The search for a fountain of youth is something that explorers have sought for thousands of years. As part of this myth, anyone who has the chance to drink from its waters avoids the struggles of aging. Yet while such a fountain is well accepted as a myth today, this hasn’t stopped pursuits to solve the aging riddle. This is notably true among scientists today who are constantly seeking new clues about aging. And as it turns out, some are discovering that such secrets might lie within the body’s stem cells. In short, if they can figure out a way to extend the longevity of stem cells, the aging process might be delayed.
In this regard, new research involving stem cells are revealing new clues about aging processes in the body. By studying stem cells within mice, scientists have discovered that the way these cells handle waste products offers some insights. Mechanisms to isolate and store unwanted metabolic byproducts are robust during youth. But with aging, these become less adept and limit the longevity of stem cells. Understanding this, some researchers suggest that finding ways to regain these preferred waste management processes could be important. Such an approach might just be a way to slow aging for a significant period of time.
(Recent research explores how to reverse the aging process–read more in this Bold story.)
“We think that if we can jump in and prevent this from happening, or improve the ability of stem cells to maintain this protein homeostasis, then we might be able to prevent the decline in stem cell function and the diseases that are associated with those changes.” – Robert Signer, Professor of Regenerative Medicine, UC San Diego
What Are Stem Cells?
In order to appreciate how the longevity of stem cells might be a good thing, it’s important to know what stem cells are. In essence, stem cells are undifferentiated cells in the body, which means they can become nearly anything. Embryos have stem cells that are called “pluripotent” since they can literally develop into any organ’s cells. Others are called multipotent or unipotent, which means their options for development are less. In any regard, stem cells are important for tissue repair, cell replacement, and organ rejuvenation. It is precisely this capacity that offers potentially innovative treatments and new clues about aging.
For scientists, collecting stem cells for research can come from a variety of areas. In some instances, mice are used to harvest stem cells. Bone marrow and blood tissue harvests are most common in this regard. Other tissues that may have stem cells of interest include the skin, muscle, and even the liver. And amazingly, scientists can even now induce cells to revert back into stem cells through special techniques. For recent studies looking at stem cells for new clues about aging, mice bone marrow sites were used. This approach allowed researchers to look at these cells over time to determine factors affecting the longevity of stem cells.
The Latest Stem Cell Research
Concerning new clues about aging, the latest stem cell research was published out of UC San Diego. Researchers there took blood and immune cells from the bone marrow of young mice. Thye then examined what happened when mishaps occurred when cells synthesized various proteins. Naturally, mistakes occasionally occur given that any given cell may produce as many as 20,000 different proteins. The key is what happens to these protein “mistakes.” It has long been suspected that an accumulation of these dysfunctional proteins “clog” cell machinery. This not only was believed to limit the longevity of stem cells but contribute to aging in general. Thus, the researchers explored stem cell changes over time in older mice as well.
The basic premise prior to the research was that stem cells used proteases to breakdown protein mistakes as they happened. In this way, the amino acids that resulted could be reused for new protein synthesis. But as it turned out, the mice failed to show this to be true. Instead, mice stem cells moved these proteins into storage areas of the cell where they stayed until later. And then eventually, enzymes called aggresomes would disintegrate these protein blobs during specific times and schedules. Interestingly, however, the ability for stem cells to do this with aging declined significantly. And as this capacity declined, so did the longevity of stem cells in general. Because this was unexpected, these findings offered new clues about aging not previously considered.
“We need a much more nuanced understanding of how protein quality control functions in aging.” – Dan Jarosz, Systems Biologist, Stanford University
The Relevance to the Aging Process
On the surface, the findings described in mice stem cells may not be that impressive. After all, whether protein mistakes are eliminated sooner or later shouldn’t really matter. As long as they don’t clog up cell operations, things should be fine. However, as it turns out, the longevity of stem cells is an important factor in preventing aging overall. In other words, stem cells are in it for the long haul, and this influences the way they prefer to manage waste. They function best when waste management occurs in a controlled and predictable way. By using aggresomes and doing this on a schedule, they are able to better perform. In contrast, when they must manage waste more acutely and frequently, they lose their ability to be their best. As such, their longevity rapidly declines when this occurs, and aging accelerates.
Understanding this, the new clues about aging revealed by this discovery pertains to how cell waste is managed. Treatments and interventions that enhance aggresomal protein waste management could extend the longevity of stem cells. In turn, because stem cells are important in tissue repair and rejuvenation, this could slow the aging process. This is the focus of many companies today. Plus, the discovery is also important because it completely changes how scientists view cell waste processes. Previously, boosting protease activity was believed to be positive, but in actuality, this might reduce the longevity of stem cells. The new clues about aging revealed by the current stem cell research totally shifts efforts in a different direction. This is yet another piece of a very complex puzzle that involves aging in general.
