bims-scepro Biomed News
on Stem cell proteostasis
Issue of 2026–05–31
twelve papers selected by
William Grey, University of York



  1. Blood. 2026 May 26. pii: blood.2025032136. [Epub ahead of print]
      Understanding how metabolism governs human hematopoietic stem cells (HSCs) function is essential for advancing regenerative therapies, yet direct metabolic profiling of human HSCs has been limited by their extreme scarcity and the technical limitations of conventional methods. Here, we apply a low-input mass spectrometry-based metabolomics platform, optimized for rare cell populations, to generate metabolic profiles of 13 immunophenotypically defined hematopoietic cell types from adult human bone marrow. Using as few as ~10,000 cells per sample, we detect over 80 metabolites and uncover both conserved metabolic programs in primitive hematopoietic stem and progenitor cells (HSPCs) and lineage-specific metabolic specializations. Notably, we identify L-carnitine-driven fatty acid oxidation (FAO) as a key metabolic feature supporting HSPC function. Mechanistically, L-carnitine activates the PPARA-TFEB signalling axis, promoting mitochondrial metabolism and autophagy to preserve regenerative capacity. Functional assays in primary CD34+ HSPCs derived from healthy donors or patients with aplastic anemia confirm that L-carnitine supplementation improves stem cell function ex vivo and in vivo. Together, this work provides a foundation for human hematopoietic metabolism and reveals a targetable metabolic circuit governing HSPC regenerative fitness with therapeutic potential for improving stem cell-based interventions.
    DOI:  https://doi.org/10.1182/blood.2025032136
  2. Nature. 2026 May 27.
      Inflammation activates blood cells, contributing to ageing and malignancy1-3. Haematopoietic stem cells (HSCs) survive a lifetime of infection to sustain life-long haematopoiesis1-9, but how human HSCs respond and adapt to inflammatory stress is largely unknown. Here, to empirically understand this adaptation, we developed xenograft inflammation-recovery models and performed single-cell multiomics on xenografted human HSCs. Two transcriptionally and epigenetically distinct HSC subsets were identified with one, termed HSC inflammatory memory (HSC-iM), retaining a molecular memory of previous inflammatory treatments. The HSC-iM subset exhibited quiescence and restrained haematopoietic output. Molecularly, the HSC-iM program was enriched in HSCs from adult and paediatric samples across conditions ranging from COVID-19 recovery, sickle cell disease, ageing and clonal haematopoiesis, establishing both the validity of our xenograft models and the physiological relevance of HSC-iM. Clonal haematopoiesis mutations in HSC-iM attenuated the effects of inflammatory stress by promoting HSC activation and differentiation. Moreover, transmission of the pro-inflammatory HSC-iM transcriptional program to differentiated immune progeny was demonstrated in xenograft and physiological settings. Finally, HSC-iM program enrichment in circulating blood cells was associated with a heightened risk score for all-cause mortality in population cohort analyses, underscoring the clinical relevance of this newly identified HSC subset in characterizing heterogeneous health outcomes across a lifetime.
    DOI:  https://doi.org/10.1038/s41586-026-10522-7
  3. Blood Adv. 2026 May 27. pii: bloodadvances.2025018449. [Epub ahead of print]
      While megakaryocytes (MKs) are essential for hemostasis, vascular integrity, and hematopoietic stem and progenitor cells (HSPCs) support, their role in bone marrow (BM) recovery has remained underexplored. Here, using a 5-fluorouracil (5-FU) injury model, we identify a transient, intramedullary space enriched in extracellular matrix (ECM) proteins such as perlecan, von Willebrand factor (vWF), and heparanase, and functionally responsive GPIbα⁺ platelet particles (termed preplatelets). During 5-FU-induced injury, this compartment undergoes dynamic changes, and its resolution depends on the presence of functional preplatelets and ECM components. Consistent with this, platelet depletion further delays restoration of the intramedullary space despite preserved MK numbers, supporting a critical local role for nascent platelets during 5-FU-induced injury. Furthermore, mice lacking the β-1,4-galactosyltransferase 1 (B4GALT1) develop persistent thrombocytopenia, exhibit mislocalized and morphologically abnormal MKs, and display expansion of MK-biased HSPCs upon 5-FU injury, collectively leading to delayed hematopoietic recovery and expansion of the BM intramedullary space. Single cell transcriptomic analysis of B4GALT1⁻/⁻ MK-biased HSPCs at steady state further revealed disruption of adhesion, cytoskeletal, and Notch1-associated programs required for proplatelet formation and MK interactions with ECM components. Our findings reveal a previously unrecognized role for locally retained platelet intermediates and identify B4GALT1-dependent glycosylation as a key regulator of megakaryocyte integrity, platelet production and hematopoietic recovery after 5-FU-induced myeloablation.
