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Clonal Hematopoiesis Landscape in Frequent Blood Donors

ABSTRACT: Donor blood saves lives, yet the potential impact of recurrent large-volume phlebotomy on donor health and hematopoietic stem cells (HSCs) remains largely unexplored. In our study, we conducted a comprehensive screening of 217 older male volunteer donors with a history of extensive blood donation (>100 life-time donations) to investigate the phenomenon of clonal hematopoiesis (CH). No significant difference in the overall incidence of CH was found in frequent donors (FD) compared to sporadic donors (<10 life-time donations, 212 donors). However, upon deeper analysis of mutations in DNMT3A, the most commonly affected gene in CH, we observed distinct mutational patterns between the FD and age/sex matched control donor (CD) cohorts. Functional analysis of FD enriched DNMT3A variants examined in CRISPR-edited human HSCs demonstrated their competitive outgrowth potential upon stimulation with erythropoietin (EPO), a hormone which increases in response to blood loss. In contrast, clones harboring leukemogenic DNMT3A R882 mutations increase upon stimulation with IFNy. Through concurrent mutational and immunophenotypic profiling of primary samples at single cell resolution, a myeloid bias of premalignant R882 mutant HSCs was found, while no significant lineage bias was observed in HSCs harboring EPO responsive DNMT3A variants. The latter exhibited preferential erythroid differentiation when persistent erythropoietic stress was applied to CRISPR-edited human HSC xenografts. Our data demonstrate a nuanced ongoing Darwinian evolution at the somatic stem cell level, with EPO identified as a novel environmental factor that favors HSCs carrying certain DNMT3A mutations.

ORGANISM(S): Homo sapiens

PROVIDER: GSE290292 | GEO | 2025/02/28

REPOSITORIES: GEO

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Project description:Hematopoietic stem cells (HSCs) with certain somatic mutations, most commonly in the DNA methyltransferase DNMT3A, gain a clonal growth advantage leading to the development of clonal hematopoiesis (CH). The distinct functional differences that allow DNMT3A-mutant HSCs to gain a fitness advantage and outcompete wild-type HSC in the context of aging are not fully elucidated. We recently discovered that HSC aging is initiated by decline in local production of insulin-like growth factor 1 (IGF1). Here, we used a mouse model of DNMT3A-mutant CH (Dnmt3aR878H/+) to investigate the extent to which decline in IGF1 alters the selective advantage of Dnmt3aR878H/+ HSCs. Upon transplant into IGF1-deficient recipient mice, Dnmt3aR878H/+ HSCs gained enhanced selective advantage over wild-type HSCs and maintained lineage balanced blood production. As IGF1/mTOR signaling is well understood to regulate energy metabolism, we investigated underlying metabolic differences between Dnmt3aR878H/+ and wild-type HSCs. Dnmt3aR878H/+ HSPCs had similar glycolytic capacity as wild-type HSCs but enhanced mitochondrial reserve capacity and mitochondrial activation potential. To evaluate whether mitochondrial function is a targetable dependency of Dnmt3aR878H/+ HSCs, we administered the mitochondrial-targeted molecule MitoQ resulting in the depletion of their mitochondrial reserve capacity. We find that MitoQ reduces the competitive advantage of Dnmt3aR878H/+ hematopoiesis. To identify the mechanism(s) by which MitoQ alters Dnmt3aR878H/+ phenotypic expansion we evaluated transcriptional changes after MitoQ treatment and find altered response to Igf1/mTOR signaling compared to wild-type HSC. The altered response to Igf1/mTOR signaling in part mediates the Dnmt3aR878H/+ hematopoietic selective advantage. Taken together, our work supports that mitochondrial metabolic regulation is a key mechanism by which DNMT3A-mutant HSCs gain a selective advantage. Targeting this mechanism may maintain polyclonal hematopoiesis during aging and reduce the risk of CH-associated disease.