Collateral Growth Research Articles

KANK4 Promotes Arteriogenesis by Potentiating VEGFR2 Signaling in a TALIN-1-Dependent Manner.

Arteriogenesis plays a critical role in maintaining adequate tissue blood supply and is related to a favorable prognosis in arterial occlusive diseases. Strategies aimed at promoting arteriogenesis have thus far not been successful because the factors involved in arteriogenesis remain incompletely understood. Previous studies suggest that evolutionarily conserved KANK4 (KN motif and ankyrin repeat domain-containing proteins 4) might involve in vertebrate vessel development. However, how the KANK4 regulates vessel function remains unknown. We aim to determine the role of endothelial cell-specifically expressed KANK4 in arteriogenesis. The role of KANK4 in regulating arteriogenesis was evaluated using Kank4-/- and KANK4iECOE mice. Molecular mechanisms underlying KANK4-potentiated arteriogenesis were investigated by employing RNA transcriptomic profiling and mass spectrometry analysis. By analyzing Kank4-EGFP reporter mice, we showed that KANK4 was specifically expressed in endothelial cells. In particular, KANK4 displayed a dynamic expression pattern from being ubiquitously expressed in all endothelial cells of the developing vasculature to being explicitly expressed in the endothelial cells of arterioles and arteries in matured vessels. In vitro microfluidic chip-based vascular morphology analysis and in vivo hindlimb ischemia assays using Kank4-/- and KANK4iECOE mice demonstrated that deletion of KANK4 impaired collateral artery growth and the recovery of blood perfusion, whereas KANK4 overexpression leads to increased vessel caliber and blood perfusion. Bulk RNA sequencing and Co-immunoprecipitation/mass spectrometry (Co-IP/MS) analysis identified that KANK4 promoted EC proliferation and collateral artery remodeling through coupling VEGFR2 (vascular endothelial growth factor receptor 2) to TALIN-1, which augmented the activation of the VEGFR2 signaling cascade. This study reveals a novel role for KANK4 in arteriogenesis in response to ischemia. KANK4 links VEGFR2 to TALIN-1, resulting in enhanced VEGFR2 activation and increased EC proliferation, highlighting that KANK4 is a potential therapeutic target for promoting arteriogenesis for arterial occlusive diseases.

The Modern Surgical Approach to Pulmonary Atresia with Ventricular Septal Defect and Major Aortopulmonary Collateral Arteries.

Pulmonary atresia with ventricular septal defect and major aortopulmonary collaterals is a complex congenital heart defect that includes a heterogeneous subgroup of patients. Variation in the sources of pulmonary blood flow contributes to the complexity of the lesion and the diversity of approaches to its management. Unifocalization and rehabilitation focus on mobilization of collateral arteries and growth of native pulmonary arteries, respectively, with the ultimate surgical goal of achieving separated systemic and pulmonary circulations with the lowest possible right ventricular pressure. Regardless of the strategy, outcomes have altered the natural history of the disease, with a complete repair rate of approximately 80% and low early and late mortality rates. Given this heterogeneity of pulmonary vasculature, a tailored approach should be adopted for each patient, using all diagnostic methods currently offered by technical developments.

The Overexpression of Sonic Hedgehog Associates with Collateral Development and Amelioration of Oxidative Stress in Stroke Patients

PurposeSonic hedgehog (SHH) signaling pathway in oxidative stress condition has been acknowledged as a key trigger for angiogenesis and collateral vessel growth in the ischemic brain, and it exerts a protective effect on neuronal cells during oxidative stress. MethodsA total of sixty patients (n = 30 good collateral profile and n = 30 poor collateral profile) diagnosed with acute cerebral ischemia were enrolled in this study. qRT-PCR was performed to analyze the expression levels of SHH, Gli1, and superoxide dismutase (SOD), genes. Also, the serum levels of oxidative stress markers were determined in experimental groups. ResultsThe expression levels of SHH and Gli1 genes were significantly (p < 0.05) higher in stroke patients with good collateral circulation compared with those with poor collateral circulation, while SOD gene expression was similar between two groups (p > 0.05). A significantly positive correlation was found between the gene expression of SHH and Gli1 (r = 0.604, p < 0.001), SOD and Gli1 (r = 0.372, p < 0.003) genes. Our findings showed that the serum level of total antioxidant capacity (TAC) and Glutathione (GSH) and SOD enzyme activity was significantly (p < 0.05) increased, while serum total oxidant status (TOS) and malondialdehyde (MDA) levels were significantly (p < 0.05) decreased in patients with good collateral circulation as compared with those with poor collateral circulation. ConclusionOur observations shed light on the association of the SHH/Gli1 signaling pathway with cerebral collateral vessel development following ischemia. Oxidative stress in stroke patients with poor collateral circulation may result in the overexpression of SHH/Gli1 signaling pathway which possibly contribute to oxidative stress attenuation, as well as modulate angiogenesis and collateral vessels development.

