Vascular Organization Research Articles

A flap based on the plantar digital artery arch branch to improve appearance of reconstructed fingers: Anatomical and clinical application

To investigate blood supply features of the flap based on the plantar digital artery arch and arch branch artery, and the treatment of outcomes of reconstructed fingers by the plantar digital artery arch branch island flap. Eight fresh foot specimens were employed with red emulsion infusion and microdissection. The vascular organization was observed in the second toe, such as initiation site, the course, and the number of the plantar digital artery arch branch. There were 15 fingers of 13 patients (8 males and 5 females) with finger defects accompanied by toe transfer, using the plantar digital artery arch branch flap inserted in the neck of the second toe to correct the appearance defect caused by a narrow "neck" and a bulbous tip. The intact plantar digital arches were identified in all specimens. The plantar digital artery arch had 5 branches. The range of external diameter of the arch branch was 0.4-0.6 mm. All the plantar digital artery arch branch island flaps and the reconstructed fingers survived. These cases were conducted with a follow-up period for 3-18 months (average, 9 months). All the plantar digital artery arch branch island flaps and reconstructed fingers demonstrated a satisfactory appearance and favorable sense function. The reconstructed finger-tip characteristic was good, with no obvious scar hyperplasia. The range of flexion and extension of reconstructed fingers was favorable as well. The plantar digital artery arch and arch branch artery possess regular vasa vasorum and abundant vascularity. A flap based on the plantar digital artery arch branch is an ideal selection for plastic surgery of reconstructed fingers.

Deregulated TGF-β/BMP Signaling in Vascular Malformations.

Correct organization of the vascular tree requires the balanced activities of several signaling pathways that regulate tubulogenesis and vascular branching, elongation, and pruning. When this balance is lost, the vessels can be malformed and fragile, and they can lose arteriovenous differentiation. In this review, we concentrate on the transforming growth factor (TGF)-β/bone morphogenetic protein (BMP) pathway, which is one of the most important and complex signaling systems in vascular development. Inactivation of these pathways can lead to altered vascular organization in the embryo. In addition, many vascular malformations are related to deregulation of TGF-β/BMP signaling. Here, we focus on two of the most studied vascular malformations that are induced by deregulation of TGF-β/BMP signaling: hereditary hemorrhagic telangiectasia (HHT) and cerebral cavernous malformation (CCM). The first of these is related to loss-of-function mutation of the TGF-β/BMP receptor complex and the second to increased signaling sensitivity to TGF-β/BMP. In this review, we discuss the potential therapeutic targets against these vascular malformations identified so far, as well as their basis in general mechanisms of vascular development and stability.

Quantitative vascular neuroimaging of the rat brain using superparamagnetic nanoparticles: New insights on vascular organization and brain function

A method called Quantitative Ultra-Short Time-to-Echo Contrast Enhanced (QUTE-CE) Magnetic Resonance Imaging (MRI) which utilizes superparamagnetic iron oxide nanoparticles (SPIONs) as a contrast agent to yield positive contrast angiograms with high clarity and definition is applied to the whole live rat brain. QUTE-CE MRI intensity data are particularly well suited for measuring quantitative cerebral blood volume (qCBV). A global map of qCBV in the awake resting-state with unprecedented detail was created via application of a 3D MRI rat brain atlas with 173 segmented and annotated brain areas. From this map we identified two distributed, integrated neural circuits showing the highest capillary densities in the brain. One is the neural circuitry involved with the primary senses of smell, hearing and vision and the other is the neural circuitry of memory. Under isoflurane anesthesia, these same circuits showed significant decreases in qCBV suggesting a role in consciousness. Neural circuits in the brainstem associated with the reticular activating system and the maintenance of respiration, body temperature and cardiovascular function showed an increase in qCBV with anesthesia. During awake CO2 challenge, 84 regions showed significant increases relative to an awake baseline state. This CO2 response provides a measure of cerebral vascular reactivity and regional perfusion reserve with the highest response measured in the somatosensory cortex. These results demonstrate the utility of QUTE-CE MRI for qCBV analysis and offer a new perspective on brain function and vascular organization.

