Biology subjects

Sandeman, L.

Publications and source records attributed to Sandeman, L..

4 recordsLinked to original sources

bioRxiv2025

Mitochondrial Dysfunction in Endothelial Cells Drives Greater Vascular Impairment in Females with Diabetes-Associated Peripheral Artery Disease

BackgroundWomen with peripheral artery disease (PAD) experience poorer clinical outcomes than men, particularly in the setting of diabetes. However, the mechanistic basis for these sex- specific disparities remains unclear. MethodsHere, we investigated endothelial cell (EC) function(s) in diabetes-associated PAD, with a focus on sex differences. Limb tissues from patients with diabetes and chronic limb-threatening ischemia (CLTI) undergoing amputation, and a diabetes mouse model of hindlimb ischemia (HLI), were assessed for vasodilatory capacity, angiogenesis, oxidative stress and changes to expression of mitochondrial complex genes. ECs exposed to a hyperglycemic environment in vitro were assessed for mitochondrial function. The therapeutic potential of the mitochondrial-targeted antioxidant MitoQ was investigated. ResultsECs from females with diabetes-associated PAD have altered responses compared to males. Specifically, limb vessels and skeletal muscle from females exhibit reduced arterial relaxation, angiogenesis and increased oxidative stress in response to HLI in mice, and in tissues from patients. Single-cell RNA sequencing of murine limbs revealed marked suppression of EC mitochondrial complex genes in females with diabetes. Female human ECs exposed to high glucose had reduced respiration, reduced expression of mitochondrial genes and increased oxidative stress. Remarkably, MitoQ restored arterial relaxation and the angiogenic response in female diabetes- associated PAD. ConclusionOur findings uncover a striking sex-specific vulnerability involving oxidative stress and mitochondrial dysfunction in EC health in diabetes-associated PAD. These results highlight the need for sex-specific therapeutic strategies in diabetic PAD, which might include mitochondrial targeted antioxidant strategies.

pathology↗

bioRxiv2025

Development of a novel murine model of in-stent neoatherosclerosis

ObjectiveIn-stent neoatherosclerosis is a phenomenon of percutaneous coronary intervention with stenting. Whilst similar to de novo atherosclerosis, it develops rapidly over 1-5 years rather than over a lifetime. No preclinical small animal models exist that allow full elucidation of neoatherosclerosis biology and future treatments. The aim of this study was to establish and validate a novel murine model of in-stent neoatherosclerosis. Approach and ResultsMurine stainless-steel stents (2.5 x 0.7 mm) were deployed into donor descending aortas of atherosclerosis-prone apolipoprotein (Apo)e-/- mice, then carotid-interposition grafted into Apoe-/- recipients. Mice (n=6-8/group) received chow or a high cholesterol diet (HCD) for 7- or 28-days post-surgery. Multimodal intravascular imaging, simultaneously combining optical coherence tomography (OCT, plaque burden) and fluorescence for indocyanine green (ICG, plaque instability), visualized in-stent neoatherosclerosis across the entire length of the stented site. Histological analyses revealed that stented vessels from mice fed HCD had neointimas with prominent lipid cores and an elevated CD68+ macrophage content, similar to human neoatherosclerosis. Mice fed chow post-stenting had distinctly different neointimas that were smooth muscle cell rich, resembling neointimal hyperplasia. Consistent with this, flow cytometry revealed a higher content of monocytes/macrophages and dendritic cells in stented aortas from mice fed HCD than in non-stented aortas. ConclusionWe have developed and validated the first murine model that replicates the unique characteristics of human in-stent neoatherosclerosis. This project has implications for exploring the mechanisms that promote neoatherosclerosis and testing targeted new therapies. RESEARCH PERSPECTIVEO_ST_ABSWhat Is New?C_ST_ABSO_LIWe have developed and validated a novel murine model of in-stent neoatherosclerosis, presenting a new platform that will facilitate the discovery of novel mechanistic targets of in-stent neoatherosclerosis and preventative therapies. C_LIO_LIThis model develops lesions with a similar morphology to human in-stent neoatherosclerosis and distinct to in-stent neointimal hyperplasia, with higher extracellular lipid and macrophage content and proportionately less smooth muscle cells. C_LIO_LIWe show a first-time visualization of murine in-stent neoatherosclerosis using bimodal intravascular imaging with simultaneous capture of structural information (optical coherence tomography, plaque burden) and the distribution of areas of plaque instability (high-sensitivity fluorescence, indocyanine green) within the plaque. C_LI What new question does this study raise?O_LIHow can the utility of this novel model be maximized as a platform for discovering novel agents that prevent in-stent neoatherosclerosis? C_LI What question should be addressed next?O_LIAre there unique mechanisms of in-stent neoatherosclerosis, distinct to de novo atherosclerosis, that can be specifically targeted to prevent disease and ultimately increase stent performance? C_LI

cell biology↗

bioRxiv2024

Reconstituted high-density lipoproteins rescue diabetes-impaired endothelial cell metabolic reprograming and angiogenic responses to hypoxia