Abstract 91: Large Vessel Occlusion Stroke Patients With Rapid Early Infarct Progression And Poor Collaterals Are Vulnerable To Blood Pressure Reductions

Introduction: The precise interactions between collateral perfusion, hemodynamics, and infarct growth after large vessel occlusion (LVO) require further definition. This study examined whether patients with poor collateral circulation and rapid early infarct progression are more vulnerable to reductions in blood pressure (BP). Methods: We prospectively enrolled patients with LVO stroke who underwent thrombectomy. Volumes of arterial tissue delay and relative cerebral blood flow (CBF) were estimated with RAPID software; a poor collateral profile was defined by a hypoperfusion intensity ratio &gt;0.4. Early infarct growth rate (EIGR) was defined as ischemic core volume (CBF&lt;30%) divided by the time from symptom onset to imaging. A fast progressor profile was assigned to patients whose EIGR was &gt;10 mL/h. The final infarct growth rate (FIGR) was the quotient of final infarct volume (FIV) and time from symptom onset to reperfusion. BP reduction was measured as the difference between admission mean arterial pressure (MAP) and lowest MAP before reperfusion. Results: Fifty-five patients (mean age 69 + 15, mean NIHSS 13) with successful reperfusion (TICI 2B/3) were included in the analysis. The median MAP reduction was 17 (IQR 9, 32). Poor collateral perfusion and EIGR were independent predictors of FIV after adjusting for age and admission NIHSS (mean FIV 70 vs. 31 mL, p=0.012 and 60 vs. 29 mL, p=0.01, respectively). A significant interaction was found between MAP reduction and both collateral status (p=0.04) and progressor profile (p=0.01). For every 10 mmHg MAP reduction, patients with poor collaterals experienced an average increase in FIGR of 3.6 mL/h (Fig. 1A). Above a critical MAP reduction threshold of 30 mmHg, mean FIV was significantly larger in patients with rapidly progressing infarcts (p&lt;0.01, Fig. 1B). Conclusions: Patients with poor collaterals and rapid early infarct growth are at higher risk of accelerated infarct growth and larger FIV related to BP reductions.

Abstract 166: Loss Of Endothelial Cell Specific EphA4 Improves Acute Leptomeningeal Collateral Growth Following Ischemic Stroke

Leptomeningeal anastomoses, or pial collateral vessels, are a major determinant of patient outcome following ischemic stroke. These vessels form in the pia mater of the brain during development and connect distal arterioles of cerebral arteries. Following vascular obstruction, pial collaterals expand through arteriogenesis, an adaptive process that allows for retrograde perfusion into the obstructed artery and its affected tissue. However, acute arteriogenesis following ischemic stroke has been poorly investigated, therefore our research aims to fill this knowledge gap. Our novel pre-clinical murine findings suggest EphA4, a receptor tyrosine kinase, plays a role in restricting arteriogenesis following permanent middle cerebral artery occlusion (pMCAO). To investigate the role of endothelial cell-specific EphA4 in acute arteriogenesis, we employed 3-month old conditional endothelial cell (EC)-specific EphA4 knockout ( EphA4 fl/fl /Cdh5::Cre ERT2 ; KO) and wild type ( EphA4 fl/fl ; WT) mice. Compared to WT controls, we find KO mice displayed a significant reduction in infarct volume (24.0±1.8mm 3 vs 14.3±2.5mm 3 ; n=9) which correlated with larger ipsilateral pial collateral vessels as early as 4.5-hours (27.31±0.6um vs 32.41±0.8um; n=15) and up to 24-hours post-pMCAO (31.14±0.8um vs 36.7±0.9um; n=15). Additionally, our previous work has indicated that EphA4 may exert its inhibitory function on arteriogenesis by hindering Tie2 signaling. To identify gene expression changes in the collateral vessels and connecting cerebral arteries, the pial surface was carefully isolated from four mice per sample and pooled. Analysis of mRNA expression in the pial surface 24-hours post-pMCAO revealed that WT mice had significantly higher fold change of angiopoietin-2 (1.4±0.2 vs 0.8± 0.09; n=5) and Tie1 (5.3±1.8 vs 0.9±0.2; n=5) compared to KO mice, indicating potential inhibition of Tie2 signaling. These findings demonstrate that EC-specific EphA4 negatively regulates collateral growth and inhibition of this receptor could serve as a novel therapeutic strategy for improving collateral response following ischemic stroke.

