Hematopoietic stem cell size heterogeneity is not linked to changes in stem cell potential of aged HSCs

Aging is associated with a decline in the function of hematopoietic stem cells (HSCs). This decline in HSC function results in reduced hematologic regenerative capacity and an increased incidence of hematologic disorders. In general, aged HSCs show on average an increase in cell size and a lower fre...

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Main Authors: Mehmet Saçma, Ali Hageb, Alex Zadro, Tanja Schuster, Mona Vogel, Karina Eiwen, Vadim Sakk, Hartmut Geiger
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-05-01
Series:Frontiers in Aging
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Online Access:https://www.frontiersin.org/articles/10.3389/fragi.2025.1596565/full
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author Mehmet Saçma
Ali Hageb
Alex Zadro
Tanja Schuster
Mona Vogel
Karina Eiwen
Vadim Sakk
Hartmut Geiger
Hartmut Geiger
author_facet Mehmet Saçma
Ali Hageb
Alex Zadro
Tanja Schuster
Mona Vogel
Karina Eiwen
Vadim Sakk
Hartmut Geiger
Hartmut Geiger
author_sort Mehmet Saçma
collection DOAJ
description Aging is associated with a decline in the function of hematopoietic stem cells (HSCs). This decline in HSC function results in reduced hematologic regenerative capacity and an increased incidence of hematologic disorders. In general, aged HSCs show on average an increase in cell size and a lower frequency of cells polar for protein polarity markers. The size of an HSCs has been proposed to be tightly linked to the potential of the HSCs, with small HSCs showing a higher potential compared to large HSCs. The increase in size of HSCs upon aging may be associated with the reduced potential of aged HSCs. HSCs are located within the bone marrow (BM) in distinct microenvironments called niches. These niches provide critical physical and molecular signals that are essential for HSC self-renewal, proliferation, migration and differentiation. There are multiple types of functional niches, and HSCs within these distinct types of niches show a distinct type of potential. Furthermore, the distribution of HSCs relative to niches changes upon aging. It is not known whether there is a correlation of HSCs size, HSCs polarity and the location of HSCs in distinct types of niches, as might be expected, as all three (size, polarity and position) have been linked to HSC potential. Here we show that in young mice smaller HSCs, which are more myeloid-biased, are preferentially located at central BM niches, including sinusoids and megakaryocytes. In contrast, larger HSCs, which show a bias toward B-lymphoid differentiation, are preferentially located in endosteal BM niches close to arterioles. However, in aged mice, which also contain HSCs of different sizes, there was no correlation between HSC size and localization and potential. Furthermore, within the hematopoietic stem and progenitor cell (HSPC) population, cell size increases as the cells become more limited in their capacity. Notably, we further report that changes in the level of polarity correlate with HSC potential even in aged mice.
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spelling doaj-art-d8f36e41479e4769b0c77ef35a3fa49c2025-08-20T02:33:11ZengFrontiers Media S.A.Frontiers in Aging2673-62172025-05-01610.3389/fragi.2025.15965651596565Hematopoietic stem cell size heterogeneity is not linked to changes in stem cell potential of aged HSCsMehmet Saçma0Ali Hageb1Alex Zadro2Tanja Schuster3Mona Vogel4Karina Eiwen5Vadim Sakk6Hartmut Geiger7Hartmut Geiger8Institute of Molecular Medicine, Ulm University, Ulm, GermanyInstitute of Molecular Medicine, Ulm University, Ulm, GermanyInstitute of Molecular Medicine, Ulm University, Ulm, GermanyInstitute of Molecular Medicine, Ulm University, Ulm, GermanyInstitute of Molecular Medicine, Ulm University, Ulm, GermanyInstitute of Molecular Medicine, Ulm University, Ulm, GermanyInstitute of Molecular Medicine, Ulm University, Ulm, GermanyInstitute of Molecular Medicine, Ulm University, Ulm, GermanyAging Research Center (ARC), Ulm University, Ulm, GermanyAging is associated with a decline in the function of hematopoietic stem cells (HSCs). This decline in HSC function results in reduced hematologic regenerative capacity and an increased incidence of hematologic disorders. In general, aged HSCs show on average an increase in cell size and a lower frequency of cells polar for protein polarity markers. The size of an HSCs has been proposed to be tightly linked to the potential of the HSCs, with small HSCs showing a higher potential compared to large HSCs. The increase in size of HSCs upon aging may be associated with the reduced potential of aged HSCs. HSCs are located within the bone marrow (BM) in distinct microenvironments called niches. These niches provide critical physical and molecular signals that are essential for HSC self-renewal, proliferation, migration and differentiation. There are multiple types of functional niches, and HSCs within these distinct types of niches show a distinct type of potential. Furthermore, the distribution of HSCs relative to niches changes upon aging. It is not known whether there is a correlation of HSCs size, HSCs polarity and the location of HSCs in distinct types of niches, as might be expected, as all three (size, polarity and position) have been linked to HSC potential. Here we show that in young mice smaller HSCs, which are more myeloid-biased, are preferentially located at central BM niches, including sinusoids and megakaryocytes. In contrast, larger HSCs, which show a bias toward B-lymphoid differentiation, are preferentially located in endosteal BM niches close to arterioles. However, in aged mice, which also contain HSCs of different sizes, there was no correlation between HSC size and localization and potential. Furthermore, within the hematopoietic stem and progenitor cell (HSPC) population, cell size increases as the cells become more limited in their capacity. Notably, we further report that changes in the level of polarity correlate with HSC potential even in aged mice.https://www.frontiersin.org/articles/10.3389/fragi.2025.1596565/fullhematopoietic stem cellsagingbone marrow nichescell size and functionregenerative potentialstem cell polarity
spellingShingle Mehmet Saçma
Ali Hageb
Alex Zadro
Tanja Schuster
Mona Vogel
Karina Eiwen
Vadim Sakk
Hartmut Geiger
Hartmut Geiger
Hematopoietic stem cell size heterogeneity is not linked to changes in stem cell potential of aged HSCs
Frontiers in Aging
hematopoietic stem cells
aging
bone marrow niches
cell size and function
regenerative potential
stem cell polarity
title Hematopoietic stem cell size heterogeneity is not linked to changes in stem cell potential of aged HSCs
title_full Hematopoietic stem cell size heterogeneity is not linked to changes in stem cell potential of aged HSCs
title_fullStr Hematopoietic stem cell size heterogeneity is not linked to changes in stem cell potential of aged HSCs
title_full_unstemmed Hematopoietic stem cell size heterogeneity is not linked to changes in stem cell potential of aged HSCs
title_short Hematopoietic stem cell size heterogeneity is not linked to changes in stem cell potential of aged HSCs
title_sort hematopoietic stem cell size heterogeneity is not linked to changes in stem cell potential of aged hscs
topic hematopoietic stem cells
aging
bone marrow niches
cell size and function
regenerative potential
stem cell polarity
url https://www.frontiersin.org/articles/10.3389/fragi.2025.1596565/full
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