Vessel Integrity Research Articles

Dedifferentiation of vascular smooth muscle cells upon vessel injury.

Highly differentiated mature vascular smooth muscle cells (VSMCs) are the predominant type of cells constituting arterial walls, which are essential for maintaining the structural and functional integrity of blood vessels. VSMCs demonstrate a notable degree of adaptability following vascular damage, a characteristic that plays a crucial role in the progression of vascular remodeling. Advances in single-cell RNA sequencing in both healthy and pathological vascular tissues have offered profound insights into the complexity of VSMCs, revealing a more intricate diversity than previously recognized. In response to injury, VSMCs undergo dedifferentiation and exhibit pluripotent markers. This review summarizes the researches that have employed lineage tracing alongside single-cell sequencing analysis to explore the dynamics of vascular damage. The primary focus of this study was on the process of dedifferentiation in VSMCs, with particular attention to its underlying mechanisms. The discussion included the impact of microenvironmental cues, the control of transcription factors, and the various molecular pathways involved in VSMCs dedifferentiation. Herein, we provide a comprehensive analysis of cells dedifferentiated from adult VSMCs upon vascular injury.

The role of the cyclooxygenase-2 pathway in tissue ischemia and revascularization following skeletal muscle injury induced by bothropic snake venom

Bothrops asper venom (Bav) contains metalloproteinases that disrupt the microvascular system, impairing muscle tissue regeneration after injury. This study investigated the impact of the cyclooxygenase-2 (COX-2) pathway on vascular injury and revascularization in muscle injuries induced by Bav. Mice were injected with Bav into the gastrocnemius muscle and treated with lumiracoxib, a selective COX-2 inhibitor, 30 min, 2 days, and 6 days post-Bav injection. Muscle tissue was analyzed at 24 h, 7 days, and 21 days post-injection. A decrease in COX-2 expression at 24 h post-Bav injection indicated significant necrosis and tissue loss. Both Bav injection and lumiracoxib treatment influenced the decrease of prostaglandin (PG)D2 and PGE2 production. Seven and 21 days post-Bav injections, COX-2 expression increased, along with PGDs levels unaffected by lumiracoxib, indicating that the other isoform COX-1 pathway could contribute to the release of PGs. Bav/lumiracoxib treated animals presented exacerbated limb ischemia, implying that COX-2-derived prostaglandins preserve vessel integrity. CD31, an angiogenesis marker, initially (24 h) decreased post-Bav injection but increased at 7 and 21 days in Bav/lumiracoxib mice, suggesting a down-modulatory role for COX-2-derived prostaglandins in early angiogenesis and tissue regeneration. Vascular endothelial growth factor (VEGF) production rose 7 days post-Bav injection, supporting its role in angiogenesis. Previous treatment with lumiracoxib promoted release of VEGF levels 21 days post-Bav injury showing that the inhibition of COX-2 pathway in the early stage of revascularization stimulates the neovascularization regulated by elevated release of VEGF. Similarly, metalloproteinases (MMPs), such as MMP-9, MMP-10, and MMP-13, crucial for vascular remodeling, were elevated 21 days after Bav/lumiracoxib treatment. In conclusion, the COX-2 pathway is essential to decrease the high grade of ischemia caused by acute injury induced by Bav. However, the decrease of activity in the COX-2 pathway in the first stages of revascularization contributes to the elevated production of key pro-angiogenic mediators that up-regulate the restoration of microvasculature and blood flow in muscle tissue injured by botropic venoms.

Fracture and Fatigue Crack Growth Behaviour of A516 Gr 60 Steel Welded Joints

The facture and fatigue behaviour of welded joints made of A516 Gr 60 was analysed, bearing in mind their susceptibility to cracking, especially in the case of components which had been in service for a long time period. With respect to fracture, the fracture toughness was determined for all three zones of a welded joint, the base metal (BM), heat-affected zone (HAZ) and weld metal (WM), by applying a standard procedure to evaluate KIc via based on JIc values (ASTM E1820). With respect to fatigue, the fatigue crack growth rates were determined according to the Paris law by the standard procedure (ASTM E647) to evaluate the behaviour of different welded joint zones under amplitude loading. The results obtained for A516 Gr. 60 structural steel showed why it is widely used in the case of static loads, since the minimum value of fracture toughness (185 MPa√m) provides relatively large critical crack lengths, whereas its behaviour under amplitude loading indicated a need for further improvement in WM and HAZ, since the crack growth rate reached values as high as 4.58 × 10−4 mm/cycle. In addition, risk-based analysis was applied to assess the structural integrity of a pressure vessel, including comparison with the high-strength low-alloy (HSLA) steel NIOVAL 50, proving once again its superior behaviour under static loading.

