Glaucoma is a neurodegenerative disorder of the optic nerve and retinal ganglion cells (RGCs) and a major cause of blindness. The two most important risk factors for glaucoma are ocular hypertension (OHT) and advanced age. In this study, we explored the combined impact of aging and OHT on retinal neuronal and microvasculature health. We induced OHT using the bead-injection model in 12 week old (young) and 1.5 year old (old) mice and monitored intraocular pressure (IOP) for 2 weeks. We then explored vascular phenotypes, blood retinal barrier components, RGC counts, and electroretinogram (ERG) changes. Aged mice displayed reduced retinal microvasculature complexity, retinal vascular phenotypes in all three retinal capillary plexi (RCPs), and abnormal ERGs. Aging also impacted basement membrane (BM) and tight junction (TJ) morphology. The impact of OHT was much more evident in old mice; RGC loss was exacerbated, retinal vascular phenotypes were magnified across all three RCPs, and BM and TJ phenotypes were much more severe. However, the impact of OHT on retinal function was unchanged in old mice. Interestingly, the nature of these phenotypes was not equivalent among all RCPs, suggesting regional shared and distinct susceptibilities to aging and OHT. Taken together, aging causes multiple neurovascular phenotypes in mouse retinas, and OHT causes more severe effects in old mice. This suggests an interaction between aging and OHT that may help explain the increased prevalence of glaucoma in older humans.

Ischemic retinopathies (IR) are major causes of blindness worldwide. They are characterized by an exuberant hypoxia-driven pathological neovascularization (NV). While it is well accepted that immune cells contribute to both physiological and pathological retinal angiogenesis, our knowledge of various processes and underlying mechanisms, especially in the direct interaction with endothelial cells (EC), is still very limited. Here, we addressed the role of microglial phagocytosis of apoptotic EC in the context of pathological hypoxia-related NV in the mouse oxygen-induced retinopathy model (OIR). We utilized endothelium-specific fluorescent reporter mice to study the kinetics of EC phagocytosis by leukocytes in OIR. Indeed, we observed phagocytic microglia in close proximity to the pathological vessels and an altered phagocytosis rate by flow cytometry compared to controls. We observed a decrease in the phagocytic rate in early hypoxia-driven stages of OIR, whereas in later stages where pathological vessels appear, the phagocytosis rate was increased. Myeloid-specific deletion of the suppressor of cytokine signaling protein 3 (SOCS3) was previously shown to induce increased phagocytic activity due to overexpression of the opsonin molecule growth arrest-specific 6 (GAS6). In myeloid SOCS3-deficient mice, we observed a reduction of pathological NV in OIR. This reduction could be reversed by neutralizing GAS6 via administration of recombinant MERTK protein, the receptor for GAS6 expressed on myeloid cells. Furthermore, exogenous GAS6 supplementation increased microglial phagocytosis in vitro and limited pathological NV in OIR. Our data suggest that the promotion of immune cell phagocytosis by the modulation of the GAS6-MERTK axis might represent a potential target for the treatment of pathological NV in IR.
© 2025. The Author(s).

