Regulation of angiogenesis by oxygen and metabolism

Numerical analysis of coil designs to expedite fracture healing using dielectrophoresis with S method

BACKGROUND

Classical methods for speeding up fracture healing usually rely on direct electrical stimulation and electromagnetic fields to boost the levels of growth factors at the fracture site. However, these techniques often concentrate on bone cells themselves rather than addressing the critical blood flow dynamics necessary for effective healing. This study introduces a mathematical model designed to explore the potential of dielectrophoretic forces (DEPFs) in improving blood flow at the fracture site. By adjusting blood flow, the model seeks to enhance the delivery of vital nutrients, hormones, and growth factors, including endothelial cells (ECs), vascular endothelial growth factor (VEGF) and oxygen, which are essential for accelerating the fracture healing process.

METHOD

The proposed approach includes a new technique, termed the S method, which assesses the non-uniformity of DEPFs by algebraically analyzing the electric field lines associated with positive and negative dielectrophoresis. We developed analytical equations to simulate various coil configurations, focusing on long bone fractures where blood flow is vertically oriented. The DEPF Factor (χDEPF) was used to measure the ratio of blood flow velocity in the presence of DEPFs compared to the absence of DEPFs, thus indicating the effectiveness of DEPF in enhancing blood flow.

RESULTS

The simulation results revealed that DEPF reaches its peak efficacy at the gamma dispersion band, with the most significant enhancement occurring at a frequency of 15 MHz. Specifically, the average values of χDEPF were 1.8, 3.2, and 7.9 for the catenary, lintearia, and valeria coils, respectively. Our computational model, which incorporated VEGF, ECs, and oxygen tension, demonstrated that the catenary coil slightly improved healing rates in impaired fractures, the lintearia coil normalized healing times between impaired and normal fractures, and the valeria coil not only accelerated healing in impaired fractures but also enhanced healing in normal fractures.

CONCLUSIONS

This paper's findings suggest that the valeria coil exhibits the best DEPF functionality, making it the optimal configuration for future experimental studies aimed at evaluating the efficacy of DEPF in promoting fracture healing. The ability of DEPFs to significantly enhance blood flow could represent a substantial advancement in the treatment of both normal and impaired fractures.

Reconstituted High-Density Lipoproteins Rescue Diabetes-Impaired Endothelial Cell Metabolic Reprograming and Angiogenic Responses to Hypoxia

BACKGROUND

Impaired angiogenic responses to ischemia underlie diabetic vascular complications. Reconstituted high-density lipoproteins (rHDLs) have proangiogenic effects in diabetes. The PDK4 (pyruvate dehydrogenase kinase 4)/PDC (pyruvate dehydrogenase complex) axis is an oxygen-conserving mechanism that preserves endothelial cell function 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 the proangiogenic properties of rHDL.

METHODS

Expression of PDK4 and phosphorylated PDC (pPDC) were measured in PBS- or rHDL-treated wounds of nondiabetic and streptozotocin-induced diabetic mice and PBS- or rHDL-treated endothelial cells exposed to glucose and hypoxia. The importance of PDK4 in the action of rHDL was determined by siRNA knockdown in vitro and PDK4 inhibitor in vivo. Chromatin immunoprecipitation assay was performed to identify the mechanism for PDK4 induction by rHDL.

RESULTS

PDK4 and pPDC were elevated early (24 hours) post-induction of wound ischemia in nondiabetic wounds, which did not occur in diabetic mice. Topical rHDL rescued this impairment, enhancing PDK4 (68%; P=0.0041) and pPDC (165%; P=0.029) in diabetic wounds. Wound neovascularization (62%; P<0.05) and closure (154%; P<0.001) were increased in diabetic rHDL-treated wounds. In vitro, PDK4 and pPDC levels were increased with hypoxia (65%, P=0.043 and 64%, P=0.026, respectively). High glucose did not elicit a further stepwise induction in PDK4/pPDC, with aberrant increases in mitochondrial respiration (19%; P=0.026), and impaired angiogenic functions. Importantly, rHDL increased PDK4 and pPDC 2-fold, returning mitochondrial respiration and angiogenic functions to normal glucose levels. PDK4 inhibition ameliorated the proangiogenic effects of rHDL. rHDL increased FOXO1 (forkhead box O1) binding to the PDK4 promoter and suppressed FOXO1 phosphorylation, presenting FOXO1 as a mechanism for rHDL-mediated induction of PDK4.

CONCLUSIONS

The PDK4/PDC axis response to ischemia is impaired in diabetes and is important for the proangiogenic effects of rHDL.

Primary Cilia, Hypoxia, and Liver Dysfunction: A New Perspective on Biliary Atresia

Ciliopathies are disorders that affect primary or secondary cellular cilia or structures associated with ciliary function. Primary cilia (PC) are essential for metabolic regulation and embryonic development, and pathogenic variants in cilia-related genes are linked to several pediatric conditions, including renal-hepatic diseases and congenital defects. Biliary atresia (BA) is a progressive infantile cholangiopathy and the leading cause of pediatric liver transplantation. Although the exact etiology of BA remains unclear, evidence suggests a multifactorial pathogenesis influenced by both genetic and environmental factors. Patients with BA and laterality defects exhibit genetic variants associated with ciliopathies. Interestingly, even isolated BA without extrahepatic anomalies presents morphological and functional ciliary abnormalities, suggesting that environmental triggers may disrupt the ciliary function. Among these factors, hypoxia has emerged as a potential modulator of this dysfunction. Hypoxia-inducible factor 1-alpha (HIF-1α) plays a central role in hepatic responses to oxygen deprivation, influencing bile duct remodeling and fibrosis, which are key processes in BA progression. This review explores the crosstalk between hypoxia and hepatic ciliopathies, with a focus on BA. It discusses the molecular mechanisms through which hypoxia may drive disease progression and examines the therapeutic potential of targeting hypoxia-related pathways. Understanding how oxygen deprivation influences ciliary function may open new avenues for treating biliary ciliopathies and improving patient outcomes.

Current state of epigenetics in giant cell arteritis: Focus on microRNA dysregulation

Giant cell arteritis (GCA) is a primary systemic vasculitis affecting the elderly, characterized by a granulomatous vessel wall inflammation of large- and medium-sized arteries. The immunopathology of GCA is complex, involving both the innate and adaptive arms of the immune system, where a maladaptive inflammatory-driven vascular repair process ultimately results in vessel wall thickening, intramural vascular smooth muscle cell proliferation, neovascularization and vessel lumen occlusion, which can lead to serious ischemic complications such as visual loss and ischemic stroke. Over the past decade, microRNA (miRNA) dysregulation has been highlighted as an important contributing factor underlying the pathogenesis of GCA. Since current understanding of miRNA involvement in GCA remains largely based on extrapolation of previously determined miRNA functions in vitro or in loss- or gain-of-function studies, an overall insight into the role of miRNA alteration in GCA pathophysiology remains limited. In this narrative review, we summarize the current knowledge on aberrantly expressed miRNAs in GCA and thoroughly discuss the impact of their altered regulatory role in the context of GCA setting. Furthermore, we address challenges and future perspectives in utilization of miRNA-based diagnostic and prognostic biomarkers of GCA in clinical settings.

Lipid Nanoparticle Delivery System for Normalization of Tumor Microenvironment and Tumor Vascular Structure

Tumors grow by receiving oxygen and nutrients from the surrounding blood vessels, leading to rapid angiogenesis. This results in functionally and structurally abnormal vasculature characterized by high permeability and irregular blood flow, causing hypoxia within the tumor microenvironment (TME). Hypoxia exacerbates the secretion of pro-angiogenic factors such as vascular endothelial growth factor (VEGF), further perpetuating abnormal vessel formation. This environment compromises the efficacy of radiotherapy, immunotherapy, and chemotherapy. In this study, we developed a pH-sensitive liposome (PSL) system, termed OD_PSL@AKB, to co-deliver oxygen (OD) and razuprotafib (AKB-9778) to tumors. This system rapidly responds to the acidic TME to alleviate hypoxia and inhibit VEGF secretion, restoring VE-cadherin expression in hypoxic endothelial cell/cancer cell cocultures. Our findings highlight the potential of OD_PSL@AKB in normalizing tumor vasculature and improving therapeutic efficacy.