Breast pericytes: a newly identified driver of tumor cell proliferation.

Effective treatment of breast cancer remains a formidable challenge, partly due to our limited understanding of the complex microenvironmental factors that contribute to disease pathology. Among these factors are tissue-resident perivascular cells, which play crucial roles in shaping vascular basement membranes, maintaining vessel integrity, and communicating with adjacent endothelial cells. Despite their essential functions, perivascular cells have been relatively overlooked. Identifying them by immunostaining has been challenging due to their low abundance, inherent heterogeneity, and shared marker expression with other cell types. These challenges have hindered efforts to purify pericytes and generate primary cell models for studying their biology. Using a recently developed FACS method, we successfully identified and purified each cell type from breast tissues, allowing us to deep-sequence their transcriptomes and generate primary cell models of each cell type-including pericytes. Here, we used these data to analyze cell-type-specific gene expression in tumors, which revealed a strong association between pericyte-specific genes and breast cancer patient mortality. To explore this association, we defined the heterogeneity of breast pericytes using single-cell RNA sequencing and identified a broad marker for visualizing perivascular cells in breast tumors. Remarkably, we discovered perivascular cells dissociated from vessels and emerged as a dominant mesenchymal cell type in a subset of breast tumors that contrasted with their normal perivascular location. Moreover, when we purified pericytes from the breast and cultured them alongside breast tumor cells, we discovered that they induced rapid tumor cell growth significantly greater than isogenic fibroblast controls. These findings identify perivascular cells as a key microenvironmental factor in breast cancer, highlighting the critical need for further research to explore their biology and identify specific stimulatory mechanisms that could be targeted therapeutically.

Free Flap Evaluation Following Reconstruction of Locally Advanced Squamous Cell Carcinoma of The Tongue

Background: Neoadjuvant chemotherapy (NAC) is a crucial component in the management of tongue-based locally advanced squamous cell carcinoma (LASCC) due to its ability to decrease tumor mass and facilitate free tissue transplantation. The utilization of adjuvant radiation and chemotherapy has been observed to decelerate the progression of post-operative tumor growth. Probability of free flap failure is elevated. Post-operative complications and the long-term functional outcomes of speaking, salivation, and swallowing determine the quality of free flaps. Methods: A retrospective review of tongue LASCC patients who underwent NAC followed by glossectomy and free tissue transfer from 2015 to 2018. Tongue functional outcomes of speaking, swallowing, and salivation were assessed using FACE-Q scale in 3 times follow-up period. Result: This study included 7 patients who underwent tongue reconstruction. Treatment modalities were based on tumor presentation, with 4 patients (57.1%) receiving Taxane, 5-Fluorouracil, and Paclitaxel/Doclitaxel (TPF), and 3 patients (42.1%) receiving Paclitaxel and 5-Fluorouracil (PF). Tongue reconstruction utilized the radial forearm free flap in 5 patients (71.4%) and the anterolateral thigh free flap in 2 patients (28.6%). Intraoperatively, NAC had no impact on the integrity of small and reliable donor vessels. Three patients died from tumor metastases after the second follow-up assessment, while one patient was lost to follow-up. The study found no significant association between chemotherapy dosage and free flap vitality (P = 0.629). FACE-Q assessments revealed moderate to low scores in speaking, eating, and drinking outcomes. Conclusion: Tongue reconstruction after NAC in LASCC patients remains a challenging procedure for surgeons. While the consideration of surgical difficulties due to damage of the donor vessels demands a more structured pre-operative plan. No correlation between the exposure of NAC or AR to free flap complication as well as functional outcome.

