Electroactive nanofibrous membrane with antibacterial and deodorizing properties for air filtration.

Water vapor from respiration can severely accelerate the charge dissipation of the face mask, reducing filtration efficiency. Moreover, the foul odor from prolonged mask wear tends to make people remove their masks, leading to the risk of infection. In this study, an electro-blown spinning electroactive nanofibrous membrane (Zn/CB@PAN) with antibacterial and deodorization properties was prepared by adding zinc (Zn) and carbon black (CB) nanoparticles to the polyacrylonitrile (PAN) nanofibers, respectively. The filtration efficiency of Zn/CB@PAN for PM0.3 was > 99% and could still maintain excellent durability within 4 h in a high-humidity environment (25 â„ƒ and RH = 95%). Moreover, the bacterial interception rate of the Zn/CB@PAN could reach 99.99%, and it can kill intercepted bacteria. In addition, the deodorization rate of Zn/CB@PAN in the moist state for acetic acid was 93.75% and ammonia was 95.23%, respectively. The excellent filtering, antibacterial, and deodorizing performance of Zn/CB@PAN can be attributed to the synergistic effect of breath-induced Zn/CB galvanic couples' electroactivity, released metal ions, and generated reactive oxygen species. The developed Zn/CB@PAN could capture and kill airborne environmental pathogens under humid environments and deodorize odors from prolonged wear, holding promise for broad applications as personal protective masks.

Relative deficiency in interferon-γ-secreting CD4+ T cells is strongly associated with poorer COVID-19 vaccination responses in older adults.

Although the two-dose mRNA vaccination regime provides protection against SARS-CoV-2, older adults have been shown to exhibit poorer vaccination responses. In addition, the role of vaccine-induced T-cell responses is not well characterised. We aim to assess the impact of age on immune responses after two doses of the BNT162b2 mRNA vaccine, focussing on antigen-specific T-cells. A prospective 3-month study was conducted on 15 young (median age 31 years, interquartile range (IQR) 25-35 years) and 14 older adults (median age 72 years, IQR 70-73 years). We assessed functional, neutralising antibody responses against SARS-CoV-2 variants using ACE-2 inhibition assays, and changes in B and T-cell subsets by high-dimensional flow cytometry. Antigen-specific T-cell responses were also quantified by intracellular cytokine staining and flow cytometry. Older adults had attenuated T-helper (Th) response to vaccination, which was associated with weaker antibody responses and decreased SARS-CoV-2 neutralisation. Antigen-specific interferon-γ (IFNγ)-secreting CD4+ T-cells to wild-type and Omicron antigens increased in young adults, which was strongly positively correlated with their neutralising antibody responses. Conversely, this relationship was negative in older adults. Hence, older adults' relative IFNγ-secreting CD4+ T cell deficiency might explain their poorer COVID-19 vaccination responses. Further exploration into the aetiology is needed and would be integral in developing novel vaccination strategies and improving infection outcomes in older adults.

Deterministic reprogramming of neutrophils within tumors.

Neutrophils are increasingly recognized as key players in the tumor immune response and are associated with poor clinical outcomes. Despite recent advances characterizing the diversity of neutrophil states in cancer, common trajectories and mechanisms governing the ontogeny and relationship between these neutrophil states remain undefined. Here, we demonstrate that immature and mature neutrophils that enter tumors undergo irreversible epigenetic, transcriptional, and proteomic modifications to converge into a distinct, terminally differentiated dcTRAIL-R1+ state. Reprogrammed dcTRAIL-R1+ neutrophils predominantly localize to a glycolytic and hypoxic niche at the tumor core and exert pro-angiogenic function that favors tumor growth. We found similar trajectories in neutrophils across multiple tumor types and in humans, suggesting that targeting this program may provide a means of enhancing certain cancer immunotherapies.

Five-year outcomes of surgical aortic valve replacement with a novel bovine pericardial bioprosthesis.