Integrative multi-Omics and network pharmacology reveal angiogenesis promotion by Quan-Du-Zhong Capsule via VEGFA/PI3K-Akt pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Quan-du-zhong capsule (QDZ), derived from the whole plant extract of Eucommiaulmoides Oliv., is a traditional Chinese herbal medicine used in treating vascular-related diseases, including hypertension and osteoporosis. Despite its established uses, its pro-angiogenic effects and underlying mechanisms require further investigation.

AIM OF THIS STUDY

This study aims to investigate the pro-angiogenic effects of QDZ and explore the underlying mechanisms.

MATERIALS AND METHODS

The chemical compositions of QDZ, including its absorbed prototypes in rats, were analyzed using UHPLC-Q Exactive-Orbitrap-MS. The pro-angiogenic activities of QDZ were evaluated in human umbilical vein endothelial cells (HUVECs) through various assays, including CCK-8, migration, scratch, tubule formation, and 3D sprouting assays. Additionally, the pro-angiogenic effects of QDZ were further assessed invivo through the matrigel plug assay and a hindlimb ischemia-reperfusion model, with three-dimensional blood flow visualized via micro-CT. A comprehensive approach involving network pharmacology, molecular docking, transcriptomics, and proteomics was utilized to explore the pro-angiogenic mechanism of QDZ, with validation by Western blot analysis.

RESULTS

QDZ significantly promoted the proliferation, migration, and tubule formation of HUVECs. The matrigel plug assay further confirmed its pro-angiogenic potential. Invivo, QDZ-treated mice displayed enhanced vascular distribution and faster blood flow recovery post-ischemia-reperfusion. Chemical analysis identified 49 compounds in QDZ, with 16 absorbed prototypes detected in rat plasma. Mechanistic investigations through network pharmacology, transcriptomics, and proteomics suggested that QDZ's pro-angiogenic effects were mediated through the VEGFA/PI3K-Akt signaling pathway, with increased phosphorylation of angiogenesis-related proteins such as PI3K, Akt, FAK, and Src.

CONCLUSIONS

This study demonstrates that QDZ promotes angiogenesis via activating the VEGFA and its downstream PI3K-Akt signaling pathway, shedding light on the mechanisms that underpin its traditional medicinal use in vascular health.

Transcriptional profile of the rat cardiovascular system at single-cell resolution

We sought to characterize cellular composition across the cardiovascular system of the healthy Wistar rat, an important model in preclinical cardiovascular research. We performed single-nucleus RNA sequencing (snRNA-seq) in 78 samples in 10 distinct regions, including the four chambers of the heart, ventricular septum, sinoatrial node, atrioventricular node, aorta, pulmonary artery, and pulmonary veins, which produced 505,835 nuclei. We identified 26 distinct cell types and additional subtypes, with different cellular composition across cardiac regions and tissue-specific transcription for each cell type. Several cell subtypes were region specific, including a subtype of vascular smooth muscle cells enriched in the large vasculature. We observed tissue-enriched cellular communication networks, including heightened Nppa-Npr1/2/3 signaling in the sinoatrial node. The existence of tissue-restricted cell types suggests regional regulation of cardiovascular physiology. Our detailed transcriptional characterization of each cell type offers the potential to identify novel therapeutic targets and improve preclinical models of cardiovascular disease.

Matrix stiffness increases energy efficiency of endothelial cells

To form blood vessels, endothelial cells rearrange their cytoskeleton, generate traction stresses, migrate, and proliferate, all of which require energy. Despite these energetic costs, stiffening of the extracellular matrix promotes tumor angiogenesis and increases cell contractility. However, the interplay between extracellular matrix, cell contractility, and cellular energetics remains mechanistically unclear. Here, we utilized polyacrylamide substrates with various stiffnesses, a real-time biosensor of ATP, and traction force microscopy to show that endothelial cells exhibit increasing traction forces and energy usage trend as substrate stiffness increases. Inhibition of cytoskeleton reorganization via ROCK inhibition resulted in decreased cellular energy efficiency, and an opposite trend was found when cells were treated with manganese to promote integrin affinity. Altogether, our data reveal a link between matrix stiffness, cell contractility, and cell energetics, suggesting that endothelial cells on stiffer substrates can better convert intracellular energy into cellular traction forces. Given the critical role of cellular metabolism in cell function, our study also suggests that not only energy production but also the efficiency of its use plays a vital role in regulating cell behaviors and may help explain how increased matrix stiffness promotes angiogenesis.

Enhancing bone repair through improved angiogenesis and osteogenesis using mesoporous silica nanoparticle-loaded Konjac glucomannan-based interpenetrating network scaffolds

We have fabricated and characterized novel bioactive nanocomposite interpenetrating polymer network (IPN) scaffolds to treat bone defects by loading mesoporous silica nanoparticles (MSNs) into blends of Konjac glucomannan, polyvinyl alcohol, and polycaprolactone. By loading MSNs, we developed a porous nanocomposite scaffold with mechanical strengths comparable to cancellous bone. In vitro cell culture studies proved the cytocompatibility of the nanocomposite scaffolds. RT-PCR studies confirmed that these scaffolds significantly upregulated major osteogenic markers. The in vivo chick chorioallantoic membrane (CAM) assay confirmed the proangiogenic activity of the nanocomposite IPN scaffolds. In vivo studies were performed using Wistar rats to evaluate the scaffolds' compatibility, osteogenic activity, and proangiogenic properties. Liver and renal function tests confirmed that these scaffolds were nontoxic. X-ray and μ-CT results show that the bone defects treated with the nanocomposite scaffolds healed at a much faster rate compared to the untreated control and those treated with IPN scaffolds. H&E and Masson's trichrome staining showed angiogenesis near the newly formed bone and the presence of early-stage connective tissues, fibroblasts, and osteoblasts in the defect region at 8 weeks after surgery. Hence, these advantageous physicochemical and biological properties confirm that the nanocomposite IPN scaffolds are ideal for treating bone defects.

The loach haplotype-resolved genome and the identification of Mex3a involved in fish air breathing

Fish air breathing is crucial for the transition of vertebrates from water to land. So far, the genes involved in fish air breathing have not been well identified. Here, we performed gene enrichment analysis of positively selected genes (PSGs) in loach (Misgurnus anguillicaudatus, an air-breathing fish) in comparison to Triplophysa tibetana (a non-air-breathing fish), haplotype-resolved genome assembly of the loach, and gene evolutionary analysis of air-breathing and non-air-breathing fishes and found that the PSG mex3a originated from ancient air-breathing fish species. Deletion of Mex3a impaired loach air-breathing capacity by inhibiting angiogenesis through its interaction with T-box transcription factor 20. Mex3a overexpression significantly promoted angiogenesis. Structural analysis and point mutation revealed the critical role of the 201st amino acid in loach Mex3a for angiogenesis. Our findings innovatively indicate that the ancient mex3a is a fish air-breathing gene, which holds significance for understanding fish air breathing and provides a valuable resource for cultivating hypoxia-tolerant fish varieties.

Mechanical strategies to promote vascularization for tissue engineering and regenerative medicine

Vascularization is a major challenge in the field of tissue engineering and regenerative medicine. Mechanical factors have been demonstrated to play a fundamental role in vasculogenesis and angiogenesis and can affect the architecture of the generated vascular network. Through the regulation of mechanical factors in engineered tissues, various mechanical strategies can be used to optimize the preformed vascular network and promote its rapid integration with host vessels. Optimization of the mechanical properties of scaffolds, including controlling scaffold stiffness, increasing surface roughness and anisotropic structure, and designing interconnected, hierarchical pore structures, is beneficial for the in vitro formation of vascular networks and the ingrowth of host blood vessels. The incorporation of hollow channels into scaffolds promotes the formation of patterned vascular networks. Dynamic stretching and perfusion can facilitate the formation and maturation of preformed vascular networks in vitro. Several indirect mechanical strategies provide sustained mechanical stimulation to engineered tissues in vivo, which further promotes the vascularization of implants within the body. Additionally, stiffness gradients, anisotropic substrates and hollow channels in scaffolds, as well as external cyclic stretch, boundary constraints and dynamic flow culture, can effectively regulate the alignment of vascular networks, thereby promoting better integration of prevascularized engineered tissues with host blood vessels. This review summarizes the influence and contribution of both scaffold-based and external stimulus-based mechanical strategies for vascularization in tissue engineering and elucidates the underlying mechanisms involved.