The essential role for endothelial cell sprouting in coronary collateral growth

RationaleCoronary collateral growth is a natural bypass for ischemic heart diseases. It offers tremendous therapeutic benefit, but the process of coronary collateral growth isincompletely understood due to limited preclinical murine models that would enable interrogation of its mechanisms and processes via genetic modification and lineage tracing. Understanding the processes by which coronary collaterals develop can unlock new therapeutic strategies for ischemic heart disease. ObjectiveTo develop a murine model of coronary collateral growth by repetitive ischemia and investigate whether capillary endothelial cells could contribute to the coronary collateral formation in an adult mouse heart after repetitive ischemia by lineage tracing. Methods and resultsA murine model of coronary collateral growth was developed using short episodes of repetitive ischemia. Repetitive ischemia stimulation resulted in robust collateral growth in adult mouse hearts, validated by high-resolution micro-computed tomography. Repetitive ischemia-induced collateral formation compensated ischemia caused by occlusion of the left anterior descending artery. Cardiac function improved during ischemia after repetitive ischemia, suggesting the improvement of coronary blood flow. A capillary-specific Cre driver (Apln-CreER) was used for lineage tracing capillary endothelial cells. ROSA mT/mG reporter mice crossed with the Apln-CreER transgene mice underwent a 17 days' repetitive ischemia protocol for coronary collateral growth. Two-photon and confocal microscopy imaging of heart slices revealed repetitive ischemia-induced coronary collateral growth initiated from sprouting Apelin+ endothelial cells. Newly formed capillaries in the collateral-dependent zone expanded in diameter upon repetitive ischemia stimulation and arterialized with smooth muscle cell recruitment, forming mature coronary arteries. Notably, pre-existing coronary arteries and arterioles were not Apelin+, and all Apelin+ collaterals arose from sprouting capillaries. Cxcr4, Vegfr2, Jag1, Mcp1, and Hif1⍺ mRNA levels in the repetitive ischemia-induced hearts were also upregulated at the early stage of coronary collateral growth, suggesting angiogenic signaling pathways are activated for coronary collaterals formation during repetitive ischemia. ConclusionsWe developed a murine model of coronary collateral growth induced by repetitive ischemia. Our lineage tracing study shows that sprouting endothelial cells contribute to coronary collateral growth in adult mouse hearts. For the first time, sprouting angiogenesis is shown to give rise to mature coronary arteries in response to repetitive ischemia in the adult mouse hearts.

Update on the pathophysiology and medical treatment of peripheral artery disease.

Approximately 6% of adults worldwide have atherosclerosis and thrombosis of the lower limb arteries (peripheral artery disease (PAD)) and the prevalence is rising. PAD causes leg pain, impaired health-related quality of life, immobility, tissue loss and a high risk of major adverse events, including myocardial infarction, stroke, revascularization, amputation and death. In this Review, I describe the pathophysiology, presentation, outcome, preclinical research and medical management of PAD. Established treatments for PAD include antithrombotic drugs, such as aspirin and clopidogrel, and medications to treat dyslipidaemia, hypertension and diabetes mellitus. Randomized controlled trials have demonstrated that these treatments reduce the risk of major adverse events. The drug cilostazol, exercise therapy and revascularization are the current treatment options for the limb symptoms of PAD, but each has limitations. Novel therapies to promote collateral and new capillary growth and treat PAD-related myopathy are under investigation. Methods to improve the implementation of evidence-based medical management, novel drug therapies and rehabilitation programmes for PAD-related pain, functional impairment and ischaemic foot disease are important areas for future research.

