Search Results (476)

Ischemic stroke remains one of the most catastrophic diseases in neurology, in which, due to a disturbance in the cerebral blood flow, the brain is acutely deprived of its oxygen and glucose oligomer, which in turn rapidly leads to energetic collapse and progressive cellular death. There is now increasing evidence that this type of stroke is not simply a type of ‘oxidative stress’ but rather a programmable loss-of-redox homeostasis, within which electron flow and the balance of oxidants/reductants are cumulatively displaced at the level of the single molecule and at the level of the cellular area. The advances being made in cryo-electron microscopy, lipidomics, and spatial omics are coupled with the introduction of a redox code produced by the interaction of the couples NADH/NAD⁺, NADPH/NADP⁺, GSH/GSSG, BH₄/BH₂, and NO/SNO, which determine the end results of the fates of the neurons, glia, endothelium, and pericytes. Within the mitochondria, pathophysiological events, including reverse electron transport, succinate overflow, and permeability transition, are found to be the first events after reperfusion, while signals intercommunicating via ER–mitochondria contact, peroxisomes, and nanotunnels control injury propagation. At the level of the tissue, events such as the constriction of the pericytes, the degradation of the glycocalyx, and the formation of neutrophil extracellular traps underlie microvascular failure (at least), despite the effective recanalization of the vessels. Systemic influences such as microbiome products, oxidized lipids, and free mitochondrial DNA in cells determine the redox imbalance, but this generally occurs outside the brain. We aim to synthesize how the progressive stages of ischemic injury evolve from the cessation of flow to the collapse of the cell structure. Within seconds of injury, there is reverse electron transport (RET) through mitochondrial complex I, with bursts of superoxide (O₂•⁻) and hydrogen peroxide (H₂O₂) being produced, which depletes the stores of superoxide dismutase, catalase, and glutathione peroxidase. Accumulated succinate and iron-induced lipid peroxidation trigger ferroptosis, while xanthine oxidase and NOX2/NOX4, as well as uncoupled eNOS/nNOS, lead to oxidative and nitrosative stress. These cascades compromise the function of neuronal mitochondria, the glial antioxidant capacity, and endothelial–pericyte integrity, leading to the degradation of the glycocalyx with microvascular constriction. Stroke, therefore, represents a continuum of redox disequilibrium, a coordinated biochemical failure linking the mitochondrial metabolism with membrane integrity and vascular homeostasis. Full article

Background/Objectives: To elucidate the differential transcriptional and intercellular signaling features of tumor components across various cancers, we conducted a comparative analysis using single-cell RNA sequencing (scRNA-seq). This technology enables detailed characterization of tumor ecosystems and may explain variations in tumor behavior among distinct cancer types. Methods: We analyzed publicly available scRNA-seq datasets (GEO) from seven cancer types—pancreatic ductal adenocarcinoma (PDAC), hepatocellular carcinoma (HCC), esophageal squamous cell carcinoma (ESCC), breast cancer (BC), thyroid cancer (TC), gastric cancer (GC), and colorectal cancer (CRC)—to define their unique molecular characteristics and intercellular interactions. Results: PDAC displayed a distinct tumor microenvironment (TME) dominated by myeloid cells (~42%), including abundant CXCR1/CXCR2-expressing tumor-associated neutrophils (TANs) that preferentially interacted with immune rather than cancer cells. The competitive receptor ACKR1 was minimally expressed on endothelial cells, consistent with PDAC hypo-vascularity. In HCC, tumor cells lacked EPCAM and expressed complement and stem cell markers; cancer-associated fibroblasts (CAFs) were scarce, and stellate cells expressed the pericyte marker RGS5. CAFs were abundant in ESCC and BC, with IGF1/2 expression, while in GC, these markers were uniquely found in plasma cells. Since BC and GC subtypes exhibit distinct TME patterns, it is necessary to perform subtype-specific analyses for these cancers. TC showed high expression of tumor-suppressor genes, including HOPX, in tumor cells. Differential interactions and the presence of “dominant signaling cell populations “ with dominant outgoing signals may underlie the heterogeneity in tumor aggressiveness across these cancers. Conclusions: Comparative scRNA-seq analysis of multiple cancers reveals distinct tumor phenotypes and cell–cell communication patterns, offering insights into the molecular architecture of human solid tumors. Full article

