Coronary Vessel Development Research Articles

Hypoxia regulate developmental coronary angiogenesis potentially through VEGF-R2- and SOX17-mediated signaling.

The development of coronary vessels in embryonic mouse heart involves various progenitor populations, including sinus venosus (SV), endocardium, and proepicardium. ELA/APJ signaling is known to regulate coronary growth from the SV, whereas VEGF-A/VEGF-R2 signaling controls growth from the endocardium. Previous studies suggest hypoxia might regulate coronary growth, but its specific downstream pathways are unclear. In this study, we further investigated the role of hypoxia and have identified SOX17- and VEGF-R2-mediated signaling as the potential downstream pathways in its regulation of developmental coronary angiogenesis. HIF-1α stabilization by knocking out von Hippel Lindau (VHL) protein in the myocardium (cKO) disrupted normal coronary angiogenesis in embryonic mouse hearts, resembling patterns of accelerated coronary growth. VEGF-R2 expression was increased in coronary endothelial cells under hypoxia in vitro and in VHL cKO hearts in vivo. Similarly, SOX17 expression was increased in the VHL cKO hearts, while its knockout in the endocardium disrupted normal coronary growth. These findings provide further evidence that hypoxia regulates developmental coronary growth potentially through VEGF-R2 and SOX17 pathways, shedding light on mechanisms of coronary vessel development.

Congenital Coronary Blood Vessel Anomalies: Animal Models and the Integration of Developmental Mechanisms.

Coronary blood vessels are in charge of sustaining cardiac homeostasis. It is thus logical that coronary congenital anomalies (CCA) directly or indirectly associate with multiple cardiac conditions, including sudden death. The coronary vascular system is a sophisticated, highly patterned anatomical entity, and therefore a wide range of congenital malformations of the coronary vasculature have been described. Despite the clinical interest of CCA, very few attempts have been made to relate specific embryonic developmental mechanisms to the congenital anomalies of these blood vessels. This is so because developmental data on the morphogenesis of the coronary vascular system derive from complex studies carried out in animals (mostly transgenic mice), and are not often accessible to the clinician, who, in turn, possesses essential information on the significance of CCA. During the last decade, advances in our understanding of normal embryonic development of coronary blood vessels have provided insight into the cellular and molecular mechanisms underlying coronary arteries anomalies. These findings are the base for our attempt to offer plausible embryological explanations to a variety of CCA as based on the analysis of multiple animal models for the study of cardiac embryogenesis, and present them in an organized manner, offering to the reader developmental mechanistic explanations for the pathogenesis of these anomalies.

Epicardium and Coronary Vessels.

Congenital anomalies and acquired diseases of the coronary blood vessels are of great clinical relevance. The early diagnosis of these conditions remains, however, challenging. In order to improve our knowledge of these ailments, progress has to be achieved in the research of the molecular and cellular mechanisms that control development of the coronary vascular bed. The aim of this chapter is to provide a succint account of the key elements of coronary blood vessel development, especially in the context of the role played by the epicardium and epicardial cellular derivatives. We will discuss the importance of the epicardium in coronary blood vessel morphogenesis, from the contribution of the epicardially derived mesenchyme to these blood vessels to its role as an instructive signaling center, attempting to relate these concepts to the origin of coronary disease.

APJ expression is lost in isolated embryonic coronary endothelial cell culture in vitro.

Coronary artery disease is one of the leading causes of death worldwide, and yet we lack the appropriate therapeutic treatments for it. Investigation into the mechanisms of coronary vessel development can provide insights into potential therapies to repair and regenerate damaged coronary arteries. Our previous study in the mouse embryo have implicated APJ, a G-protein coupled receptor that is expressed by coronary endothelial cells in vivo, to be an important regulator of coronary vessel development. In this study, we report an unexpected finding that the isolated embryonic coronary endothelial cells lose APJ expression in culture in vitro.

Effect of obstructive sleep apnoea on coronary collateral vessel development in patients with ST-segment elevation myocardial infarction.