Elastic Laminar Reorganization Occurs with Outward Diameter Expansion during Collateral Artery Growth and Requires Lysyl Oxidase for Stabilization.

When a large artery becomes occluded, hemodynamic changes stimulate remodeling of arterial networks to form collateral arteries in a process termed arteriogenesis. However, the structural changes necessary for collateral remodeling have not been defined. We hypothesize that deconstruction of the extracellular matrix is essential to remodel smaller arteries into effective collaterals. Using multiphoton microscopy, we analyzed collagen and elastin structure in maturing collateral arteries isolated from ischemic rat hindlimbs. Collateral arteries harvested at different timepoints showed progressive diameter expansion associated with striking rearrangement of internal elastic lamina (IEL) into a loose fibrous mesh, a pattern persisting at 8 weeks. Despite a 2.5-fold increase in luminal diameter, total elastin content remained unchanged in collaterals compared with control arteries. Among the collateral midzones, baseline elastic fiber content was low. Outward remodeling of these vessels with a 10–20 fold diameter increase was associated with fractures of the elastic fibers and evidence of increased wall tension, as demonstrated by the straightening of the adventitial collagen. Inhibition of lysyl oxidase (LOX) function with β-aminopropionitrile resulted in severe fragmentation or complete loss of continuity of the IEL in developing collaterals. Collateral artery development is associated with permanent redistribution of existing elastic fibers to accommodate diameter growth. We found no evidence of new elastic fiber formation. Stabilization of the arterial wall during outward remodeling is necessary and dependent on LOX activity.

Perfusion Imaging Collateral Scores Predict Infarct Growth in Non-Reperfused DEFUSE 3 Patients

ObjectiveThis study evaluated the associations of perfusion imaging collateral profiles with radiographic and clinical outcome in late presenting, non-reperfused patients in the DEFUSE 3 clinical trial. MethodsNon-reperfused patients in both treatment arms were included. Baseline ischemic core, Tmax >6s, and Tmax >10s perfusion volumes were calculated with RAPID software; infarct volumes obtained 24 hours after randomization were manually determined from DWI or CT. Substantial infarct growth was defined as a >25mL increase between baseline and 24-hour follow-up. Hypoperfusion Intensity Ratio (HIR) was defined as the proportion of the Tmax >6s lesion with Tmax >10s delay; CBV index was calculated by RAPID from mean CBV values within the Tmax >6s lesion compared to regions of normal CBV. ResultsEighty-four patients were included. ROC analysis showed HIR ≥0.34 (AUC=0.68) and CBV index ≤0.74 (AUC=0.72) optimally predicted substantial infarct growth in follow-up. Median growth was 23.4 versus 73.2mL with HIR threshold of 0.34 (p=0.005), and 24.3 versus 58.7mL with CBV index threshold of 0.74 (p=0.004). If baseline HIR and CBV index were both favorable, median growth was 21.7mL, 40.9mL if one was favorable, and 108.2mL if both were unfavorable (p<0.001). Baseline perfusion profile was not associated with 90-day functional outcome. ConclusionsPerfusion collateral scores forecast infarct growth in late presenting, non-reperfused ischemic stroke patients. These parameters may be useful for guiding transfer decisions, such as need for repeat imaging upon thrombectomy center arrival, and may help identify slow progressing patients more likely to have persistent salvageable ischemic tissue beyond 24 hours.

Angiotensin-converting enzyme inhibitors stimulate cerebral arteriogenesis.

