Vasculature Network Research Articles

Collagen Microfibers Induce Blood Capillary Orientation and Open Vascular Lumen.

Achieving vascularization of engineered tissues or structures is a major challenge in the field of tissue engineering. Hitherto, studies on vascularization have demonstrated limited control of vascular network geometry, such as vasculature direction and network density. An open vascular lumen is crucial to ensure that cells survive and that metabolic activity is fully functional in large-sized tissues. Herein, a method based on high water-dispersible collagen microfibers (CMF) to fabricate capillary orientation-controllable 3D tissue with an open vascular lumen using a dispensing machine is reported. A twenty micrometers-long CMF (CMF-20) with high dispersion property are shown to be more effective for dispensing a homogenous tissue and inducing formation of an interconnected capillary network than two hundred micrometers-long CMF (CMF-200). One of the advantages is the prevention of shrinkage on the z-axis of hydrogel-based tissue which acts as a microscaffold. The gaps between the fibers can support endothelial cell migration and maturation, thus forming a larger vascular lumen compared to CMF-free controls. Besides, shear forces produced by the dispensing process cause the collagen microfibers to align, and these microfibers guide cell alignment by integrin-induced adhesion. The findings based on CMF to allow blood capillary alignment and vascular lumen stabilization will be an important technology in tissue engineering.

Lung Microvascular Niche, Repair, and Engineering

Biomaterials have been used for a long time in the field of medicine. Since the success of “tissue engineering” pioneered by Langer and Vacanti in 1993, tissue engineering studies have advanced from simple tissue generation to whole organ generation with three-dimensional reconstruction. Decellularized scaffolds have been widely used in the field of reconstructive surgery because the tissues used to generate decellularized scaffolds can be easily harvested from animals or humans. When a patient’s own cells can be seeded onto decellularized biomaterials, theoretically this will create immunocompatible organs generated from allo- or xeno-organs. The most important aspect of lung tissue engineering is that the delicate three-dimensional structure of the organ is maintained during the tissue engineering process. Therefore, organ decellularization has special advantages for lung tissue engineering where it is essential to maintain the extremely thin basement membrane in the alveoli. Since 2010, there have been many methodological developments in the decellularization and recellularization of lung scaffolds, which includes improvements in the decellularization protocols and the selection and preparation of seeding cells. However, early transplanted engineered lungs terminated in organ failure in a short period. Immature vasculature reconstruction is considered to be the main cause of engineered organ failure. Immature vasculature causes thrombus formation in the engineered lung. Successful reconstruction of a mature vasculature network would be a major breakthrough in achieving success in lung engineering. In order to regenerate the mature vasculature network, we need to remodel the vascular niche, especially the microvasculature, in the organ scaffold. This review highlights the reconstruction of the vascular niche in a decellularized lung scaffold. Because the vascular niche consists of endothelial cells (ECs), pericytes, extracellular matrix (ECM), and the epithelial–endothelial interface, all of which might affect the vascular tight junction (TJ), we discuss ECM composition and reconstruction, the contribution of ECs and perivascular cells, the air–blood barrier (ABB) function, and the effects of physiological factors during the lung microvasculature repair and engineering process. The goal of the present review is to confirm the possibility of success in lung microvascular engineering in whole organ engineering and explore the future direction of the current methodology.

Role of VEGFs in metabolic disorders.

Obesity and metabolic disorders are important public health problems. In this review, the role of vasculature network and VEGF in the adipose tissue maintenance and supplementation is discussed. Angiogenesis is a key process implicated in regulation of tissues homeostasis. Dysregulation of new blood vessels formation may be crucial and contribute to the onset of several pathological conditions, including metabolic syndrome-associated disorders. Adipose tissue homeostasis is fine regulated by vascular network. Vessels support adipose structure. Vasculature modulates the balance between positive and negative regulator factors. In white adipose tissue, vascular endothelial growth factor (VEGF) controls the metabolic activities of adipocytes promoting the trans-differentiation from white to beige phenotype. Trans-differentiation results in an increase of energy consumption. VEGF exerts an opposite effect on brown adipose tissue, where VEGF increases oxygen supply and improves energy expenditure inducing the whitening of adipocytes.