Theranostics: aptamer-assisted carbon nanotubes as MRI contrast and photothermal agent for breast cancer therapy

Breast cancer is one of the leading causes of death among women globally, making its diagnosis and treatment challenging. The use of nanotechnology for cancer diagnosis and treatment is an emerging area of research. To address this issue, multiwalled carbon nanotubes (MWCNTs) were ligand exchanged with butyric acid (BA) to gain hydrophilic character. The successful functionalization was confirmed by FTIR spectroscopy. Surface morphology changes were observed using SEM, while TEM confirmed the structural integrity of the MWCNTs after functionalization. Particle size, zeta potential, and UV spectroscopy were also performed to further characterize the nanoparticles. The breast cancer aptamer specific to Mucin-1 (MUC-1) was then conjugated with the functionalized MWCNTs. These MWCNTs successfully targeted breast cancer cells (MDA-MB-231) as examined by cellular uptake studies and exhibited a reduction in cancer-induced inflammation, as evidenced by gene transcription (qPCR) and protein expression (immunoblotting) levels. Immunoblot and confocal-based immunofluorescence assay (IFA) indicated the ability of CNTs to induce photothermal cell death of MDA-MB-231 cells. Upon imaging, cancer cells were effectively visualized due to the MWCNTs' ability to act as magnetic resonance imaging (MRI) contrast agents. Additionally, MWCNTs demonstrated photothermal capabilities to eliminate bound cancer cells. Collectively, our findings pave the way for developing aptamer-labeled MWCNTs as viable "theranostic alternatives" for breast cancer treatment.

Endothelial progenitor cells for fabrication of engineered vascular units and angiogenesis induction

The promotion of vascularization and angiogenesis in the grafts is a crucial phenomenon in the healing process and tissue engineering. It has been shown that stem cells, especially endothelial progenitor cells (EPCs), can stimulate blood vessel formation inside the engineered hydrogels after being transplanted into the target sites. The incorporation of EPCs into the hydrogel can last the retention time, long-term survival, on-target delivery effects, migration and differentiation into mature endothelial cells. Despite these advantages, further modifications are mandatory to increase the dynamic growth and angiogenesis potential of EPCs in in vitro and in vivo conditions. Chemical modifications of distinct composites with distinct physical properties can yield better regenerative potential and angiogenesis during several pathologies. Here, we aimed to collect recent findings related to the application of EPCs in engineered vascular grafts and/or hydrogels for improving vascularization in the grafts. Data from the present article can help us in the application of EPCs as valid cell sources in the tissue engineering of several ischemic tissues.

Inhibiting endothelial Rhoj blocks profibrotic vascular intussusception and angiocrine factors to sustain lung regeneration

Lung regeneration after fibrosis requires formation of functional new vasculature, which is essential for gas exchange and cellular cross-talk with other lung cells. It remains unknown how the lung vasculature can be regenerated without fibrosis. Here, we tested the role of N6-methyladenosine (m6A) modification of forkhead box protein O1 (Foxo1) mRNA in lung regeneration after pneumonectomy (PNX) in mice, a model for lung regrowth after surgical resection. Endothelial cell (EC)-specific knockout of methyltransferase-like 3 (Mettl3) and Foxo1 caused nonproductive intussusceptive angiogenesis (IA), which impaired regeneration and enhanced fibrosis. This nonproductive IA was characterized by enhanced endothelial proliferation and increased vascular splitting with increased numbers of pillar ECs. Endothelial-selective knockout of Mettl3 in mice stimulated nonproductive IA and up-regulation of profibrotic factors after PNX, promoting regeneration to fibrotic transition. EC-specific mutation of m6A modification sites in the Foxo1 gene in mice revealed that endothelial Mettl3 modified A504 and A2035 sites in the Foxo1 mRNA to maintain pro-regenerative endothelial glycolysis, ensuring productive IA and lung regeneration without fibrosis. Suppression of Mettl3-Foxo1 signaling stimulated a subset of hyperglycolytic and hyperproliferative 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (Pfkfb3)+, Ras homolog family member J (Rhoj)+, and platelet-derived growth factor subunit B (Pdgfb)+ ECs in both human and mouse lungs with fibrosis. Inhibiting this Pfkfb3+Rhoj+Pdgfb+ EC subset normalized IA, alleviated fibrosis, and restored regeneration in bleomycin (BLM)-injured mouse lungs. We found that m6A modification of Foxo1 in the mouse vasculature promoted lung regeneration over fibrosis after PNX and BLM injury.

Leptin signaling promotes blood vessel formation in the Xenopus tail during the embryo-larval transition

The signals that regulate peripheral blood vessel formation during development are still under investigation. The hormone leptin promotes blood vessel formation, adipose tissue establishment and expansion, tumor growth, and wound healing, but the underlying mechanisms for these actions are currently unknown. We investigated whether leptin promotes angiogenesis in the developing tail fin using embryonic transgenic xflk-1:GFP Xenopus laevis, which express a green fluorescent protein on vascular endothelial cells to mark blood vessels. We found that leptin protein is expressed in endothelial cells of developing blood vessels and that leptin treatment via injection increased phosphorylated STAT3 signaling, which is indicative of leptin activation of its receptor, in blood vessels of the larval tail fin. Leptin administration via media increased vessel length, branching, and reconnection with the cardinal vein, while decreased leptin signaling via immunoneutralization had an opposing effect on vessel development. We also observed disorganization of major vessels and microvessels of the tail fin and muscle when leptin signaling was decreased. Reduced leptin signaling lowered mRNA expression of cenpk, gpx1, and mmp9, markers for cell proliferation, antioxidation, and extracellular matrix remodeling/cell migration, respectively, in the developing tail, providing insight into three possible mechanisms underlying leptin's promotion of angiogenesis. Together these results illustrate that leptin levels are correlated with embryonic angiogenesis and that leptin coordinates multiple aspects of blood vessel growth and development, showing that leptin is an important morphogen during embryonic development.

The Edifice of Vasculature-On-Chips: A Focused Review on the Key Elements and Assembly of Angiogenesis Models

The conception of vascularized organ-on-a-chip models provides researchers with the ability to supply controlled biological and physical cues that simulate the in vivo dynamic microphysiological environment of native blood vessels. The intention of this niche research area is to improve our understanding of the role of the vasculature in health or disease progression in vitro by allowing researchers to monitor angiogenic responses and cell-cell or cell-matrix interactions in real time. This review offers a comprehensive overview of the essential elements, including cells, biomaterials, microenvironmental factors, microfluidic chip design, and standard validation procedures that currently govern angiogenesis-on-a-chip assemblies. In addition, we emphasize the importance of incorporating a microvasculature component into organ-on-chip devices in critical biomedical research areas, such as tissue engineering, drug discovery, and disease modeling. Ultimately, advances in this area of research could provide innovative solutions and a personalized approach to ongoing medical challenges.

Bioactive glass 1393 promotes angiogenesis and accelerates wound healing through ROS/P53/MMP9 signaling pathway

Compared to bioactive glass 45S5, bioactive glass 1393 has shown greater potential in activating tissue cells and promoting angiogenesis for bone repair. Nevertheless, the effect of bioactive glass 1393 in the context of wound healing remains extensively unexplored, and its mechanism in wound healing remains unclear. Considering that angiogenesis is a critical stage in wound healing, we hypothesize that bioactive glass 1393 may facilitate wound healing through the stimulation of angiogenesis. To validate this hypothesis and further explore the mechanisms underlying its pro-angiogenic effects, we investigated the impact of bioactive glass 1393 on wound healing angiogenesis through both in vivo and in vitro studies. The research demonstrated that bioactive glass 1393 accelerated wound healing by promoting the formation of granulation, deposition of collagen, and angiogenesis. The results of Western blot analysis and immunofluorescence staining revealed that bioactive glass 1393 up-regulated the expression of angiogenesis-related factors. Additionally, bioactive glass 1393 inhibited the expression of ROS and P53 to promote angiogenesis. Furthermore, bioactive glass 1393 stimulated angiogenesis through the P53 signaling pathway, as evidenced by P53 activation assays. Collectively, these findings indicate that bioactive glass 1393 accelerates wound healing by promoting angiogenesis via the ROS/P53/MMP9 signaling pathway.