The impact of obstructive sleep apnoea (OSA) in the setting of acute ST-segment elevation myocardial infarction (STEMI) is complex and divergent. This study aimed to investigate the association between OSA and coronary collateral vessel (CCV) development in patients with STEMI. The present study prospectively screened 282 STEMI patients with an overnight sleep study. OSA was defined as apnoea-hypopnoea index (AHI) ≥15 events/h. The coronary angiograms were used for the assessment of Rentrop grades representing CCVs. Among 119 patients enrolled, 60 patients had OSA (50.4%). The prevalence of CCV development (Rentrop grade ≥ 2) was significantly higher in OSA group than in the non-OSA group (43.3% vs. 5.1%, p < 0.001). There was a parallel increase in the Rentrop grades associated with OSA severity and worsening of hypoxaemia indicators (minimum arterial oxygen saturation [SaO2 ], mean SaO2 and time with SaO2 below 90%). After adjustment for clinical and angiographic characteristics, and pre-procedure medications that might interact with OSA, AHI as a continuous variable (OR 1.11, 95% CI 1.08-1.21, p < 0.001) and the presence of OSA (OR 11.41, 95% CI 2.70-48.15, p=0.001) were both associated with dramatically higher incidence of CCV development. Our study demonstrated that the presence of OSA might augment CCV development in STEMI patients. The potential protective effects and mechanisms of OSA in the acute setting of STEMI should be further investigated in larger studies.

AJAP1 Gene Silencing Alters Protein Expression in Epithelial Cells

IntroductionThe epicardial layer of the heart is formed during cardiovascular development from a transitory structure known as the proepicardium (PE). Proepicardial cells migrate out of the PE to surround and adhere to the myocardium to form a layer of epithelial cells that compose the epicardium. A subset of the epicardial cells delaminate and migrate into the subepicardial space where they undergo epithelial‐mesenchymal transition (EMT) to become epicardial‐derived cells (EPDCs). These EPDCs invade the myocardium and differentiate into a subset of cells that make up the coronary vessels. During this entire process, the epicardium receives input from several transcription factors including Tbx5. Mice with a conditional deletion of Tbx5 exhibit impaired epicardium formation and coronary vessel development. Tbx5‐deficient mouse hearts have a significant decrease in mRNA expression of adherens junction associated protein (Ajap1). Our studies show that knockdown of endogenous AJAP1 (AJAP1 KD) mRNA expression in epithelial cells leads to increased cell adhesion, reduced cell migration, enhanced expression of epithelial markers of EMT, and altered expression of transcripts associated with adherens junctions, tight junctions and EMT. Specifically, our qPCR array data shows a significant alteration in ZEB2 mRNA expression in AJAP1 KD cells versus negative control cells.Study ObjectiveThe goal of this study was to examine the role of AJAP1 in regulating protein expression of ZEB2 as it may be necessary for epicardium formation. Based on previous cell function and mRNA expression data, we hypothesize that the ZEB2 protein is an important functional mediator of AJAP1 in epithelial cells for undergoing EMT.MethodsWe utilized the primary human mammary epithelial cell line (HMEpiC) as an in vitro system to examine contributions of AJAP1 to epithelial cell biology. We silenced AJAP1 mRNA expression in HMEpiCs using small interfering RNAs and examined protein expression of ZEB2. We compared ZEB2 expression in negative control versus AJAP1 KD HMEpiCs.ResultsReduced expression of AJAP1transcripts produced noticeable changes in protein expression of ZEB2 in epithelial cells, and it had significant effects on expression of adherens junction‐related transcripts. Western blot analysis revealed an increase in ZEB2 protein expression in AJAP1 KD versus negative control HMEpiCs.ConclusionOur data indicate that AJAP1 contributes to epithelial cell function, and it does this potentially by mediating ZEB2 protein expression. ZEB2 is known to regulate EMT, which is a biological process that is crucial for the formation of the epicardium and its subsequent formation of the coronary vasculature.

Heterogeneous pdgfrb+ cells regulate coronary vessel development and revascularization during heart regeneration.

