The telomereless erythrocytes and telomere-length dependent erythropoiesis

Approximately 25 trillion erythrocytes (red blood cells) circulate in the bloodstream of an adult human, surpassing the number of circulating leukocytes (white blood cells) by a factor of about 1000. Moreover, the erythrocyte turnover rate accounts for approximately 76% of the turnover rate of all circulating blood cells. This simple math shows that the hematopoietic system principally spends its telomere length-dependent replicative capacity on building and maintaining the erythrocyte blood pool. Erythropoiesis (red blood cell production) is thus the principal cause of telomere shortening with age in hematopoietic cells (HCs), a conclusion that holds significant implications for linking telomere length dynamics in HCs to health and lifespan of modern humans.

Automated summary

Approximately 25 trillion erythrocytes circulate in the bloodstream of an adult human, outnumbering leukocytes by a factor of about 1000. The turnover rate of erythrocytes accounts for approximately 76% of the turnover rate of all circulating blood cells. Therefore, erythropoiesis is the main factor causing telomere shortening in hematopoietic cells, which has significant implications for understanding the relationship between telomere length dynamics, health, and lifespan in modern humans.