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World J Stem Cells. Jun 26, 2021; 13(6): 594-604
Published online Jun 26, 2021. doi: 10.4252/wjsc.v13.i6.594
Growing and aging of hematopoietic stem cells
Ion Udroiu, Antonella Sgura
Ion Udroiu, Antonella Sgura, Department of Science, Roma Tre University, Rome 00146, Italy
Author contributions: All authors equally contributed to this paper with conception, literature review and analysis, manuscript drafting, critical revision, and editing, and approval of the final version.
Conflict-of-interest statement: No potential conflicts of interest exist.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Ion Udroiu, PhD, Research Fellow, Department of Science, Roma Tre University, Viale G. Marconi 446, Rome 00146, Italy. ion.udroiu@uniroma3.it
Received: November 20, 2020
Peer-review started: November 20, 2020
First decision: December 21, 2020
Revised: December 22, 2020
Accepted: February 1, 2021
Article in press: February 1, 2021
Published online: June 26, 2021
Abstract

In the hematopoietic system, a small number of stem cells produce a progeny of several distinct lineages. During ontogeny, they arise in the aorta-gonad-mesonephros region of the embryo and the placenta, afterwards colonise the liver and finally the bone marrow. After this fetal phase of rapid expansion, the number of hematopoietic stem cells continues to grow, in order to sustain the increasing blood volume of the developing newborn, and eventually reaches a steady-state. The kinetics of this growth are mirrored by the rates of telomere shortening in leukocytes. During adulthood, hematopoietic stem cells undergo a very small number of cell divisions. Nonetheless, they are subjected to aging, eventually reducing their potential to produce differentiated progeny. The causal relationships between telomere shortening, DNA damage, epigenetic changes, and aging have still to be elucidated.

Keywords: Bone marrow, Fetus, Growth and development, Hematopoietic stem cells, Leukemia, Liver

Core Tip: During ontogeny, hematopoietic stem cells undergo a fetal and neonatal phase of rapid expansion. The kinetics of this growth are mirrored by the rates of telomere shortening in leukocytes. During adulthood, hematopoietic stem cells undergo a very small number of cell divisions. Nonetheless, they are subjected to aging, eventually reducing their potential to produce differentiated progeny.