Age and stress related phenotypical changes in bone marrow CD34⁺cells

Abstract

In this study, we found that the absolute and relative numbers of BM CD34(+)CD38(-) progenitor cells increase with age. The increment is attenuated in patients with AMI.

Skewed X-inactivation patterns in ageing healthy and myelodysplastic haematopoiesis determined by a pyrosequencing based transcriptional clonality assay

“…In contrast, the concept of stem cell exhaustion or senescence leading to clonal haematopoiesis of very few residual stem cells has been postulated in several studies. This hypothesis is rather inconsistent with our findings and those from others demonstrating an age-related increase of phenotypically assessable HSC numbers in healthy donors45 46 as well as polyclonal progenitor cells in steady state haematopoiesis47 and after autologous stem cell transplantation in MDS patients 48. Moreover, serial BM transplantation assays in mice demonstrated that HSC repopulation and expansion capacity exceed several lifespans 49 50…”

Stem cells and the aging hematopoietic system

“…Strikingly, and in contrast to the previously reported age-dependent decrease of CD34 + BM cells, we observed a significant age-associated increase in frequency of lineage − CD34 + CD38 − CD90 + cells (Figure 2b), a surface phenotype most rigorously used to define HSCs [28]. Consistent with these results, Taraldsrud et al recently reported a significant age-associated increase in CD34 + CD38 − bone marrow frequency [33 •• ]. Thus, counter to the prevailing view that hematopoietic stem cell frequency diminishes during aging, these results suggest that the frequency of primitive human HSCs in bone marrow increases with advancing age.…”

Epigenetic regulation of aging stem cells

“…Early reports examining changes to whole bone marrow (Ogawa et al, 2000) or a heterogeneous CD34 þ cell population (Waterstrat et al, 2008) indicated a decrease in progenitor cell frequency. However, the most recent studies of more pure cell fractions report higher numbers of primitive stem and progenitor cells with age (Taraldsrud et al, 2009;Beerman et al, 2010b). Thus, although there is currently no strong consensus in the field, studies using increasingly homogenous populations suggest an age-dependent increase in HSCs in humans and some mouse strains.…”