Mechanical forces inducing oxaliplatin resistance in pancreatic cancer can be targeted by autophagy inhibition

Pancreatic cancer remains one of the most lethal malignancies, with limited treatment options and poor prognosis. A common characteristic among pancreatic cancer patients is the biomechanically altered tumor microenvironment (TME), which among others is responsible for the elevated mechanical stresses in the tumor interior. Although significant research has elucidated the effect of mechanical stress on cancer cell proliferation and migration, it has not yet been investigated how it could affect cancer cell drug sensitivity. Here, we demonstrated that mechanical stress triggers autophagy activation, correlated with increased resistance to oxaliplatin treatment in pancreatic cancer cells. Our results demonstrate that inhibition of autophagy using hydroxychloroquine (HCQ) enhanced the oxaliplatin-induced apoptotic cell death in pancreatic cancer cells exposed to mechanical stress. The combined treatment of HCQ with losartan, a known modulator of mechanical abnormalities in tumors, synergistically enhanced the therapeutic efficacy of oxaliplatin in murine pancreatic tumor models. Furthermore, our study revealed that the use of HCQ enhanced the efficacy of losartan to alleviate mechanical stress levels and restore blood vessel integrity beyond its role in autophagy modulation. These findings underscore the potential of co-targeting mechanical stresses and autophagy as a promising therapeutic strategy to overcome drug resistance and increase chemotherapy efficacy.

Mission profile oriented energy efficiency and CO2 footprint assessment of naval vessels at conceptual design phase: A comparative case study of conventional and hybrid energy systems

CO2 is the main green house gas (GHG) produced in fossil fuel burning engines on ships. The growth of activities of sea-going vessels, have been increasing interest and concerns over ship-born CO2 emissions. Consequently, numerous studies have been introduced for emission estimation. Each estimation approach has its own assumptions, thus uncertainty with data of vessel activities, vessel attributes, and calculating methods. The conceptual design phase is the first phase of ship design. One of the issues addressed at this phase is the assessment of energy system alternatives of relevant ship. A ship energy system provides propulsion and electrical power. The assessment of energy system alternatives for a naval vessel is a very complicated business that has a significant impact and interaction on overall vessel integration. Naval vessels and their energy systems constitute a noteworthy part of the total world ship fleet. The present study aims to present a realistic methodology for estimating efficiency, hence CO2 emissions, for candidate energy systems of surface vessels at conceptual design phase. A frigate is selected as the case (baseline) vessel. Three energy systems, namely CODAD, CODOG, and CODLOG-CC, are proposed as alternatives for the case vessel. Instead of general emission estimation approaches, the present study proposes a mission profile-oriented estimation methodology which provides more precise and accurate results. The Energy Efficiency Design Index (EEDI) defines efficiency and sets limitation during design and construction of specific merchant vessels, but since this index does not comply with unique characteristics of mission profile of surface vessels, the novel efficiency design index defined as integral warship EEDI (IWEEDI) is implemented for the case vessel. According to the analysis, CODAD is found to be the most efficient alternative, followed by CODLOG-CC and CODOG, respectively.

Endothelial Rho kinase controls blood vessel integrity and angiogenesis.