Background/Objectives: The tumour microenvironment in pancreatic ductal adenocarcinoma (PDA) is highly complex, influencing both vascular function and therapy response. P21-activated kinases (PAKs) are key regulators of the cellular and immune system, but the specific roles of PAK1 and PAK4 in pancreatic tumour vasculature and chemotherapy sensitivity are unclear. This study investigated the effects of PAK1 and PAK4 on tumour vasculature and therapeutic response in an immunocompromised mouse model. Methods: KPC-derived wild type (WT), PAK1 knockout (KO), PAK4KO, or PAK1&4KO pancreatic cancer cells were injected subcutaneously into SCID mice, followed by gemcitabine treatment. Tumour growth, vessel density, pericyte coverage, and endothelial adhesion molecule expression were analysed by histology and immunostaining. A proteomic study was used to identify protein changes. Results: PAK1KO significantly reduced tumour growth, enhanced vascular normalisation, upregulated stromal ICAM-1 and VCAM-1, but reduced gemcitabine efficacy. PAK4KO did not inhibit tumour growth but increased vessel diameter and enhanced gemcitabine efficacy. Proteomics study indicated that PAK1KO downregulated proteins involved in the VEGF pathway, while PAK4KO upregulated most proteins involved in the VEGF pathway and downregulated DNA repair proteins, contributing to improved chemotherapy sensitivity. The double knockout of PAK1 and PAK4 did not inhibit tumour growth, although it stimulated vascular normalisation, indicating an outcome balanced between PAK1 and PAK4. Conclusions: PAK1 and PAK4 differentially regulated pancreatic tumour vasculature and chemotherapy response. PAK1KO suppressed tumour growth by reducing angiogenesis and enhancing vascular normalisation, whereas PAK4KO enhanced gemcitabine efficacy through vessel dilation. Full article

A functional blood vessel network is required to deliver oxygen and nutrients to the cancer cells for their growth. Angiogenesis, the formation of new blood vessels from pre-existing ones, is one of the major mechanisms to create this vascular network. Anti-angiogenic therapy was conceived as the inhibition of the cellular and molecular players involved in tumor angiogenesis such as vascular endothelial growth factor and its main receptors. Due to limitations of this therapy, different approaches of vessel modulation such as vascular normalization or vascular promotion have been studied showing benefits in different tumor models and clinical trials. In contrast to anti-angiogenic therapy, which inhibits the blood vessels that are being formed, vascular disruption therapy aims to destroy already formed tumor vessels. These malignant vascular structures differ from other blood vessels in terms of endothelial cell states, pericyte coverage and basement membrane development. The molecules used for vascular disruption are microtubule-binding molecules, flavonoids that induce endothelial cell apoptosis or molecules vectorized to endothelial receptors. Many vascular disruption agents have been tested in clinical trials showing some promising results, but with some limitations that include resistant rim cells or the development of hypoxia that induces cancer regrowth and poor delivery of the anti-tumor agents. The main objective of this review is to focus on vascular disruption agents therapy, novel molecules, new ways to overcome therapy resistance to them, current clinical status and, especially, the upcoming challenges and applications of these molecules. Full article

Cancer-associated fibroblasts (CAFs) are key components of the tumor microenvironment (TME) that influence cancer progression via extracellular matrix (ECM) remodeling and secretion of growth factors and cytokines. Endothelial-to-mesenchymal transition (EndMT) is emerging as an important axis among the heterogeneous origins of CAFs. This review introduces the diverse methods used to induce EndMT in cancer—mouse tumor models, conditioned-medium treatment, co-culture, targeted gene perturbation, ligand stimulation, exosome exposure, irradiation, viral infection, and three-dimensional (3D) culture systems—and summarizes EndMT cell-type evidence uncovered using transcriptomic and proteomic technologies. Hallmark EndMT features include spindle-like morphology, increased motility, impaired angiogenesis and barrier function, decreased endothelial markers (CD31, VE-cadherin), and increased mesenchymal markers (α-SMA, FN1). Reported mechanisms include signaling via TGF-β, cytoskeletal/mechanical stress, reactive oxygen species, osteopontin, PAI-1, IL-1β, GSK-3β, HSP90α, Tie1, TNF-α, HSBP1, and NOTCH. Cancer-induced EndMT affects tumors and surrounding TME—promoting tumor growth and metastasis, expanding cancer stem cell-like cells, driving macrophage differentiation, and redistributing pericytes—and is closely associated with poor survival and therapy resistance. Finally, we indicate each study’s stance: some frame cancer-induced EndMT as a source of CAFs, whereas others, from an endothelial perspective, emphasize barrier weakening and promotion of metastasis. Full article