An Effective Segmentation of Retinal Blood Vessels using Optimized PCA and Morphological Operators

The structure of blood vessels interior in the eye is a significant source of indicator for many diseases if exist in a human body. The extraction of vasculature network of blood vessels which plays a vital role in the study and diagnosis of many eye related diseases like diabetic retinopathy, glaucoma, and many cardiovascular diseases is a challenging task. In this paper, a new method to derive tree-shaped vasculature from retinal fundus RGB images is proposed. This proposed algorithm is performed in two stages: (1) Pre-processing stage involves Particle Swarm Optimization (PSO) algorithm to compute optimized image which holds the global optimal pixels of the input RGB image followed by conversion of PSO optimized image to gray image using PCA which is then contrast enhanced with CLAHE. (2) Post-processing stage is carried out working on the contrast enhanced gray image for attaining better accuracy of retinal blood vessel segmentation by using Thresholding as well as morphological operator. The performance measures of proposed method are evaluated on DRIVE and STARE databases and obtained best results with an average accuracy of 96.44% and proven to be an outstanding method compared to other existing retina vessel segmentation algorithms.

Structural Redundancy in Supracellular Actomyosin Networks Enables Robust Tissue Folding.

Tissue morphogenesis is strikingly robust. Yet, howtissues are sculpted under challenging conditions is unknown. Here, we combined network analysis, experimental perturbations, and computational modeling to determine how network connectivity between hundreds of contractile cells on the ventral side of the Drosophila embryo ensures robust tissue folding. We identified two network properties that mechanically promote robustness. First, redundant supracellular cytoskeletal network paths ensure global connectivity, even with network degradation. By forming many more connections than are required, morphogenesis is not disrupted by local network damage, analogous to the way redundancy guarantees the large-scale function of vasculature and transportation networks. Second, directional stiffening ofedges oriented orthogonal to the folding axis promotesfurrow formation at lower contractility levels. Structural redundancy and directional network stiffeningensure robust tissue folding with proper orientation.

INVESTIGATING THE LOCAL DISTORTION OF THE FRACTAL COMPLEXITY OF THE RETINAL VASCULAR ALTERATIONS IN COGNITIVELY IMPAIRED PATIENTS

We investigated whether multifractal dimension and lacunarity analyses performed in sectoral regions of the retina may reveal local distortion in cognitive impaired (CI) patients that may be masked in the analysis considering the whole retinal branching pattern. Quantification of the retinal vasculature and function were conducted for every subject (19 healthy controls (HC) and 20 CI's patients) using advanced retinal imaging, full-field electroretinogram (ERG) and visual performance exams. The Montreal Cognitive Assessment (MoCA) was used to measure CI. The skeletonized vasculature network that comprised the whole branching pattern was obtained for each image and divided into nine equal regions (superotemporal, superior, superonasal, macular, optic disc, nasal, inferotemporal, inferior, inferonasal). The multifractal behavior was analyzed by calculating the generalized dimensions (Do, D1, D2), lacunarity parameter and singularity spectrum f(α) in the regions and whole retina. Statistical analyses were performed to find associations between all parameters in both groups (p< 0.05, statistically significant). The Do, D1 and D2 values in the HC individuals were significantly greater in the optic disc region (1.59 ± 0.05, 1.57 ± 0.05, 1.56 ± 0.05) vs. CI's participants (1.52 ± 0.08, 1.50 ± 0.08, 1.49 ± 0.08); p<0.05. Similar trends were observed in the optic disc region for the f(α). The lacunarity values were greater for CI's participants (0.329 ± 0.035) than controls (0.307 ± 0.024), p = 0.026 in the optic disc region but this difference was absent in the whole retina, p = 0.45. The Do and αo values were significantly associated with MoCA scores in the macular region, r = 0.47, p = 0.039; r = 0.46, p = 0.043; respectively but these associations were absent in the whole retina. Also, significant correlations between multifractal and lacunarity parameters with the MoCA and ERG's parameters were observed in the regional analysis; a trend was not found in the whole retina analysis. The regional analysis uncovered significant differences in CI's patients vs. HCs that were masked in the whole retinal analysis. Regional multifractal and lacunarity analyses may add additional diagnostic value to the use of retinal biomarkers for early diagnosis of CI.

