Lentiviral vector (LV)-mediated ex vivo gene therapy for haematopoietic stem and progenitor cells (HSPCs) has delivered on the promise of a 'one-and-done' treatment for several genetic diseases1. However, ex vivo manipulation and patient conditioning before transplantation are major hurdles that could be overcome by an in vivo approach. Here we demonstrate that in vivo gene delivery to HSPCs after systemic LV administration is enabled by the substantial trafficking of these cells from the liver to the bone marrow in newborn mice. We improved gene-transfer efficiency using a phagocytosis-shielded LV, successfully reaching bona fide HSPCs capable of long-term multilineage output and engraftment after serial transplantation, as confirmed by clonal tracking. HSPC mobilization further increased gene transfer, extending the window of intervention, although permissiveness to LV transduction declined with age. We successfully tested this in vivo strategy in mouse models of adenosine deaminase deficiency, autosomal recessive osteopetrosis and Fanconi anaemia. Interestingly, in vivo gene transfer provided a selective advantage to corrected HSPCs in Fanconi anaemia, leading to near-complete haematopoietic reconstitution and prevention of bone marrow failure. Given that circulating HSPCs in humans are also most abundant shortly after birth, in vivo HSPC gene transfer holds strong translational potential across multiple diseases.
© 2025. The Author(s).

Homozygous knockout of scavenger receptor class B type I (SR-B1) in mice with atherogenic mutations (such as knockout of the apolipoprotein E or low density lipoprotein receptor genes) results in spontaneous or diet-induced coronary heart disease characterized by atherosclerosis development in the aortic sinus and coronary arteries, platelet accumulation in coronary artery plaques, myocardial fibrosis, and early death. However, the extent of coronary artery atherothrombosis and myocardial fibrosis in mice lacking SR-B1 alone (homozygous SR-B1 knockout mice) has not been examined. Although age is a major risk factor for coronary artery disease, few studies directly examine the effects of age on susceptibility to atherosclerosis or coronary artery atherothrombosis and myocardial fibrosis in mice. Therefore, we set out to examine the effects of age on diet-induced atherosclerosis in female homozygous SR-B1 knockout mice.
SR-B1 knockout mice exhibited little-to-no aortic sinus or coronary artery atherosclerosis at 52 weeks of age, when fed a normal diet. However when fed a high-fat, high-cholesterol, cholate-containing (HFCC) diet for 12 weeks from either 14 weeks of age (26-week-old at analysis) or 40 weeks of age (52-week-old at analysis), they developed similar degrees of atherosclerosis in their aortic sinuses. Interestingly, the older aged SR-B1 knockout mice exhibited increased coronary artery atherosclerosis, increased vascular cell adhesion molecule 1 levels and platelet accumulation in coronary arteries, and increased myocardial fibrosis and plasma levels of cardiac troponin I compared to the younger aged mice. Older-aged HFCC diet-fed SR-B1 knockout mice also exhibited reduced survival to humane endpoint. Moreover, older-aged HFCC diet-fed SR-B1 knockout mice exhibited a greater inflammatory state with increased levels of circulating interleukin-6, tumour necrosis factor alpha, and neutrophils, despite plasma lipid levels being unchanged. Consistent with the increased circulating neutrophils, older-aged HFCC diet-fed SR-B1 knockout mice exhibited increased accumulation of the neutrophil marker myeloperoxidase and increased neutrophil extracellular traps in atherosclerotic plaques in the aortic sinus and increased abundance of atherosclerotic coronary arteries containing neutrophil extracellular traps.
HFCC diet-fed homozygous SR-B1 knockout mice develop occlusive coronary artery atherothrombosis and myocardial fibrosis in an age-dependent manner, and exhibit an increased inflammatory state with older age. Therefore, aged SR-B1 knockout mice may prove to be an attractive mouse model to analyze age-dependent mechanisms associated with coronary artery disease development, which may facilitate the discovery of more effective therapeutics to treat cardiovascular disease.
Copyright: © 2025 Lee et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Anti-programmed death 1 (αPD1) immune checkpoint blockade is used in combination for cancer treatment but associated with cardiovascular toxicity. Leflunomide (Lef) can suppress the growth of several tumor and mitigate cardiac remodeling in mice. However, the role of Lef in αPD1-induced cardiotoxicity remains unclear. Here, we report that Lef treatment inhibits αPD1-related cardiotoxicity without compromising the efficacy of αPD1-mediated immunotherapy. Lef changes community structure of gut microbiota in αPD1-treated melanoma-bearing mice. Moreover, mice receiving microbiota transplants from Lef+αPD1-treated melanoma-bearing mice have better cardiac function compared to mice receiving transplants from αPD1-treated mice. Mechanistically, we analyze metabolomics and identify indole-3-propionic acid (IPA), which protects cardiac dysfunction in αPD1-treated mice. IPA can directly bind to the aryl hydrocarbon receptor and promote phosphoinositide 3-kinase expression, thus curtailing the cardiomyocyte response to immune injury. Our findings reveal that Lef mitigates αPD1-induced cardiac toxicity in melanoma-bearing mice through modulation of the microbiota-IPA-heart axis.
© 2025. The Author(s).

The role of somatic mitochondrial DNA (mtDNA) mutations in leukemogenesis remains poorly characterized. To determine the impact of somatic mtDNA mutations on this process, we assessed the leukemogenic potential of hematopoietic progenitor cells (HPCs) from mtDNA mutator mice (Polg D257A) with or without NMyc overexpression. We observed a higher incidence of spontaneous leukemogenesis in recipients transplanted with heterozygous Polg HPCs and a lower incidence of NMyc-driven leukemia in those with homozygous Polg HPCs compared to controls. Although mtDNA mutations in heterozygous and homozygous HPCs caused similar baseline impairments in mitochondrial function, only heterozygous HPCs responded to and supported altered metabolic demands associated with NMyc overexpression. Homozygous HPCs showed altered glucose utilization with pyruvate dehydrogenase inhibition due to increased phosphorylation, exacerbated by NMyc overexpression. The impaired growth of NMyc-expressing homozygous HPCs was partially rescued by inhibiting pyruvate dehydrogenase kinase, highlighting a relationship between mtDNA mutation burden and metabolic plasticity in leukemogenesis.

Limited immune infiltration within the tumor microenvironment (TME) hampers the efficacy of immune checkpoint blockade (ICB) therapy. To enhance immune infiltration, mild photothermal therapy (PTT) is often combined with immunotherapy. However, the impact of mild PTT on the TME remains unclear. The bioinformatics analyses reveal that mild PTT amplifies immune cell infiltration and stimulates T-cell activity. Notably, it accelerates the release of tumor cell-derived exosomes (TEX) and upregulates PD-L1 expression on both tumor cells and TEX. Consequently, it is proposed that locally inhibiting TEX release is crucial for overcoming the adverse effects of mild PTT, thereby enhancing ICB therapy. Thus, a multi-stage drug delivery system is designed that concurrently delivers photosensitizers (reduced graphene oxide nanosheets, NRGO), anti-PD-L1 antibodies, and exosome inhibitors (sulfisoxazole). The system employs a temperature-sensitive lipid gel as the primary carrier, with NRGO serving as a secondary carrier that supports photothermal conversion and incorporation of sulfisoxazole. Importantly, controlled drug release is achieved using near-infrared radiation. The findings indicate that this local combination therapy remodels the immunosuppressive TME through exosome inhibition and enhanced immune cell infiltration, while also boosting T-cell activity to trigger systemic antitumor immunity, showcasing the remarkable efficacy of this combination strategy in eradicating cold tumors.
© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.