Dynamic optical coherence tomography of skin blood vessels - proposed terminology and practical guidelines.

Dynamic optical coherence tomography (D-OCT) has recently been introduced in dermatology. In contrast to 'Standard' OCT imaging, which exclusively relies on the morphological analysis of the tissue, D-OCT allows the in vivo visualization of blood flow. Preliminary D-OCT data showed differences in the vascularization of nevus to melanoma transition, suggesting that this technology may help to differentiate between benign and malignant lesions. Several factors may influence the quality of D-OCT imaging. Therefore, standard operating procedures as well as a common terminology are required for better validation and comparison of the images. Here, we present practical guidelines for optimal image acquisition and a proposed terminology on vascular patterns observed by D-OCT. Dynamic OCT allows the morphologic distinction of different vascular shapes (e.g. dots, blobs, curves, lines), their distribution and organization within skin lesions. D-OCT adds functional information on skin microvasculature and the vascular networks within lesions.

Microfibrous Scaffolds Enhance Endothelial Differentiation and Organization of Induced Pluripotent Stem Cells.

Human induced pluripotent stem cells (iPSCs) are a promising source of endothelial cells (iPSC-ECs) for engineering three-dimensional (3D) vascularized cardiac tissues. To mimic cardiac microvasculature, in which capillaries are oriented in parallel, we hypothesized that endothelial differentiation of iPSCs within topographically aligned 3D scaffolds would be a facile one-step approach to generate iPSC-ECs as well as induce aligned vascular organization. Human iPSCs underwent endothelial differentiation within electrospun 3D polycaprolactone (PCL) scaffolds having either randomly oriented or parallel-aligned microfibers. Using transcriptional, protein, and endothelial functional assays, endothelial differentiation was compared between conventional two-dimensional (2D) films and 3D scaffolds having either randomly oriented or aligned microfibers. Furthermore, the role of parallel-aligned microfiber patterning on the organization of vessel-like networks was assessed. The cells in both the randomly oriented and aligned 3D scaffolds demonstrated an 11-fold upregulation in gene expression of the endothelial phenotypic marker, CD31, compared to cells on 2D films. This upregulation corresponded to >3-fold increase in CD31 protein expression in 3D scaffolds, compared to 2D films. Concomitantly, other endothelial phenotypic markers including CD144 and endothelial nitric oxide synthase also showed significant transcriptional upregulation in 3D scaffolds by >7-fold, compared to 2D films. Nitric oxide production, which is characteristic of endothelial function, was produced 4-fold more abundantly in 3D scaffolds, compared to on 2D PCL films. Within aligned scaffolds, the iPSC-ECs displayed parallel-aligned vascular-like networks with 70% longer branch length, compared to cells in randomly oriented scaffolds, suggesting that fiber topography modulates vascular network-like formation and patterning. Together, these results demonstrate that 3D scaffold structure promotes endothelial differentiation, compared to 2D substrates, and that aligned topographical patterning induces anisotropic vascular network organization.

A small population of liver endothelial cells undergoes endothelial-to-mesenchymal transition in response to chronic liver injury.