Bright AIEgen–Protein Hybrid Nanocomposite for Deep and High‐Resolution In Vivo Two‐Photon Brain Imaging

AbstractTwo‐photon fluorescence imaging allows in vivo study of biological structures and activities in deep tissues, in which bright fluorophores with high photostability and good biocompatibility are highly desirable. Herein, a small‐molecule fluorogen with aggregation‐induced emission (AIEgen) is complexed with fetal bovine serum (FBS) proteins to develop a protein‐sized AIEgen–protein hybrid nanocomposite (TPEPy‐FBS) with bright far‐red/near‐infrared (NIR) emission, excellent photostability, and low phototoxicity for deep and high‐resolution in vivo two‐photon brain vasculature imaging. Upon complexation with FBS, the fluorescence of TPEPy is greatly intensified and a sixfold enhancement is observed with 10% FBS in aqueous media. The yielded TPEPy‐FBS shows good physical stability in aqueous media and the phototoxicity of TPEPy is dramatically inhibited after complexation with FBS. Moreover, TPEPy‐FBS exhibits bright two‐photon fluorescence in far‐red/NIR region and good photostability upon femtosecond laser excitation, which facilitates high performance in vivo imaging. A large imaging depth of 656 µm is obtained in brain vasculature network imaging with a high signal‐to‐background ratio of 234, where a small blood capillary of 1.05 µm can be resolved at an imaging depth of 656 µm. Highlighted is a simple and versatile strategy to develop efficient two‐photon probes for in vivo biological imaging.

Super-Resolution Contrast-Enhanced Ultrasound Methodology for the Identification of In Vivo Vascular Dynamics in 2D.

ObjectivesThe aim of this study was to provide an ultrasound-based super-resolution methodology that can be implemented using clinical 2-dimensional ultrasound equipment and standard contrast-enhanced ultrasound modes. In addition, the aim is to achieve this for true-to-life patient imaging conditions, including realistic examination times of a few minutes and adequate image penetration depths that can be used to scan entire organs without sacrificing current super-resolution ultrasound imaging performance.MethodsStandard contrast-enhanced ultrasound was used along with bolus or infusion injections of SonoVue (Bracco, Geneva, Switzerland) microbubble (MB) suspensions. An image analysis methodology, translated from light microscopy algorithms, was developed for use with ultrasound contrast imaging video data. New features that are tailored for ultrasound contrast image data were developed for MB detection and segmentation, so that the algorithm can deal with single and overlapping MBs. The method was tested initially on synthetic data, then with a simple microvessel phantom, and then with in vivo ultrasound contrast video loops from sheep ovaries. Tracks detailing the vascular structure and corresponding velocity map of the sheep ovary were reconstructed. Images acquired from light microscopy, optical projection tomography, and optical coherence tomography were compared with the vasculature network that was revealed in the ultrasound contrast data. The final method was applied to clinical prostate data as a proof of principle.ResultsFeatures of the ovary identified in optical modalities mentioned previously were also identified in the ultrasound super-resolution density maps. Follicular areas, follicle wall, vessel diameter, and tissue dimensions were very similar. An approximately 8.5-fold resolution gain was demonstrated in vessel width, as vessels of width down to 60 μm were detected and verified (λ = 514 μm). Best agreement was found between ultrasound measurements and optical coherence tomography with 10% difference in the measured vessel widths, whereas ex vivo microscopy measurements were significantly lower by 43% on average. The results were mostly achieved using video loops of under 2-minute duration that included respiratory motion. A feasibility study on a human prostate showed good agreement between density and velocity ultrasound maps with the histological evaluation of the location of a tumor.ConclusionsThe feasibility of a 2-dimensional contrast-enhanced ultrasound-based super-resolution method was demonstrated using in vitro, synthetic and in vivo animal data. The method reduces the examination times to a few minutes using state-of-the-art ultrasound equipment and can provide super-resolution maps for an entire prostate with similar resolution to that achieved in other studies.

Engineering Organoid Vascularization.

