Retinal structural and microvascular abnormalities in retinal dysplasia imaged by OCT and OCT angiography.

OBJECTIVE: To describe the in vivo structural characteristics of multifocal and geographic retinal dysplasia visualized with advanced retinal imaging including confocal scanning laser ophthalmoscopy (cSLO), optical coherence tomography (OCT), en face OCT, and the novel vascular imaging technique OCT angiography (OCTA). DOGS STUDIED AND PROCEDURES: Two dogs were diagnosed with unilateral multifocal or geographic retinal dysplasia and underwent advanced retinal imaging under general anesthesia at the Retinal Disease Studies Facility of the University of Pennsylvania. RESULTS: In both cases, the morphological pattern of the lesions was similar including outer retinal folds that invaginated and formed tubular retinal rosettes, surrounding a central inner retinal thickening (multifocal) or plaque (geographic). The two dogs had multiple vascular anomalies in the lesions such as increased tortuosity, abnormal change of vessel diameter including aneurysms and capillary network disruption. We also identified increased autofluorescence by AF cSLO with short wavelength light source (488 nm and barrier filter at 500 nm), and several areas of photoreceptor loss associated with the lesions. CONCLUSION: The use of OCTA allowed the identification of microvascular abnormalities associated with multifocal and geographic retinal dysplasia in two dogs. To our knowledge, this is the first report where the dye-free OCTA technique is used to study vascular lesions in canine retinas.

Identification of novel sublingual parameters to analyze and diagnose microvascular dysfunction in sepsis: the NOSTRADAMUS study.

BACKGROUND: The availability of handheld, noninvasive sublingual video-microscopes allows for visualization of the microcirculation in critically ill patients. Recent studies demonstrate that reduced numbers of blood-perfused microvessels and increased penetration of erythrocytes into the endothelial glycocalyx are essential components of microvascular dysfunction. The aim of this study was to identify novel microvascular variables to determine the level of microvascular dysfunction in sepsis and its relationship with clinical variables. METHODS: This observational, prospective, cross-sectional study included 51 participants, of which 34 critically ill sepsis patients were recruited from intensive care units of a university hospital. Seventeen healthy volunteers served as controls. All participants underwent sublingual videomicroscopy by sidestream darkfield imaging. A new developed version of the Glycocheck™ software was used to quantify vascular density, perfused boundary region (PBR-an inverse variable of endothelial glycocalyx dimensions), red blood cell (RBC) velocity, RBC content, and blood flow in sublingual microvessels with diameters between 4 and 25 µm. RESULTS: A detailed analysis of adjacent diameter classes (1 µm each) of vessels between 4 and 25 µm revealed a severe reduction of vascular density in very small capillaries (5-7 µm), which correlated with markers of sepsis severity. Analysis of RBC velocity (VRBC) revealed a strong dependency between capillary and feed vessel VRBC in sepsis patients (R2 = 0.63, p < 0.0001) but not in healthy controls (R2 = 0.04, p = 0.43), indicating impaired capillary (de-)recruitment in sepsis. This finding enabled the calculation of capillary recruitment and dynamic capillary blood volume (CBVdynamic). Moreover, adjustment of PBR to feed vessel VRBC further improved discrimination between sepsis patients and controls by about 50%. By combining these dynamic microvascular and glycocalyx variables, we developed the microvascular health score (MVHSdynamic™), which decreased from 7.4 [4.6-8.7] in controls to 1.8 [1.4-2.7] in sepsis patients (p < 0.0001) and correlated with sepsis severity. CONCLUSION: We introduce new important diameter-specific quantification and differentiated analysis of RBC kinetics, a key to understand microvascular dysfunction in sepsis. MVHSdynamic, which has a broad bandwidth to detect microvascular (dys-) function, might serve as a valuable tool to detect microvascular impairment in critically ill patients.

Retinal Microvascular Signs as Screening and Prognostic Factors for Cardiac Disease: A Systematic Review of Current Evidence.