Rising evidence points to endothelial-to-mesenchymal transition (EndMT) as a significant source of the mesenchymal cell population in fibrotic diseases. In this context, we hypothesized that liver endothelial cells undergo EndMT during fibrosis progression. Cirrhosis in mice was induced by CCl4 A transgenic mouse expressing a red fluorescent protein reporter under the control of Tie2 promoter (Tie2-tdTomato) was used to trace the acquisition of EndMT. Sinusoidal vascular connectivity was evaluated by intravital microscopy and high-resolution three-dimensional confocal microscopy. A modest but significant fraction of liver endothelial cells from both cirrhotic patients and CCl4-treated Tie2-tdTomato mice acquired an EndMT phenotype characterized by the coexpression of CD31 and α-smooth muscle actin, compared with noncirrhotic livers. Bone morphogenetic protein-7 (BMP-7) inhibited the acquisition of EndMT induced by transforming growth factor-β1 (TGF-β1) treatment in cultured primary mouse liver endothelial cells from control mice. EndMT was also reduced significantly in vivo in cirrhotic Tie2-tdTomato mice treated intraperitoneally with BMP-7 compared with untreated mice (1.9 ± 0.2 vs. 3.8 ± 0.3%, respectively; P < 0.05). The decrease of EndMT in cirrhotic livers correlated with a significant decrease in liver fibrosis (P < 0.05) and an improvement in the vascular disorganization rate (P < 0.05). We demonstrated the acquisition of the EndMT phenotype by a subpopulation of endothelial cells from cirrhotic livers in both animal models and patients. BMP-7 treatment decreases the occurrence of the EndMT phenotype and has a positive impact on the severity of disease by reducing fibrosis and sinusoidal vascular disorganization.NEW & NOTEWORTHY A subpopulation of liver endothelial cells from cirrhotic patients and mice with liver fibrosis undergoes endothelial-to-mesenchymal transition. Liver endothelial cells from healthy mice could transition into a mesenchymal phenotype in culture in response to TGF-β1 treatment. Fibrotic livers treated chronically with BMP-7 showed lower EndMT acquisition, reduced fibrosis, and improved vascular organization.

Influences of placental growth factor on mouse retinal vascular development.

Placental growth factor (PGF) is important for wound-healing and vascular collaterogenesis. PGF deficiency is associated with preeclampsia, a hypertensive disease of human pregnancy. Offspring born to preeclamptic mothers display cognitive impairments and brain vascular and neurostructural deviations. Low PGF production during development may contribute to alterations in offspring cerebrovascular beds. Retina is a readily accessible part of the central nervous system with a well-described pattern of vascular development in mice. Impacts of PGF deficiency were addressed during mouse retinal vascularization. Retinal vessels were compared between Pgf-/- and congenic C57BL/6 (B6) mice. PGF deficiency altered neonatal retinal vascularization patterns. Some anatomic alterations persisted into adulthood, particularly in males. Greater arterial wall collagen IV expression was found in adult Pgf-/- females. Pregnancy (studied in adult females at gestational days 11.5 or 18.5) induced subtle changes upon the mother's retinal vasculature but these pregnancy-induced changes did not differ between genotypes. Significant sex-related differences occurred between adult male and female B6 although sexually dimorphic retinal vascular differences were absent in B6 neonates. Overall, PGF has a role in retinal vascular angiogenesis and vessel organization during development but does not affect retinal vessel adaptations in adult females during pregnancy. Developmental Dynamics 246:700-712, 2017. © 2017 Wiley Periodicals, Inc.