    DOI:  https://doi.org/10.1182/bloodadvances.2025018449
  4. Mol Ther. 2026 May 26. pii: S1525-0016(26)00401-6. [Epub ahead of print]
      Ex vivo expansion of mobilized peripheral blood (mPB) hematopoietic stem cells (HSCs) represents a promising approach to advance cell and gene therapy strategies yet is hampered by loss of stem cell function when applying commonly used culture protocols. We performed in-depth characterization of mPB expansion cultures by single cell RNA sequencing, which highlighted differentiation trajectories with preservation of lineage fidelity in committed progenitors. Defining a putative HSC cluster allowed an estimation of transduction efficiency in ex vivo cultures, which correlated with long-term gene marking in xenografts and patients enrolled in a gene therapy study. We then developed a clinically translatable, GMP-compliant process to expand lentivirus (LV)-transduced HSCs from mPB of pediatric patients and adult donors, by biologically informed protocol improvements of cytokine supplementation, media choice, timing of LV transduction and combinations of small molecules preventing the activation of differentiation programs. Our optimized process outperforms validated state-of-the-art cord blood expansion protocols when applied to mPB. LV integration site analysis and genomic barcode-based clonal tracking provided definitive proof for symmetric HSC self-renewal divisions occurring during ex vivo culture. These results warrant clinical testing of this HSC transduction/expansion process in an upcoming clinical gene therapy trial for autosomal recessive osteopetrosis (EU CT 2024-518972-30).
    DOI:  https://doi.org/10.1016/j.ymthe.2026.05.014
  5. Immunity. 2026 May 29. pii: S1074-7613(26)00180-9. [Epub ahead of print]
      Chronic inflammation and aging skew hematopoiesis toward myelopoiesis at the expense of lymphoid output. We screened type 2 and anti-inflammatory cytokines to identify extrinsic signals capable of restoring lymphoid lineage commitment in hematopoietic stem and progenitor cells (HSPCs). Interleukin 4 (IL-4) specifically inhibited inflammation-induced myelopoiesis and shifted multipotent progenitor (MPP) differentiation toward the lymphoid lineage. IL-4 activated a signal transducer and activator of transcription 6 (STAT6)-dependent transcriptional program in MPPs, increasing the expression of lymphoid-specific genes. Mechanistically, the receptor tyrosine kinase FMS-like tyrosine kinase 3 (FLT3), which is highly expressed in MPPs, interacted with IL-4Rα to facilitate STAT6 activation. In vivo, IL-4 reversed inflammation-induced hematopoietic imbalance and accelerated lymphoid recovery. In aged mice, IL-4 administration shifted the MPP composition toward a lymphoid bias and restored B and T lymphocyte output. Long-term IL-4 treatment in aged mice improved immune, metabolic, physical, and cognitive functions; these rejuvenating effects were recapitulated by transplantation of IL-4-treated HSPCs. Promoting IL-4 signaling in MPPs may enable correction of hematopoietic dysregulation in inflammatory and aging-related conditions.
    Keywords:  FLT3; IL-4 signaling; MPP; aging; hematopoiesis; inflammaging
    DOI:  https://doi.org/10.1016/j.immuni.2026.04.018
  6. Nat Cell Biol. 2026 May 25.
      Haematopoietic stem cells (HSCs) display extensive molecular and functional heterogeneity. However, a cohesive model that explains the relationship and biological relevance of these diverse HSC states remains elusive. Here, by performing single-cell transplantations of over 1,000 highly purified murine long-term HSCs combined with in-depth phenotyping of their clonal progeny, we define kinetics-based reconstitution parameters which aligned HSCs into a single hierarchical trajectory reflective of functional potency. This approach revealed that previously identified lineage biases are actually transitory states along this linear trajectory, not a discrete stable condition. Single-cell secondary transplantations validated hierarchical ordering based on reconstitution kinetics, whereas mathematical modelling combined with experimental modulation of lineage-biased blood production revealed that apparent lineage-biased outputs actually arise from cell-extrinsic feedback regulation and clonal competition between slow- and fast-engrafting clones to fill mature lineages to their compartment size limit. This study reconciles multiple layers of HSC heterogeneity into a unifying framework.