OBJECTIVES: The short-term performance of the Cingular bovine pericardial aortic valve was proven. This study evaluated its 5-year safety and haemodynamic outcomes. METHODS: It enrolled 148 patients who underwent surgical aortic valve replacement with the Cingular bovine pericardial aortic valve between March 2016 and October 2017 in 5 clinical centres in China. Safety and haemodynamic outcomes were followed up to 5 years. The incidence of all-cause mortality, structural valve deterioration and reintervention was estimated by Kaplan-Meier analysis. RESULTS: The mean age of patients was 67.7 [standard deviation (SD) 5.1] years, and 36.5% of patients were female. The mean follow-up was 5.3 (SD 1.2) years. Five-year freedom from all-cause mortality, structural valve deterioration and all-cause reintervention were 91.2%, 100% and 99.3%, respectively. At 5 years, the mean gradient and effective orifice area of all sizes combined were 14.0 (SD 5.5) mmHg and 1.9 (SD 0.3) cm2, respectively. For 19- and 21-mm sizes of aortic prostheses, the mean gradients and effective orifice area at 5 years were 17.5 (SD 7.0) mmHg and 1.6 (SD 0.2) cm2 and 13.7 (SD 6.7) mmHg and 1.8 (SD 0.3) cm2, respectively. The incidence of moderate or severe patient-prosthesis mismatch was 4.1% and 0.0% patients at 5 years, respectively. CONCLUSIONS: The 5-year safety and haemodynamic outcomes of Cingular bovine pericardial aortic valve are encouraging. Longer-term follow-up is warranted to assess its true durability.

Unsupervised spatially embedded deep representation of spatial transcriptomics.

Optimal integration of transcriptomics data and associated spatial information is essential towards fully exploiting spatial transcriptomics to dissect tissue heterogeneity and map out inter-cellular communications. We present SEDR, which uses a deep autoencoder coupled with a masked self-supervised learning mechanism to construct a low-dimensional latent representation of gene expression, which is then simultaneously embedded with the corresponding spatial information through a variational graph autoencoder. SEDR achieved higher clustering performance on manually annotated 10 × Visium datasets and better scalability on high-resolution spatial transcriptomics datasets than existing methods. Additionally, we show SEDR's ability to impute and denoise gene expression (URL: https://github.com/JinmiaoChenLab/SEDR/ ).

Feasibility Study of a Novel Transapical Chordal Implantation System in a Porcine Model.

Transapical beating-heart mitral repair with chordal implantation system has been considered as an alternative treatment for degenerative mitral regurgitation. This study aimed to assess the feasibility and safety of the E-Chord system (Med-Zenith Medical, Beijing, China) for transapical beating-heart mitral valve repair in a porcine model. Artificial chordae were transapically implanted on the mitral valves of 12 anesthetized pigs under epicardial echocardiographic guidance and secured outside the left ventricular apex. The study endpoints included procedural success, device durability, and tissue response to the device. The procedural success rate was 100% (12/12). All animals were implanted with E-Chord in the anterior and posterior leaflets, respectively, and survived uneventfully until euthanized as planned. During the 180-day follow-up, no animal had significant mitral valve dysfunction. The gross observation showed no evidence of anchor detachment and chordal rupture, and there was no obvious damage or changes to mitral leaflets. Microscopic evaluation revealed that the endothelialization of anchor and chordae was completed 90 days after implantation and there was no evidence of chordal rupture, thrombosis, or infection during the 180-day follow-up. The E-Chord system was found to be feasible and safe for heart-beating mitral chordal implantation in a porcine model. The findings of this study suggest that the E-Chord system may be a potential alternative for the treatment of degenerative mitral regurgitation in humans.

Transcatheter mitral valve replacement with Mi-thos system: First-in-human experience.

BACKGROUND: Transcatheter mitral valve replacement (TMVR) has become an alternative for high-risk patients with severe mitral regurgitation (MR). The aim of this study was to evaluate the safety and feasibility of the Mi-thos TMVR system (NewMed Medical) for high-risk patients with severe MR. METHODS: This was a prospective, two-center, single-arm early feasibility study. Baseline characteristics, procedural data and 30-day follow-up outcomes were collected and analyzed. The primary endpoint was intraoperative success rate of device implantation. The second endpoints were all-cause mortality and major post-procedural complications. Echocardiographic data were evaluated by an independent core laboratory. Clinical events were adjudicated by a clinical events committee. RESULTS: Ten high-risk patients with severe MR were enrolled at two sites from August 2021 to November 2022. The median age was 70.5 years, and 60% of patients were female. The median Society of Thoracic Surgeons Predicted Risk of Mortality was 9.5%. The Mi-thos TMVR system was successfully implanted via transapical access in all patients. There was no pericedural mortality or major postpericedural complications during the 30-day follow-up. All implanted prosthetic valves had no or trace valvular or paravalvular MR, and the median mitral valve gradient at 30 days was 2.0 mmHg (IQR: 2.0-3.0 mmHg). There was one mild left ventricular outflow tract obstruction. CONCLUSIONS: The favorable short-term outcomes of the Mi-thos TMVR system demonstrated that it might be a feasible and safe therapeutic alternative for high-risk patients with severe MR. Nevertheless, further evaluation of the Mi-thos TMVR system is warranted.