The Rho kinases 1 and 2 (ROCK1/2) are serine-threonine specific protein kinases that control actin cytoskeleton dynamics. They are expressed in all cells throughout the body, including cardiomyocytes, smooth muscle cells and endothelial cells, and intimately involved in cardiovascular health and disease. Pharmacological ROCK inhibition is beneficial in mouse models of hypertension, atherosclerosis, and neointimal thickening that display overactivated ROCK. However, the consequences of endothelial ROCK signaling deficiency in vivo remain unknown. To address this issue, we analyzed endothelial cell (EC) specific ROCK1 and 2 deletions. We generated Cdh5-CreERT2 driven, tamoxifen inducible loss of function alleles of ROCK1 and ROCK2 and analyzed mouse survival and vascular defects through cellular, biochemical, and molecular biology approaches. We observed that postnatal or adult loss of endothelial ROCK1 and 2 was lethal within a week. Mice succumbed to multi-organ hemorrhage that occurred because of loss of vascular integrity. ECs displayed deficient cytoskeletal actin polymerization that prevented focal adhesion formation and disrupted junctional integrity. Retinal sprouting angiogenesis was also perturbed, as sprouting vessels exhibited lack of polymerized actin and defective lumen formation. In a three-dimensional endothelial sprouting assay, combined knockdown of ROCK1/2 or knockdown or ROCK2 but not ROCK1 led to reduced sprouting, lumenization and cell polarization defects caused by defective actin and altered VE-cadherin dynamics. The isoform specific role of endothelial ROCK2 correlated with ROCK2 substrate specificity for FAK and LIMK. By analyzing single and three allele mutants we show that one intact allele of ROCK2 is sufficient to maintain vascular integrity in vivo. Endothelial ROCK1 and 2 maintain junctional integrity and ensure proper angiogenesis and lumen formation. The presence of one allele of ROCK2 is sufficient to maintain vascular growth and integrity. These data indicate the need of careful consideration for the use of ROCK inhibitors in disease settings.

Rivaroxaban as a protector of Oxidative Stress-induced Vascular Endothelial Glycocalyx Damage via The IQGAP1/PAR1-2/PI3K/Akt Pathway.

The vascular endothelial glycocalyx, crucial for blood vessel integrity and homeostasis, is vulnerable to oxidative stress, leading to endothelial dysfunction, which strongly correlates with cardiovascular disease (CVD). This study investigates the protective effects of rivaroxaban, a FXa inhibitor, on the glycocalyx under oxidative stress condition. We examined the impact of rivaroxaban on human umbilical vein endothelial cells (HUVECs) exposed to acute and chronic H₂O₂-induced oxidative stress. Rivaroxaban dose-dependently suppressed syndecan-1, a key component of the glycocalyx, shedding from cell surface, and enhanced protease-activated receptor (PAR)1-PAR2/ phosphatidylinositol-3-kinase (PI3K)-dependent cell viability after acute induction of H2O2. This protective effect was linked to the translocation of IQGAP1, a scaffold protein that modulates the actin cytoskeleton, to the perinucleus from the cell membrane. Under chronic H2O2 treatments, rivaroxaban improves cell viability accompanied by an increase in hyaluronidase activities, aiding the turnover and remodeling of hyaluronic acid within the glycocalyx. We identify that rivaroxaban protects against oxidative stress-induced endothelial glycocalyx damage and cell viability through IQGAP1/PAR1-2/PI3K/Akt pathway, offering a potential to be a therapeutic target for CVD prevention.

Targeting endoplasmic reticulum stress-induced lymphatic dysfunction for mitigating bisphosphonate-related osteonecrosis.

Bisphosphonates (BPs) are the first-line treatment to stop bone resorption in diseases, including osteoporosis, Paget's disease, multiple myeloma and bone metastases of cancer. However, BPs-related osteonecrosis of the jaw (BRONJ), characterized by local inflammation and jawbone necrosis, is a severe intractable complication. The cumulative inflammatory burden often accompanies impaired lymphatic drainage, but its specific impact on BRONJ and the underlying mechanisms remain unclear. The mouse BRONJ model was established to assess the integrity and drainage function of lymphatic vessels by tissue clearing techniques, injected indocyanine green lymphatic clearance assay, flow cytometry analysis and histopathological staining. RNA sequencing, metabolome analysis, transmission electron microscopy and Western blotting were utilized to analyze the impacts of Zoledronate acid (ZA) on endoplasmic reticulum stress (ERS) and function of lymphatic endothelial cells (LECs). By constructing Lyve1creERT; SIRT6f/f and Lyve1creERT; ATG5f/f mice, we evaluated the role of ERS-induced LECs apoptosis in the progression of BRONJ. Additionally, we developed a nanoparticle-loaded ZA and rapamycin (ZDPR) to enhance autophagy and evaluated its potential in mitigating BRONJ. The mouse BRONJ model displayed impaired lymphatic drainage, accompanied by significant local inflammation and bone necrosis. The prolonged stimulation of ZA resulted in the extension of ERS and the inhibition of autophagy in LECs, ultimately leading to apoptosis. Mechanistically, ZA activated XBP1s through the NAD+/SIRT6 pathway, initiating ERS-induced apoptosis in LECs. The conditional knockout mouse models demonstrated that the deletion of SIRT6 or ATG5 significantly worsened lymphatic drainage and inflammatory infiltration in BRONJ. Additionally, the innovative nanoparticle ZDPR alleviated ERS-apoptosis in LECs and enhanced lymphatic function, facilitating inflammation resolution. Our study has elucidated the role of the NAD+/SIRT6/XBP1s pathway in ERS-induced apoptosis in ZA-treated LECs, and further confirmed the therapeutic potential of ZDPR in restoring endothelial function and improving lymphatic drainage, thereby effectively mitigating BRONJ. Bisphosphonate-induced lymphatic drainage impairment exacerbates bone necrosis. Zoledronate acid triggers endoplasmic reticulum stress and apoptosis in lymphatic endothelial cells via the NAD+/SIRT6/XBP1s pathway. Novel nanoparticle-loaded Zoledronate acid and rapamycin enhances autophagy, restores lymphatic function, and mitigates bisphosphonates-related osteonecrosis of the jaw progression.