EMBRYO‐FORM PROJECT: HOW ACCURATE WAS MISS D. PADGET? STUDY OF THE HUMAN VENOUS CEREBRAL SYSTEM

INTRODUCTIONThroughout her entire work, Miss Padget gave to the international scientific community several rules concerning the setting of the superficial venous network of the brainstem. These rules can be extended to the whole brain venous organization.She described the venous vascular organization in seven phases. We proposed to review and illustrate the overall venous human embryonic organization using the latest current 3D‐reconstruction possibilities “The Embryo‐form project”MATERIAL &amp; METHODWe recently published the method (1) of this systematic reformation process and the material used selected among the French university collections in the framework of a conservation program (under the auspices of the French Morphologists Association). Permission and consent were obtained by the local ethic committee (CRENHU; University Hospital Nancy, France). This gathering brought together 20 human embryos prepared in serial histological sections, collected during the mid 50's. We also get access to the Carnegie's embryos collection thanks to her curator Miss E Lockett.20 Embryos were digitalized with a flatbed scanner at 2400 DPI resolution.RESULTSThanks to this method we were able to reconstruct 20 embryos, which present good vascular enhancement (due to histologic dye or direct vascular injection of India‐Ink).We have compared our results to the classic artwork of Miss Padget, confirming the global pattern of the 3 first stages consisting in the organization of primitive dural sinuses composed of three main stem: the anterior, middle and posterior dural plexus draining the neural tube.At stage 4, the neural tube is covered by a plexiform capillary net draining into short veins at the dorsal and ventro‐lateral aspects of the neural tube, and joining the dural venous plexus formed in former stages: the primary transverse anastomoses.During the next phases (Padget phase 5 and 6), at CS 19‐20‐21, and due to the growth of the cerebral vesicles, these short pia‐arachnoïdal veins i.e. the primary transverse anastomoses, were stretched. This phenomenon led to a reduction in number, leaving only one to two veins on each side of the neural tube: the vascular cleavage phase.We observed in the next stage (stage 6 ‐ CS 20‐21) the further establishment of pia‐arachnoidal veins anastomoses, particularly visible at the metencephalic level, by extension of the longitudinal anastomoses.Our pictorial essay is meant to present new views of the developing venous network of the brain stem and to illustrate some additional hemodynamic solutions depicted in different embryos.ConclusionOur technique opens new perspectives for re‐use and analysis of “historical” microanatomy collections.We provide an accessible, costless, and reliable method for three‐dimensional analysis of recent or old histologic collections.Our technique provides a powerful tool for understanding the making of the human cerebral vasculogenesis based on the legacy of Miss Padget and its remarkable and detailed anatomical drawings.

The age-specific features of the pharyngeal tonsil in the adult subjects

The authors studied the age-related features of the vascular organization of the adenoid tissue. A total of 46 subjects (n=46) were examined; they were divided into two groups one of which included subjects at the age from 7 to 12 years (n=25) whereas the other group was comprised of 21 subjects at the age from 18 to 42 years (n=21). 29 participants of the study were men (63%) and 17 (37%) women. The histological examination of the adenoid tissue revealed the characteristic changes in the adenoid vasculature in the subjects of either age-group. The subjects above 18 years of age were shown to have developed sclerosis and hyalinosis of the vascular walls with the formation of cavernously dilated plethoric veins having the thickened rigid walls. The morphological changes in the connective tissue (basal) layer were documented responsible for the manifestation of the phenomenon of 'immersion' of the lymphoid tissue with the well developed microcirculatory bed. It is concluded that the results of the histological examination can serve as one of the indicators for the use of electrophysical methods to perform adenotomy in the patients older than 18 years.

Arteries and Veins of the Cerebellum.

Surgery of the posterior fossa represents a technical challenge because of the proximity of the vessels of the cerebellum. If the arterial vascularization of the cerebellum is well known, the main arterial variations and the whole venous vascularization are probably under recognized. We describe the vascular organization and the main variations through photographs of colored latex perfused brains, obtained with a surgical microscope. The arterial vascularization of the cerebellum is based on three arteries which all originate from the vertebrobasilar system: the superior cerebellar artery (SCA), the anterior and inferior cerebellar artery (AICA), and the posterior and inferior cerebellar artery (PICA). The main arterial variations involve essentially the origin of these vessels. Concerning the SCA, its origin depends on the embryology. The AICA can arise from a common trunk AICA-PICA. It can be sometimes doubled and rarely absent. The PICA also can arise from a common trunk AICA-PICA and sometimes from the extradural segment of the vertebral artery. Concerning the venous organization, we distinguish the superficial and deep veins. The superficial veins drain the cerebellar cortex and transit on the surface of the cerebellum. The deep veins refer to the veins transiting in the fissures between the cerebellum and the brainstem. All these veins terminate as bridging veins that we can divide in three groups: a superior group emptying into the great vein, a posterior group emptying into the transtentorial sinus, and a lateral group ending into the superior petrosal sinus. The surgical implications are discussed.

