Adult Stem Cells
Adult stem cells are self-renewing cells that can generate specific types of differentiated cells. They differ from embryonic stem cells in that they are usually limited to cell types within a certain category, such as cartilage, bone, and connective tissue, or blood-forming stem cells. Some researchers prefer to call adult stem cells tissue stem cells or somatic stem cells as they are also present in foetal tissue which can lead to confusion. Self-renewal is defined as cell division where either one or both of the daughter cells is also a stem cell that retains the same developmental capacity as the mother cell.
The most heavily researched stem cells are those found in the blood and in the skin. However, adult stem cells have also been extracted from adipose (fatty) tissue, the liver, lungs, eyes, gastrointestinal tract, brain, heart, and blood vessels. Tissues which have a high rate of turnover tend to be those with a larger presence of adult stem cells, in contrast to neuronal tissue which either has a low turnover rate or does not turn over at all.
Adult stem cells do not however, allow continuous regeneration of damaged tissue. If this were the case then the body would be unlikely to ever actually ‘wear out’. Instead, most adult stem cells are fairly inactive and researchers are frantically scrambling for answers regarding the activation of these stem cells in order to treat or cure disease and pathology. The main potential uses of adult stem cells are centered on helping us understand basic biological mechanisms, improving organ and tissue health by promoting cell growth and differentiation, and regenerating old or damaged tissues. The apparently limited life-span of adult stem cells is presumed dependent on a number of factors such as accumulated DNA damage, oxidative stress from reactive oxygen species, aberrant changes in gene expression, the attrition of telomeres, and damage to the stem cell niche (protective area) with age.
Adult Stem Cell Research
Research has been conducted on adult stem cells for over forty years (compared to just twenty years or so for embryonic stem cells). This means that adult stem cells are those most likely to be used in any stem cell treatment and such standard treatments as bone marrow transplants have been used for a considerable length of time. As adult stem cells appear more controllable in terms of the cell types into which they differentiate when implanted in living tissue, they avoid some of the risks of embryonic stem cells which scientists remain wary of due to their capacity to form any tissue in situ, even those undesirable.
A further advantage of adult stem cell use is that there is little ethical controversy around the extraction and use of adult stem cells. In the majority of cases the patient is able to give informed consent for a procedure and knows the origin of the stem cells when an autologous or donor-matched transplant takes place. Some reports have surfaced of adult stem cells being able to do everything that hESCs can; the research was found to be faulty however, and unable to be replicated. The ability of scientists to reprogramme adult stem cells is increasing rapidly and some success has been had in mimicking the human embryonic stem cells’ differentiation abilities.
Continue Reading –> Where to find adult stem cells