Abstract 098: Endovascular Treatment of Symptomatic Bilateral Carotid Artery Occlusions

Introduction The annual incidence of acute ischemic strokes or transient ischemic attacks due to chronic carotid occlusion (CCO) is estimated at 5‐10%. While initial trials did not show a clear benefit for surgical treatment of symptomatic CCO, emerging data suggests that endovascular treatment (EVT) may offer significant advantages over best medical management (BMM) in selected cases. However, the use of EVT for bilateral symptomatic CCO has not been previously investigated. Method We present the case of a 67‐year‐old male with a history of oropharyngeal carcinoma, treated with extensive neck radiation, leading to bilateral common carotid artery occlusions. The patient, initially presenting for elective gastric endoscopy, experienced hypotension during anesthesia induction and subsequently became comatose. Imaging revealed complete occlusion of the bilateral common carotid arteries and the right vertebral artery, with CT perfusion showing extensive global hypoperfusion correlating with severe EEG attenuation. Due to the failure of medical management, EVT was deemed necessary. Results A femoral approach was utilized for endovascular access to each common carotid artery. The procedure involved the use of a guide catheter, microwires for crossing occlusions, and multiple angioplasties with various balloon sizes to create a passage through the occlusions. An embolic protection device was employed to prevent iatrogenic distal embolization. Rheolytic thrombectomy aided in recanalization, followed by the placement of several stents in a telescopic fashion to achieve vessel patency. Intravascular ultrasound (IVUS) was performed pre‐ and post‐recanalization to evaluate vessel integrity. The procedure resulted in the complete recanalization of both carotid arteries, with subsequent resolution of perfusion abnormalities and normalization of electroencephalographic patterns. The patient returned to his neurological baseline within days post‐procedure. Conclusion This case demonstrates the safe and effective use of EVT for the treatment of bilateral chronic carotid artery occlusions. It highlights the potential of EVT as a promising therapeutic option in managing CCO, particularly in cases where medical management fails.

IL-33/ST2 signaling in monocyte-derived macrophages maintains blood-brain barrier integrity and restricts infarctions early after ischemic stroke