Singapore's diverse immunology landscape: interconnected research networks enabling blue sky ideas through to translation.

Singapore stands as a dynamic hub for cutting-edge immunological research and innovation. The country's vibrant research ecosystem is supported by collaborative networks across the many national medical and scientific research institutes, fostering meaningful alliances between academia and industry. In this article, we speak to Assistant Professor Jinmiao Chen from the Agency for Science, Technology, and Research (A*STAR) and Professor Nicholas Gascoigne from the National University of Singapore (NUS), Duke-NUS Medical School and Nanyang Technological University (NTU) about immunology in Singapore. Credit: Kate Forbes.

Inhibition of heme oxygenase 1 alleviates thoracic aortic aneurysm via restoration of extracellular matrix.

BACKGROUND: Thoracic aortic aneurysm (TAA) is a silent but life-threatening cardiovascular disease. Heme oxygenase 1 (HO-1) plays an important role in the cardiovascular diseases but is poorly understood in TAA. This study aims at investigating the role of HO-1 in TAA. METHODS: Single-cell RNA sequencing, Western blot and histological assay were performed to identify specific cellular expression of HO-1 in both human and ß-aminopropionitrile (BAPN)-induced mice TAA. Zinc protoporphyrin (ZnPP), a pharmacological inhibitor of HO-1, was used to investigate whether inhibition of HO-1 could attenuate BAPN-induced TAA in rodent model. Histological assay, Western blot assay, and mRNA sequencing were further performed to explore the underlying mechanisms. RESULTS: Single-cell transcriptomic analyses of 113,800 thoracic aortic cells identified an increase of HO-1(+) macrophage in aneurysmal thoracic aorta from BAPN-induced TAA mice and TAA patients. Histological assay verified HO-1 overexpression in clinical TAA specimens, which was co-localized with CD68(+) macrophage. HO-1(+) macrophage was closely associated with pro-inflammatory response and immune activation. Inhibition of HO-1 through ZnPP significantly alleviated BAPN-induced TAA in mice and restored extracellular matrix (ECM) in vivo. Further experiments showed that ZnPP treatment suppressed the expression of matrix metalloproteinases (MMPs) in aneurysmal thoracic aortic tissues from BAPN-induced TAA mice, including MMP2 and MMP9. Macrophages from myeloid specific HO-1 knockout mice displayed weakened pro-inflammatory activity and ECM degradation capability. CONCLUSION: HO-1(+) macrophage subgroup is a typical hallmark of TAA. Inhibition of HO-1 through ZnPP alleviates BAPN-induced TAA in mice, which might work through restoration of ECM via suppressing MMP2 and MMP9 expression.

Oxidative stress drives vascular smooth muscle cell damage in acute Stanford type A aortic dissection through HIF-1α/HO-1 mediated ferroptosis.

Background: Acute Stanford type A aortic dissection (ATAAD) is characterized by intimal tearing and false lumen formation containing large amounts of erythrocytes with heme. Heme oxygenase 1 (HO-1) is the key enzyme to degrade heme for iron accumulation and further ferroptosis. The current study aimed at investigating the role of HO-1 in the dissection progression of ATAAD. Methods: Bioinformatic analyses and experimental validation were performed to reveal ferroptosis and HO-1 expression in ATAAD. Human aortic vascular smooth muscle cell (HA-VSMC) was used to explore underlying molecular mechanisms and the role of HO-1 overexpression in ATAAD. Results: Ferroptosis was identified as a critical manner of regulated cell death in ATAAD. HO-1 was screened as a key signature of ferroptosis in ATAAD, which was closely associated with oxidative stress. Single cell/nucleus transcriptomic analysis and histological staining revealed that HO-1 and HIF-1α were upregulated in vascular smooth muscle cell (VSMC) of ATAAD. Further in vitro experiments showed that H2O2-induced oxidative stress increased VSMC ferroptosis with the overexpression of HO-1, which could be suppressed by HIF-1α inhibitor PX-478. HIF-1α could transcriptionally regulate the expression of HO-1 through binding to its promoter region. Pharmacological inhibition of HO-1 by zinc protoporphyrin (ZnPP) did not reduce H2O2-induced HA-VSMC damage without heme co-incubation. However, H2O2-induced HA-VSMC damage was worsened when heme was added into the medium, and ZnPP could reduce HA-VSMC damage in this condition. Conclusion: HO-1 is a key signature of VSMC ferroptosis in ATAAD. HIF-1α/HO-1 mediated ferroptosis might participate in oxidative stress induced VSMC damage.