    DOI:  https://doi.org/10.1038/s41556-026-01958-0
  7. Blood. 2026 May 29. pii: blood.2025028877. [Epub ahead of print]
      Infant ALL (iALL) is initiated in utero, most often by rearrangement of the KMT2A gene (KMT2Ar). It carries a very poor prognosis despite a lack of additional oncogenic driver mutations common in childhood ALL. Here, we aimed to identify specific properties of human fetal hematopoietic stem/progenitor cells (HSPC) that promote leukemic transformation in KMT2Ar iALL using molecular, functional and in vivo assays. Through comparison of human fetal HSPC with adult HSPC transcriptomes we derived a fetal-specific gene signature and identified the fetal oncogene LIN28B and its downstream effectors among the top hits. These genes were also expressed in iALL. Functional assays revealed that LIN28B was essential in human fetal liver (FL) CD34+ cells to maintain proliferation and stem-like properties, and support B- and NK-lymphopoiesis. To interrogate the role of LIN28B in iALL, we utilized a human FL-derived CRISPR-Cas9 KMT2A::AFF1 model. In this CRISPRKMT2A::AFF1 model, human FL CD34+ cells fail to transform upon induction of KMT2A::AFF1 translocation in the absence of LIN28B. Furthermore, LIN28B-expressing CRISPRKMT2A::AFF1 leukemias were more proliferative in vitro and in vivo, with this advantage being lost upon LIN28B knockdown. Mechanistic studies showed that LIN28B acts by stabilizing key early B-lymphoid genes, epigenetic regulators, and cell cycle and anti-apoptotic genes. Thus, LIN28B has an essential role in normal human fetal B-lymphopoiesis, and is necessary for the initiation of KMT2A::AFF1 iALL in human fetal cells in the absence of co-operating mutations. LIN28B activity may help explain why KMT2A::AFF1 leukemias are so aggressive, making it a potential target in LIN28B-expressing leukemias.
    DOI:  https://doi.org/10.1182/blood.2025028877
  8. Mater Today Bio. 2026 Jun;38 103260
      Acute myeloid leukemia (AML) is characterized by uncontrolled malignant clonal proliferation of leukemic cells resulting from the blockade of myeloid hematopoietic stem/progenitor cell differentiation. The disease-causing fusion protein AML1-ETO (also known as RUNX1-ETO or RUNX1-RUNX1T1) and the chemokine (C-X-C motif) receptor 4 (CXCR4) have been recognized as crucial effectors. Strategies targeting each individual factor have been applied to develop new therapeutic approaches; however, clinical demands remain unmet, and much is still unknown about the crosstalk between the two factors. In this study, we utilized a lipid nanoparticle platform to carry AML1-ETO siRNA and the CXCR4 antagonistic peptide E5 (E5-LNP@siAE) to simultaneously deplete the fusion protein and inhibit CXCR4 activation, aiming to elucidate the crosstalk between the two factors and to develop a novel dual-functional therapeutic approach based on lipid nanoparticles. The resulting nanoparticles were investigated in a refractory AML mouse model (AML1-ETO & C-KITD816V) with a high level of CXCR4 and in the t(8; 21)-positive AML cell line Kasumi-1. It was shown that E5-LNP@siAE effectively achieved RNAi of AML1-ETO and antagonism of CXCR4, thereby synergistically inducing effective multi-lineage differentiation, leading to significantly enhanced differentiation-post apoptotic responses of AML cells to homoharringtonine and remarkably prolonged survival in refractory AML mice.
    Keywords:  Antagonistic peptide; CXCR4; Fusion protein AML1-ETO; Leukemia; Lipid nanoparticles
    DOI:  https://doi.org/10.1016/j.mtbio.2026.103260
  9. Hum Pathol. 2026 May 27. pii: S0046-8177(26)00143-7. [Epub ahead of print] 106174
      Acute myeloid leukemia (AML) is an aggressive hematologic malignancy characterized by clonal expansion of myeloid precursor cells. The pathologic evaluation of AML integrates multiple levels of characterization, including morphology of cells circulating in peripheral blood and bone marrow, identification of blast lineage by immunohistochemistry and flow cytometry immunophenotyping, and genetic studies including karyotype, fluorescence in-situ hybridization, and next generation sequencing (NGS). NGS analysis is utilized routinely to define the mutational landscape of AML, which informs risk stratification and choice of therapy. However, the current methods of immunophenotypic classification in clinical practice use a relatively small number of surface markers to coarsely determine hematopoietic lineage, and bulk sequencing approaches are largely unable to accurately capture clonal complexity, resolve mutational order, and distinguish residual leukemia from clonal hematopoiesis. Single-cell sequencing techniques have transformed our understanding of normal and malignant hematopoiesis by moving beyond the classical hematopoietic hierarchy to define transitional cell states, thereby unraveling clonal complexity with unprecedented resolution. Single-cell multi-omic approaches that span genomics, transcriptomics, proteomics, epigenomics, and metabolomics have the potential to unravel the vast disease heterogeneity in AML, address the discordance between genetic subtypes and functional phenotypes, and improve risk stratification. The latest frontier, spatial single-cell techniques apply these multi-omic approaches to study cells in situ, offering new insights into the bone marrow microenvironment. Here, we review how single cell sequencing technologies have been utilized to study AML throughout the course of disease, including initial diagnosis, assessment of measurable residual disease in remission, and clonal evolution at relapse, and we look ahead to future applications that may impact clinical practice.