BackgroundBrain microglia and infiltrating monocyte-derived macrophages are vital in preserving blood vessel integrity after stroke. Understanding mechanisms that induce immune cells to adopt vascular-protective phenotypes may hasten the development of stroke treatments. IL-33 is a potent chemokine released from damaged cells, such as CNS glia after stroke. The activation of IL-33/ST2 signaling has been shown to promote neuronal viability and white matter integrity after ischemic stroke. The impact of IL-33/ST2 on blood-brain barrier (BBB) integrity, however, remains unknown. The current study fills this gap and reveals a critical role of IL-33/ST2 signaling in macrophage-mediated BBB protection after stroke.MethodsTransient middle cerebral artery occlusion (tMCAO) was performed to induce ischemic stroke in wildtype (WT) versus ST2 knockout (KO) male mice. IL-33 was applied intranasally to tMCAO mice with or without dietary PLX5622 to deplete microglia/macrophages. ST2 KO versus WT bone marrow or macrophage cell transplantations were used to test the involvement of ST2+ macrophages in BBB integrity. Macrophages were cocultured in transwells with brain endothelial cells (ECs) after oxygen-glucose deprivation (OGD) to test potential direct effects of IL33-treated macrophages on the BBB in vitro.ResultsThe ST2 receptor was expressed in brain ECs, microglia, and infiltrating macrophages. Global KO of ST2 led to more IgG extravasation and loss of ZO-1 in cerebral microvessels 3 days post-tMCAO. Intranasal IL-33 administration reduced BBB leakage and infarct severity in microglia/macrophage competent mice, but not in microglia/macrophage depleted mice. Worse BBB injury was observed after tMCAO in chimeric WT mice reconstituted with ST2 KO bone marrow, and in WT mice whose monocytes were replaced by ST2 KO monocytes. Macrophages treated with IL-33 reduced in vitro barrier leakage and maintained tight junction integrity after OGD. In contrast, IL-33 exerted minimal direct effects on the endothelial barrier in the absence of macrophages. IL-33-treated macrophages demonstrated transcriptional upregulation of an array of protective factors, suggesting a shift towards favorable phenotypes.ConclusionOur results demonstrate that early-stage IL-33/ST2 signaling in infiltrating macrophages reduces the extent of acute BBB disruption after stroke. Intranasal IL-33 administration may represent a new strategy to reduce BBB leakage and infarct severity.

The Lymphatic Highway: How Lymphatics Drive Lung Health and Disease.

The pulmonary lymphatic system has emerged as a critical regulator of lung homeostasis and a key contributor to the pathogenesis of respiratory diseases. As the primary conduit responsible for maintaining fluid balance and facilitating immune cell trafficking, the integrity of lymphatic vessels is essential for preserving normal pulmonary structure and function. Lymphatic abnormalities manifest across a broad spectrum of pulmonary disorders, underscoring their significance in respiratory health and disease. This review provides an overview of pulmonary lymphatic biology and delves into the involvement of lymphatics in four major lung diseases: chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), asthma, and lung transplant rejection. We examine how lymphatic abnormalities manifest in each of these conditions and investigate the mechanisms through which lymphatic remodeling and dysfunction contribute to disease progression. Furthermore, we explore the therapeutic potential of targeting the lymphatic system to ameliorate these debilitating respiratory conditions. Despite the current knowledge, several crucial questions remain unanswered, such as the spatial and temporal dynamics of lymphatic changes, the molecular crosstalk between lymphatics and the lung microenvironment, and the distinction between protective versus detrimental lymphatic phenotypes. Unraveling these mysteries holds the promise of identifying novel molecular regulators, characterizing lymphatic endothelial phenotypes, and uncovering bioactive mediators. By harnessing this knowledge, we can pave the way for the development of innovative disease-modifying therapies targeting the lymphatic highway in lung disorders.

Safety Analysis of Metallic Tokamak-I Against Electromagnetic and Structural Loads

During tokamak operation, the structural integrity of the vacuum vessel (VV) of Metallic Tokamak-I (MT-I), a small spherical tokamak, was evaluated. This evaluation involved simulating real experimental data of electromagnetic (EM) and structural loads using the ANSYS platform. Internal heat generation, induced currents, and inertial and pressure loads in the VV were analyzed to determine their effects on the VV. This analysis was conducted on a 180-deg sector model over a 10-ms-event period. To create multiple checkpoint events, the plasma current was assumed to be formed at variable positions of the VV, hence inducing variable current for each event. The events are divided into four cases based on the radial and vertical displacements of plasma. The response of the VV structure was calculated using coupling of EM and structural modules of ANSYS. It is observed from the numerical results that the maximum stress on the VV is in a safe range and that the temperature rise on the vessel can be reduced by natural convection only if the event is ended in 10 ms. A prolonged event can result in permanent deformation in the VV structure. A disruption event on the limiter region is also studied.