The development of increasingly biomimetic human tissue analogs has been a long-standing goal in two important biomedical applications: drug discovery and regenerative medicine. In seeking to understand the safety and effectiveness of newly developed pharmacological therapies and replacement tissues for severely injured non-regenerating tissues and organs, there remains a tremendous unmet need in generating tissues with both functional complexity and scale. Over the last decade, the advent of organoids has demonstrated that cells have the ability to reorganize into complex tissue-specific structures given minimal inductive factors. However, a major limitation in achieving truly in vivo-like functionality has been the lack of structured organization and reasonable tissue size. In vivo, developing tissues are interpenetrated by and interact with a complex network of vasculature which allows not only oxygen, nutrient and waste exchange, but also provide for inductive biochemical exchange and a structural template for growth. Conversely, in vitro, this aspect of organoid development has remained largely missing, suggesting that these may be the critical cues required for large-scale and more reproducible tissue organization. Here, we review recent technical progress in generating in vitro vasculature, and seek to provide a framework for understanding how such technologies, together with theoretical and developmentally inspired insights, can be harnessed to enhance next generation organoid development.

Deep convolutional neural networks for segmenting 3D in vivo multiphoton images of vasculature in Alzheimer disease mouse models.

The health and function of tissue rely on its vasculature network to provide reliable blood perfusion. Volumetric imaging approaches, such as multiphoton microscopy, are able to generate detailed 3D images of blood vessels that could contribute to our understanding of the role of vascular structure in normal physiology and in disease mechanisms. The segmentation of vessels, a core image analysis problem, is a bottleneck that has prevented the systematic comparison of 3D vascular architecture across experimental populations. We explored the use of convolutional neural networks to segment 3D vessels within volumetric in vivo images acquired by multiphoton microscopy. We evaluated different network architectures and machine learning techniques in the context of this segmentation problem. We show that our optimized convolutional neural network architecture with a customized loss function, which we call DeepVess, yielded a segmentation accuracy that was better than state-of-the-art methods, while also being orders of magnitude faster than the manual annotation. To explore the effects of aging and Alzheimer’s disease on capillaries, we applied DeepVess to 3D images of cortical blood vessels in young and old mouse models of Alzheimer’s disease and wild type littermates. We found little difference in the distribution of capillary diameter or tortuosity between these groups, but did note a decrease in the number of longer capillary segments (>75μm) in aged animals as compared to young, in both wild type and Alzheimer’s disease mouse models.

Pharmacological restoration of visual function in a zebrafish model of von-Hippel Lindau disease

Von Hippel-Lindau (VHL) syndrome is a rare, autosomal dominant disorder, characterised by hypervascularised tumour formation in multiple organ systems. Vision loss associated with retinal capillary hemangioblastomas remains one of the earliest complications of VHL disease. The mortality of Vhl−/− mice in utero restricted modelling of VHL disease in this mammalian model. Zebrafish harbouring a recessive germline mutation in the vhl gene represent a viable, alternative vertebrate model to investigate associated ocular loss-of-function phenotypes. Previous studies reported neovascularisation of the brain, eye and trunk together with oedema in the vhl−/− zebrafish eye. In this study, we demonstrate vhl−/− zebrafish almost entirely lack visual function. Furthermore, hyaloid vasculature networks in the vhl−/− eye are improperly formed and this phenotype is concomitant with development of an ectopic intraretinal vasculature. Sunitinib malate, a multi tyrosine kinase inhibitor, market authorised for cancer, reversed the ocular behavioural and morphological phenotypes observed in vhl−/− zebrafish. We conclude that the zebrafish vhl gene contributes to an endogenous molecular barrier that prevents development of intraretinal vasculature, and that pharmacological intervention with sunitinib can improve visual function and hyaloid vessel patterning while reducing abnormally formed ectopic intraretinal vessels in vhl−/− zebrafish.