Endothelial cells emerge from the atrioventricular canal to form coronary blood vessels in juvenile zebrafish hearts. We find that pdgfrb is first expressed in the epicardium around the atrioventricular canal and later becomes localized mainly in the mural cells. pdgfrb mutant fish show severe defects in mural cell recruitment and coronary vessel development. Single-cell RNA sequencing analyses identified pdgfrb+ cells as epicardium-derived cells (EPDCs) and mural cells. Mural cells associated with coronary arteries also express cxcl12b and smooth muscle cell markers. Interestingly, these mural cells remain associated with coronary arteries even in the absence of Pdgfrβ, although smooth muscle gene expression is downregulated. We find that pdgfrb expression dynamically changes in EPDCs of regenerating hearts. Differential gene expression analyses of pdgfrb+ EPDCs and mural cells suggest that they express genes that are important for regeneration after heart injuries. mdka was identified as a highly upregulated gene in pdgfrb+ cells during heart regeneration. However, pdgfrb but not mdka mutants show defects in heart regeneration after amputation. Our results demonstrate that heterogeneous pdgfrb+ cells are essential for coronary development and heart regeneration.

“Association of Coronary Collateral Formation and Diabetes Patients with Ischaemic Heart Disease”

Background: Diabetes mellitus (DM) is a complex and heterogeneous chronic metabolic disease caused by elevated levels of blood glucose. Although myocardial ischemia is known to be significantly related to the development of coronary collateral vessels (CCVs), there is considerable variation between patients with ischemic heart disease in the presence of collateral development. Methods: This observational study was done in Department of Cardiology, Mymensingh Medical College Hospital, Bangladesh from January to December 2020. Out of 110 patients who had a stenosis of &gt;95% in any major coronary artery in angiograms were included in the study. Of these patients, 35 patients constitute the diabetic group. Remaining 75 patients were non-diabetic. For case-control matching, 35 non-diabetic patients (mean age, 52.03± 8.69 years) were selected randomly and were included in the control group. The CCVs were graded according to the Rentrop scoring system, and the collateral score was calculated by summing the Rentrop numbers of every patient. Results: There was no statistical difference between patients with and without DM in clinical baseline characteristics. The mean number of diseased vessels in the DM group (2.10±0.76) was higher than that in the nondiabetic group (1.63± 0.72 P.017). The mean collateral score was (1.13± 0.86) in the DM group and (1.97± 1.61) in the control group. After confounding variables were controlled for, the collateral score in the diabetic group was significantly different from that in the nondiabetic group (p=0.015). Conclusion: Our findings suggest that CCV development is poorer in patients with DM than in patients without DM. Thus, we can speculate that DM is an important factor affecting CCV development.

Expression Profile of Genes Encoding Proteins Involved in Regulation of Vasculature Development and Heart Muscle Morphogenesis-A Transcriptomic Approach Based on a Porcine Model.

Despite significant advances in treatment of acute coronary syndromes (ACS) many subjects still develop heart failure due to significantly reduced ejection fraction. Currently, there are no commonly available treatment strategies that replace the infarcted/dysfunctional myocardium. Therefore, understanding the mechanisms that control the regeneration of the heart muscle is important. The development of new coronary vessels plays a pivotal role in cardiac regeneration. Employing microarray expression assays and RT-qPCR validation expression pattern of genes in long-term primary cultured cells isolated form the right atrial appendage (RAA) and right atrium (RA) was evaluated. After using DAVID software, it indicated the analysis expression profiles of genes involved in ontological groups such as: “angiogenesis”, “blood vessel morphogenesis”, “circulatory system development”, “regulation of vasculature development”, and “vasculature development” associated with the process of creation new blood vessels. The performed transcriptomic comparative analysis between two different compartments of the heart muscle allowed us to indicate the presence of differences in the expression of key transcripts depending on the cell source. Increases in culture intervals significantly increased expression of SFRP2, PRRX1 genes and some other genes involved in inflammatory process, such as: CCL2, IL6, and ROBO1. Moreover, the right atrial appendage gene encoding lysyl oxidase (LOX) showed much higher expression compared to the pre-cultivation state.

Endocardial/endothelial angiocrines regulate cardiomyocyte development and maturation and induce features of ventricular non-compaction.