Cerebral vasospasm (CVS) following a subarachnoid hemorrhage (SAH) is a critical complication driven by imbalances between vasodilators and vasoconstrictors. This review explores the bidirectional interplay between nitric oxide (NO) and endothelin-1 (ET-1) in CVS pathogenesis. NO, a potent vasodilator mainly produced by endothelial and neuronal nitric oxide synthase (eNOS/nNOS) under normal physiological conditions, is scavenged early after SAH by hemoglobin derivatives, leading to microcirculatory dysfunction, pericyte constriction, and impaired neurovascular coupling. Conversely, ET-1 exacerbates vasoconstriction by suppressing NO synthesis via ROS-dependent eNOS uncoupling and Rho-kinase activation. The NO/ET-1 axis further influences delayed cerebral ischemia (DCI) through mechanisms like 20-HETE-mediated cGMP suppression and oxidative stress. Emerging therapies—including NO donors, NOS gene therapy, and ET-1 receptor antagonists—aim to restore this balance. Understanding these pathways offers translational potential for mitigating CVS and improving outcomes post-SAH. Full article

Background: Alzheimer’s disease (AD) is a multifactorial neurodegenerative disorder characterized by amyloid-β (Aβ) plaques, neurofibrillary tangles, and progressive cognitive decline. Recent evidence has highlighted the role of blood–brain barrier (BBB) dysfunction in the early stages of AD pathology. Objective: We sought to explore the histological structure and physiological function of the blood–brain barrier, and to identify the shared pathological mechanisms between BBB disruption and Alzheimer’s disease progression. Methods: This narrative review was conducted through a comprehensive search of peer-reviewed literature from 1997 to 2024, using databases such as PubMed, Elsevier, Scopus, and Google Scholar. Results: Multiple histological and cellular components—including endothelial cells, pericytes, astrocytes, and tight junctions—contribute to BBB integrity. The breakdown of this barrier in AD is associated with chronic inflammation, oxidative stress, vascular injury, pericyte degeneration, astrocyte polarity loss, and dysfunction of nutrient transport systems like Glucose Transporter Type 1 (GLUT1). These alterations promote neuroinflammation, amyloid-β (Aβ) accumulation, and progressive neuronal damage. Conclusions: BBB dysfunction is not merely a consequence of AD but may act as an early and active driver of its pathogenesis. Understanding the mechanisms of BBB breakdown can lead to early diagnostic markers and novel therapeutic strategies aimed at preserving or restoring barrier integrity in Alzheimer’s disease. Full article

Traumatic brain injury (TBI) disrupts the blood–brain barrier (BBB), resulting in increased permeability, neuronal loss, and cognitive dysfunction. This study investigates the therapeutic potential of thyroid hormone (T4) to reduce BBB dysfunction following moderate fluid percussion injury. T4 injection (intraperitoneal) after TBI restores the levels of pericytes and endothelial cells vital for BBB integrity, reduces edema by downregulating AQP-4 gene expression, and enhances levels of the tight junction protein ZO-1. T4 counteracts the TBI-related increase in MMP-9 and TLR-4, significantly reducing BBB permeability. Furthermore, T4 enhances the neuroprotective functions of astrocytes by promoting the activity of A2 astrocytes. Additionally, T4 treatment increases DHA levels (important for membrane integrity and function), stimulates mitochondrial biogenesis, and leads to a notable improvement in spatial learning and memory retention. These findings suggest that T4 has significant potential to reduce vascular leakage and inflammation after TBI, thereby improving cognitive function and maintaining BBB integrity. Full article