The substantial burden of heart disease promotes an interest in new ways of screening for early disease diagnosis, especially by means of noninvasive imaging. Increasing evidence for association between retinal microvascular signs and heart disease prompted us to systematically investigate the relevant current literature on the subject. We scrutinized the current literature by searching PubMed and Embase databases from 2000 to 2020 for clinical studies of the association between retinal microvascular signs and prevalent or incident heart disease in humans. Following exclusions, we extracted the relevant data from 42 publications (comprising 14 prospective, 26 cross-sectional, and 2 retrospective studies). Our search yielded significant associations between retinal vascular changes, including diameter, tortuosity, and branching, and various cardiac diseases, including acute coronary syndrome, coronary artery disease, heart failure, and conduction abnormalities. The findings of our research suggest that the retinal microvasculature can provide essential data about concurrent cardiac disease status and predict future risk of cardiac-related events.

Mural Cell-Specific Deletion of Cerebral Cavernous Malformation 3 in the Brain Induces Cerebral Cavernous Malformations.

OBJECTIVE: Cerebral cavernous malformations (CCM), consisting of dilated capillary channels formed by a single layer of endothelial cells lacking surrounding mural cells. It is unclear why CCM lesions are primarily confined to brain vasculature, although the 3 CCM-associated genes (CCM1, CCM2, and CCM3) are ubiquitously expressed in all tissues. We aimed to determine the role of CCM gene in brain mural cell in CCM pathogenesis. Approach and Results: SM22α-Cre was used to drive a specific deletion of Ccm3 in mural cells, including pericytes and smooth muscle cells (Ccm3smKO). Ccm3smKO mice developed CCM lesions in the brain with onset at neonatal stages. One-third of Ccm3smKO mice survived upto 6 weeks of age, exhibiting seizures, and severe brain hemorrhage. The early CCM lesions in Ccm3smKO neonates were loosely wrapped by mural cells, and adult Ccm3smKO mice had clustered and enlarged capillary channels (caverns) formed by a single layer of endothelium lacking mural cell coverage. Importantly, CCM lesions throughout the entire brain in Ccm3smKO mice, which more accurately mimicked human disease than the current endothelial cell-specific CCM3 deletion models. Mechanistically, CCM3 loss in brain pericytes dramatically increased paxillin stability and focal adhesion formation, enhancing ITG-ß1 (integrin ß1) activity and extracellular matrix adhesion but reducing cell migration and endothelial cell-pericyte associations. Moreover, CCM3-wild type, but not a paxillin-binding defective mutant, rescued the phenotypes in CCM3-deficient pericytes. CONCLUSIONS: Our data demonstrate for the first time that deletion of a CCM gene in the brain mural cell induces CCM pathogenesis.

Multimodal imaging of aberrant macular microvessel crossing the foveal avascular zone in two young adults.

BACKGROUND: The traditional view is that there are no vessels in the foveal avascular zone. The two cases we report show microvessels crossing the foveal avascular zone. CASE PRESENTATION: A man and a woman, both 25 years old, were both incidentally found on optical coherence tomography angiography (OCTA) to have unilateral aberrant microvessels crossing the foveal avascular zone in their left eyes. Visual acuity was preserved in both patients. The vessel density (VD) and perfusion density (PD) of the eyes with the aberrant microvessels were all higher than those of the contralateral eyes. Nevertheless, measurements of foveal avascular zone (FAZ) dimensions, including its area, perimeter and circularity, were smaller in the left eyes than in the right eyes. No complications were recorded. CONCLUSIONS: To date, aberrant microvessels crossing the foveal avascular zone have not been found to impair visual function. OCTA is a non-invasive and quick method that does not require dilation or the use of fluorescein dye. It is a reliable tool for the detection of aberrant microvessels crossing the foveal avascular zone.