Role of Exosomes in Cancer and Aptamer-Modified Exosomes as a Promising Platform for Cancer Targeted Therapy

Exosomes are increasingly recognized as important mediators of intercellular communication in cancer biology. Exosomes can be derived from cancer cells as well as cellular components in tumor microenvironment. After secretion, the exosomes carrying a wide range of bioactive cargos can be ingested by local or distant recipient cells. The released cargos act through a variety of mechanisms to elicit multiple biological effects and impact most if not all hallmarks of cancer. Moreover, owing to their excellent biocompatibility and capability of being easily engineered or modified, exosomes are currently exploited as a promising platform for cancer targeted therapy. In this review, we first summarize the current knowledge of roles of exosomes in risk and etiology, initiation and progression of cancer, as well as their underlying molecular mechanisms. The aptamer-modified exosome as a promising platform for cancer targeted therapy is then briefly introduced. We also discuss the future directions for emerging roles of exosome in tumor biology and perspective of aptamer-modified exosomes in cancer therapy.

Biomaterials-Based Strategies to Enhance Angiogenesis in Diabetic Wound Healing

Amidst the present healthcare issues, diabetes is unique as an emerging class of affliction with chronicity in a majority of the population. To check and control its effects, there have been huge turnover and constant development of management strategies, and though a bigger part of the health care area is involved in achieving its control and the related issues such as the effect of diabetes on wound healing and care and many of the works have reached certain successful outcomes, still there is a huge lack in managing it, with maximum effect yet to be attained. Studying pathophysiology and involvement of various treatment options, such as tissue engineering, application of hydrogels, drug delivery methods, and enhancing angiogenesis, are at constantly developing stages either direct or indirect. In this review, we have gathered a wide field of information and different new therapeutic methods and targets for the scientific community, paving the way toward more settled ideas and research advances to cure diabetic wounds and manage their outcomes.

Effects of maternal nutrient restriction during gestation on bovine serum microRNA abundance

The objective was to determine the effects of maternal nutrient restriction during gestation on serum microRNA (miRNA) abundance in cattle. Primiparous Angus-cross cows (n=22) were fed either control (CON; to gain 1 Kg/week) or nutrient restricted (NR; 0.55% NEm) diets based on National Research Council requirements. On day 30 of gestation, cows were blocked by body condition and randomly assigned to one of three diets: CON (n=8) days 30-190; NR (n=7) days 30-110 followed by CON days 110-190 (NR/C); or CON (n=7) days 30-110 followed by NR days 110-190 (C/NR). At 190 days of gestation, maternal serum was collected for RNA isolation and analyzed using a miRNA microarray of known Bos taurus sequences. Data were normalized using LOWESS and analyzed via ANOVA. At 190 days of gestation, 16 miRNAs exhibited differential abundance (P<0.05) between treatments. Cows that underwent NR, irrespective of when the insult occurred, had downregulated bta-miR-126-3p compared to CON cows. Bta-miR-16b was downregulated and three miRNAs upregulated in NR/C compared to C/NR and CON cows. Additionally, seven miRNAs were downregulated and four miRNAs upregulated in C/NR compared to NR/C and CON cows. Comparison of NR/C and C/NR cows revealed three differentially abundant (P<0.04) miRNAs (bta-miR-2487_L-2R-3_1ss15CT, bta-miR-215, and bta-miR-760-5p). Top KEGG pathway enrichment of target genes included: pathways in cancer, PI3K-Akt signaling, focal adhesion, Ras signaling, proteoglycans in cancer, and MAPK signaling. In summary, maternal nutrient restriction altered serum miRNA abundance profiles irrespective of the time at which the nutritional insult was induced.

Homeostatic Regulation of Pro-Angiogenic and Anti-Angiogenic Proteins via Hedgehog, Notch Grid, and Ephrin Signaling in Tibial Dyschondroplasia

Precise coupling of two fundamental mechanisms, chondrogenesis and osteogenesis via angiogenesis, plays a crucial role during rapid proliferation of growth plates, and alteration in their balance might lead to pathogenic conditions. Tibial dyschondroplasia (TD) is characterized by an avascular, non-mineralized, jade-white "cartilaginous wedge" with impaired endochondral ossification and chondrocyte proliferation at the proximal end of a tibial bone in rapidly growing poultry birds. Developing vascular structures are dynamic with cartilage growth and are regulated through homeostatic balance among pro and anti-angiogenic proteins and cytokines. Pro-angiogenic factors involves a wide spectrum of multifactorial mitogens, such as vascular endothelial growth factors (VEGF), platelet-derived growth factors (PDGF), basic fibroblast growth factor (bFGF), placental growth factors, transforming growth factor-β (TGF-β), and TNF-α. Considering their regulatory role via the sonic hedgehog, notch-gridlock, and ephrin-B2/EphB4 pathways and inhibition through anti-angiogenic proteins like angiostatin, endostatin, decoy receptors, vasoinhibin, thrombospondin, PEX, and troponin, their possible role in persisting inflammatory conditions like TD was studied in the current literature review. Balanced apoptosis and angiogenesis are vital for physiological bone growth. Any homeostatic imbalance among apoptotic, angiogenetic, pro-angiogenic, or anti-angiogenic proteins ultimately leads to pathological bone conditions like TD and osteoarthritis. The current review might substantiate solid grounds for developing innovative therapeutics for diseases governed by the disproportion of angiogenesis and anti-angiogenesis proteins.

Transcriptional profile of the rat cardiovascular system at single cell resolution

Background

Despite the critical role of the cardiovascular system, our understanding of its cellular and transcriptional diversity remains limited. We therefore sought to characterize the cellular composition, phenotypes, molecular pathways, and communication networks between cell types at the tissue and sub-tissue level across the cardiovascular system of the healthy Wistar rat, an important model in preclinical cardiovascular research. We obtained high quality tissue samples under controlled conditions that reveal a level of cellular detail so far inaccessible in human studies.

Methods and Results

We performed single nucleus RNA-sequencing in 78 samples in 10 distinct regions including the four chambers of the heart, ventricular septum, sinoatrial node, atrioventricular node, aorta, pulmonary artery, and pulmonary veins (PV), which produced an aggregate map of 505,835 nuclei. We identified 26 distinct cell types and additional subtypes, including a number of rare cell types such as PV cardiomyocytes and non-myelinating Schwann cells (NMSCs), and unique groups of vascular smooth muscle cells (VSMCs), endothelial cells (ECs) and fibroblasts (FBs), which gave rise to a detailed cell type distribution across tissues. We demonstrated differences in the cellular composition across different cardiac regions and tissue-specific differences in transcription for each cell type, highlighting the molecular diversity and complex tissue architecture of the cardiovascular system. Specifically, we observed great transcriptional heterogeneities among ECs and FBs. Importantly, several cell subtypes had a unique regional localization such as a subtype of VSMCs enriched in the large vasculature. We found the cellular makeup of PV tissue is closer to heart tissue than to the large arteries. We further explored the ligand-receptor repertoire across cell clusters and tissues, and observed tissue-enriched cellular communication networks, including heightened Nppa - Npr1/2/3 signaling in the sinoatrial node.

Conclusions

Through a large single nucleus sequencing effort encompassing over 500,000 nuclei, we broadened our understanding of cellular transcription in the healthy cardiovascular system. The existence of tissue-restricted cellular phenotypes suggests regional regulation of cardiovascular physiology. The overall conservation in gene expression and molecular pathways across rat and human cell types, together with our detailed transcriptional characterization of each cell type, offers the potential to identify novel therapeutic targets and improve preclinical models of cardiovascular disease.