A Risk Score Model to Characterize Predictors of Survival After Elective Endovascular Abdominal Aortic Aneurysm Repair

The purpose of this study was to identify significant predictors of mortality after elective abdominal aortic aneurysm repair. We included all elective endovascular aneurysm repairs from 16 centers across the “Virginia's group” of the Society for Vascular Surgery Patient Safety Organization. Patients were classified into normal (estimated glomerular filtration rate [eGFR] ≥60 mL/min/1.73 m2), moderate chronic renal insufficiency (eGFR 30-59), or severe chronic renal insufficiency (eGFR <30). Kaplan-Meier and Cox regression were used to measure and to determine the predictors of mortality. A score equation was developed to categorize patients into low, medium, and high mortality risk. A total of 5678 endovascular aneurysm repair patients were included with an age of 73.6 ± 8.2 years. The majority were male (81.6%) with a history of smoking (86.1%). There were three deaths within 30 days (0.1%). Overall survival was 81.2% and 69.2% at 5 and 8 years, respectively. Several factors were associated with poor survival: unstable angina (hazard ratio [HR], 2.8; P = .008), on dialysis (HR, 3.7; P < .001), eGFR 80 (HR, 3.2; P < .001), age 75 to 79 years (HR, 2.2; P < .001), chronic obstructive pulmonary disease on oxygen (HR, 3.3; P5.8 cm (HR, 1.2; P = .043), and high risk for surgery (HR, 1.4; P = .043). Preoperative aspirin use and body mass index of 25 to 35 were both found to be protective (HR, 0.78 [P = .017] and HR, 0.8 [P = .024], respectively. The 5- and 8-year survival rates for patients with low, medium, and high risk were 89.2%, 79.7%, and 80.7% and 68.9%, 64.1%, and 47.5%, respectively (P < .001). Survival for patients with high-risk score was 47.5% at 8 years. This risk score model offers an objective tool to better guide recommendations for interventions in this era of cost-effectiveness.

Systematic variation of population receptive field properties across cortical depth in human visual cortex

Receptive fields (RFs) in visual cortex are organized in antagonistic, center-surround, configurations. RF properties change systematically across eccentricity and between visual field maps. However, it is unknown how center-surround configurations are organized in human visual cortex across lamina. We use sub-millimeter resolution functional MRI at 7Tesla and population receptive field (pRF) modeling to investigate the pRF properties in primary visual cortex (V1) across cortical depth. pRF size varies according to a U-shaped function, indicating smaller pRF center size in the middle compared to superficial and deeper intra-cortical portions of V1, consistent with non-human primate neurophysiological measurements. Moreover, a similar U-shaped function is also observed for pRF surround size. However, pRF center-surround ratio remains constant across cortical depth. Simulations suggest that this pattern of results can be directly linked to the flow of signals across cortical depth, with the visual input reaching the middle of cortical depth and then spreading towards superficial and deeper layers of V1. Conversely, blood-oxygenation-level-dependent (BOLD) signal amplitude increases monotonically towards the pial surface, in line with the known vascular organization across cortical depth. Independent estimates of the haemodynamic response function (HRF) across cortical depth show that the center-surround pRF size estimates across cortical depth cannot be explained by variations in the full-width half maximum (FWHM) of the HRF.