Identification of two distinct hereditary hemorrhagic telangiectasia patient subsets with different hepatic perfusion properties by combination of contrast-enhanced ultrasound (CEUS) with perfusion imaging quantification.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is marked by arteriovenous fusion comprising hepatic vascular malformations (HVaMs) with the chance of bleeding. AIMS: We investigated HVaMs in HHT patients by combination of contrast-enhanced ultrasound (CEUS) with perfusion imaging quantification to be able to sub-classify a high risk cohort of asymptomatic HHT patients. METHODS: The imaging characteristics on CEUS in 34 patients (aged 21-84 years; mean 58.9) with HHT were retrospectively evaluated. Real-time contrast harmonic imaging, sulfur hexafluoride-filled microbubbles and motion adjustment were utilized. Cine loops of the liver were digital stored, perfusion was quantified using a software reading DICOM data`s. RESULTS: HVaMs were diagnosed in 31 out of 34 patients. Significant uppermost peak enhancement (PE), wash-in area under the curve (WiAUC) and wash-in perfusion index (WiPI) were identified in the shunt region (100%), next in the hilar region (PE 32.6%; WiAUC 33.9%; WiPI 34.1%), and the lowest in the hepatic parenchyma (PE 10.2%; WiAUC 12.0%; WiPI 9.5%). The perfusion parameters in the shunt region compared to the other regions were significantly increased in one subgroup of patients. Consistent with this, the intrahepatic portal vein diameter and Buscarini grading was significantly higher, while portal vein peak velocity was significantly lower in this patient subset. By statistical analysis, we could correlate PE and WiPI to these clinical parameters, while WiAUC showed no clinical association. CONCLUSIONS: For the first time we combined CEUS findings with motion adjustment software to quantitative determine perfusion parameters of a cohort of HHT patients. Hereby, we could identify a subset of HHT patients with two markedly increased parameter values in the shunt region compared to the hilus/hepatic parenchyma. This could contribute to sub-classify a high-risk group of HHT patients with therapeutic indication.

Angioarchitecture and hemodynamics of microvascular arterio-venous malformations.

INTRODUCTION: Arteriovenous malformations (AVMs) are characterized by pathological high flow, low resistance connections between arteries and veins. Treatment is critically dependent on correct interpretation of angioarchitectural features. However, some microfistular AVMs do not match the characteristics described in current AVM classification systems. Therefore, we propose a new subgroup of microfistular AVMs, composed of enlarged, fistulous paths on the venous half of capillaries and/or dilated draining venules (hyperdynamic, capillary-venulous malformation [CV-AVM]). CV-AVMs still ensure arterial flow to the periphery and fistulous venous drainage is less pronounced than in classical AVMs such that these lesions are often misinterpreted as venous malformations. MATERIALS AND METHODS: We developed a computational model to study the effects of microvascular anomalies on local hemodynamics, as well as their impact on angiographic contrast propagation. Flow rates and pressures were computed with a lumped parameter description, while contrast propagation was determined by solving the 1D advection-diffusion equation. RESULTS AND CONCLUSIONS: For the newly proposed CV-AVM angioarchitecture, the computational model predicts increased arterio-venous contrast agent transit times and highly dispersive transport characteristics, compared to microfistular, interstitial type IV AVMs and high flow type II and III AVMs. We related these findings to time-contrast intensity curves sampled from clinical angiographies and found that there is strong evidence for the existence of CV-AVM.

Brain microvasculature defects and Glut1 deficiency syndrome averted by early repletion of the glucose transporter-1 protein.

Haploinsufficiency of the SLC2A1 gene and paucity of its translated product, the glucose transporter-1 (Glut1) protein, disrupt brain function and cause the neurodevelopmental disorder, Glut1 deficiency syndrome (Glut1 DS). There is little to suggest how reduced Glut1 causes cognitive dysfunction and no optimal treatment for Glut1 DS. We used model mice to demonstrate that low Glut1 protein arrests cerebral angiogenesis, resulting in a profound diminution of the brain microvasculature without compromising the blood-brain barrier. Studies to define the temporal requirements for Glut1 reveal that pre-symptomatic, AAV9-mediated repletion of the protein averts brain microvasculature defects and prevents disease, whereas augmenting the protein late, during adulthood, is devoid of benefit. Still, treatment following symptom onset can be effective; Glut1 repletion in early-symptomatic mutants that have experienced sustained periods of low brain glucose nevertheless restores the cerebral microvasculature and ameliorates disease. Timely Glut1 repletion may thus constitute an effective treatment for Glut1 DS.

Abnormal Vessel Architecture Persists in the Microvasculature of the Massive Weight Loss Patient.