Whole organ sheep kidney tissue engineering and in vivo transplantation: Effects of perfusion-based decellularization on vascular integrity

IntroductionDuring the past decade, increased efforts have been made to develop alternative management options instead of dialysis and homograft renal transplantation for end-stage renal disease. State-of-the-art methods employ tissue engineering to produce natural acellular scaffolds that could resolve the concern of allograft rejection and obviate the need for immunosuppressive therapy. Complete decellularization of kidney with intact extracellular matrix is crucial for in vivo compatibility and success of transplantation. Herein, we evaluate the efficacy of two different whole organ decellularization protocols, vasculature integrity, and in vivo transplantation of sheep kidneys. Materials and methodsEight sheep kidneys were decellularized by perfusion-based method utilizing two different protocols (Protocol 1: 1% Triton X-100 and 0.5% SDS vs. Protocol 2: 1% SDS). The samples were evaluated by histopathology in terms of decellularization and extracellular matrix preservation. Computerized tomography angiography was performed to evaluate vasculature. Subsequently, both methods were transplanted in four sheep and monitored for vascular integrity and extravasations in short-term. ResultsScaffolds obtained from both protocols were entirely decellularized. However; the extracellular matrix was better preserved in protocol 1 compared to protocol 2. In addition, the vascular integrity was intact in decellularized scaffolds treated with Triton X-100 plus SDS (protocol 1). After transplantation, the samples treated with protocol 2 showed extravasation of fluid in the interstitial space while the samples treated with protocol 1 showed intact extracellular matrix and vasculature. ConclusionsThis study demonstrated the efficacy of well-preserved acellular scaffold and vasculature network in post renal transplant outcome in a sheep model. These results have potential to pave the road for further investigations in acellular whole organ transplantation.

Endovascular therapy of arteriovenous malformation in a male patient with severe post-coital pelvic pain

PurposeCongenital pelvic arteriovenous malformations (AVMs) are high-flow vascular lesions consisting of abnormal shunts between arteries and veins within a nidus. The rare presentation and extensive network of vasculature contributes to the difficulty in effective treatment. Optimal therapeutic options are determined based on the clinical presentation, the location of the lesion, and possible complications.Case reportA 24-year-old male patient with a history of recurrent pain following sexual intercourse presented with complaints of intense pelvic pain radiating to the perineal area. Computed tomography angiography (CTA) revealed a large venous aneurysm as an outflow vein of a right-sided pelvic AVM. Embolisation of the outflow veins was established along with direct percutaneous delivery of fibre coils and thrombin to the venous aneurysm of the AVM. With recurring symptoms and AVM recanalisation on angiography, another direct puncture and placement of pushable coils was made. Total AVM occlusion was achieved with no recanalisation on follow-up digital subtraction angiography (DSA), and the patient remained asymptomatic.ConclusionsEndovascular embolisation of the nidus area may result in a complete occlusion of an AVM. Therefore, a thorough understanding of the vascular anatomy of the AVM is essential in choosing an effective embolisation strategy and to minimise the risk of possible complications.

Early diabetic retinopathy diagnosis based on local retinal blood vessel analysis in optical coherence tomography angiography (OCTA) images.

This paper introduces a new computer-aided diagnosis (CAD) system for detecting early-stage diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA) images. The proposed DR-CAD system is based on the analysis of new local features that describe both the appearance and retinal structure in OCTA images. It starts with a new segmentation approach that has the ability to extract the blood vessels from superficial and deep retinal OCTA maps. The high capability of our segmentation approach stems from using a joint Markov-Gibbs random field stochastic model integrating a 3D spatial statistical model with a first-order appearance model of the blood vessels. Following the segmentation step, three new local features are estimated from the segmented vessels and the foveal avascular zone (FAZ): (a) vessels density, (b) blood vessel calibre, and (c) width of the FAZ. To distinguish mild DR patients from normal cases, the estimated three features are used to train and test a support vector machine (SVM) classifier with the radial basis function (RBF) kernel. On a cohort of 105 subjects, the presented DR-CAD system demonstrated an overall accuracy (ACC) of 94.3%, a sensitivity of 97.9%, a specificity of 87.0%, the area under the curve (AUC) of 92.4%, and a Dice similarity coefficient (DSC) of 95.8%. This in turn demonstrates the promise of the proposed CAD system as a supplemental tool for early detection of DR. We developed a new DR-CAD system that is capable of diagnosing DR in its early stage. The proposed system is based on extracting three different features from the segmented OCTA images, which reflect the changes in the retinal vasculature network.

Automated motion-artifact correction in an OCTA image using tensor voting approach.