Impact of body mass index on perioperative mortality of acute stanford type A aortic dissection: a systematic review and meta-analysis.

BACKGROUND: Obesity may increase perioperative mortality of acute Stanford type A aortic dissection (ATAAD). However, the available evidence was limited. This study aimed to systematically review published literatures about body mass index (BMI) and perioperative mortality of ATAAD. METHODS: Electronic literature search was conducted in PubMed, Medline, Embase and Cochrane Library databases. All observational studies that investigated BMI and perioperative mortality of ATAAD were included. Pooled odds ratio (OR) and 95% confidence interval (CI) were calculated using a random-effects model. Meta-regression analysis was performed to assess the effects of different clinical variables on BMI and perioperative mortality of ATAAD. Sensitivity analysis was performed to determine the sources of heterogeneity. Egger's linear regression method and funnel plot were used to determine the publication bias. RESULTS: A total of 12 studies with 5,522 patients were eligible and included in this meta-analysis. Pooled analysis showed that perioperative mortality of ATAAD increased by 22% for each 1 kg/m2 increase in BMI (OR = 1.22, 95% CI: 1.10-1.35). Univariable meta-regression analysis indicated that age and female gender significantly modified the association between BMI and perioperative mortality of ATAAD in a positive manner (meta-regression on age: coefficient = 0.04, P = 0.04; meta-regression on female gender: coefficient = 0.02, P = 0.03). Neither significant heterogeneity nor publication bias were found among included studies. CONCLUSIONS: BMI is closely associated with perioperative mortality of ATAAD. Optimal perioperative management needs to be further explored and individualized for obese patient with ATAAD, especially in elderly and female populations. TRIAL REGISTRATION: PROSPERO (CRD42022358619). BMI and perioperative mortality of ATAAD.

iPS-cell-derived microglia promote brain organoid maturation via cholesterol transfer.

Microglia are specialized brain-resident macrophages that arise from primitive macrophages colonizing the embryonic brain1. Microglia contribute to multiple aspects of brain development, but their precise roles in the early human brain remain poorly understood owing to limited access to relevant tissues2-6. The generation of brain organoids from human induced pluripotent stem cells recapitulates some key features of human embryonic brain development7-10. However, current approaches do not incorporate microglia or address their role in organoid maturation11-21. Here we generated microglia-sufficient brain organoids by coculturing brain organoids with primitive-like macrophages generated from the same human induced pluripotent stem cells (iMac)22. In organoid cocultures, iMac differentiated into cells with microglia-like phenotypes and functions (iMicro) and modulated neuronal progenitor cell (NPC) differentiation, limiting NPC proliferation and promoting axonogenesis. Mechanistically, iMicro contained high levels of PLIN2+ lipid droplets that exported cholesterol and its esters, which were taken up by NPCs in the organoids. We also detected PLIN2+ lipid droplet-loaded microglia in mouse and human embryonic brains. Overall, our approach substantially advances current human brain organoid approaches by incorporating microglial cells, as illustrated by the discovery of a key pathway of lipid-mediated crosstalk between microglia and NPCs that leads to improved neurogenesis.

Analyzing COVID-19 Vaccine Responses in Transplant Recipients.

COVID-19 vaccination has significantly impacted the global pandemic by reducing the severity of infection, lowering rates of hospitalization, and reducing morbidity/mortality in healthy individuals. However, the degree of vaccine-induced protection afforded to renal transplant recipients who receive forms of maintenance immunosuppression remains poorly defined. This is particularly important when we factor in the emergence of SARS-CoV-2 variants of concern (VOCs) that have defined mutations that reduce the effectiveness of Ab responses targeting the Spike Ags from the ancestral Wuhan-Hu-1 variants employed in the most widely used vaccine formats. In this study, we describe a qualitative, longitudinal analysis of neutralizing Ab responses against multiple SARS-CoV-2 VOCs in 129 renal transplant recipients who have received three doses of the Pfizer-BioNTech COVID-19 vaccine (BNT162b2). Our results reveal a qualitative and quantitative reduction in the vaccine-induced serological response in transplant recipients versus healthy controls where only 51.9% (67 of 129) made a measurable vaccine-induced IgG response and 41.1% (53 of 129) exhibited a significant neutralizing Ab titer (based on a pseudovirus neutralization test value >50%). Analysis on the VOCs revealed strongest binding toward the wild-type Wuhan-Hu-1 and Delta variants but none with both of the Omicron variants tested (BA1 and BA2). Moreover, older transplant recipients and those who are on mycophenolic acid as part of their maintenance therapy exhibited a profound reduction in all of the analyzed vaccine-induced immune correlates. These data have important implications for how we monitor and manage transplant patients in the future as COVID-19 becomes endemic in our populations.