Non-compaction cardiomyopathy is a devastating genetic disease caused by insufficient consolidation of ventricular wall muscle that can result in inadequate cardiac performance. Despite being the third most common cardiomyopathy, the mechanisms underlying the disease, including the cell types involved, are poorly understood. We have previously shown that endothelial cell-specific deletion of the chromatin remodeller gene Ino80 results in defective coronary vessel development that leads to ventricular non-compaction in embryonic mouse hearts. We aimed to identify candidate angiocrines expressed by endocardial and endothelial cells (ECs) in wildtype and LVNC conditions in Tie2Cre;Ino80fl/fltransgenic embryonic mouse hearts, and test the effect of these candidates on cardiomyocyte proliferation and maturation. We used single-cell RNA-sequencing to characterize endothelial and endocardial defects in Ino80-deficient hearts. We observed a pathological endocardial cell population in the non-compacted hearts and identified multiple dysregulated angiocrine factors that dramatically affected cardiomyocyte behaviour. We identified Col15a1 as a coronary vessel-secreted angiocrine factor, downregulated by Ino80-deficiency, that functioned to promote cardiomyocyte proliferation. Furthermore, mutant endocardial and endothelial cells up-regulated expression of secreted factors, such as Tgfbi, Igfbp3, Isg15, and Adm, which decreased cardiomyocyte proliferation and increased maturation. These findings support a model where coronary endothelial cells normally promote myocardial compaction through secreted factors, but that endocardial and endothelial cells can secrete factors that contribute to non-compaction under pathological conditions.

Every Beat You Take-The Wilms' Tumor Suppressor WT1 and the Heart.

Nearly three decades ago, the Wilms’ tumor suppressor Wt1 was identified as a crucial regulator of heart development. Wt1 is a zinc finger transcription factor with multiple biological functions, implicated in the development of several organ systems, among them cardiovascular structures. This review summarizes the results from many research groups which allowed to establish a relevant function for Wt1 in cardiac development and disease. During development, Wt1 is involved in fundamental processes as the formation of the epicardium, epicardial epithelial-mesenchymal transition, coronary vessel development, valve formation, organization of the cardiac autonomous nervous system, and formation of the cardiac ventricles. Wt1 is further implicated in cardiac disease and repair in adult life. We summarize here the current knowledge about expression and function of Wt1 in heart development and disease and point out controversies to further stimulate additional research in the areas of cardiac development and pathophysiology. As re-activation of developmental programs is considered as paradigm for regeneration in response to injury, understanding of these processes and the molecules involved therein is essential for the development of therapeutic strategies, which we discuss on the example of WT1.

冠状动脉血管发育与再生

<p indent=0mm>Cardiovascular disease is the leading cause of death worldwide, and the coronary artery disease (CAD) is the main factor leading the cardiovascular disease. However, there is still leaking efficient clinical treatment to CAD until now. An in-depth understanding of the formation of coronary vessels during development and regeneration after heart injury will provide more ideas for developing treatment strategies of coronary diseases. Recently, with the development of the genetic lineage tracing technology <italic>in vivo</italic>, scientists have gained some new insights into the cellular origins and molecular mechanisms of coronary blood vessel formation during development and regeneration. These mechanisms provide new possibility for improving heart repair by targeting new vessels formation. Here, we highlight these recent finding about the development and regeneration of coronary vessels and discuss the possible application value in the treatment of ischemic heart disease.

VEGF-B Promotes Endocardium-Derived Coronary Vessel Development and Cardiac Regeneration

Recent discoveries have indicated that, in the developing heart, sinus venosus and endocardium provide major sources of endothelium for coronary vessel growth that supports the expanding myocardium. Here we set out to study the origin of the coronary vessels that develop in response to vascular endothelial growth factor B (VEGF-B) in the heart and the effect of VEGF-B on recovery from myocardial infarction. We used mice and rats expressing a VEGF-B transgene, VEGF-B-gene-deleted mice and rats, apelin-CreERT, and natriuretic peptide receptor 3-CreERT recombinase-mediated genetic cell lineage tracing and viral vector-mediated VEGF-B gene transfer in adult mice. Left anterior descending coronary vessel ligation was performed, and 5-ethynyl-2'-deoxyuridine-mediated proliferating cell cycle labeling; flow cytometry; histological, immunohistochemical, and biochemical methods; single-cell RNA sequencing and subsequent bioinformatic analysis; microcomputed tomography; and fluorescent- and tracer-mediated vascular perfusion imaging analyses were used to study the development and function of the VEGF-B-induced vessels in the heart. We show that cardiomyocyte overexpression of VEGF-B in mice and rats during development promotes the growth of novel vessels that originate directly from the cardiac ventricles and maintain connection with the coronary vessels in subendocardial myocardium. In adult mice, endothelial proliferation induced by VEGF-B gene transfer was located predominantly in the subendocardial coronary vessels. Furthermore, VEGF-B gene transduction before or concomitantly with ligation of the left anterior descending coronary artery promoted endocardium-derived vessel development into the myocardium and improved cardiac tissue remodeling and cardiac function. The myocardial VEGF-B transgene promotes the formation of endocardium-derived coronary vessels during development, endothelial proliferation in subendocardial myocardium in adult mice, and structural and functional rescue of cardiac tissue after myocardial infarction. VEGF-B could provide a new therapeutic strategy for cardiac neovascularization after coronary occlusion to rescue the most vulnerable myocardial tissue.