The Female mdx Mouse: An Unexpected Vascular Story

Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disease, caused by absence of functional dystrophin and inevitably leading to death. A variable proportion of women carriers (2.5 to 19%) can also manifest symptoms ranging from myalgia to cardiomyopathy, and pathophysiological mechanisms are still not completely understood. Our study focused on 12 month-old female mdx mice, displaying marked chronic muscle lesions, similar to the lesions observed in human DMD. Our aim was to focus on the alterations of the vascular network organisation, and functional repercussions using a combination of histology/morphometry techniques and totally non-invasive functional approach (multiparametric and functional nuclear magnetic resonance), clearly relevant for clinical diagnosis and research, combining arterial spin labeling imaging of perfusion, and 31P-spectroscopy of phosphocreatine kinetics. Collectively, our results demonstrate that the vasculature, both in its steady state organisation and dynamic behaviour after an ischemia-reperfusion stress, is altered in the 12 month-old female mdx mouse: increased density of vascular sections in histology, modification of the post-ischemic hyperemia profile, increase in mitochondrial oxidative rephosphorylation capacity, in striking opposition to what was observed in age-matched male mdx mice. We believe the apparent discordance between vascular and muscular features in the female mdx mouse make it an interesting tool to decipher further dystrophinopathy pathophysiological mechanisms.

Novel Risk Score Model for Prediction of Survival Following Elective Endovascular Abdominal Aortic Aneurysm Repair.

The purpose of this study was to identify significant predictors of long-term mortality after elective endovascular abdominal aortic aneurysm repair (EVAR). We included all cases with elective EVAR based on a national data set from the Society for Vascular Surgery Patient Safety Organization. Clinical and anatomic variables were analyzed with a Kaplan-Meier and Cox-regression model to determine predictors of mortality and develop a score equation to categorize patients into low, medium, and high long-term mortality risk. A total of 5678 patients with EVAR were included with an average age of 73.6 ± 8.2 years. The majority were male (81.6%) with a history of smoking (86.1%). There were 3 deaths within 30 days (0.1%). Several factors were associated with poor survival: unstable angina (hazard ratio [HR], 2.8; P = .008), dialysis (HR, 3.7; P < .001), estimated glomerular filtration rate (eGFR) <30 (HR, 1.7; P = .044), eGFR 30 to 59 (HR, 1.4; P = .002), age >80 (HR, 3.2; P < .001), age 75 to 79 (HR, 2.2; P < .001), chronic obstructive pulmonary disease on oxygen (HR, 3.3; P < .001), aortic diameter >5.8 cm (HR, 1.2; P = .043), and high risk for surgery (HR, 1.4; P = .043). Preoperative aspirin use and body mass index 25 to 35 were both found to be protective (HR, 0.78; P = .017 and HR, 0.8; P = .024, respectively). With our scoring model, 5- and 10-year survival rates for patients with low, medium, and high risk were 89.2%, 80.7%, and 64.1% and 77.2%, 60.1%, and 40.1%, respectively (P < .001). Ten-year survival following EVAR in patients with a high-risk score utilizing the model provided was 40.1%. Patients with multiple comorbidities at risk for decreased long-term survival can be identified with our model, which is more applicable for high-volume contemporary institutions.

Abstract TP452: Systemic Inflammation Reverses Stroke-induced Changes in Astrocytic Aquaporin-4 Expression

Introduction: Aquaporin-4 (AQP4) is a perivascular water channel that plays a key role in regulating the blood-brain barrier (BBB). Stroke acutely reduces expression and polarization of AQP4 on astrocytic endfeet, and these vascular changes might persist chronically and evolve with systemic inflammation. Reduced polarization of AQP4 after traumatic brain injury (TBI) leads to impaired perivascular clearance of debris and cognitive decline in mice, and if similar changes occur after stroke, then they may also contribute to post-stroke dementia. Hypothesis: Stroke will cause lasting changes in vascular organization, reducing astrocytic AQP4 expression and polarization in the area of injury. Methods: Thirty male Balb/cJ mice were subjected to distal middle cerebral artery ligation, allowed to survive for 28 days, and sacrificed 24 hours after injection with lipopolysaccharide (LPS, 0.33 mg/kg i.p.) or saline to model systemic inflammation. Three sequential coronal sections (20 μm) near the site of infarct (0.25 mm from Bregma) were stained with lectin, AQP4, and glial fibrillary acidic protein (GFAP) to evaluate BBB organization. Vessel density was evaluated with AngioTool. AQP4 expression was evaluated by Western blot. Results: Stroke increased vascular density in the injured hemisphere (11 ± 0.8% vs 7.6 ± 0.8% in sham mice, p &lt; 0.05). Decreased AQP4 expression and polarization near the site of the infarct was observed, which were reversed with LPS (Figure 1). LPS increased AQP4 protein levels in stroke (2.5 ± 0.37 fold-increase, p &lt; 0.05), but not sham mice. Conclusions: Stroke caused a chronic increase in vascular density, with peri-infarct vessels displaying decreased expression and changed polarity of AQP4. However, with systemic inflammation, this is reversed, potentially contributing to neuroinflammation and worsened cognitive outcomes in stroke patients who encounter infections via increased permeability of these abnormal vessels.

