As the human body ages, most systems fail or function at a reduced rate. Today, science understands very little about this process, but new evidence is beginning to unravel the complex scheme. This is the case with blood stem cells in their long mission of cell renewal.
After a series of studies, scientists at the University of California at San Diego, in the United States, advanced in understanding how some stem cells are fundamental in the blood. When they start to present a defect or the balance of the environment in which they work is broken, cases of anemia, irregular clotting and even cancer become more recurrent.
As far as is known, the process of decline in hematopoietic stem cells (HSCs) is inevitable with aging, but, after the recent discovery, the group of researchers wants to find ways to stop this mechanism.
What gets in the way of stem cells in the cell renewal process?
Before we continue, it is worth explaining that the type of stem cell investigated is located in the bone marrow, produces proteins and is responsible for specializing (developing) into blood tissue and immune system cells.
In normal situations, HSCs synthesize new proteins at a slow pace, giving preference to the quality of the process. Despite this, some flaws occur naturally, creating misfolded proteins. These can be toxic if they accumulate.
In the body, the most common way of disposing of damaged proteins is the proteasome. It’s as if he works like a general janitor, breaking down proteins into their original components (amino acids) almost instantly. Lo and behold, according to the study published in the journal Cell Stem Cell, they do not take care of the waste from HSCs.
Unlike the standard rule, damaged proteins are captured by aggressors, which concentrate them in a single location. After being cornered, they are collectively destroyed by the lysosome—a cell organelle loaded with digestive enzymes. This process is called aggrephagia.
Why do stem cells treat their “waste” better?
According to the authors, the different cleaning strategy seeks to create a concentrated deposit of amino acids. It is as if the stem cells wanted to preserve, very close to the action field, the basic pieces for the construction of other proteins.
To prove the hypothesis, the group of scientists genetically deactivated the agrephagia process. In this way, stem cells began to accumulate defective proteins, affecting their regenerative capabilities. The induced problem also occurs in aging organisms, as HSCs have few agressomes.
“Our hope is that if we can improve the ability of stem cells to maintain the aggrephagia process, we will better preserve stem cell function during aging and attenuate blood and immune disorders,” says Robert Signer, lead author of the study. , in a statement.
It is worth noting that the recent discovery and most research with stem cells use rodents as a research model. Although the organisms are similar, in the future the process should be validated with humans. Without this, the field of knowledge that seeks to delay aging and maintain quality of life will not advance.
Source: Cell Stem Cell e UC San Diego