BACKGROUND: Research demonstrates a link between obesity and increased circulating inflammatory cytokines, which lead to changes in the microvasculature. Massive weight loss patients often experience delayed wound healing after body-contouring procedures; however, no studies exist to explore the inflammatory response of massive weight loss on microvasculature. This study hypothesized that massive weight loss patients who undergo body-contouring procedures maintain persistently elevated inflammatory markers in the microvasculature that delay wound healing. METHODS: Superficial inferior epigastric artery vessels were harvested during abdominally based free flap surgery and abdominal contouring surgery for normal weight and massive weight loss patients, respectively. Vessels were histologically assessed using immunohistochemistry and trichome staining to assess and compare vessel architecture. Analysis was performed for intimal proliferation and luminal occlusion ratio. RESULTS: All patients (n = 23) were female. Quantitative analysis of immunohistochemistry stains revealed no difference between normal weight and massive weight loss patients. Trichrome staining demonstrated abnormal vessel architecture in the massive weight loss group. Intimal proliferation was 11.4 ± 4.8 percent for normal weight patients compared with 29.5 ± 4.9 percent for massive weight loss patients (p < 0.0001). Occlusion ratio for normal weight patients was 29.9 ± 3.9 percent compared with 46.2 ± 8.1 percent for massive weight loss patients (p < 0.0001) CONCLUSIONS:: Despite the return to normal levels of inflammatory markers after massive weight loss, trichrome staining demonstrated irregular composition in the tunica adventitia and tunica media and increased intimal proliferation and occlusion ratio. This suggests vasculopathy that could explain delayed wound healing in the massive weight loss population.

Sepsis impairs microvascular autoregulation and delays capillary response within hypoxic capillaries.

INTRODUCTION: The microcirculation supplies oxygen (O2) and nutrients to all cells with the red blood cell (RBC) acting as both a deliverer and sensor of O2. In sepsis, a proinflammatory disease with microvascular complications, small blood vessel alterations are associated with multi-organ dysfunction and poor septic patient outcome. We hypothesized that microvascular autoregulation-existing at three levels: over the entire capillary network, within a capillary and within the erythrocyte-was impaired during onset of sepsis. This study had three objectives: 1) measure capillary response time within hypoxic capillaries, 2) test the null hypothesis that RBC O2-dependent adenosine triphosphate (ATP) efflux was not altered by sepsis and 3) develop a framework of a pathophysiological model. METHODS: This was an animal study, comparing sepsis with control, set in a university laboratory. Acute hypotensive sepsis was studied using cecal ligation and perforation (CLP) with a 6-hour end-point. Rat hindlimb skeletal muscle microcirculation was imaged, and capillary RBC supply rate (SR = RBC/s), RBC hemoglobin O2 saturation (SO2) and O2 supply rate (qO2 = pLO2/s) were quantified. Arterial NOx (nitrite + nitrate) and RBC O2-dependent ATP efflux were measured using a nitric oxide (NO) analyzer and gas exchanger, respectively. RESULTS: Sepsis increased capillary stopped-flow (p = 0.001) and increased plasma lactate (p < 0.001). Increased plasma NOx (p < 0.001) was related to increased capillary RBC supply rate (p = 0.027). Analysis of 30-second SR-SO2-qO2 profiles revealed a shift towards decreased (p < 0.05) O2 supply rates in some capillaries. Moreover, we detected a three- to fourfold increase (p < 0.05) in capillary response time within hypoxic capillaries (capillary flow states where RBC SO2 < 20 %). Additionally, sepsis decreased the erythrocyte's ability to respond to hypoxic environments, as normalized RBC O2-dependent ATP efflux decreased by 62.5 % (p < 0.001). CONCLUSIONS: Sepsis impaired microvascular autoregulation at both the individual capillary and erythrocyte level, seemingly uncoupling the RBC acting as an "O2 sensor" from microvascular autoregulation. Impaired microvascular autoregulation was manifested by increased capillary stopped-flow, increased capillary response time within hypoxic capillaries, decreased capillary O2 supply rate and decreased RBC O2-dependent ATP efflux. This loss of local microvascular control was partially off-set by increased capillary RBC supply rate, which correlated with increased plasma NOx.

Microvasculature and incident atrioventricular conduction abnormalities in the Multi-Ethnic Study of Atherosclerosis (MESA).