Decidual macrophages: key regulators of vascular remodeling in human pregnancy

Successful remodeling of the uterine spiral arteries is essential for a complication-free pregnancy and is best described in terms of its morphologic features. The molecular mediators and cellular sources of spiral artery remodeling are not known, although a role for uterine leukocytes has been proposed. Immunohistochemical assessment of placental bed biopsies demonstrated uterine NK cells, macrophages, and T lymphocytes in the wall and adventitia of spiral arteries at different stages of remodeling, regardless of the presence of extravillous trophoblast cells. Leukocytes were more prevalent in vessel adventitia than wall, and macrophages were the most abundant leukocyte population. Macrophages, separated from early pregnancy decidua, did not alter extravillous trophoblast cells invasion or vascular smooth muscle cell organization or differentiation status but did induce extracellular matrix breakdown (reduced immunostaining of laminin, P = 0.05; fibronectin, P = 0.02) and were able to phagocytose apoptotic vascular smooth muscle cells. Decidual macrophages were shown to secrete a wide range of cytokines (IL-1β, -2, -4, -5, -6, -8, -10, and -13 and TNF-α), proteases (matrix metalloproteinase-1, -2, -7, -9, and -10), and angiogenic growth factors (angiogenin, keratinocyte growth factor, fibroblast growth factor B, vascular endothelial growth factor A, and angiopoietin-1 and -2). We conclude that spiral artery remodeling involves the coordinated activity of a range of cell types, including extravillous trophoblast cells, decidual uterine NK cells, and macrophages in a carefully, spatiotemporally regulated manner.

Fibronectin Deposition Participates in Extracellular Matrix Assembly and Vascular Morphogenesis.

The extracellular matrix (ECM) has been demonstrated to facilitate angiogenesis. In particular, fibronectin has been documented to activate endothelial cells, resulting in their transition from a quiescent state to an active state in which the cells exhibit enhanced migration and proliferation. The goal of this study is to examine the role of polymerized fibronectin during vascular tubulogenesis using a 3 dimensional (3D) cell-derived de-cellularized matrix. A fibronectin-rich 3D de-cellularized ECM was used as a scaffold to study vascular morphogenesis of endothelial cells (ECs). Confocal analyses of several matrix proteins reveal high intra- and extra-cellular deposition of fibronectin in formed vascular structures. Using a small peptide inhibitor of fibronectin polymerization, we demonstrate that inhibition of fibronectin fibrillogenesis in ECs cultured atop de-cellularized ECM resulted in decreased vascular morphogenesis. Further, immunofluorescence and ultrastructural analyses reveal decreased expression of stromal matrix proteins in the absence of polymerized fibronectin with high co-localization of matrix proteins found in association with polymerized fibronectin. Evaluating vascular kinetics, live cell imaging showed that migration, migration velocity, and mean square displacement, are disrupted in structures grown in the absence of polymerized fibronectin. Additionally, vascular organization failed to occur in the absence of a polymerized fibronectin matrix. Consistent with these observations, we tested vascular morphogenesis following the disruption of EC adhesion to polymerized fibronectin, demonstrating that block of integrins α5β1 and αvβ3, abrogated vascular morphogenesis. Overall, fibronectin deposition in a 3D cell-derived de-cellularized ECM appears to be imperative for matrix assembly and vascular morphogenesis.

