neuron (a nerve cell), an astrocyte (a cell that supports neurons), or other types of cells. Once a cell has differentiated, the reverse process can't always be acheived. That is, a neuron doesn't in its normal lifetime revert back into become a stem cell. As adults, although we have a great deal less stem cells than we did as a young embryo, we still retain populations of stem cells in our body. They serve a number of novel functions, such as replacing blood cells that die or become non-functional, or to create new neurons in the brain in a process called neurogenesis. Much of the contemporary excitement with stem cells comes from applications like administering them via injection or transplantation into patients with severe dementia, or to cancer patients that have lost a lot of blood cells with chemotherapy. Administered neuronal stem cells have shown to migrate to areas of damage in the brain and repair the function of the lost cells. In cancer, transplantation of stem cells into the bone marrow can lead to the repopulation of blood stem cells. There are many interesting uses for stem cell technology, and it has great potential for improving health through clinical application. At present, however, researchers have focused on animal experimentation with models of diseases to ascertain how to clinically apply stem cell technology in humans.
Seven days after ischemic stroke was induced in rats, stem cells obtained from human bone marrow resulted in the rats regaining the use of their limbs. In another study, rats with severe stroke recovered after injections of stem-cell like cells obtained from human blood. Human volunteers were injected with granulocyte stimulating factor to release stem cells from the bone marrow into the bloodstream and these stem cells collected for the treatment of the rats. This method of obtaining stem cells is much easier and less controversial than obtaining cells directly from bone marrow or from embryos. Both the method of obtaining these cells and the marked recovery herald the future use of such techniques for human stroke patients.
Recently scientists have been studying the gene expression of stem cells and comparing them with differentiated cells, and they have found a particular gene of interest they've dubbed "nanog" that is active only in stem cells. Understanding how nanog is regulated may one day lead to the ability to take differentiated cells, say a skin cells from my fingers which are now typing, and then changing the gene expression in the cell to induce it to become a stem cell. In this manner, the difficulties of obtaining quantities of stem cells for therapy or research (the practical difficulties, not the "ethical" ones which are absurd) might be circumvented.
The potential for stem cell technology is both very broad and largely unexplored. Despite the resources devoted to stem cell research, there is much more discovery ahead given how much we have yet to know about the specific gene-expression profile of various stem cells and also how to fully apply stem cell technologies clinically. With regard to aging, it is evident with the studies like that involving rat stroke models that stem cells cells have much potential to treat disorders that are labelled as having simply "aging" as their cause, like cancer or many forms of dementia. Quality of life and average lifespan might be very well augmented by this.
Perhaps in the future stem cells might also be used as vectors for introducing mutation-corrected cell populations into the elderly. The DNA mutation-accumulation theory holds that a significant part of aging is due to the accumulation of DNA damage over time. This in turn affects the production of protein products, ie. a cell will basically fail to due its job of producing whatever it is supposed to, or might produce toxic proteins. More relevantly, accumulated damage from free radicals, UV light, etc. that correction enzymes fail to correct can induce a cell to become carcinogenic. As aging takes place and cells are less capable of repairing the damage inflicted upon DNA, even though only a small part of the DNA in a cell might be expressed, this accumulated damage can lead to serious problems. If this theory has much bearing on the aging of cells, and stem cells are also prey to DNA damage that may harmfully modulate the protein expression of affected stem cells, then I think it might be possible to reprogram the mutated-DNA of stem cells so that these cells produce more normal cells without the DNA damage. Depending on how telomerase is expressed in stem cells and how certain stem cells repopulate the cells in the human body, a similar technique might allow the lengthing of a cells telomeres without the danger of carcinogenesis experienced when the enzyme telmerase is left on to extend the telomeres indefinitely. This is obviously conjecture on my part, but thinking along such lines might provide a way to treat aging in itself rather than the pathologies that are attributed to aging.