Conserved and Unique Roles of bHLH-PAS Transcription Factors in Insects - From Clock to Hormone Reception

A dozen bHLH-PAS transcription factors have evolved since the dawn of the animal kingdom; nine of them have mutual orthologs between arthropods and vertebrates. These proteins are master regulators in a range of developmental processes from organogenesis, nervous system formation and functioning, to cell fate decisions defining identity of limbs or photoreceptors for color vision. Among the functionally best conserved are bHLH-PAS proteins acting in the animal circadian clock. On the other side of the spectrum are fundamental physiological mechanisms such as those underlying xenobiotic detoxification, oxygen homeostasis, and metabolic adaptation to hypoxia, infection or tumor progression. Predictably, malfunctioning of bHLH-PAS regulators leads to pathologies. Performance of the individual bHLH-PAS proteins is modulated at multiple levels including dimerization and other protein-protein interactions, proteasomal degradation, and by binding low-molecular weight ligands. Despite the vast evolutionary gap dividing arthropods and vertebrates, and the differences in their anatomy, many functions of orthologous bHLH-PAS proteins are remarkably similar, including at the molecular level. Our phylogenetic analysis shows that one bHLH-PAS protein type has been lost during vertebrate evolution. This protein has a unique function as a receptor of the sesquiterpenoid juvenile hormones of insects and crustaceans. Although some other bHLH-PAS proteins are regulated by binding small molecules, the juvenile hormone receptor presents an unprecedented case, since all other non-peptide animal hormones activate members of the nuclear receptor family. The purpose of this review is to compare and highlight parallels and differences in functioning of bHLH-PAS proteins between insects and vertebrates.

The Triple Crown: NO, CO, and H2S in cancer cell biology

Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) are three endogenously produced gases with important functions in the vasculature, immune defense, and inflammation. It is increasingly apparent that, far from working in isolation, these three exert many effects by modulating each other's activity. Each gas is produced by three enzymes, which have some tissue specificities and can also be non-enzymatically produced by redox reactions of various substrates. Both NO and CO share similar properties, such as activating soluble guanylate cyclase (sGC) to increase cyclic guanosine monophosphate (cGMP) levels. At the same time, H2S both inhibits phosphodiesterase 5A (PDE5A), an enzyme that metabolizes sGC and exerts redox regulation on sGC. The role of NO, CO, and H2S in the setting of cancer has been quite perplexing, as there is evidence for both tumor-promoting and pro-inflammatory effects and anti-tumor and anti-inflammatory activities. Each gasotransmitter has been found to have dual effects on different aspects of cancer biology, including cancer cell proliferation and apoptosis, invasion and metastasis, angiogenesis, and immunomodulation. These seemingly contradictory actions may relate to each gas having a dual effect dependent on its local flux. In this review, we discuss the major roles of NO, CO, and H2S in the context of cancer, with an effort to highlight the dual nature of each gas in different events occurring during cancer progression.

Studying sprouting angiogenesis under combination of oxygen gradients and co-culture of fibroblasts using microfluidic cell culture model

Sprouting angiogenesis is an essential process for expanding vascular systems under various physiological and pathological conditions. In this paper, a microfluidic device capable of integrating a hydrogel matrix for cell culture and generating stable oxygen gradients is developed to study the sprouting angiogenesis of endothelial cells under combinations of oxygen gradients and co-culture of fibroblast cells. The endothelial cells can be cultured as a monolayer endothelium inside the device to mimic an existing blood vessel, and the hydrogel without or with fibroblast cells cultured in it provides a matrix next to the formed endothelium for three-dimensional sprouting of the endothelial cells. Oxygen gradients can be stably established inside the device for cell culture using the spatially-confined chemical reaction method. Using the device, the sprouting angiogenesis under combinations of oxygen gradients and co-culture of fibroblast cells is systematically studied. The results show that the oxygen gradient and the co-culture of fibroblast cells in the hydrogel can promote sprouting of the endothelial cells into the hydrogel matrix by altering cytokines in the culture medium and the physical properties of the hydrogel. The developed device provides a powerful in vitro model to investigate sprouting angiogenesis under various in vivo-like microenvironments.

NF-κB: a mediator that promotes or inhibits angiogenesis in human diseases?

The nuclear factor of κ-light chain of enhancer-activated B cells (NF-κB) signaling pathway, which is conserved in invertebrates, plays a significant role in human diseases such as inflammation-related diseases and carcinogenesis. Angiogenesis refers to the growth of new capillary vessels derived from already existing capillaries and postcapillary venules. Maintaining normal angiogenesis and effective vascular function is a prerequisite for the stability of organ tissue function, and abnormal angiogenesis often leads to a variety of diseases. It has been suggested that NK-κB signalling molecules under pathological conditions play an important role in vascular differentiation, proliferation, apoptosis and tumourigenesis by regulating the transcription of multiple target genes. Many NF-κB inhibitors are being tested in clinical trials for cancer treatment and their effect on angiogenesis is summarised. In this review, we will summarise the role of NF-κB signalling in various neovascular diseases, especially in tumours, and explore whether NF-κB can be used as an attack target or activation medium to inhibit tumour angiogenesis.

STAT3 and HIF1α cooperatively mediate the transcriptional and physiological responses to hypoxia

STAT3 and HIF1α are two fundamental transcription factors involved in many merging processes, like angiogenesis, metabolism, and cell differentiation. Notably, under pathological conditions, the two factors have been shown to interact genetically, but both the molecular mechanisms underlying such interactions and their relevance under physiological conditions remain unclear. In mouse embryonic stem cells (ESCs) we manage to determine the specific subset of hypoxia-induced genes that need STAT3 to be properly transcribed and, among them, fundamental genes like Vegfa, Hk1, Hk2, Pfkp and Hilpda are worth mentioning. Unexpectedly, we also demonstrated that the absence of STAT3 does not affect the expression of Hif1α mRNA nor the stabilization of HIF1α protein, but the STAT3-driven regulation of the hypoxia-dependent subset of gene could rely on the physical interaction between STAT3 and HIF1α. To further elucidate the physiological roles of this STAT3 non-canonical nuclear activity, we used a CRISPR/Cas9 zebrafish stat3 knock-out line. Notably, hypoxia-related fluorescence of the hypoxia zebrafish reporter line (HRE:mCherry) cannot be induced when Stat3 is not active and, while Stat3 Y705 phosphorylation seems to have a pivotal role in this process, S727 does not affect the Stat3-dependent hypoxia response. Hypoxia is fundamental for vascularization, angiogenesis and immune cells mobilization; all processes that, surprisingly, cannot be induced by low oxygen levels when Stat3 is genetically ablated. All in all, here we report the specific STAT3/HIF1α-dependent subset of genes in vitro and, for the first time with an in vivo model, we determined some of the physiological roles of STAT3-hypoxia crosstalk.

Review on Additives in Hydrogels for 3D Bioprinting of Regenerative Medicine: From Mechanism to Methodology

The regeneration of biological tissues in medicine is challenging, and 3D bioprinting offers an innovative way to create functional multicellular tissues. One common way in bioprinting is bioink, which is one type of the cell-loaded hydrogel. For clinical application, however, the bioprinting still suffers from satisfactory performance, e.g., in vascularization, effective antibacterial, immunomodulation, and regulation of collagen deposition. Many studies incorporated different bioactive materials into the 3D-printed scaffolds to optimize the bioprinting. Here, we reviewed a variety of additives added to the 3D bioprinting hydrogel. The underlying mechanisms and methodology for biological regeneration are important and will provide a useful basis for future research.

Blood pressure and risk of venous thromboembolism: a cohort analysis of 5.5 million UK adults and Mendelian randomization studies

AIMS

Evidence for the effect of elevated blood pressure (BP) on the risk of venous thromboembolism (VTE) has been conflicting. We sought to assess the association between systolic BP and the risk of VTE.

METHODS AND RESULTS

Three complementary studies comprising an observational cohort analysis, a one-sample and two-sample Mendelian randomization were conducted using data from 5 588 280 patients registered in the Clinical Practice Research Datalink (CPRD) dataset and 432 173 UK Biobank participants with valid genetic data. Summary statistics of International Network on Venous Thrombosis genome-wide association meta-analysis was used for two-sample Mendelian randomization. The primary outcome was the first occurrence of VTE event, identified from hospital discharge reports, death registers, and/or primary care records. In the CPRD cohort, 104 017(1.9%) patients had a first diagnosis of VTE during the 9.6-year follow-up. Each 20 mmHg increase in systolic BP was associated with a 7% lower risk of VTE [hazard ratio: 0.93, 95% confidence interval (CI): (0.92-0.94)]. Statistically significant interactions were found for sex and body mass index, but not for age and subtype of VTE (pulmonary embolism and deep venous thrombosis). Mendelian randomization studies provided strong evidence for the association between systolic BP and VTE, both in the one-sample [odds ratio (OR): 0.69, (95% CI: 0.57-0.83)] and two-sample analyses [OR: 0.80, 95% CI: (0.70-0.92)].