Central nervous system (CNS) involvement and/or relapse remains one of the most important causes of morbidity/mortality in paediatric B-cell precursor acute lymphoblastic leukaemia (BCP-ALL) patients. To identify novel therapeutic targets and develop less aggressive therapies, a better understanding of the cellular and molecular microenvironment in leptomeningeal metastases is key. Here, we aimed to investigate the formation of metastatic leptomeningeal aggregates and their relevance to the expansion, survival and chemoresistance acquisition of leukaemia cells.
We used BCP-ALL xenograft mouse models, combined with immunohistofluorescence and flow cytometry, to study the development of CNS metastasis and the contribution of leptomeningeal cells to the organisation of leukaemic aggregates. To in vitro mimic the CNS metastasis, we established co-cultures of three-dimensional (3D) ALL cell spheroids and human leptomeningeal cells (hLMCs) and studied the effects on gene expression, proliferation, cytokine production, and chemoresistance.
In xenografted mice, ALL cells infiltrated the CNS at an early stage and, after crossing an ER-TR7+ fibroblast-like meningeal cell layer, they proliferated extensively and formed large vascularised leukaemic aggregates supported by a network of podoplanin+ leptomeningeal cells. In leukaemia spheroid-hLMC co-cultures, unlike conventional 2D co-cultures, meningeal cells strongly promoted the proliferation of leukaemic cells and generated a pro-inflammatory microenvironment. Furthermore, in 3D cell aggregates, leukaemic cells also developed chemoresistance, at least in part due to ABC transporter up-regulation.
Our results provide evidence for the formation of metastatic ALL-leptomeningeal cell aggregates, their pro-inflammatory profile and their contribution to leukaemic cell expansion, survival and chemoresistance in the CNS.
© 2025. The Author(s).

Small extracellular vesicles (sEVs) obtained from mesenchymal stromal cells (MSCs) have shown considerable promise as restorative stroke treatment. In a head-to-head comparison in mice exposed to transient proximal middle cerebral artery occlusion (MCAO), sEVs obtained from MSCs cultured under hypoxic conditions particularly potently enhanced long-term brain tissue survival, microvascular integrity, and angiogenesis. These observations suggest that hypoxic preconditioning might represent the strategy of choice for harvesting MSC-sEVs for clinical stroke trials. To test the efficacy of hypoxic MSCs in a second stroke model in an additional species, we now exposed 6-8-month-old Sprague-Dawley rats to permanent distal MCAO and intravenously administered vehicle, platelet sEVs, or sEVs obtained from hypoxic MSCs (1% O2; 2 × 106 or 2 × 107 cell equivalents/kg) at 24 h, 3, 7, and 14 days post-MCAO. Over 28 days, motor-coordination recovery was evaluated by rotating pole and cylinder tests. Ischemic injury, brain inflammatory responses, and peri-infarct angiogenesis were assessed by infarct volumetry and immunohistochemistry. sEVs obtained from hypoxic MSCs did not influence infarct volume in this permanent MCAO model, but promoted motor-coordination recovery over 28 days at both sEV doses. Ischemic injury was associated with brain ED1+ macrophage infiltrates and Iba1+ microglia accumulation in the peri-infarct cortex of vehicle-treated rats. Hypoxic MSC-sEVs reduced brain macrophage infiltrates and microglia accumulation in the peri-infarct cortex. In vehicle-treated rats, CD31+/BrdU+ proliferating endothelial cells were found in the peri-infarct cortex. Hypoxic MSC-sEVs increased the number of CD31+/BrdU+ proliferating endothelial cells. Our results provide evidence that hypoxic MSC-derived sEVs potently enhance neurological recovery, reduce neuroinflammation. and increase angiogenesis in rat permanent distal MCAO.
© 2024. The Author(s).

Cachexia is the wasting of skeletal muscle in cancer and is a major complication that impacts a person's quality of life. We hypothesized that cachexia is mediated by dysfunction of the vascular system, which is essential for maintaining perfusion and tempering inappropriate immune responses. Using transparent tissue topography, we discovered that loss of muscle vascular density precedes muscle wasting in multiple complementary tumor models, including pancreatic adenocarcinoma, colon carcinoma, lung adenocarcinoma and melanoma models. We also observed that persons suffering from cancer cachexia exhibit substantial loss of muscle vascular density. As tumors progress, increased circulating activin A remotely suppresses the expression of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC1α) in the muscle endothelium, thus inducing vascular leakage. Restoring endothelial PGC1α activity preserved vascular density and muscle mass in tumor-bearing mice. Our study suggests that restoring muscle endothelial function could be a valuable therapeutic approach for cancer cachexia.
© 2025. The Author(s).