Arteriogenesis constitutes the most efficient endogenous rescue mechanism in cases of cerebral ischaemia. The aim of this work was to investigate whether angiotensin-converting enzyme inhibitors (ACEi) stimulates, and angiotensin II receptor type 1 blockers (ARB) inhibits cerebral collateral growth by applying a three-vessel occlusion (3-VO) model in rat. Cerebral collateral growth was measured post 3-VO (1) by assessing blood flow using the cerebrovascular reserve capacity (CVRC) technique, and (2) by assessing vessel diameters in the posterior cerebral artery (PCA) via the evaluation of latex angiographies. A stimulatory effect on arteriogenesis was investigated for ACEi administration±bradykinin receptor 1 (B1R) and 2 (B2R) blockers, and an inhibitory effect was analysed for ARB administration. Results were validated by immunohistochemical analysis and mechanistic data were collected by human umbilical vein endothelial cell (HUVEC) viability or scratch assay and monocyte (THP-1) migration assay. An inhibitory effect of ARB on arteriogenesis could not be demonstrated. However, collateral growth measurements demonstrated a significantly increased CVRC and PCA diameters in the ACEi group. ACEi stimulates cell viability and migration, which could be partially reduced by additional administration of bradykinin receptor 1 inhibitor (B1Ri). ACEi inhibits the degradation of pro-arteriogenic bradykinin derivatives, but combined ACEi+B1Ri+B1Ri (BRB) treatment did not reverse the stimulatory effect. Yet, co-administration of ACEi+BRB enhances arteriogenesis and cell migration. We demonstrate a potent stimulatory effect of ACEi on cerebral arteriogenesis in rats, presumable via B1R. However, results imply a pleiotropic and compensatory effect of ACEi on bradykinin receptor-stimulated arteriogenesis.

Citrate-Saline-Formulated mRNA Delivery into the Heart Muscle with an Electromechanical Mapping and Injection Catheter Does Not Lead to Therapeutic Effects in a Porcine Chronic Myocardial Ischemia Model

Based on recent success in using modified RNA in clinical applications, we tested the safety, feasibility, and efficacy of direct delivery of citrate-saline-formulated mRNA into an hibernating ischemic heart muscle using an electromechanical mapping and injection catheter system (NOGA/Myostar) in a porcine chronic myocardial ischemia model. Chronic ischemia was induced in domestic pigs (n = 24) using a bottleneck stent placed in the left anterior descending coronary artery. Low (1 mg) and high (7.5 mg) doses of citrate-saline-formulated vascular endothelial growth factor (VEGF)-A165 mRNA were administered in the study. LacZ mRNA and citrate-saline buffer were used as controls. Ten intramyocardial injections (200 μL each) of the mRNAs or citrate-saline buffer were given endovascularly into the hibernating ischemic myocardium using the NOGA catheter. Positron emission tomography 15O-radiowater imaging was performed 7 days after the induction of ischemia and 28 days after the mRNA delivery to measure quantitative myocardial blood perfusion. Coronary angiography, left ventricular function measurements, and clinical chemistry were obtained at each time point. Thirty-five days after the mRNA transfers, pigs were sacrificed, and infarct size and general histology were analyzed. LacZ mRNA pigs were sacrificed 24 h after the transduction. Citrate-saline-formulated mRNA delivery into the ischemic myocardium with endovascular injection catheter did not lead to meaningful transduction with the translation of VEGF-A165, nor therapeutic effects in the heart. VEGF-A165 mRNA showed no statistically significant improvements in left ventricular ejection fraction (LVEF), cardiac output, myocardial perfusion, infarct size, collateral growth, or capillary area in the study groups. However, there was a trend in the high-dose group toward an improved LVEF and cardiac output at rest. No significant adverse effects were observed. In conclusion, the NOGA/Myostar injection catheter system is ineffective in delivering citrate-saline-formulated mRNAs into the heart muscle with the doses and methods used in a porcine chronic myocardial ischemia model.

Endothelial Hyaluronan Synthase 3 Augments Postischemic Arteriogenesis Through CD44/eNOS Signaling.