CONCLUSION

We found an increased risk of VTE with lower BP, and this association was independently confirmed in two Mendelian randomization analyses. The benefits of BP reduction are likely to outweigh the harms in most patient groups, but in people with predisposing factors for VTE, further BP reduction should be made cautiously.

System-wide health risk prediction for 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene(MBP), a major active metabolite of environmental pollutant and food contaminant - Bisphenol A

Human exposure to plastic contaminated foods and environmental micro/nano plastic derived chemicals necessitates system-wide health risk assessment. Hence, current study intend to explore the mode of action (MoA) based adverse outcome pathways of 4-methyl-2,4-bis(4-hydroxyphenyl)pent-1-ene (MBP), the major active metabolite of bisphenol A (BPA). The computational study employed broad range of target prediction, systems biology tools and molecular docking protocols. Further, validation of MBP targets was done using protein-ligand fluorescence quenching assay, endothelial cell culture and chicken embryo vascular angiogenesis models. Interestingly, the current results illustrate that various physiological signaling pathways (MAPK and VEGF related angiogenesis signaling) and disease progression pathways (hypertension, cancer and endocrine disorders) were enriched as potential targets of MBP. Further, docking studies highlights the possible binding mechanism of MBP with important targets including endothelial nitric oxide synthase (eNOS) and serum albumin (BSA). In addition, the validation studies on MBP-BSA interaction (fluorescence quenching), eNOS derived nitric oxide (NOx) generation in endothelial cells and chicken embryo angiogenesis support the system-wide impacts of MBP with highlights on cardiovascular pathogenesis. Thus, the current observation provides novel insights into the system wide impacts of MBP for the futuristic health risk assessment of plastic derived chemicals.

Extracellular Matrix (ECM) and Fibrosis in Adipose Tissue: Overview and Perspectives

Fibrosis in adipose tissue is a major driver of obesity-related metabolic dysregulation. It is characterized by an overaccumulation of extracellular matrix (ECM) during unhealthy expansion of adipose tissue in response to over nutrition. In obese adipose-depots, hypoxia stimulates multiple pro-fibrotic signaling pathways in different cell populations, thereby inducing the overproduction of the ECM components, including collagens, noncollagenous proteins, and additional enzymatic components of ECM synthesis. As a consequence, local fibrosis develops. The result of fibrosis-induced mechanical stress not only triggers cell necrosis and inflammation locally in adipose tissue but also leads to system-wide lipotoxicity and insulin resistance. A better understanding of the mechanisms underlying the obesity-induced fibrosis will help design therapeutic approaches to reduce or reverse the pathological changes associated with obese adipose tissue. Here, we aim to summarize the major advances in the field, which include newly identified fibrotic factors, cell populations that contribute to the fibrosis in adipose tissue, as well as novel mechanisms underlying the development of fibrosis. We further discuss the potential therapeutic strategies to target fibrosis in adipose tissue for the treatment of obesity-linked metabolic diseases and cancer. © 2023 American Physiological Society. Compr Physiol 13:4387-4407, 2023.

Electrospun hybrid nanofibers: Fabrication, characterization, and biomedical applications

Nanotechnology is one of the most promising technologies available today, holding tremendous potential for biomedical and healthcare applications. In this field, there is an increasing interest in the use of polymeric micro/nanofibers for the construction of biomedical structures. Due to its potential applications in various fields like pharmaceutics and biomedicine, the electrospinning process has gained considerable attention for producing nano-sized fibers. Electrospun nanofiber membranes have been used in drug delivery, controlled drug release, regenerative medicine, tissue engineering, biosensing, stent coating, implants, cosmetics, facial masks, and theranostics. Various natural and synthetic polymers have been successfully electrospun into ultrafine fibers. Although biopolymers demonstrate exciting properties such as good biocompatibility, non-toxicity, and biodegradability, they possess poor mechanical properties. Hybrid nanofibers from bio and synthetic nanofibers combine the characteristics of biopolymers with those of synthetic polymers, such as high mechanical strength and stability. In addition, a variety of functional agents, such as nanoparticles and biomolecules, can be incorporated into nanofibers to create multifunctional hybrid nanofibers. Due to the remarkable properties of hybrid nanofibers, the latest research on the unique properties of hybrid nanofibers is highlighted in this study. Moreover, various established hybrid nanofiber fabrication techniques, especially the electrospinning-based methods, as well as emerging strategies for the characterization of hybrid nanofibers, are summarized. Finally, the development and application of electrospun hybrid nanofibers in biomedical applications are discussed.

Succinate at the Crossroad of Metabolism and Angiogenesis: Roles of SDH, HIF1α and SUCNR1

Angiogenesis is an essential process by which new blood vessels develop from existing ones. While adequate angiogenesis is a physiological process during, for example, tissue repair, insufficient and excessive angiogenesis stands on the pathological side. Fine balance between pro- and anti-angiogenic factors in the tissue environment regulates angiogenesis. Identification of these factors and how they function is a pressing topic to develop angiogenesis-targeted therapeutics. During the last decade, exciting data highlighted non-metabolic functions of intermediates of the mitochondrial Krebs cycle including succinate. Among these functions is the contribution of succinate to angiogenesis in various contexts and through different mechanisms. As the concept of targeting metabolism to treat a wide range of diseases is rising, in this review we summarize the mechanisms by which succinate regulates angiogenesis in normal and pathological settings. Gaining a comprehensive insight into how this metabolite functions as an angiogenic signal will provide a useful approach to understand diseases with aberrant or excessive angiogenic background, and may provide strategies to tackle them.

An Altered Neurovascular System in Aging-Related Eye Diseases

The eye has a complex and metabolically active neurovascular system. Repeated light injuries induce aging and trigger age-dependent eye diseases. Damage to blood vessels is related to the disruption of the blood-retinal barrier (BRB), altered cellular communication, disrupted mitochondrial functions, and exacerbated aggregated protein accumulation. Vascular complications, such as insufficient blood supply and BRB disruption, have been suggested to play a role in glaucoma, age-related macular degeneration (AMD), and Alzheimer's disease (AD), resulting in neuronal cell death. Neuronal loss can induce vision loss. In this review, we discuss the importance of the neurovascular system in the eye, especially in aging-related diseases such as glaucoma, AMD, and AD. Beneficial molecular pathways to prevent or slow down retinal pathologic processes will also be discussed.

Chemical inhibition of oxygen-sensing prolyl hydroxylases impairs angiogenic competence of human vascular endothelium through metabolic reprogramming

Endothelial cell (EC) metabolism has emerged as a driver of angiogenesis. While hypoxia inactivates the oxygen sensors prolyl-4 hydroxylase domain-containing proteins 1-3 (PHD1-3) and stimulates angiogenesis, the effects of PHDs on EC functions remain poorly defined. Here, we investigated the impact of chemical PHD inhibition by dimethyloxalylglycine (DMOG) on angiogenic competence and metabolism of human vascular ECs. DMOG reduced EC proliferation, migration, and tube formation capacities, responses that were associated with an unfavorable metabolic reprogramming. While glycolytic genes were induced, multiple genes encoding sub-units of mitochondrial complex I were suppressed with concurrent decline in nicotinamide adenine dinucleotide (NAD+) levels. Importantly, the DMOG-induced defects in EC migration could be partially rescued by augmenting NAD+ levels through nicotinamide riboside or citrate supplementation. In summary, by integrating functional assays, transcriptomics, and metabolomics, we provide insights into the effects of PHD inhibition on angiogenic competence and metabolism of human vascular ECs.