Association of Diabetes with Coronary Collateral Formation in Patients with Ischaemic Heart Disease

Background: Although myocardial ischemia is known to be significantly related to the development of coronary collateral vessels (CCVs), there is considerable variation between patients with ischemic heart disease in the presence of collateral development. The nature of this variability is not well known. Likewise, it remains unclear whether diabetes mellitus (DM) has any effect on CCVs. The aim of this study was to evaluate the effect of DM on CCVs.&#x0D; Methods: A total of 100 patients who had a stenosis of &gt;95% in any major coronary artery in angiograms were included in the study. Of these patients, 30 patients constitute the diabetic group. Remaining 70 patients were non-diabetic. For case-control matching, 30 non-diabetic patients (mean age, 52.03± 8.69 years) were selected randomly and were included in the control group. The CCVs were graded according to the Rentrop scoring system, and the collateral score was calculated by summing the Rentrop numbers of every patient.&#x0D; Results: There was no statistical difference between patients with and without DM in clinical baseline characteristics. The mean number of diseased vessels in the DM group (2.10±0.76) was higher than that in the nondiabetic group (1.63± 0.72 P.017). The mean collateral score was (1.13± 0.86) in the DM group and (1.97± 1.61) in the control group. After confounding variables were controlled for, the collateral score in the diabetic group was significantly different from that in the nondiabetic group (p=0.015).&#x0D; Conclusions: Our findings suggest that CCV development is poorer in patients with DM than in patients without DM. Thus, we can speculate that DM is an important factor affecting CCV development.&#x0D; Cardiovasc. j. 2020; 12(2): 89-95

O-linked β-N-acetylglucosamine transferase plays an essential role in heart development through regulating angiopoietin-1.

O-linked N-acetylglucosamine (GlcNAc) transferase (OGT) is the only enzyme catalyzing O-GlcNAcylation. Although it has been shown that OGT plays an essential role in maintaining postnatal heart function, its role in heart development remains unknown. Here we showed that loss of OGT in early fetal cardiomyocytes led to multiple heart developmental defects including hypertrabeculation, biventricular dilation, atrial septal defects, ventricular septal defects, and defects in coronary vessel development. In addition, RNA sequencing revealed that Angiopoietin-1, required within cardiomyocytes for both myocardial and coronary vessel development, was dramatically downregulated in cardiomyocyte-specific OGT knockout mouse hearts. In conclusion, our data demonstrated that OGT plays an essential role in regulating heart development through activating expression of cardiomyocyte Angiopoietin-1.

In Vitro Model of Coronary Angiogenesis.

Here, we describe an in vitro culture assay to study coronary angiogenesis. Coronary vessels feed the heart muscle and are of clinical importance. Defects in these vessels represent severe health risks such as in atherosclerosis, which can lead to myocardial infarctions and heart failures in patients. Consequently, coronary artery disease is one of the leading causes of death worldwide. Despite its clinical importance, relatively little progress has been made on how to regenerate damaged coronary arteries. Nevertheless, recent progress has been made in understanding the cellular origin and differentiation pathways of coronary vessel development. The advent of tools and technologies that allow researchers to fluorescently label progenitor cells, follow their fate, and visualize progenies in vivo have been instrumental in understanding coronary vessel development. In vivo studies are valuable, but have limitations in terms of speed, accessibility, and flexibility in experimental design. Alternatively, accurate in vitro models of coronary angiogenesis can circumvent these limitations and allow researchers to interrogate important biological questions with speed and flexibility. The lack of appropriate in vitro model systems may have hindered the progress in understanding the cellular and molecular mechanisms of coronary vessel growth. Here, we describe an in vitro culture system to grow coronary vessels from the sinus venosus (SV) and endocardium (Endo), the two progenitor tissues from which many of the coronary vessels arise. We also confirmed that the cultures accurately recapitulate some of the known in vivo mechanisms. For instance, we show that the angiogenic sprouts in culture from SV downregulate COUP-TFII expression similar to what is observed in vivo. In addition, we show that VEGF-A, a well-known angiogenic factor in vivo, robustly stimulates angiogenesis from both the SV and Endo cultures. Collectively, we have devised an accurate in vitro culture model to study coronary angiogenesis.