scNCL: transferring labels from scRNA-seq to scATAC-seq data with neighborhood contrastive regularization.

MOTIVATION: scATAC-seq has enabled chromatin accessibility landscape profiling at the single-cell level, providing opportunities for determining cell-type-specific regulation codes. However, high dimension, extreme sparsity, and large scale of scATAC-seq data have posed great challenges to cell-type identification. Thus, there has been a growing interest in leveraging the well-annotated scRNA-seq data to help annotate scATAC-seq data. However, substantial computational obstacles remain to transfer information from scRNA-seq to scATAC-seq, especially for their heterogeneous features. RESULTS: We propose a new transfer learning method, scNCL, which utilizes prior knowledge and contrastive learning to tackle the problem of heterogeneous features. Briefly, scNCL transforms scATAC-seq features into gene activity matrix based on prior knowledge. Since feature transformation can cause information loss, scNCL introduces neighborhood contrastive learning to preserve the neighborhood structure of scATAC-seq cells in raw feature space. To learn transferable latent features, scNCL uses a feature projection loss and an alignment loss to harmonize embeddings between scRNA-seq and scATAC-seq. Experiments on various datasets demonstrated that scNCL not only realizes accurate and robust label transfer for common types, but also achieves reliable detection of novel types. scNCL is also computationally efficient and scalable to million-scale datasets. Moreover, we prove scNCL can help refine cell-type annotations in existing scATAC-seq atlases. AVAILABILITY AND IMPLEMENTATION: The source code and data used in this paper can be found in https://github.com/CSUBioGroup/scNCL-release.

No Sex-Based Differences Exist in Clinical Outcomes of Extended Aortic Arch Repair for Acute Type A Aortic Dissection.

BACKGROUND: Reports regarding the association between sex and clinical outcomes after surgical repair of acute type A aortic dissection (ATAAD) are not exhaustive and in part even conflicting. METHODS: A total of 786 eligible adult patients with ATAAD undergoing extended arch repair from January 2015 to December 2021 were included. They were divided into a female group (n = 161) and a male group (n = 625). In-hospital outcomes (surgical mortality and major postoperative morbidity) and midterm outcomes (survival and aortic reintervention) between the 2 groups were compared before and after propensity score matching (1:1). RESULTS: Compared with male patients, female patients were more likely to be older (median [interquartile range]: 57 [46-67] vs 50 [42-59] years; P < 0.001) and to have a lower body mass index, but were less likely to be current smokers. Operative death occurred in 66 patients (6.8% female vs 8.8% male), without significant differences between groups before and after matching (P = 0.422 and P > 0.999, respectively). Major postoperative morbidity was observed in 313 patients (39.8%), including 57 (35.4%) female and 256 (41.0%) male patients (P = 0.199). Sex-based grouping was not significantly associated with operative mortality or major postoperative morbidity. The 5-year cumulative survival and incidence of aortic reintervention among female patients were 90.6% and 6.0%, respectively, which were not statistically different from those observed in male patients before and after matching. CONCLUSIONS: No sex-based differences were found in terms of in-hospital and midterm outcomes of extended arch repair for ATAAD.

The axis of complement C1 and nucleolus in antinuclear autoimmunity.