PK Papyrus covered stent to treat traumatic pseudoaneurysm of the internal carotid artery – A technical note and review of the literature

Intracranial pseudoaneurysms account for approximately 1% of all intracranial aneurysms and are associated with high rebleeding risk and mortality. Traditional treatments of these lesions include microsurgical or endovascular reconstruction and parent vessel sacrifice. Reconstruction of the vessel is challenging due to poor vessel integrity and incomplete wall structure. An alternative endovascular reconstructive treatment includes deployment of a covered stent. Original covered stents such as the Jostent Graftmaster and the Willis stent suffer from stiff constructs that limit deployment in tortuous anatomy. The PK Papyrus covered coronary stent may be a satisfactory treatment alternative for these lesions. We present a case of an enlarging traumatic distal cavernous segment internal carotid artery pseudoaneurysm treated with trans-radial deployment of a PK Papyrus stent at our institution. We propose that the PK Papyrus covered stent may be an alternative reconstructive endovascular treatment for intracranial pseudoaneurysms. Further larger scale prospective case series would provide further support for this management strategy.

SAMPO-P: A prototypical scale low-temperature experiment on two-layer melt pool heat transfer in LWR lower head

To better understand the thermal behavior of a two-layer melt pool with a high Rayleigh number—a pattern observed in the RASPLAV study, which indicates a significant risk to pressure vessel integrity and the success of in-vessel retention (IVR) strategies—this paper reports experimental findings from a 2D, full-scale (1:1 ratio) prototypical stratified melt pool (SAMPO-P). A series of experimental tests were carried out with varying heating powers and top layer heights, achieving a Rayleigh number of 3.77×1015, comparable to that found in light water reactors (LWR). Water was used to simulate the bottom layer, while n-octanol represented the top layer. Internal decay heat was modeled in the bottom layer using electric heating rods. After analyzing the main heat transfer parameters from the experiment, this paper derived several useful heat transfer correlations. The normalized temperature and heat flux distributions remained consistent across different power levels, and the normalized heat flux in the bottom layer aligned well with existing experimental correlations. In the bottom layer, the downward heat transfer coefficient was lower compared to other single-layer correlations, likely due to increased upward heat transfer.

THE ROLE OF PERICYTES IN BONE TISSUE REGENERATION AND THERAPEUTIC APPLICATIONS

The regeneration of massive bone defects poses a significant challenge in traumatology and orthopedics, often requiring bone grafting procedures following tumor resection, surgery, or severe injury. Current treatment methods include autologous and allogeneic bone grafts, as well as bone substitutes. While autologous transplantation is considered the standard, it is limited by donor site morbidity and availability. Allogeneic transplantation presents risks such as graft rejection and disease transmission. Bone substitutes may not fully restore bone defects. Tissue-engineered biomaterials offer promise for effective regeneration, utilizing stem cells, growth factors, and scaffolds. Adipose tissue, rich in mesenchymal stem cells and perivascular stem cells (pericytes), is a promising cell source for tissue engineering. This thesis explores the therapeutic potential of pericytes combined with various biological carriers and stimulating factors to enhance bone tissue regeneration. Pericytes, contractile cells surrounding small blood vessels, are crucial for vessel integrity and blood flow regulation. They express markers like α-SMA and PDGFR-β and participate in angiogenesis, immune function, and tissue repair. Interactions with endothelial cells via signaling pathways involving molecules like VEGF and TGF-β are vital for vessel formation and stability. With their multipotent nature, pericytes show promise for regenerative medicine. Ongoing research is essential to address challenges in pericyte biology, including identification and understanding their roles in tissue regeneration. Studies highlight the potential of adipose tissue-derived pericytes in bone regeneration, particularly CD146+ pericytes, showing efficacy in spinal fusion and nonunion fracture treatment when combined with DBM. Preclinical studies confirm their effectiveness, especially when incorporated into various scaffold materials. Clinical studies using adipose-derived stem cells and autologous microfragmented adipose tissue have shown promise, with pericyte-enriched fractions holding potential for improved outcomes. Future research into pericyte application, combined with growth factors and scaffolds, could significantly advance bone tissue regeneration and regenerative medicine. Human pericytes show promise for bone tissue regeneration due to their mesenchymal stem cell properties and role in vascular stabilization. Injectable hydrogels are crucial for bone tissue engineering, with various biomaterials developed for this purpose. Studies using injectable hydrogels with pericytes have demonstrated their efficacy in accelerating bone regeneration in different models. Further advancements in injectable hydrogel technology incorporating stem cells and osteoinductive factors are needed for more efficient bone tissue restoration.