Stearoyl-CoA Desaturase Regulates Angiogenesis and Energy Metabolism in Ischemic Cardiomyocytes

New blood vessel formation is a key component of the cardiac repair process after myocardial infarction (MI). Hypoxia following MI is a major driver of angiogenesis in the myocardium. Hypoxia-inducible factor 1α (HIF1α) is the key regulator of proangiogenic signaling. The present study found that stearoyl-CoA desaturase (SCD) significantly contributed to the induction of angiogenesis in the hypoxic myocardium independently of HIF1α expression. The pharmacological inhibition of SCD activity in HL-1 cardiomyocytes and SCD knockout in an animal model disturbed the expression and secretion of proangiogenic factors including vascular endothelial growth factor-A, proinflammatory cytokines (interleukin-1β, interleukin-6, tumor necrosis factor α, monocyte chemoattractant protein-1, and Rantes), metalloproteinase-9, and platelet-derived growth factor in ischemic cardiomyocytes. These disturbances affected the proangiogenic potential of ischemic cardiomyocytes after SCD depletion. Together with the most abundant SCD1 isoform, the heart-specific SCD4 isoform emerged as an important regulator of new blood vessel formation in the murine post-MI myocardium. We also provide evidence that SCD shapes energy metabolism of the ischemic heart by maintaining the shift from fatty acids to glucose as the substrate that is used for adenosine triphosphate production. Furthermore, we propose that the regulation of the proangiogenic properties of hypoxic cardiomyocytes by key modulators of metabolic signaling such as adenosine monophosphate kinase, protein kinase B (AKT), and peroxisome-proliferator-activated receptor-γ coactivator 1α/peroxisome proliferator-activated receptor α depends on SCD to some extent. Thus, our results reveal a novel mechanism that links SCD to cardiac repair processes after MI.

Potential of the TRPM7 channel as a novel therapeutic target for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is an intractable vascular disease characterized by a progressive increase in pulmonary vascular resistance caused by pulmonary vascular remodeling, which ultimately leads to right-sided heart failure. PAH remains incurable, despite the development of PAH-targeted therapeutics centered on pulmonary artery relaxants. It is necessary to identify the target molecules that contribute to pulmonary artery remodeling. Transient receptor potential (TRP) channels have been suggested to modulate pulmonary artery remodeling. Our study focused on the transient receptor potential ion channel subfamily M, member 7, or the TRPM7 channel, which modulates endothelial-to-mesenchymal transition and smooth muscle proliferation in the pulmonary artery. In this review, we summarize the role and expression profile of TRPM7 channels in PAH progression and discuss TRPM7 channels as possible therapeutic targets. In addition, we discuss the therapeutic effect of a Chinese herbal medicine, Ophiocordyceps sinensis (OCS), on PAH progression, which partly involves TRPM7 inhibition.

Insulin regulates neurovascular coupling through astrocytes

Mice with insulin receptor (IR)-deficient astrocytes (GFAP-IR knockout [KO] mice) show blunted responses to insulin and reduced brain glucose uptake, whereas IR-deficient astrocytes show disturbed mitochondrial responses to glucose. While exploring the functional impact of disturbed mitochondrial function in astrocytes, we observed that GFAP-IR KO mice show uncoupling of brain blood flow with glucose uptake. Since IR-deficient astrocytes show higher levels of reactive oxidant species (ROS), this leads to stimulation of hypoxia-inducible factor-1α and, consequently, of the vascular endothelial growth factor angiogenic pathway. Indeed, GFAP-IR KO mice show disturbed brain vascularity and blood flow that is normalized by treatment with the antioxidant N-acetylcysteine (NAC). NAC ameliorated high ROS levels, normalized angiogenic signaling and mitochondrial function in IR-deficient astrocytes, and normalized neurovascular coupling in GFAP-IR KO mice. Our results indicate that by modulating glucose uptake and angiogenesis, insulin receptors in astrocytes participate in neurovascular coupling.

A Retrospective Case Series on Free Flap Reconstruction for Ischemic Diabetic Foot: The Nutrient Flap Further Explained

BACKGROUND

This retrospective case series compares the outcomes and postoperative oxygen levels in patients who underwent free flap versus primary closure/local flap reconstruction for ischemic diabetic foot wounds to determine the influence of free flap on the surrounding ischemic tissues. The authors hypothesized that the free flap would benefit the surrounding ischemic tissue as a nutrient flap by increasing the tissue oxygen content.

METHODS

The patients were divided into two groups: group 1 underwent free flap reconstruction, and group 2 underwent partial foot amputation with primary closure/local flap. Patient demographics, endovascular intervention, surgical outcome, postreconstruction intervention, and prereconstruction and postreconstruction transcutaneous oximetry were analyzed.

RESULTS

Among 54 patients, 36 were in group 1 and 18 were in group 2. There were no differences in patient demographics between the two groups. All patients had successful angioplasty. Statistical significance was noted in postreconstruction intervention in which group 2 required 2.8 ± 2.9 débridements (versus 1.2 ± 2.5 for group 1) and seven of 18 below-knee amputations (versus three of 36 for group 1) (p < 0.05). Transcutaneous partial pressure of oxygen levels were significantly higher in group 1 at 6 months after reconstruction (61.6 ± 7.5 versus 32.6 ± 5.8 mmHg) (p < 0.01).

CONCLUSION

This study shows that the role of the free flap in ischemic diabetic limb may expand beyond that of providing coverage over the vital structures, and it supports the use of the free flap as a nutrient to increase oxygen content in the ischemic diabetic foot.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Prolyl Hydroxylase Domain Protein Inhibitor Not Harboring a 2-Oxoglutarate Scaffold Protects against Hypoxic Stress

Hypoxia-inducible factor-α (HIF-α) activation has shown promising results in the treatment of ischemia, such as stroke, myocardial infarction, and chronic kidney disease. A number of HIF-α activators have been developed to improve the symptoms of these diseases. Many feature 2-oxoglutarate (2-OG) scaffolds that interact with the active centers of prolyl hydroxylase domain-containing proteins (PHDs), displacing the coenzyme 2-OG. This stabilizes HIF-α. Therefore, the specificity of the 2-OG analogs is not high. Here, we identified 5-(1-acetyl-5-phenylpyrazolidin-3-ylidene)-1,3-dimethylbarbituric acid (PyrzA) among over 10 000 compounds as a novel HIF activator that does not contain a 2-OG scaffold. In cultured cells, PyrzA enhanced HIF-α stability and upregulated the expression of HIF target genes. Interestingly, PyrzA decreased HIF-1α prolyl hydroxylation, suggesting that PyrzA may activate HIF to prevent the degradation of HIF-α. These results indicate that PyrzA stabilizes HIF via a novel mechanism and could be a potential HIF activator candidate.

Electron Transfer Flavoprotein (ETF) α Controls Blood Vessel Development by Regulating Endothelial Mitochondrial Bioenergetics and Oxygen Consumption

While impairment of vascular homeostasis induced by hypercholesterolemia is the first step of cardiovascular diseases, the molecular mechanism behind such impairment is not well known. Here, we reported that high-cholesterol diet (HCD) induced defective vessel sprouting in zebrafish larvae. Electron transfer flavoprotein subunit α (ETFα) (encoded by the ETFA gene), a protein that mediates transfer of electrons from a series of mitochondrial flavoenzymes to the respiratory chain, was downregulated in HCD-fed zebrafish and in endothelial cells treated with oxidized low-density lipoprotein. Knockdown of ETFα with morpholino antisense oligonucleotides reproduced vascular sprouting defects in zebrafish larvae, while replenishing with exogeneous ETFA mRNA could successfully rescue these defects. ETFA knockdown in endothelial cells reduces cell migration, proliferation, and tube formation in vitro. Finally, knockdown of ETFA in endothelial cells also reduced fatty acid oxidation, oxygen consumption rate, and hypoxia-inducible factor-1α (HIF1α) protein levels. Taken together, we demonstrate that downregulation of ETFα is involved in hypercholesterolemia-induced defective vessel sprouting in zebrafish larvae via inhibition of endothelial proliferation and migration. The molecular mechanism behind this phenomenon is the decrease of HIF1α induced by downregulation of ETFα in endothelial cells. This work suggests that disturbance of ETFα-mediated oxygen homeostasis is one of the mechanisms behind hypercholesterolemia-induced vascular dysfunction.

3D Microvascularized Tissue Models by Laser-Based Cavitation Molding of Collagen

3D tissue models recapitulating human physiology are important for fundamental biomedical research, and they hold promise to become a new tool in drug development. An integrated and defined microvasculature in 3D tissue models is necessary for optimal cell functions. However, conventional bioprinting only allows the fabrication of hydrogel scaffolds containing vessel-like structures with large diameters (>100 µm) and simple geometries. Recent developments in laser photoablation enable the generation of this type of structure with higher resolution and complexity, but the photo-thermal process can compromise cell viability and hydrogel integrity. To address these limitations, the present work reports in situ 3D patterning of collagen hydrogels by femtosecond laser irradiation to create channels and cavities with diameters ranging from 20 to 60 µm. In this process, laser irradiation of the hydrogel generates cavitation gas bubbles that rearrange the collagen fibers, thereby creating stable microchannels. Such 3D channels can be formed in cell- and organoid-laden hydrogel without affecting the viability outside the lumen and can enable the formation of artificial microvasculature by the culture of endothelial cells and cell media perfusion. Thus, this method enables organs-on-a-chip and 3D tissue models featuring complex microvasculature.