Reelin Signaling in Vascular Endothelial Cell Biology

IntroductionEstablishment of the coronary circulation is a critical step in heart development. Formation of functional coronary vessels is required for the heart to undergo successful compaction of the ventricular myocardium. Oxygen and nutrients are delivered to the contractile myocardium through the coronary vasculature. Molecular signaling pathways that control formation of the coronary vessels are being identified. Immunofluorescent studies from our lab indicate that the Reelin extracellular matrix glycoprotein is expressed within the vascular endothelial cells of developing and mature coronary vessels of the mouse heart. The Reelin signaling pathway is known to contribute to brain and lymphatic system development by influencing neuronal and endothelial cell behaviors such as adhesion and migration. However, its role in coronary vascular development is as yet unidentified.Study ObjectiveThe goal of this study was to elucidate the potential roles of Reelin in formation of the coronary vasculature by identifying how it regulates vascular endothelial cell behaviors. We hypothesized that Reelin signaling regulates establishment of coronary vessel integrity during cardiogenesis by influencing vascular endothelial cell adhesion as well as cell membrane permeability and resistance.MethodsWe utilized the primary human dermal microvascular endothelial cell line (HDMEC) as an in vitro system to examine contributions of Reelin to vascular endothelial cell behavior. A small interfering RNA‐mediated approach was used to silence the endogenous RELN gene in HDMECs and reduce Reelin protein expression. Transfected HDMECs were subjected to cell‐based assays to assess changes in vascular endothelial cell behavior in response to RELN silencing. We assessed vascular endothelial cell adhesion on extracellular matrices that are required during coronary vessel development. Vessel integrity was examined by assaying endothelial cell membrane permeability and resistance in RELN‐silenced cells. Also, we examined the effect of Reelin expression on cell viability.ResultsRELN‐silenced HDMECs exhibited a &gt;90% reduction in Reelin expression in comparison to non‐targeting, negative control HDMECs. This significant Reelin reduction altered vascular endothelial cell adhesion to certain extracellular matrices. These RELN‐silenced HDMECs exhibited a significant decrease in baseline cell membrane permeability and concomitant changes in cell membrane resistance. Furthermore, we observed changes in cell morphology in RELN‐silenced cells versus control cells. Preliminary data suggests that loss of RELN expression affects vascular endothelial cell morphology and expression of components within the Reelin signaling pathway.ConclusionsBased on this evidence, we conclude that Reelin influences adhesion, morphology, membrane permeability and membrane resistance of vascular endothelial cells in order to regulate vessel wall integrity. These findings may provide key evidence as to how Reelin expression in nascent vascular endothelial cells impacts formation of the coronary vessels during mammalian cardiovascular development.Support or Funding InformationAHA 17AIREA3360773 and PCOM Center for Chronic Disorders of AgingThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Epithelial Cell Requirement for AJAP1 in Cardiac Development