Abnormalities of the microvasculature are linked to major cardiac events, but their role in the development of atrioventricular conduction abnormalities (AVCA) is unknown. We examined the association between central retinal arteriolar equivalent (CRAE), a measure of the microvasculature, and incident AVCA. This analysis included 3975 participants free of AVCA at baseline from the Multi-Ethnic Study of Atherosclerosis (MESA). Incident AVCA was defined as a composite of new heart rate-adjusted PR interval ⩾ 200 ms (first-degree AV block) and advanced block (second-degree or complete AV block) detected from the MESA exam 5 electrocardiogram (ECG). CRAE was measured from retinal photographs at exam 2. Both ECGs and retinal photographs were collected using standardized methods and read and graded at central core labs. Incident AVCA were present in 7.4% (n=290) of the participants, of which 94% were first-degree AV block. Incident AVCA were increasingly more common in participants with narrower CRAE (4.6% in Q4, 6.4% in Q3, 7.0% in Q2 and 10.8% in Q1, p-value for trend < 0.0001). The socio-demographic and cardiovascular disease risk-adjusted odds of incident AVCA in the Q1 group (the group with the narrowest retinal arteriolar diameter) was nearly twice the odds in the Q4 group (OR: 1.68, 95% CI: 1.15-2.51). This association remained significant after adjustment for major ECG abnormalities and incident cardiovascular disease (Q1 vs Q4, OR: 1.65, 95% CI: 1.01-2.71). In conclusion, narrower retinal arteriolar caliber is associated with development of new AV conduction abnormalities.

Hypertrophic cardiomyopathy: Cardiac structural and microvascular abnormalities as evaluated with multi-parametric MRI.

PURPOSE: To determine the relationship between myocardial structural and microvascular abnormality in hypertrophic cardiomyopathy (HCM) by multi-parametric cardiac MRI. MATERIALS AND METHODS: Twenty-four HCM and eighteen controls were retrospectively included. Left ventricle mass (LVM), LV end-systolic and end-diastolic volume (LVESV, LVEDV), LV ejection fraction (LVEF), and 16-segment wall thickness at ES and ED (SESWT, SEDWT) were assessed with a 2D cine-MRI. Myocardial perfusion (reflected by K(trans)), interstitial volume (Ve) and mean transmit time (MTT) were evaluated with a model-dependent dynamic contrast-enhanced MRI. Myocardial fibrosis was assessed with late gadolinium enhancement (LGE) imaging. RESULTS: K(trans) was significantly decreased in LGE-present (0.74±0.15mL/g/min) against LGE-absent (0.55±0.14mL/g/min, p=0.030) and normal group (0.81±0.32mL/g/min, p<0.001), but was unchanged in LGE-absent against normal group (p>0.05). Ve and MTT were significantly increased in LGE-present (Ve: 26.7±15.7%; MTT: 28.6±21.3s) against LGE-absent (37.6±18.3%; 49.8±30.5s) and normal group (19.7±6.9%; 15.1±3.9s; all p<0.001), and were significantly increased in LGE-absent against normal group (p<0.001). LGE significantly correlated to K(trans), Ve, MTT, and SESWT (ρ=0.232, -0.247, -0.443, and -0.207, respectively). K(trans) negatively correlated to SEDWT and SESWT (ρ=-0.224 and -0.231). Ve and MTT positively correlated to SEDWT (Ve: ρ=0.223; MTT: ρ=0.239) and SESWT (Ve: ρ=0.248; MTT: ρ=0.254). CONCLUSIONS: Consistent relationship was determined between myocardial structural abnormality and microvascular dysfunction in HCM.

Increased plasma soluble urokinase plasminogen activator receptor levels in systemic sclerosis: possible association with microvascular abnormalities and extent of fibrosis.

