Functional loss of stem cells plays a vital role in the aging process. Characterized by dysfunction of multiple tissues and organs,
aging results from the reduced function of effective stem cell populations. Reversing age-related stem cell decline has long been
a topic of considerable interest in longevity science. Recent advances in anti-aging research have uncovered the tremendous potential of stem cell therapy,
as a way to achieve organismic rejuvenation .
Stem cells are undifferentiated cells of a multicellular organism which are capable of giving rise to indefinitely more cells of the same type, and from which certain other kinds of cell arise by differentiation. In humans, there are two broad types of stem cells: embryonic stem cells and adult stem cells. In adult organisms, stem cells act as a repair system for the body, replenishing adult tissues. In a developing embryo, stem cells can differentiate into various specialized cells, while maintaining the normal turnover of regenerative organs .
Over the past years, researchers have identified three accessible sources of adult stem cells:
1. Bone marrow - complex procedure which requires extraction by drilling into bone (typically the femur or iliac crest)
2. Adipose tissue (lipid cells) - which implies extraction by liposuction
3. Blood - which requires extraction through apheresis, a procedure where blood is drawn from the donor and passed through a machine that extracts stem cells only and returns other portions of the blood to the donor .
Another possibility, less practiced, is extracting stem cells from umbilical cord blood just after birth. Of all procedures, autologous harvesting involves the least risk for immune rejection. Autologous cells are obtained from one's own body, thus preventing the risk of unfavorable immune reactions. A new area of research, are induced pluripotent stem cells (iPSCs) - adult stem cells that have been genetically reprogrammed to go back to an embryonic stem cell - like state. The reprogrammed cells function similarly to embryonic stem cells, with the ability to differentiate into any cell of the body and to create an unlimited source of cells. Pioneered by Japanese researchers in 2006, iPSC technology has significant implications for anti-aging research.
The field of stem cell research has been characterized by remarkable developments in recent years. Stem cells are nowadays used for the modeling of diseases as well as for rejuvenating purposes. One aspect that has limited to some extent this therapy, was the uncertainty that after collection, injected stem cells maintain their rejuvenating function once they reach the blood stream or targeted organs. In order to preserve stem cells in their natural state, Penn University researchers developed a system to collect and store them without manipulating them, thus making stem cells available for administration via injections. They found that stem cells collected directly from human fat - called adipose-derived stem cells (ASCs) - can make more proteins than originally thought. This gives them the ability to replicate and maintain their stability, a finding that can potentially open the door to new therapies for the prevention and treatment of aging-related diseases .
One form of stem cell therapy that has been widely practiced for over 30 years is bone marrow transplantation, and has been used to treat cancer patients with conditions such as leukemia and lymphoma. Another stem-cell therapy called Prochymal, was approved in Canada in 2012 for the treatment of acute graft-vs-host disease in children unresponsive to steroids . Moreover, FDA has already approved five hematopoietic stem-cell products derived from umbilical cord blood, for the treatment of blood and immunological diseases. The number of clinical trials increases exponentially, as researchers try to tap into the potential of this revolutionary technique .
According to a study, conducted by the Cedars-Sinai Heart Institute, stem cells taken from younger hearts can be used to reverse the aging process, thus giving "old hearts" the chance to rejuvenate. All treated mice had improved heart functionality, were able to exercise 20 percent longer, regrew hair at a faster rate, and had longer heart cell telomeres (telomeres are compounds found at the ends of chromosomes whose shortening is directly correlated to the aging process) .
Moreover, scientists recently proved that stem cell brain injections could reverse aging. Researchers at Albert Einstein College of Medicine gave old mice a new lease on life by transplanting stem cells straight into hormone-producing regions of their brains. This study could open a new perspective in the quest for immortality. While stem cells have long held promise for regenerating specific tissues, the new findings suggest they could be used to override the entire aging process. Research leader Dongsheng Cai explains that the discovery that lays the ground for this work is that the hypothalamus - a section of the brain which secretes key hormones - controls the speed of aging throughout the body. This function is mainly attributed to a tiny group of adult stem cells, which restock the brain with neurons. Studies in animals showed that by replenishing those stem cells it's possible to slow and even reverse various aspects of aging throughout the body .
Another study, conducted at the University of Rochester, found that the loss of stem cells in muscles leads to muscular decline in older mice, something that also happens to humans as they grow old. Therefore, stem cells might hold the key to people maintaining strength despite their muscles' decline that starts in their 30s. The scientists are now focusing to build upon their research and discover a drug which could help individuals maintain the stem cell pools within their muscles .
Injections of stem cells derived from human embryos have been successfully used to treat multiple sclerosis in mice. The study revealed that stem cell-treated mice were able to walk and run around normally while untreated animals continued to be paralyzed. The researchers believe the findings are promising enough to move to clinical trials on patients in the hope of developing effective treatments for this degenerative disease .
In the cosmetic industry, stem cell injections are referred to as the ultimate anti-aging treatment. Studies showed that stem cells can replace, regrow, rejuvenate and repair the skin at a cellular level. Moreover, participants who have undergone stem cell infusion to slow down aging report other beneficial effects, such as: relief from aches and pains, dramatic boost in energy level, weight loss to normal level, increase in ability to do physical exercise, etc .
The numerous stem cell studies in progress across the globe are only a first step on the long road towards curing degenerative and age-related diseases. Because of their unlimited ability to self-renew and to differentiate, embryonic stem cells remain of great significance for regenerative medicine. There are still challenges to overcome before stem cells can be safely, effectively, and routinely used in the clinical setting. However, their potential benefits hold tremendous promise for an array of new anti-aging therapies and treatments.
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