Rejuvenation of stem cells
Researchers led by Dr. Jason Butler from Cornell University found that the functional characteristics of hematopoietic stem cells strongly depend on the condition of blood vessels.
The figure shows a vascular wall defect due to age-related changes: an increased content of reactive oxygen species (purple) in the endothelium of bone marrow vessels (red and green with blue nuclei) may interfere with their ability to maintain normal stem cell functions. Source: Journal of Clinical Investigation.
Transplantation of vascular endothelial cells from young mice to elderly individuals leads to the "rejuvenation" of their own stem cells: the latter acquire the functions of young cells, which leads to the improvement of the blood system and provides a faster recovery after antitumor treatment.
Hematopoietic, or hematopoietic, stem cells (HSCs) are localized to the bone marrow and give rise to all types of blood cells. As the body ages, HSCs also undergo age–related changes, which affects the cellular composition of the blood and leads to a decrease in the body's resistance to infections, as well as a predisposition to leukemia, for example, acute myeloblastic leukemia (AML), which is characterized by the presence of immature myeloblast cells in the peripheral blood).
Butler and his group report that the age of bone marrow vascular endothelial cells influences the functional state of stem cells. In addition, in a study on mice, they found a way to "rejuvenate" them by transplanting endothelial cells of a younger organism.
The researchers isolated the endothelial cells of young and elderly individuals and combined them in Petri dishes with young or old stem cells. In the samples in which young endothelial cells were combined with old stem cells, an improvement in the functional characteristics of the latter was noted. When transplanted back into mice, these stem cells gave rise to healthy blood cells.
In other samples in which old endothelial cells were combined with young stem cells, the opposite effect was noted: the stem cells "aged". This suggests that the functional characteristics of blood stem cells strongly depend on the condition of vascular cells.
When the researchers transplanted young endothelial cells into old mice, and then exposed them to a high dose of radiation, they noted that the cellular composition of peripheral blood quickly recovered, which once again proved that young vascular endothelial cells improve the functions of stem cells.
In another experiment, mice were exposed to radiation comparable to what patients receive before bone marrow transplantation (at the same time, all stem cells are destroyed in it). After that, one group of mice was injected with a small number of stem cells, the other with the same number of stem cells along with vascular endothelial cells. In the second case, the survival rate was higher, besides, the normal blood composition was restored much faster. Endothelial cells also had a protective effect on other organs, including the intestine and spleen.
Elderly people are predisposed to leukemia, especially AML. They also recover worse after chemotherapy and radiation therapy, the main side effect of which is the destruction of stem cells, including hematopoietic cells. The results of this study provide a basis for improving approaches to the treatment of leukemia and bone marrow transplantation in people not only elderly, but also young; they allow us to develop new tactics for the recovery of elderly patients after aggressive methods of cancer treatment.
Article by Michael G. Poulos et al. Endothelial transplantation rejuvenates aged hematopoietic stem cell function published in The Journal of Clinical Investigation.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru according to the materials Weill Cornell Medicine: Transplantation of Young Blood Vessel Cells Boosts Function of Aging Stem Cells