Engineered human CD34+ hematopoietic stem cells as an innovative approach to modulate the immunoinflammatory response during atherosclerosis

Aim Immune cells are key players in atherosclerosis development, and the growing recognition of their role, coupled with the availability of targeted biologic therapies, highlight the need of models to translate from animals to human the molecular mechanisms and strategies for atherosclerosis immunotherapies. An immune-metabolic characterization of a novel human-immune system mouse on an atheroprone background is presented. Methods TKO-L (Rag2KO/IL2rgKO/CD47KO-LDLRKO) pups received a hepatic injection of hCD34 either commercial or iPSCs-derived (250.000-300.000 cells/mouse). Humanized HuTKOL were checked for human cells engraftment at 12 weeks and then fed 12-week high-cholesterol diet to investigate immunometabolic phenotype and atherosclerosis, coupled to scRNAseq on bone marrow. Results HuTKOL presented human hCD45+ (24,83%, SE2,94%) in the circulation after engraftment with commercial hCD34+ cells, while it’s on going the engraftment with iPSCs-derived CD34+. In adult HuTKOL, B cells were the most abundant population at 12 weeks, but they decreased over time, compared to T cells that were the predominant population at 24 weeks, similar to human lymphocyte profile. hCD45+ were also successfully engrafted in the thymus (64,58%), spleen (19,89%), bone marrow (27,54%) and liver (32,94%) and atherogenic diet increased circulating memory CD4 T cells and atherosclerosis antigen-related IgM in both sexes. However, a different trend of circulating hCD45+ engraftment has been observed between male and female (M:10,84%, F:34,34%). HuTKOL developed dyslipidemia (plasma cholesterol levels: 1137,43 mg/dl, SE± 45,77) and atherosclerosis (% aortic sinus plaque occlusion: 18,24%, SE±0,02%) when fed a high-cholesterol diet, despite to a less extend compared to immunocompetent mice. scRNA sequencing of bone marrow revealed that human cells impact myeloid (monocytes/neutrophils) response. Conclusions HuTKOL mice show a human-like adaptive immune cell profile offering a valuable model for investigating the immunomodulation in atherosclerosis. Interestingly, our data suggest a role of adaptive cells on myeloid response that could affect atherosclerosis development.