ObjectiveImpaired angiogenic responses to ischemia underlie diabetic vascular complications. Reconstituted high-density lipoproteins (rHDL) have proangiogenic effects in diabetes. The pyruvate dehydrogenase kinase 4 (PDK4)/pyruvate dehydrogenase complex (PDC) axis is an oxygen-conserving mechanism that preserves EC functions in hypoxia. We aimed to determine the role of the PDK4/PDC axis in angiogenesis, the effect of diabetes on its regulation in response to ischemia, and in the proangiogenic properties of rHDL. Approach and ResultsIn a murine wound healing model, PDK4 and pPDC were elevated early (24h) post induction of wound ischemia in non-diabetic wounds, which did not occur in diabetic mice. Topical rHDL rescued this impairment, enhancing PDK4 (68%, P<0.05) and pPDC (165%, P<0.01) in diabetic wounds. In parallel, wound neovascularization (62%, P<0.05) and closure (154%, P<0.0001) were increased in diabetic rHDL-treated wounds. In vitro, PDK4 and pPDC levels were increased in ECs exposed to hypoxia (65%, 70% respectively, P<0.05). High glucose did not elicit a further step-wise induction in PDK4/pPDC, with aberrant increases in mitochondrial respiration (19%, P<0.05), coupled with impaired EC angiogenic functions. Importantly, rHDL increased PDK4 and pPDC two-fold, returning mitochondrial respiration and EC angiogenic functions to normal glucose levels. In vitro, PDK4 siRNA knockdown attenuated the proangiogenic effects of rHDL. In vivo PDK4 inhibition ameliorated topical rHDL-mediated increases in wound angiogenesis and closure. Using chromatin immunoprecipitation, rHDL increased forkhead box O1 (FOXO1) binding to the PDK4 promoter and suppressed FOXO1 phosphorylation, presenting FOXO1 as a mechanism for the induction of PDK4 by rHDL. ConclusionThe PDK4/PDC axis response to ischemia is impaired in diabetes and important for the proangiogenic effects of rHDL.

cell biology↗

bioRxiv2024

Multifunctional biomimetic porphyrin-lipid nanoparticles - novel nanoscale theranostics for atherosclerotic cardiovascular disease

BackgroundHigh-density lipoprotein (HDL) nanoagents have unrealized potential for atherosclerosis theranostics. Porphyrin-lipid HDL mimetic nanoparticles (Por-HDL-NPs) incorporate porphyrin-lipid which permits near infrared fluorescence imaging and positron emission tomography (PET) through chelation of Copper-64 (64Cu). The outer shell contains apolipoprotein A-I mimetic peptide R4F that interacts with scavenger receptor SR-BI, enabling macrophage targeting and therapeutic effects. We leveraged the theranostic properties of Por-HDL-NPs for testing in atherosclerosis. Methods and ResultsIn vitro, Por-HDL-NPs were internalised by immortalised bone marrow-derived macrophages (iBMDMs), visualised via fluorescence microscopy and flow cytometry. Por-HDL-NPs increased cholesterol efflux from [3H]-cholesterol-loaded iBMDMs, (49%, P<0.05), compared to reconstituted HDL. Incubation of iBMDMs with Por-HDL-NPs reduced mRNA levels of inflammatory mediators Il-1{beta} (88%), Il-18 (54%) and Ccl5 (75%), and protein secretion of IL-1{beta} (69%) and CCL5 (82%), P<0.05. Por-HDL-NPs suppressed inflammasome components Nlrp3 (69%) and Asc (36%), P<0.05. Studies using siRNA deletion of SR-B1 and methyl-{beta}-cyclodextrin, revealed the anti-inflammatory properties of Por-HDL-NPs were independent of SR-B1 and cholesterol efflux. However, Por-HDL-NPs suppressed activation of inflammatory transcription factor NF-{kappa}B (53%, P<0.05). In Apoe-/- mice, PET imaging showed 64Cu-Por-HDL-NPs localised in hearts and detected increases in plaque over time with high-cholesterol diet. Por-HDL-NP fluorescence was visualised in aortic sinus plaques, co-localised with CD68+ macrophages, and by fluorescence IVIS imaging in aortic arch plaque. Por-HDL-NP-treated mice had smaller early-stage (22%) and unstable plaques (52%) and fewer circulating monocytes (32%) than control PBS-treated mice, P<0.05 for all. ConclusionsPor-HDL-NPs have theranostic properties, exhibiting both multi-modal imaging capabilities for identifying plaque and athero-protective therapeutic effects. Clinical PerspectiveO_ST_ABSWhat is new?C_ST_ABSO_LIPorphyrin high-density lipoprotein (HDL) mimetic nanoparticles (Por-HDL-NPs) have theranostic application in atherosclerosis. C_LIO_LIPor-HDL-NPs are internalized by macrophages in vitro and plaque macrophages in vivo, enabling the visualization of atherosclerosis by both positron emission tomography and multiple fluorescence imaging modalities. C_LIO_LIPor-HDL-NPs exhibit atheroprotective effects and suppress inflammation, promote cholesterol efflux, reduce atherosclerotic plaque development and lower the number of circulating monocytes. C_LI What are the clinical implications?O_LIThe PET imaging and plaque targeting capabilities of Por-HDL-NPs have implications for improved non-invasive tracking of human atherosclerosis development. C_LIO_LIThe excellent fluorescence imaging and plaque targeting properties of Por-HDL-NPs have clinical significance for improved detection of early-stage plaque using intravascular imaging strategies. C_LIO_LIPor-HDL-NPs provide therapeutic capabilities that target plaque directly, independent of lipid-lowering, suggestive of their potential to provide benefit on top of current lipid-lowering strategies. C_LI

cell biology↗