Pericytes produce vascular endothelial growth factor-A (VEGF-A; hereafter referred to as VEGF). VEGF inhibits pericyte proliferation and migration through enhanced VEGFR2 and PDGFRβ heterodimerization. Heterodimerization of these receptors on perivascular supporting cells, mediated by VEGF in culture, mitigates signaling through these receptors and promotes a quiescent phenotype. However, the detailed cellular mechanisms and the significance of these interactions in vivo require further investigation. The cell-autonomous activities of pericyte VEGF expression during vascular development and neovascularization remain unknown. Here we utilized mice conditionally lacking Vegfa in pericytes (Vegfa^PC) to examine its impact on retinal vascular development and pathological ocular neovascularization. Vascular integrity was also assessed in older mice using fundus imaging and fluorescein angiography. The lack of Vegfa pericyte expression delayed the initial spreading of the superficial layer of the retinal vasculature. Mice lacking Vegfa pericyte expression had similar numbers of retinal endothelial cells and arteries to their wild-type littermates. However, the number of pericytes was significantly reduced in younger Vegfa^PC mice but increased in more mature mice. In addition, pericyte Vegfa deficiency did not impact responses during oxygen-induced ischemic retinopathy and laser-induced choroidal neovascularization. Thus, pericyte VEGF expression plays a role during early stages of retinal vascular development with limited influence on mature retinal vascularization, its integrity, and neovascularization. Full article

During diabetic retinopathy (DR), cell death has been characterized in all of the major retinal cell types, but was observed initially in the microvasculature, particularly the mural cells: pericytes and vascular smooth muscle cells (VSMCs). Indeed, our ability to identify the mural cell corpses called “ghost cells” within the vascular basement membranes (BMs) in eyes of diabetic patients and animal models is indicative that removal of dead cells, or efferocytosis (EF), is dysfunctional during this disease. EF is the process whereby apoptotic cells are eliminated through phagocytic engulfment and digestion and is essential to maintain tissue integrity and immune homeostasis. The process occurs in three distinct phases: finding and recognition, engulfment, and digestion, under the direction of “find me” and “eat me” signals and a large array of their cognate receptors and bridging molecules. Efferocytosis can be performed by many cell types, but most efficiently by professional phagocytes, and with such rapidity that the process is extremely difficult to detect in healthy tissues. As delayed EF is a recognized cause of autoimmune and inflammatory disease, mural cell death in DR may create inflammatory foci in the neurovascular unit (NVU). Here we discuss the basic mechanisms of EF in the context of DR and the impact of diabetic metainflammation on EF effector cell dysfunction. Full article

Islet transplantation can improve glycemic control in a subset of patients with type 1 diabetes mellitus (T1DM). This therapeutic approach is often limited by scarcity of adequate donor islets and an insufficient revascularization capacity of grafted islets. Recent findings reveal that sex is an important determinant for the outcome of islet transplantation. However, it is still unknown how the biological sex of islet donors and recipients affects the revascularization of the grafts during the initial ischemic post-transplantation phase. In this study, we observed in a mouse dorsal skinfold chamber model a higher revascularization capacity of female islets transplanted in female or male recipient mice when compared to male islets transplanted in female or male recipients. To mimic the ischemic in vivo conditions ex vivo, we subjected isolated female and male islets to oxygen-glucose deprivation. Under these conditions female islets expressed and secreted significantly more glucagon (GCG). By a panel of functional angiogenesis assays, we could further demonstrate that GCG exhibits a strong pro-angiogenic function. This effect was pronounced in blood vessels as well as endothelial cells and pericytes of female origin due to a higher expression of GCG receptor. Taken together, these results not only confirm the clinical observation that transplantation of female islets improves the outcome of islet transplantation but also indicate that this is mediated by an accelerated GCG-driven islet engraftment. Full article

Background: The proportion of people suffering from neurodegenerative conditions, such as Alzheimer’s disease (AD), is increasing in the population year on year. Despite the constant effort of researchers, these conditions remain incurable and can only be managed by alleviation or delaying of symptoms. The lack of suitable treatment is caused by constricted access to the brain, limited by the brain-blood barrier. The aim of this work was to investigate two pegylated gold nanoparticles as potential carriers of therapeutic siRNA and their impact on the cellular functions of Human Brain Endothelial Cells. Methods and Results: Nanoparticles AuNP14a and AuNP14b complexed with siRNA were internalized by HBEC-5i cells and located in the cytoplasm. The genotoxicity assay proved that the nucleus was not affected and complexed nanoparticles did not cause DNA damage. The reactive oxygen species formation and mitochondrial membrane potential changes were measured and showed an adaptive response of cells after compound administration. Results obtained in a cytotoxicity assay conducted on astrocytes and pericytes, which are components of the blood–brain barrier, confirmed the biosafety of tested nanoparticles. Conclusions: In summary, it was shown that AuNP14a and AuNP14b are promising candidates as nanocarriers for therapeutic nucleic acids through biological barriers. Full article