Optical coherence tomography angiography (OCTA) is a promising tool for imaging subsurface microvascular networks owing to its micron-level resolution and high sensitivity. However, it is not uncommon that OCTA imaging suffers from strip artifacts induced by tissue motion. Although various algorithms for motion correction have been reported, a method that enables motion correction on a single en face OCTA image remains a challenge. In this study, we propose a motion correction approach based on microvasculature detection and broken gap filling. Unlike previous methods using registration to restore disturbed vasculature during motion artifact removal, tensor voting is performed in an individual projected image to connect the broken vasculature. Both simulation and in vivo 3D OCTA imaging of the mouse bladder are performed to validate the effectiveness of this method. A comparison of in vivo images before and after motion correction shows that our method effectively corrects tissue motion artifacts while preserving the continuity of vasculature network. Furthermore, in vivo results of this technique are presented to demonstrate its utility for imaging tumor angiogenesis in the mouse bladder.

Parallel fast isogeometric L2 projection solver with GALOIS system for 3D tumor growth simulations

We present a parallel solver for isogeometric L2 projections implemented in GALOIS system. We use the solver for isogeometric finite element method simulations of tumor growth. First, we describe the dependencies between the quantities describing the melanoma tumor growth in three-dimensions. Later, we derive the system of partial differential equations modeling the tumor dynamics, including tumor cell density, tumor angiogenic factor, flux, pressure, extracellular and degraded extracellular matrices. The continuous model is coupled every ten-time steps with graph grammar model describing the vasculature network. The resulting system of PDEs is solved with our parallel solver over the shared memory Linux cluster node. We show high computational efficiency and accuracy of our model and we demonstrate its perfect parallel scalability with the number of CPU cores. We discuss the application of our solver in predictive oncology.

INVESTIGATING DIAGNOSTIC BIOMARKERS OF COGNITIVE IMPAIRMENT BY UTILIZING VASCULAR AND NEUROGENIC CHANGES IN THE RETINA

Previous studies have demonstrated that Alzheimer's disease (AD) it is not limited to the brain but also affects the retina. We investigated the correlation between the retinal vascular complexity and neurodegenerative changes in patients with mild cognitive impairment (MCI). Quantification of the retinal structure and function using advanced retinal imaging and full-field electroretinogram (ERG) was performed. Also, visual performance exams were conducted using the Rabin cone contrast test (CCT). Retinal images and ERGs from each subject were obtained. Retinal vascular parameters were calculated using the Singapore Institute Vessel Assessment (SIVA) software which was also used to calculate the fractal dimension (FD) of the retinal vasculature network and retinal vascular caliber, summarized as central retinal artery equivalent (CRAE) and central retinal vein equivalent (CRVE). The Montreal Cognitive Assessment (MoCA) was used to assess cognitive dysfunction. Spearman's linear correlation was performed between variables, the level of significance was set at 5%. For the analysis, Statistics 7.0 software was used (Statsoft Inc., Tulsa, OK). Of the 55 participants, 21 had cognitive impairment (38%), 34 served as healthy controls. We found that the complexity of the branching pattern and caliber of retinal vessels were lower in patients with MCI (FD (mean±SE): 1.310±0.020; CRVE (92.65±1.60; age range [76-86]) in comparison to healthy controls (FD: 1.382±0.002; CRVE: 202.15±0.76; age range [76-86]). Also, drusen and retinal pigment mottling were noted in some elderly MCI subjects. For all full-field ERG measurements, smaller amplitudes and larger peak times were observed in the MCI subjects. The visual performance test with the computerized Rabin CCT revealed functional loss in color vision. Interestingly, FD significantly correlated with CRVE (p=0.0212, r=-0.4628) and with the ERG's implicit time (p=0.0240, r=0.4910) in MCI individuals. To our knowledge, this is the first study to examine the association between FD and full field ERG implicit time in patients with MCI. Our preliminary findings also show that our approach to evaluating visual capacities in elderly individuals may add predictive value of early visual pathway injury associated with MCI and facilitate the introduction of a novel multimodal eye biomarker for the early detection of AD.