Objective: The dominant driver of arteriogenesis is elevated shear stress sensed by the endothelial glycocalyx thereby promoting arterial outward remodeling. Hyaluronan, a critical component of the endothelial glycocalyx, is synthesized by 3 HAS isoenzymes (hyaluronan synthases 1-3) at the plasma membrane. Considering further the importance of HAS3 for smooth muscle cell and immune cell functions we aimed to evaluate its role in collateral artery growth. Approach and Results: Male Has3-deficient (Has3-KO) mice were subjected to hindlimb ischemia. Blood perfusion was monitored by laser Doppler perfusion imaging and endothelial function was assessed by measurement of flow-mediated dilation in vivo. Collateral remodeling was monitored by high resolution magnetic resonance angiography. A neutralizing antibody against CD44 (clone KM201) was injected intraperitoneally to analyze hyaluronan signaling in vivo. After hindlimb ischemia, Has3-KO mice showed a reduced arteriogenic response with decreased collateral remodeling and impaired perfusion recovery. While postischemic leukocyte infiltration was unaffected, a diminished flow-mediated dilation pointed towards an impaired endothelial cell function. Indeed, endothelial AKT (protein kinase B)-dependent eNOS (endothelial nitric oxide synthase) phosphorylation at Ser1177 was substantially reduced in Has3-KO thigh muscles. Endothelial-specific Has3-KO mice mimicked the hindlimb ischemia-induced phenotype of impaired perfusion recovery as observed in global Has3-deficiency. Mechanistically, blocking selectively the hyaluronan binding site of CD44 reduced flow-mediated dilation, thereby suggesting hyaluronan signaling through CD44 as the underlying signaling pathway. Conclusions: In summary, HAS3 contributes to arteriogenesis in hindlimb ischemia by hyaluronan/CD44-mediated stimulation of eNOS phosphorylation at Ser1177. Thus, strategies augmenting endothelial HAS3 or CD44 could be envisioned to enhance vascularization under pathological conditions.

Infodemics and infodemiology: a short history, a long future.

ABSTRACTAn “infodemic” is defined as “an overabundance of information – some accurate and some not – occurring during an epidemic”. This paper describes the characteristics of an infodemic, which combines an inordinately high volume of information (leading to problems relating to locating the information, storage capacity, ensuring quality, visibility and validity) and rapid output (making it hard to assess its value, manage the gatekeeping process, apply results, track its history, and leading to a waste of effort). This is bound up with the collateral growth of misinformation, disinformation and malinformation. Solutions to the problems posed by an infodemic will be sought in improved technology and changed social and regulatory frameworks. One solution could be a new trusted top-level domain for health information. The World Health Organization has so far made two unsuccessful attempts to create such a domain, but it is suggested this could be attempted again, in the light of the COVID-19 infodemic experience. The vital role of reliable information in public health should also be explicitly recognized in the Sustainable Development Goals, with explicit targets. All countries should develop knowledge preparedness plans for future emergencies.

Coronary microvascular adaptations distal to epicardial artery stenosis.

Until recently, epicardial coronary stenosis has been considered the primary outcome of coronary heart disease, and clinical interventions have been dedicated primarily to the identification and removal of flow-limiting stenoses. However, a growing body of literature indicates that both epicardial stenosis and microvascular dysfunction contribute to damaging myocardial ischemia. In this review, we discuss the coexistence of macro- and microvascular disease, and how the structure and function of the distal microcirculation is impacted by the hemodynamic consequences of an epicardial, flow-limiting stenosis. Mechanisms of endothelial dysfunction as well as alterations of smooth muscle function in the coronary microcirculation distal to stenosis are discussed. Risk factors including diabetes, metabolic syndrome, and aging exacerbate microvascular dysfunction in the myocardium distal to a stenosis, and our current understanding of the role of these factors in limiting collateralization and angiogenesis of the ischemic myocardium is presented. Importantly, exercise training has been shown to promote collateral growth and improve microvascular function distal to stenosis; thus, the current literature reporting the mechanisms that underlie the beneficial effects of exercise training in the microcirculation distal to epicardial stenosis is reviewed. We also discuss recent studies of therapeutic interventions designed to improve microvascular function and stimulate angiogenesis in clinically relevant animal models of epicardial stenosis and microvascular disease. Finally, microvascular adaptation to removal of epicardial stenosis is considered.