ATM phosphorylation of CD98HC increases antiporter membrane localization and prevents chronic toxic glutamate accumulation in Ataxia telangiectasia.

Ataxia telangiectasia (A-T) is a rare genetic disorder characterized by neurological defects, immunodeficiency, cancer predisposition, radiosensitivity, decreased blood vessel integrity, and diabetes. ATM, the protein mutated in A-T, responds to DNA damage and oxidative stress, but its functional relationship to the progressive clinical manifestation of A-T is not understood. CD98HC chaperones cystine/glutamate (x c - ) and cationic/neutral amino acid (y + L) antiporters to the cell membrane, and CD98HC phosphorylation by ATM accelerates membrane localization to acutely increase amino acid transport. Loss of ATM impacts tissues reliant on SLC family antiporters relevant to A-T phenotypes, such as endothelial cells (telangiectasia) and pancreatic α-cells (fatty liver and diabetes) with toxic glutamate accumulation. Bypassing the antiporters restores intracellular metabolic balance both in ATM-deficient cells and mouse models. These findings provide new insight into the long-known benefits of N-acetyl cysteine to A-T cells beyond oxidative stress through removing excess glutamate by production of glutathione.

Ultralow-dose irradiation enables engraftment and intravital tracking of disease initiating niches in clonal hematopoiesis

Recent advances in imaging suggested that spatial organization of hematopoietic cells in their bone marrow microenvironment (niche) regulates cell expansion, governing progression, and leukemic transformation of hematological clonal disorders. However, our ability to interrogate the niche in pre-malignant conditions has been limited, as standard murine models of these diseases rely largely on transplantation of the mutant clones into conditioned mice where the marrow microenvironment is compromised. Here, we leveraged live-animal microscopy and ultralow dose whole body or focal irradiation to capture single cells and early expansion of benign/pre-malignant clones in the functionally preserved microenvironment. 0.5 Gy whole body irradiation (WBI) allowed steady engraftment of cells beyond 30 weeks compared to non-conditioned controls. In-vivo tracking and functional analyses of the microenvironment showed no change in vessel integrity, cell viability, and HSC-supportive functions of the stromal cells, suggesting minimal inflammation after the radiation insult. The approach enabled in vivo imaging of Tet2+/− and its healthy counterpart, showing preferential localization within a shared microenvironment while forming discrete micro-niches. Notably, stationary association with the niche only occurred in a subset of cells and would not be identified without live imaging. This strategy may be broadly applied to study clonal disorders in a spatial context.

Identification of hypoxic macrophages in glioblastoma: Unveiling therapeutic insights from tumour microenvironment analysis.

Tumor-associatedmacrophages (TAMs) exhibit remarkable heterogeneity in glioblastoma. Spatially resolved single-cell transcriptomic studies identified a monocyte-derived TAM subset localized in the peri-necrotic niche, driven by hypoxic cues to acquire ahypoxia response signature. These hypoxia-TAMs destabilize endothelial adherens junctions through adrenomedullin paracrine signaling, promoting the formation of hyperpermeable neovasculature that impedes drug delivery. Blocking adrenomedullin produced by hypoxia-TAMs restores vascular integrity, increases drug deliveryinto tumors, and provides combinatorial therapeutic benefits. Here we discuss the heterogeneity of TAMs regarding functional states and locations in glioblastomas, and propose future directions for studying the temporospatial dynamics of multifaceted TAM. HIGHLIGHTS: Single-cell omics reveal a functionally and spatially distinct hypoxia-TAM subset in glioblastoma. Adrenomedullin secreted by hypoxia-TAM destabilizes tumor vasculature and its blockade enhances vessel integrity and drug delivery.