US researchers have reported that receiving a single blood transfusion from old mice caused the ageing of tissue in young mice.
But treatment of older mice with senolytic agents – drugs that eliminate senescent cells (a hallmark of ageing, when cells stop growing and dividing) – before blood transfusions to young mice reduced the levels of senescence markers in young mice.
The study by scientists at the University of California, published in Nature Metabolism, shows senescence can occur not only due to wear-and-tear associated with ageing, but also blood- borne factors.
Study author Professor Irina Conboy told medicalnewstoday.com: ‘Our study shows cellular senescence is neither cell intrinsic nor a purely chronological, damage-accumulation phenomenon; it can be quickly induced in 2 weeks in young animals. Senolytics only partially reduce the negative effects of old blood on young cells and tissues, suggesting additional therapeutic avenues.’ She added the study substantiates the role of factors in old blood in promoting ageing.
In the study, researchers examined whether senescence could be transferred from older mice to younger ones through blood transfusions from aged mice (22-24 months) to their younger counterparts (3 months). The control group consisted of young rats (3 months) receiving blood transfusions from other young rats of the same age.
At 14 days after receiving the transfusion, young mice receiving blood from older mice showed increased expression of senescence biomarkers in the muscle, kidney and liver; however, such an increase was absent in the lungs, heart and brain. Hence senescence induced in young animals after receiving blood from old mice was tissue-specific.
The young mice that received blood transfusions from older mice also showed deficits in tasks assessing muscle strength and exhibited lower physical endurance.
In contrast, the researchers also transfused blood from younger mice to older mice and found receiving young blood decreased tissue damage in the liver, kidney and muscles of old mice. Researchers then investigated whether eliminating senescent cells in aged mice could prevent the induction of senescence in young mice after blood exchange. Treatment with the senolytic drugs reduced levels of secreted factors associated with senescence in the plasma of the old mice.
Treatment with senolytics also reduced decline in liver, muscle and kidney function and reduced damage to these organs in young mice receiving old blood. And young mice receiving blood from older mice treated with senolytic drugs also showed lower levels of proteins associated with inflammation – an indication of senescence.
These experiments showed that ‘besides being caused by stress or ageing, senescence can also occur due to exposure to factors present in old blood’, noted medicalnewstoday.com.