Spatial Metrics of Tumour Vascular Organisation Predict Radiation Efficacy in a Computational Model.

Intratumoural heterogeneity is known to contribute to poor therapeutic response. Variations in oxygen tension in particular have been correlated with changes in radiation response in vitro and at the clinical scale with overall survival. Heterogeneity at the microscopic scale in tumour blood vessel architecture has been described, and is one source of the underlying variations in oxygen tension. We seek to determine whether histologic scale measures of the erratic distribution of blood vessels within a tumour can be used to predict differing radiation response. Using a two-dimensional hybrid cellular automaton model of tumour growth, we evaluate the effect of vessel distribution on cell survival outcomes of simulated radiation therapy. Using the standard equations for the oxygen enhancement ratio for cell survival probability under differing oxygen tensions, we calculate average radiation effect over a range of different vessel densities and organisations. We go on to quantify the vessel distribution heterogeneity and measure spatial organization using Ripley’s L function, a measure designed to detect deviations from complete spatial randomness. We find that under differing regimes of vessel density the correlation coefficient between the measure of spatial organization and radiation effect changes sign. This provides not only a useful way to understand the differences seen in radiation effect for tissues based on vessel architecture, but also an alternate explanation for the vessel normalization hypothesis.

A synergistic approach to the design, fabrication and evaluation of 3D printed micro and nano featured scaffolds for vascularized bone tissue repair

3D bioprinting has begun to show great promise in advancing the development of functional tissue/organ replacements. However, to realize the true potential of 3D bioprinted tissues for clinical use requires the fabrication of an interconnected and effective vascular network. Solving this challenge is critical, as human tissue relies on an adequate network of blood vessels to transport oxygen, nutrients, other chemicals, biological factors and waste, in and out of the tissue. Here, we have successfully designed and printed a series of novel 3D bone scaffolds with both bone formation supporting structures and highly interconnected 3D microvascular mimicking channels, for efficient and enhanced osteogenic bone regeneration as well as vascular cell growth. Using a chemical functionalization process, we have conjugated our samples with nano hydroxyapatite (nHA), for the creation of novel micro and nano featured devices for vascularized bone growth. We evaluated our scaffolds with mechanical testing, hydrodynamic measurements and in vitro human mesenchymal stem cell (hMSC) adhesion (4 h), proliferation (1, 3 and 5 d) and osteogenic differentiation (1, 2 and 3 weeks). These tests confirmed bone-like physical properties and vascular-like flow profiles, as well as demonstrated enhanced hMSC adhesion, proliferation and osteogenic differentiation. Additional in vitro experiments with human umbilical vein endothelial cells also demonstrated improved vascular cell growth, migration and organization on micro-nano featured scaffolds.

HYDRODYNAMIC FUNDAMENTALS FOR PHYSICAL-MATHEMATICAL MODEL OF MYOCARDIUM CIRCULATION

Currently the diseases of heart and vessels are the primary cause of disability and mortality. Recent understanding of myocardial angioarchitectonics does not reveal fully the relation of coronary anatomy with their function related to their aim for sufficient blood supply in coronary system at tissue level. Filtration liquid currents in non-homogenic porous mediums are widely spread in nature and technology and highly attractable for researches. Also, there is broadly discussed filtration in multilayered non-homogenic grounds. Myocard and its vessels can be represented as the model of porous medium, towards which the hydrodynamic laws can be applied, that are in use for liquid perfusion assessement in porous mediums perfusion. This has never been applied to circulation of a human organs and tissues. The direction is presented for collaboration of physicians and physicshydrodynamicians to obtain results for better assessment of vascular organization net and hydrodynamical circumstances of the heart circulation, which might further lead to universalized criteria for reference ranges definition and myocardium perfusion levels of disorder; to objectify pathogenetic approaches to cardiovascular patients treatment.