BACKGROUND: Urokinase plasminogen activator receptor (uPAR) is a key component of the fibrinolytic system involved in extracellular matrix remodeling and angiogenesis. Novel animal models supported the key role of uPAR not only in fibrosis but also in systemic sclerosis (SSc)-related microvascular abnormalities. The aim of this study was to investigate plasma soluble uPAR (suPAR) levels in SSc, and their association with organ-specific involvement. METHODS: suPAR concentrations were measured by ELISA in SSc patient (n=83) and in healthy controls (n=29). Simultaneously, CRP and ESR were assessed. Detailed clinical data including skin, lung, heart and microvascular characteristics were evaluated at sampling. RESULTS: suPAR values were higher in SSc patients than in controls. Subgroup analysis showed higher suPAR values in diffuse cutaneous- than in limited cutaneous SSc and correlated with anti-Scl-70+. suPAR levels also associated with pulmonary function test parameters of fibrosis, presence of microvascular lesions (e.g., Raynaud phenomenon, naifold capillaroscopic abnormalities and digital ulcers) and arthritis. CONCLUSIONS: Our data indicate that suPAR might be a valuable early diagnostic marker of SSc which also correlates with disease severity.

Bilateral segmental agenesis of carotid and vertebral arteries with rete mirabile and the prominent anterior and posterior spinal arteries as compensations.

Agenesis of carotid or vertebrobasilar arteries with rete formation is rare. The anterior spinal artery or posterior spinal arteries supplying the posterior circulation with steno-occlusion or agenesis of bilateral vertebral arteries is also uncommon. Here, we describe a very rare case of concomitant segmental agenesis of bilateral carotid and vertebral arteries with collateral compensations from the prominent anterior spinal artery and posterior spinal arteries, as well as some transdural arterial networks which were considered a rete mirabile. We discuss its embryological and anatomic significance.

Induction of brain arteriovenous malformation in the adult mouse.

Brain arteriovenous malformations (bAVM) are tangles of abnormal, dilated vessels that directly shunt blood between the arteries and veins. The pathogenesis of bAVM is currently unknown. Patients with hereditary hemorrhagic telangiectasia (HHT) have a higher prevalence of bAVM than the general population. Animal models are important tools for dissecting the disease etiopathogenesis and for testing new therapies. Here, we introduce a method that induces the bAVM phenotype through regional deletion of activin-like kinase 1 (Alk1, the causal gene for HHT2) and vascular endothelial growth factor (VEGF) stimulation.

Transforming growth factor-beta1 induces microvascular abnormalities through a down-modulation of neural cell adhesion molecule in human hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a very angiogenic and malignant cancer. Conventional chemotherapy is poorly effective because of the abnormal structural organization of HCC-infiltrating vessels. In previous work, we demonstrated that HCC angiogenesis is driven by transforming growth factor beta-1(TGF-ß1)/CD105 axis, stimulating liver-derived microvascular endothelial cells (Ld-MECs) migration. As TGF-ß1 also affects mural cells (MCs) recruitment and maturation, we asked whether it may contribute to HCC-induced vascular abnormalities. HCC and adjacent non-neoplastic liver (nNL) biopsies obtained from 12 patients were analyzed by immunohistochemistry for angiogenic markers CD105, TGF-ß1, CD44 and vascular endothelial growth factor-a (VEGFa) and for MC markers NG2, α-smooth muscle actin (αSMA) and neural cell adhesion molecule (NCAM). The same markers were also investigated by immunocytochemistry on cultured HCC-derived stromal cells (HCC-StCs) and nNL-derived StCs (nNL-StCs) isolated from the same liver biopsies. Angiogenic factors released by StCs were analyzed by ELISA and the interaction between StCs and Ld-MECs by adhesion assay. Compared with nNL, HCC biopsies showed increased angiogenic markers and αSMA that was localized in vessels. By contrast, NG2 and NCAM were substantially localized in tumor cells but absent in vessels and stroma. Cultured HCC-StCs showed less expression of NG2, αSMA and NCAM. They also demonstrated a lower capacity to release angiogenic factors and adhered on Ld-MECs. HCC-StCs and nNL-StCs treated with TGF-ß1 or with of HepG2 (a human hepatoma cell line) derived conditioned medium (CM), down-modulated NCAM expression, whereas anti-NCAM antibodies significantly reduced the adhesion of StCs to Ld-MECs. By further blocking TGF-ß1 with anti-TGF-ß1 antibodies or with Ly-364947 (a specific inhibitor TGF-ß1-receptor) adhesion to Ld-MECs and NCAM expression respectively was partially restored. TGF-ß1 contributes to HCC-induced vascular alterations by affecting the interaction between HCC-StCs and Ld-MECs through a down-modulation of NCAM expression.