Autologous fat grafting of human lipoaspirate (LA) is increasingly used in reconstructive and cosmetic surgery for lipofilling and stem cell-rich “nanofat” reinjection for regenerative medicine. While commercial devices (e.g., REVOLVE and Puregraft) are available, many surgeons use non-standardized manual washing techniques, leading to inconsistent graft retention (20–80%). Moreover, no system can unite washing directly with mechanical processing to produce a nanofat-like product directly from raw LA. We developed a novel preparation device (PD) that is designed for peristaltic pump-driven washing of LA and can be seamlessly combined with our previously developed Emulsification and Micronization Device (EMD) into an automated closed-loop platform. Human LA samples were washed with the PD and compared to standard manual washing via visual colorimetric analysis. We then evaluated the mechanical processing of PD-washed LA using our EMD and assessed cell count, viability, and stromal vascular fraction-derived subpopulations (i.e., mesenchymal stem cells, endothelial progenitor cells (EPCs), pericytes, transit-amplifying (TA) progenitor cells, and supra-adventitial adipose stromal cells). Recirculating LA through the PD for at least one minute resulted in sufficient mixing, producing LA with equivalent color and quality to manual washing. Integrating the EMD within a platform enabled both washing and mechanical processing under peristaltic flow, enriching key subpopulations compared to manual methods. Thus, our fluidic platform effectively washes LA in a closed-loop system, minimizing LA tissue manipulation and opportunity for contamination while also simplifying the workflow for mechanical processing. Further refinement and automation of this platform would enhance the reproducibility and quality of small-volume fat grafts, cell-assisted lipotransfer, and stem/progenitor cell injections to promote wound healing and angiogenesis. Full article

Vascularization remains a critical challenge in tissue engineering, limiting graft survival, integration, and clinical translation. Although bioprinting enables spatial control over vascular architectures, many existing approaches prioritize geometric precision over biological performance. Bioprinted vasculature can be understood as a dynamic and time-dependent system that requires tissue-specific maturation. Within this framework, hydrogel systems act as active microenvironments rather than passive scaffolds. Hydrogel platforms vary from natural matrices and synthetic polymers to bioinspired or stimuli-responsive systems, each offering tunable control over stiffness, degradation, and biochemical signaling needed for vascular maturation. The design requirements of large and small vessels differ in terms of mechanical demands, remodeling capacity, and host integration. A key limitation in current models is the absence of time-resolved evaluation, as critical processes such as lumen formation, pericyte recruitment, and flow-induced remodeling occur progressively and are not captured by static endpoints. Advancements in bioprinting technologies are evaluated based on their capacity to support hydrogel-mediated vascularization across varying length scales and structural complexities. A framework for functional assessment is proposed, and translational challenges related to immunogenicity, scalability, and regulatory requirements are discussed. Such integration of hydrogel-driven biological cues and bioprinting fidelity is critical to advancing vascularized constructs toward clinical translation. Full article

Cardiac tissue engineering is a promising strategy to restore cardiac function in heart failure patients. Understanding the cardiac tissue architecture including the cardiac stroma is essential for developing not only advanced cardiac tissue engineering but also novel therapeutic strategies. One of the crucial components of the cardiac stroma is the myocardial vasculature. To enhance the spatial visualization of the cardiac stromal cytoarchitecture with a particular focus on myocardial vasculature, we performed 3D reconstructions of the murine cardiac micro vessels using Serial Block-Face Scanning Electron Microscopy (SBF-SEM). These analyses revealed that pericyte cell bodies were primarily oriented lengthwise and extended several cellular protrusions towards the endothelium. At capillary branching points, some pericytes made contact with both capillaries emerging from branching. In addition to pericytes that are completely encapsulated by the common basal lamina together with capillary endothelial cells, we identified other vascular-associated cells located outside this sheath. Based on marker expression, these cells were distinguished from fibroblasts and suggested to be telocytes. The vascular-associated cells formed electron-dense contact zones with endothelial cells, suggesting functional coupling between these both cell types. In conclusion, this study provides detailed three-dimensional visualizations of the cardiac stroma with a particular focus on cardiac microvasculature, offering enhanced insight into the cardiac stromal cytoarchitecture. Full article