Antinuclear autoantibodies (ANA) are heterogeneous self-reactive antibodies that target the chromatin network, the speckled, the nucleoli, and other nuclear regions. The immunological aberration for ANA production remains partially understood, but ANA are known to be pathogenic, especially, in systemic lupus erythematosus (SLE). Most SLE patients exhibit a highly polygenic disease involving multiple organs, but in rare complement C1q, C1r, or C1s deficiencies, the disease can become largely monogenic. Increasing evidence point to intrinsic autoimmunogenicity of the nuclei. Necrotic cells release fragmented chromatins as nucleosomes and the alarmin HMGB1 is associated with the nucleosomes to activate TLRs and confer anti-chromatin autoimmunogenecity. In speckled regions, the major ANA targets Sm/RNP and SSA/Ro contain snRNAs that confer autoimmunogenecity to Sm/RNP and SSA/Ro antigens. Recently, three GAR/RGG-containing alarmins have been identified in the nucleolus that helps explain its high autoimmunogenicity. Interestingly, C1q binds to the nucleoli exposed by necrotic cells to cause protease C1r and C1s activation. C1s cleaves HMGB1 to inactive its alarmin activity. C1 proteases also degrade many nucleolar autoantigens including nucleolin, a major GAR/RGG-containing autoantigen and alarmin. It appears that the different nuclear regions are intrinsically autoimmunogenic by containing autoantigens and alarmins. However, the extracellular complement C1 complex function to dampen nuclear autoimmunogenecity by degrading these nuclear proteins.

Septuagenarians with acute type A aortic dissection undergoing extended aortic arch repair: a retrospective cohort study.

BACKGROUND: Extended arch repair in elderly patients with acute type A aortic dissection (ATAAD) remains challenging for cardiac surgeons. Data on extended arch repair for ATAAD in septuagenarians are scarce. MATERIALS AND METHODS: Consecutive adult patients with ATAAD undergoing extended arch repair from January 2015 to December 2021 were identified. According to age at presentation, 714 eligible patients were entered into either an elderly group (septuagenarians, n =65) or a control group (patients aged less than 70, n =649). Using propensity score matching, 60 pairs of patients were successfully established at a 1:1 ratio. In-hospital outcomes (operative death and major postoperative morbidity) and midterm outcomes (survival and aortic reintervention) were compared before and after matching. RESULTS: Operative death occurred in 64 patients (9.0%), including seven septuagenarians (10.8%) and 57 (8.8%) from the control group, without significant differences between groups before and after matching ( P =0.593 and 0.774, respectively). Major postoperative morbidity was observed in 298 patients (41.7%), including 29 (44.6%) in the elderly group and 269 (41.4%) in the control group ( P =0.622). Age-based grouping was not significantly associated with operative mortality or major postoperative morbidity in the crude, multivariable, and propensity score analyses. The 5-year cumulative survival and cumulative aortic reintervention rates in the elderly group were 83.5 and 4.6%, respectively, which were not statistically different from those in the control group before and after matching. CONCLUSIONS: Extended arch repair may be safely and effectively performed in septuagenarians with ATAAD, with in-hospital and midterm outcomes comparable to those obtained in patients aged less than 70 years.

Establishing a human bone marrow single cell reference atlas to study ageing and diseases.

Introduction: Ageing in the human bone marrow is associated with immune function decline that results in the elderly being vulnerable to illnesses. A comprehensive healthy bone marrow consensus atlas can serve as a reference to study the immunological changes associated with ageing, and to identify and study abnormal cell states. Methods: We collected publicly available single cell transcriptomic data of 145 healthy samples encompassing a wide spectrum of ages ranging from 2 to 84 years old to construct our human bone marrow atlas. The final atlas has 673,750 cells and 54 annotated cell types. Results: We first characterised the changes in cell population sizes with respect to age and the corresponding changes in gene expression and pathways. Overall, we found significant age-associated changes in the lymphoid lineage cells. The naïve CD8+ T cell population showed significant shrinkage with ageing while the effector/memory CD4+ T cells increased in proportion. We also found an age-correlated decline in the common lymphoid progenitor population, in line with the commonly observed myeloid skew in haematopoiesis among the elderly. We then employed our cell type-specific ageing gene signatures to develop a machine learning model that predicts the biological age of bone marrow samples, which we then applied to healthy individuals and those with blood diseases. Finally, we demonstrated how to identify abnormal cell states by mapping disease samples onto the atlas. We accurately identified abnormal plasma cells and erythroblasts in multiple myeloma samples, and abnormal cells in acute myeloid leukaemia samples. Discussion: The bone marrow is the site of haematopoiesis, a highly important bodily process. We believe that our healthy bone marrow atlas is a valuable reference for studying bone marrow processes and bone marrow-related diseases. It can be mined for novel discoveries, as well as serve as a reference scaffold for mapping samples to identify and investigate abnormal cells.