    Keywords:  Acute myeloid leukemia; Clonal evolution; Single cell sequencing
    DOI:  https://doi.org/10.1016/j.humpath.2026.106174
  10. Nat Chem Biol. 2026 May 28.
      Interferon regulatory factor 4 (IRF4) is an oncogenic transcription factor (TF) in several hematological malignancies. To date, no pharmacological agents have been developed specifically for IRF4 due to the challenging nature of targeting TFs. Here we first identified (S)-H1, a binder of IRF4, by targeting the SPI1-IRF4 interaction on IRF4's interferon association domain via high-throughput screening. Next, we successfully turned our binder into dIRF4-2, a first-in-class proteolysis-targeting chimera of IRF4, by linking (S)-H1 to E3 ligase ligands of cereblon. dIRF4-2 can induce highly selective proteasomal degradation of IRF4 and has strong cytotoxic effects in all multiple myeloma lines evaluated in vitro. Our study showcases methodology to effectively target the IRF family of TFs and illustrates how to convert an inert binder into a powerful chemical probe for studying the functions of important oncoproteins that are structurally difficult to target.
    DOI:  https://doi.org/10.1038/s41589-026-02228-8
  11. Blood. 2026 May 26. pii: blood.2025031268. [Epub ahead of print]
      IDH1 and IDH2 are frequently mutated in various cancers, including acute leukemias. However, the distinct mechanisms by which mutant IDH1 or IDH2 drive hematopoietic neoplasms remain poorly understood. Here, we analyzed DNA methylation in IDH1- and IDH2-mutant AML and found neutrophil lineage-specific epigenetic alterations in IDH1-mutant cases that went along with severely impaired neutrophil differentiation. Transcriptional analysis of normal hematopoiesis in humans and mice revealed a strong physiological upregulation of IDH1/Idh1 in myeloid progenitors. To study the functional effects of Idh1 mutations on hematopoiesis in a pre-leukemic setting, we used a genetically engineered inducible mouse model expressing a heterozygous Idh1 mutation under control of the endogenous promotor. Our study revealed a cell-intrinsic block in neutrophil differentiation caused by repression of myeloid transcription programs in neutrophil progenitors. This included impaired expression of Cebpe, which encodes a key transcription factor regulating neutrophil differentiation. Reactivation of Cebpe expression, by overexpression of its upstream regulator Cebpa or following treatment with hypomethylating agents restored differentiation, indicating that the differentiation block is reversible.In summary, we found a reversible, pre-leukemic impairment of neutrophil differentiation in IDH1-mutant hematopoiesis that correlates with elevated IDH1 expression in myeloid progenitors and likely explains the strong association of IDH1 mutations with myeloid neoplasms.
    DOI:  https://doi.org/10.1182/blood.2025031268
  12. J Genet Genomics. 2026 May 22. pii: S1673-8527(26)00182-7. [Epub ahead of print]
      Stem cells reside in specific microenvironments where they divide to maintain themselves and differentiate into functional cells that replace old, dead, or damaged cells to maintain tissue homeostasis. Some stem cells could also be cultured in vitro for self-renewal and directed differentiation towards specific lineages for both mechanistic interrogation and clinic investigation. A deeper understanding of the regulatory mechanisms underlying stem cell properties is essential for advancing their translational applications. Deep learning (DL), a branch of artificial intelligence, has been widely and deeply incorporated into different fields including biology. The application of DL in stem cells has revolutionized our research strategies and provided significant technical advantages. Here, we review the latest advances of the application of DL in analyzing bioimaging data and exploring large-scale genomics data in stem cells. We also summarize the limitations of current DL models and challenges of the application of these models in stem cell research.
    Keywords:  Deep learning; Regulatory mechanism; Stem cell imaging; Stem cell omics; Stem cells
    DOI:  https://doi.org/10.1016/j.jgg.2026.05.008