Angiogenesis: A Pivotal Therapeutic Target in the Drug Development of Gynecologic Cancers

Since the discovery of angiogenesis and its relevance to the tumorigenesis of gynecologic malignancies, a number of therapeutic agents have been developed over the last decade, some of which have become standard treatments in combination with other therapies. Limited clinical activity has been demonstrated with anti-angiogenic monotherapies, and ongoing trials are focused on combination strategies with cytotoxic agents, immunotherapies and other targeted treatments. This article reviews the science behind angiogenesis within the context of gynecologic cancers, the evidence supporting the targeting of these pathways and future directions in clinical trials.

Impact of Oxidative Stress on Embryogenesis and Fetal Development

Multiple cellular processes are regulated by oxygen radicals or reactive oxygen species (ROS) where they play crucial roles as primary or secondary messengers, particularly during cell proliferation, differentiation, and apoptosis. Embryogenesis and organogenesis encompass all these processes; therefore, their role during these crucial life events cannot be ignored, more so when there is an imbalance in redox homeostasis. Perturbed redox homeostasis is responsible for damaging the biomolecules such as lipids, proteins, and nucleic acids resulting in leaky membrane, altered protein, enzyme function, and DNA damage which have adverse impact on the embryo and fetal development. In this article, we attempt to summarize the available data in literature for an in-depth understanding of redox regulation during development that may help in optimizing the pregnancy outcome both under natural and assisted conditions.

β3-Adrenoceptor, a novel player in the round-trip from neonatal diseases to cancer: Suggestive clues from embryo

The role of the β-adrenoceptors (β-ARs) in hypoxia-driven diseases has gained visibility after the demonstration that propranolol promotes the regression of infantile hemangiomas and ameliorates the signs of retinopathy of prematurity (ROP). Besides the role of β2-ARs, preclinical studies in ROP have also revealed that β3-ARs are upregulated by hypoxia and that they are possibly involved in retinal angiogenesis. In a sort of figurative round trip, peculiarities typical of ROP, where hypoxia drives retinal neovascularization, have been then translated to cancer, a disease equally characterized by hypoxia-driven angiogenesis. In this step, investigating the role of β3-ARs has taken advantage of the assumption that cancer growth uses a set of strategies in common with embryo development. The possibility that hypoxic induction of β3-ARs may represent one of the mechanisms through which primarily embryo (and then cancer, as an astute imitator) adapts to grow in an otherwise hostile environment, has grown evidence. In both cancer and embryo, β3-ARs exert similar functions by exploiting a metabolic shift known as the Warburg effect, by acquiring resistance against xenobiotics, and by inducing a local immune tolerance. An additional potential role of β3-AR as a marker of stemness has been suggested by the finding that its antagonism induces cancer cell differentiation evoking that β3-ARs may help cancer to grow in a nonhospital environment, a strategy also exploited by embryos. From cancer, the round trip goes back to neonatal diseases for which new possible interpretative keys and potential pharmacological perspectives have been suggested.

COX5B-Mediated Bioenergetic Alterations Modulate Cell Growth and Anticancer Drug Susceptibility by Orchestrating Claudin-2 Expression in Colorectal Cancers

Oxidative phosphorylation (OXPHOS) consists of four enzyme complexes and ATP synthase, and is crucial for maintaining physiological tissue and cell growth by supporting the main bioenergy pool. Cytochrome c oxidase (COX) has been implicated as a primary regulatory site of OXPHOS. Recently, COX subunit 5B (COX5B) emerged as a potential biomarker associated with unfavorable prognosis by modulating cell behaviors in specific cancer types. However, its molecular mechanism remains unclear, particularly in colorectal cancers (CRCs). To understand the role of COX5B in CRCs, the expression and postoperative outcome associations using independent in-house patient cohorts were evaluated. A higher COX5B tumor/nontumor expression ratio was associated with unfavorable clinical outcomes (p = 0.001 and 0.011 for overall and disease-free survival, respectively. In cell-based experiments, the silencing of COX5B repressed cell growth and enhanced the susceptibility of CRCs cells to anticancer drugs. Finally, downstream effectors identified by RNA sequencing followed by RT-qPCR and functional compensation experiments revealed that the tight junction protein Claudin-2 (CLDN2) acts downstream of COX5B-mediated bioenergetic alterations in controlling cell growth and the sensitivity to anticancer drugs in CRCs cells. In conclusion, it was found that COX5B promoted cell growth and attenuated anticancer drugs susceptibility in CRCs cells by orchestrating CLDN2 expression, which may contribute to unfavorable postoperative outcomes of patients with CRCs.

Cx43 Promotes Endothelial Cell Migration and Angiogenesis via the Tyrosine Phosphatase SHP-2

The gap junction protein connexin 43 (Cx43) is associated with increased cell migration and to related changes of the actin cytoskeleton, which is mediated via its C-terminal cytoplasmic tail and is independent of its channel function. Cx43 has been shown to possess an angiogenic potential, however, the role of Cx43 in endothelial cell migration has not yet been investigated. Here, we found that the knock-down of Cx43 by siRNA in human microvascular endothelial cells (HMEC) reduces migration, as assessed by a wound assay in vitro and impaired aortic vessel sprouting ex vivo. Immunoprecipitation of Cx43 revealed an interaction with the tyrosine phosphatase SHP-2, which enhanced its phosphatase activity, as observed in Cx43 expressing HeLa cells compared to cells treated with an empty vector. Interestingly, the expression of a dominant negative substrate trapping mutant SHP-2 (CS) in HMEC, via lentiviral transduction, also impaired endothelial migration to a similar extent as Cx43 siRNA compared to SHP-2 WT. Moreover, the reduction in endothelial migration upon Cx43 siRNA could not be rescued by the introduction of a constitutively active SHP-2 construct (EA). Our data demonstrate that Cx43 and SHP-2 mediate endothelial cell migration, revealing a novel interaction between Cx43 and SHP-2, which is essential for this process.

Circ_0006768 upregulation attenuates oxygen-glucose deprivation/reoxygenation-induced human brain microvascular endothelial cell injuries by upregulating VEZF1 via miR-222-3p inhibition

Circular RNAs (circRNAs) have been widely implicated in multiple diseases, including ischemic stroke. This study aimed to explore the function and functional mechanism of circ_0006768 in oxygen-glucose deprivation/reoxygenation (OGD/R)-induced brain injury models of ischemic stroke. Human brain microvascular endothelial cells (HBMECs) were induced by OGD/R to mimic ischemic stroke models in vitro. The expression of circ_0006768, microRNA-222-3p (miR-222-3p) and vascular endothelial zinc finger 1 (VEZF1) was detected by quantitative real-time PCR (qPCR). Cell viability, angiogenesis ability and cell migration were assessed by cell counting kit-8 (CCK-8) assay, tube formation assay and wound healing assay, respectively. The releases of pro-inflammatory factors were determined by commercial enzyme-linked immunosorbent assay (ELISA) kits. The protein levels of vascular endothelial growth factor A (VEGFA), N-cadherin and VEZF1 were detected by western blot. The putative relationship between miR-222-3p and circ_0006768 or VEZF1 was validated by dual-luciferase reporter assay, RNA Immunoprecipitation (RIP) assay and pull-down assay. Circ_0006768 was poorly expressed in ischemic stroke plasma and OGD/R-induced HBMECs. OGD/R inhibited cell viability, angiogenesis and cell migration and promoted the releases of pro-inflammatory factors, while circ_0006768 overexpression or miR-222-3p inhibition partially abolished the effects of OGD/R. MiR-222-3p was targeted by circ_0006768, and VEZF1 was a target of miR-222-3p. Circ_0006768 enriched the expression of VEZF1 via mediating miR-222-3p inhibition. Rescue experiments presented that the effects of circ_0006768 overexpression were reversed by miR-222-3p restoration or VEZF1 knockdown. Circ_0006768 overexpression attenuates OGD/R-induced HBMEC injuries by upregulating VEZF1 via miR-222-3p inhibition.