IntroductionCardiovascular development occurs through a series of molecular and cellular processes. Disruption of these processes result in congenital heart defects that compromise normal cardiovascular function. During mammalian cardiovascular development, the transitory proepicardium (PE) is a progenitor cell source for the epicardium and a subset of coronary vascular cells. The PE is composed of epithelial‐like mesothelial cells that migrate onto the myocardium to form the epicardium. These epicardial cells proliferate, and undergo apoptosis and epithelial‐mesenchymal transition to become epicardial‐derived cells (EPDCs). These EPDCs delaminate and migrate into the myocardium to form a subset of primitive coronary vascular cells. Molecular signals that contribute to formation of the epicardium and coronary vessels are being examined. Immunofluorescent studies from our lab indicate that the adherens junction‐associated protein (Ajap1) is expressed in the transitory PE, epicardium and primitive coronary vessels of mouse hearts. AJAP1 is a cell adhesion molecule that associates with β‐catenin in the E‐catenin‐cadherin complex to form cell adherens junctions in extra‐cardiac tissues. However, its role in the heart remains unknown.Study ObjectiveWe sought to elucidate how AJAP1 influences epithelial cell behaviors including cell proliferation, apoptosis, migration and epithelial‐mesenchymal transition (EMT). Previous investigations indicated that cell cycle regulatory properties often associate with EMT. Based on this idea, we hypothesized that AJAP1 regulates establishment of the epithelial‐like layer of epicardial cells by influencing epithelial cell proliferation, apoptosis, migration and EMT.MethodsWe utilized primary human mammary epithelial cells (HMEpiCs) as an in vitro system to explore contributions of AJAP1 to epithelial cell behavior. A small interfering RNA (siRNA)‐mediated approach was used to silence endogenous AJAP1 gene expression and reduce its protein expression. siRNA‐transfected HMEpiCs were subjected to gene expression analyses and cell‐based assays to examine changes in epithelial cell behavior respondent to AJAP1 silencing. We assessed epithelial cell morphology, proliferation, apoptosis, migration and EMT induction via TGFβ1 stimulation.ResultsAJAP1‐silenced HMEpiCs exhibited a &gt;75% decrease in AJAP1 mRNA expression in comparison to non‐targeting, negative control HMEpiCS. Reduced AJAP1 expression produced discernable changes in cell morphology prompting us to explore other cell behaviors. We observed alterations in expression of cell cycle and apoptotic markers in AJAP1‐silenced HMEpiCs versus control cells. These findings led us to investigate how these cell cycle alterations influenced epithelial cell migration and EMT via marker analysis.ConclusionWe conclude that AJAP1 contributes to pertinent behaviors of epithelial cells, including cell morphology, viability and differentiation. These findings will potentially elucidate how AJAP1 contributes to epicardium formation and subsequent development of coronary vessels.Support or Funding InformationPCOM Center for Chronic Disorders of AgingThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

OBSTRUCTIVE SLEEP APNEA AND ACUTE CORONARY SYNDROME: COULD ISCHEMIC PRECONDITIONING IMPACT CORONARY COLLATERALS?

Obstructive sleep apnea (OSA) has been associated with adverse long-term cardiovascular outcomes. Recent investigations have suggested ischemic preconditioning may lead to increased coronary collateral vessel (CCV) development. Ninety-one patients without current treatment for OSA presented with

Could platelet distribution width predict coronary collateral development in stable coronary artery disease?

OBJECTIVE:We hypothesized that hemogram parameters should be related to the development of coronary collateral vessels. For this purpose, we aimed to compare platelet distribution width (PDW) and PDW to platelet ratio (PPR) in subjects with stable coronary artery disease having adequate or inadequate coronary collateral development.METHODS:A total of 398 patients with stable angina pectoris undergoing coronary angiography were enrolled and divided on the basis of the development of coronary collateral (CCD) (inadequate CCD (n=267) and adequate CCD (n=131). Routine complete blood count and biochemical parameters were measured before coronary arteriography.RESULTS:Mean PDW and PPR values of inadequate and adequate CCD groups were 17.5% (10–23) and 12.4% (9.8–22) %, p<0.001, respectively. In multivariate analysis, age (p=0.012, 95% CI for OR: 0.958 (0.933–0.983) and PDW (p<0.001, 95% CI for OR: 1.432 (1.252–1.618) were found to be statistically significantly different inadequate CCD group compared to adequate CCD group. Receiver operating curve (ROC) analyses revealed that a PPR value greater than 0.057 had 76% sensitivity and 51% specificity and a PDW higher than 16.2% had 80% sensitivity and 66% specificity in predicting inadequate CCD.CONCLUSION:The present study suggests that PDW and PPR may be associated with the degree of collateral development in chronic stable coronary artery disease (CAD).