The role of Gdf11 in Coronary Collateral Growth

Cardiovascular disease is the leading cause of death in the United States of America, being responsible for 610,000 deaths annually. One in seven of which are related to Ischemic Heart Disease (IHD). Collateral growth is found to be vital to cardiovascular health, with those who have poor collateral networks having a more difficult time recovering and are more likely to have a recurring problem than those with healthy collateral networks. In this study, we investigate if GDF11 affects these collateral networks. To further investigate this, we will use the GDF11 deficient mice and wild type control mice. GDF11 is controversial in its function in aging. However, our study is more focused on the function of GDF11 in coronary collateral growth. We will compare the coronary collaterals among the following groups: 1) naïve wild type and Gdf 11 knockout mice without any intervention; 2) wild type and Gdf 11 knockout mice whose left anterior descending artery (LAD) had been ligated, to mimic a myocardial infarction; 3) wild type and Gdf 11 knockout mice with repetitive ischemia stimulation. Microfil and micro-CT will be used to measure the coronary collaterals and contrast echocardiograph will be used to measure the coronary blood flow. These structure and function data will demonstrate the role of GDF 11 in coronary collateral growth.

The role of CXCR4 in vascular endothelial cells in myocardial ischemia

CXCR4 and CXCL12 signaling pathway is important for stem cell homing in myocardial ischemia and cardiovascular regeneration. Recently report shows that CXCR4 and CXCL12 signaling pathway is involved in coronary collateral growth in myocardial ischemia. Endothelial cells are a key players in the coronary collateral growth. In this study, we use genetically modified mice CXCR4 endothelial cell specific knockout mice to study the role of CXCR4 in endothelial cells in myocardial ischemia. First, we study the role of CXCR4 in endothelial cells in coronary collateral growth in our mouse model by inducing repetitive ischemia. Second, we use the mouse myocardial infarction model to study the role of CXCR4 in endothelial cells in cardiovascular regeneration. We measure the cardiac function, vessel density and coronary blood flow in the the heart. Our preliminary data showed that the deletion of CXCR4 changes cardiac function and coronary collateral growth and the CXCR4 and CXCL12 signaling pathway is essential to cardiovascular regeneration. It suggested that CXCR4/CXCL12 signaling pathway as a potential target for the development of therapeutic treatment for coronary artery diseases and prevention of heart attack.

Somatosensory Crossmodal Plasticity in Superior Colliculus of Visually Deafferented Rats

Terminal fields of a certain pathway result denervated if the regeneration after the lesion of the pathway fails. If the lesion happened in a young animal, terminal fields of other nervous pathways that are spatially coincident or are close to the denervated field, growth of axon collaterals or reactive synaptogenesis could take place and reinervate deafferented neurons. In that way these denervated neurons can be recruited for functional compensatory responses and can convey information to areas that result enriched with additional inputs to be processed. The present paper reviews the plastic reactions that take place in the superior colliculus, a mesencephalic layered structure, after the neonatal suppression of its visual afferents that terminate in its superficial layers. The postlesional reactive ascending growth of somatosensory afferents that in control animals innervate intermediate and deep collicular layers invade the superficial layers and connect with visually deafferented cells that result recruited for descendent collicular responses and to send sensory information to the visual cortex via the colliculo-geniculate payhway. In that way in neonatally deafferented animals, somatosensory information gains additional territory to be processed. Two somatosensory connections to the superior collicuus will be discussed in this review. One ascending from the cuneitorm nucleus and the other descending that originates in the barrel cortex.

Heat therapy improves body composition and muscle function but does not affect capillary or collateral growth in a model of obesity and hindlimb ischemia.

