# Investigating hematopoietic stem cell dysfunction during sickle cell disease

> **NIH NIH R01** · ST. JUDE CHILDREN'S RESEARCH HOSPITAL · 2024 · $694,406

## Abstract

Project Summary
Chronic insults, such as inflammation and replicative stress, impair and exhaust blood-sustaining
hematopoietic stem cells (HSCs), leading to dysfunction and selection for leukemia-associated mutations. We
propose to study HSC insults in sickle cell disease (SCD), a chronic hemolytic anemia with a large
inflammatory component and increased hematopoietic demand. Hematopoietic abnormalities in SCD include
increased circulating hematopoietic stem and progenitors (HSPCs), increased numbers of BM HSPCs with
perturbed phenotypes and damage to the bone marrow (BM) niche. Older SCD patients also mobilize HSPCs
poorly and can become refractory to hydroxyurea. Mounting evidence indicates that SCD patients may have
enhanced rates of clonal hematopoiesis, as well as MDS and AML at baseline and following allogeneic HSC
transplantation or autologous HSC gene therapy. Considering that these are the only curative therapies for
SCD, it is important to better understand and prevent SCD-induced insults to HSCs and their micro-
environment. Thus, here we will examine the fitness of the HSC pool in individuals with SCD. Pilot
data reveals a dramatic loss of both phenotypic and functional HSCs in middle-aged mouse models of SCD.
HSCs in these mice also display evidence of increased cell cycling. Paradoxically, RNA-sequencing reveals
senescence-related changes in SCD HSCs. Indeed, substantially more SCD HSPCs were positive for biomarkers
of senescence in both mice and individuals with SCD, relative to age-matched controls. Based on our
preliminary findings, we hypothesize that premature senescence driven by pathologic stress
contributes to HSC dysfunction during SCD. In Aim 1 of this proposal, we will interrogate HSCs isolated
from mice with SCD for molecular and functional hallmarks of senescence using high-resolution microscopy,
single cell transcriptomics and quantitative assays for HSC function. We will also test if treating SCD mice with
drugs that eliminate senescent cells can restore function to the HSC pool. In Aim 2, we will interrogate BM
HSCs from pediatric SCD patients for molecular and functional hallmarks of senescence, relative to age-
matched controls. We will define more precisely the age of onset of damage to the HSC pool in these young
individuals with SCD using quantitative limiting dilution xenotransplantation and ex vivo single cell assays for
lineage potential. HSPCs isolated from peripheral blood before and after plerixafor-mobilization will also be
studied, as pilot studies suggest that plerixafor mobilizes senescent HSPCs in these patients. Aim 3 will focus
on investigating mechanisms that contribute to premature senescence in SCD HSCs. Here, we will employ
high-resolution microscopy, ex vivo culture, and single cell functional assays to specifically test the hypothesis
that replicative stress and hemolysis contribute directly to premature senescence in SCD HSCs. We will also
test if treatment with hemopexin, which eliminates f...

## Key facts

- **NIH application ID:** 10805470
- **Project number:** 5R01HL168893-02
- **Recipient organization:** ST. JUDE CHILDREN'S RESEARCH HOSPITAL
- **Principal Investigator:** SHANNON L MCKINNEY-FREEMAN
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $694,406
- **Award type:** 5
- **Project period:** 2023-04-01 → 2027-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10805470

## Citation

> US National Institutes of Health, RePORTER application 10805470, Investigating hematopoietic stem cell dysfunction during sickle cell disease (5R01HL168893-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10805470. Licensed CC0.

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