Simultaneous Blood–Brain Barrier Crossing and Protection for Stroke Treatment Based on Edaravone-Loaded Ceria Nanoparticles

Cerebral vasculature and neuronal networks will be largely destroyed due to the oxidative damage by overproduced reactive oxygen species (ROS) during a stroke, accompanied by the symptoms of ischemic injury and blood-brain barrier (BBB) disruption. Ceria nanoparticles, acting as an effective and recyclable ROS scavenger, have been shown to be highly effective in neuroprotection. However, the brain access of nanoparticles can only be achieved by targeting the damaged area of BBB, leading to the disrupted BBB being unprotected and to turbulence of the microenvironment in the brain. Nevertheless, the integrity of the BBB will cause very limited accumulation of therapeutic nanoparticles in brain lesions. This dilemma is a great challenge in the development of efficient stroke nanotherapeutics. Herein, we have developed an effective stroke treatment agent based on monodisperse ceria nanoparticles, which are loaded with edaravone and modified with Angiopep-2 and poly(ethylene glycol) on their surface (E-A/P-CeO2). The as-designed E-A/P-CeO2 features highly effective BBB crossing via receptor-mediated transcytosis to access brain tissues and synergistic elimination of ROS by both the loaded edaravone and ceria nanoparticles. As a result, the E-A/P-CeO2 with low toxicity and excellent hemo/histocompatibility can be used to effectively treat strokes due to great intracephalic uptake enhancement and, in the meantime, effectively protect the BBB, holding great potentials in stroke therapy with much mitigated harmful side effects and sequelae.

Engineering Microvascular Networks in LED Light-Cured Cell-Laden Hydrogels.

The success of tissue engineering inevitably depends on the fabrication of tissue constructs that can be vascularized and that anastomose with the host vasculature. In this report, we studied the effects of light-emitting diode (LED) photopolymerized gelatin methacryloyl hydrogels (GelMA), encapsulated with stem cells from the apical papilla (SCAP) and human umbilical vein endothelial cells (HUVECs), in promoting vasculature network formation as a function of hydrogel physical and mechanical properties, as well as total cell density. Lithium acylphosphinate (LAP) was used as the photoinitiator in concentrations of 0.05, 0.075, 0.1% (w/v). GelMA hydrogel precursors of 5% (w/v) were encapsulated with cocultures of SCAPs and HUVECs at different cell densities (1×, 5×, and 10 × 106 cells/mL) and photo-cross-linked for 5 s. Results suggested that the compressive modulus of GelMA hydrogels increased as a function of LAP concentration, and had a maximum stiffness of 3.2 kPa. GelMA hydrogels photopolymerized using 0.05 or 0.075% LAP, which had an average of 1.5 and 1.6 kPa of elastic modulus respectively, had the most efficient vasculature formation after 5 days, and these results were further enhanced when the highest cell density (10 × 106 cells/mL) was used. Immunofluorescence images showed that SCAP cells spread in close contact with endothelial networks and expressed alpha smooth muscle actin (αSMA), which is suggestive of their differentiation into pericyte-like cells. αSMA expression was also apparently higher in hydrogels polymerized with 0.05% LAP and 10 × 106 cells/mLl. In conclusion, photopolymerization of GelMA hydrogels using an LED-light source can be an effective method for potential chair-side/in situ procedures for engineering of vascularized tissue constructs in regenerative medicine.

Transcriptome profiling of the interconnection of pathways involved in malignant transformation and response to hypoxia.

In tumor tissues, hypoxia is a commonly observed feature resulting from rapidly proliferating cancer cells outgrowing their surrounding vasculature network. Transformed cancer cells are known to exhibit phenotypic alterations, enabling continuous proliferation despite a limited oxygen supply. The four-step isogenic BJ cell model enables studies of defined steps of tumorigenesis: the normal, immortalized, transformed, and metastasizing stages. By transcriptome profiling under atmospheric and moderate hypoxic (3% O2) conditions, we observed that despite being highly similar, the four cell lines of the BJ model responded strikingly different to hypoxia. Besides corroborating many of the known responses to hypoxia, we demonstrate that the transcriptome adaptation to moderate hypoxia resembles the process of malignant transformation. The transformed cells displayed a distinct capability of metabolic switching, reflected in reversed gene expression patterns for several genes involved in oxidative phosphorylation and glycolytic pathways. By profiling the stage-specific responses to hypoxia, we identified ASS1 as a potential prognostic marker in hypoxic tumors. This study demonstrates the usefulness of the BJ cell model for highlighting the interconnection of pathways involved in malignant transformation and hypoxic response.