Heat therapy (HT) has emerged as a potential adjunctive therapy to alleviate the symptoms of peripheral artery disease (PAD), but the mechanisms underlying the positive effects of this treatment modality remain undefined. Using a model of diet-induced obesity (DIO) and ischemia-induced muscle damage, we tested the hypothesis that HT would alter body composition, promote vascular growth and mitochondrial biogenesis, and improve skeletal muscle function. Male DIO C57Bl/6J mice underwent bilateral ligation of the femoral artery and were randomly allocated to receive HT or a control intervention for 30 min daily over 3 wk. When compared with a group of lean, sham-operated animals, ligated DIO mice exhibited increases in body and fat masses, exercise intolerance, and contractile dysfunction of the isolated soleus (SOL) and extensor digitorum longus (EDL) muscles. Repeated HT averted an increase in body mass induced by high-fat feeding due to reduced fat accrual. Fat mass was ∼25% and 29% lower in the HT group relative to controls after 2 and 3 wk of treatment, respectively. Muscle mass relative to body mass and maximal absolute force of the EDL, but not SOL, were higher in animals exposed to HT. There were no group differences in skeletal muscle capillarization, the expression of angiogenic factors, mitochondrial content, and the diameter of the gracilis arteries. These findings indicate that HT reduces diet-induced fat accumulation and rescues skeletal muscle contractile dysfunction. This practical treatment may prove useful for diabetic and obese PAD patients who are unable to undergo conventional exercise regimens.NEW & NOTEWORTHY The epidemic of obesity-related dyslipidemia and diabetes is a central cause of the increasing burden of peripheral artery disease (PAD), but few accessible therapies exist to mitigate the metabolic and functional abnormalities in these patients. We report that daily exposure to heat therapy (HT) in the form of lower-body immersion in water heated to 39 °C for 3 weeks attenuates fat accumulation and weight gain, and improves muscle strength in obese mice with femoral artery occlusion.

Implication of collateral growth in the process of cardiac regeneration after neonatal myocardium infarction in mice

The recent discovery of the capacity of the mammalian heart to completely regenerate during a short period of time after birth opened a new area of research in the cardiovascular field. The revascularization of the ischemic area is an important process to favor cardiac regeneration and we have previously shown that pre-existing coronary arteries undergo major remodeling events following adult MI. This mechanism of arteriogenesis is known as collateral growth but it has not been well described during cardiac regeneration. We hypothesize that collateral growth occurs more frequently in regenerative hearts compared to non-regenerative ones. To investigate the coronary arteries remodeling and collateral growth during cardiac regeneration after neonatal myocardial infarction (MI). Neonatal MI was performed by the permanent ligation of the left coronary artery on one day-old (P1) and seven day-old (P7) mice. MI surgery was performed on P1 or P7 pups from the Cx40-GFP mouse line in which the fluorescent protein GFP is specifically expressed in coronary arteries. Hearts were collected at 1, 2, 4, 7 and 14 dpi and processed for clearing using CUBIC solution. 3D reconstruction was acquired from images of cleared hearts. Our data show the dynamic remodeling of the ligated coronary artery, which completely regenerates in two weeks, starting one day-post-injury (dpi) by the migration of isolated arterial endothelial cells migrating from the injured artery to form a new vessel at 4dpi. We observed a larger number of collaterals branching from the injured left artery to healthy right or septal arteries in regenerating hearts (P1) in comparison with non-regenerating hearts (P7). These results highlight the rapid phase of arterial remodeling that would play an important role in inducing cardiac regeneration.

Exploiting collateral sensitivity controls growth of mixed culture of sensitive and resistant cells and decreases selection for resistant cells in a cell line model

BackgroundCDK4/6 inhibitors such as ribociclib are becoming widely used targeted therapies in hormone-receptor-positive (HR+) human epidermal growth factor receptor 2-negative (HER2−) breast cancer. However, cancers can advance due to drug resistance, a problem in which tumor heterogeneity and evolution are key features.MethodsRibociclib-resistant HR+/HER2− CAMA-1 breast cancer cells were generated through long-term ribociclib treatment. Characterization of sensitive and resistant cells were performed using RNA sequencing and whole exome sequencing. Lentiviral labeling with different fluorescent proteins enabled us to track the proliferation of sensitive and resistant cells under different treatments in a heterogeneous, 3D spheroid coculture system using imaging microscopy and flow cytometry.ResultsTranscriptional profiling of sensitive and resistant cells revealed the downregulation of the G2/M checkpoint in the resistant cells. Exploiting this acquired vulnerability; resistant cells exhibited collateral sensitivity for the Wee-1 inhibitor, adavosertib (AZD1775). The combination of ribociclib and adavosertib achieved additional antiproliferative effect exclusively in the cocultures compared to monocultures, while decreasing the selection for resistant cells.ConclusionsOur results suggest that optimal antiproliferative effects in heterogeneous cancers can be achieved via an integrative therapeutic approach targeting sensitive and resistant cancer cell populations within a tumor, respectively.