Abnormal hemodynamic loading during heart development leads to myocardial hypoxia, stimulating collagen production in the subendocardium. Therefore, EFE in this chick embryonic model of HLHS appears to be a secondary effect of abnormal hemodynamics. Developmental Dynamics 247:509-520, 2018. © 2017 Wiley Periodicals, Inc.

Angiogenesis is the physiological process of forming new capillaries from existing vessels. It is a tiered process involving activation of the existing endothelial cells, degradation of the extracellular matrix, proliferation and migration of endothelial cells, invasion of the stroma by the surrounding cells, and remodeling the extracellular matrix. Regulation of endothelial cell survival and migration strongly depends on the interaction of endothelial cells with extracellular matrix proteins via cell adhesion molecules, and the activities of growth factors and cytokines. Angiogenesis is characteristic of regeneration of normal tissues and hence is an important factor determining the safe and successful use of biomaterials in regenerative medicine (Chavakis and Dimmeler, 2002) as perfusion of the implant is needed to provide a feasible infrastructure upon which the new tissue can mature (Anderson et al., 2011). Induction of angiogenesis and subsequent development of a vascular bed in the engineered tissue is being actively pursued through combinations of physical and chemical cues, notably through the presentation of suitable topographies and growth factors (Klagsburn and Moses, 1999;Liu et al., 2012;Kant and Coulombe, 2018).

Human natural killer (HNK)‐1 antibody is an established marker of developing cardiac conduction system (CCS) in birds and mammals. In our search for the evolutionary origin of the CCS, we tested this antibody in a variety of sauropsid species (Crocodylus niloticus, Varanus indicus, Pogona vitticeps, Pantherophis guttatus, Eublepharis macularius, Gallus gallus, and Coturnix japonica). Hearts of different species were collected at various stages of embryonic development and studied to map immunoreactivity in cardiac tissues. We performed detection on alternating serial paraffin sections using immunohistochemistry for smooth muscle actin or sarcomeric actin as myocardial markers, and HNK‐1 to visualize overall staining pattern and then positivity in specific myocyte populations. We observed HNK‐1 expression of various intensity distributed in the extracellular matrix and mesenchymal cell surface of cardiac cushions in most of the examined hearts. Strong staining was found in the cardiac nerve fibers and ganglia in all species. The myocardium of the sinus venosus and the atrioventricular canal exhibited transitory patterns of expression. In the Pogona and Crocodylus hearts, as well as in the Gallus and Coturnix ones, additional expression was detected in a subset of myocytes of the (inter)ventricular septum. These results support the use of HNK‐1 as a conserved marker of the CCS and suggest that there is a rudimentary CCS present in developing reptilian hearts. Anat Rec, 302:69–82, 2019. © 2018 Wiley Periodicals, Inc.

During development, the ventricles of mammals and birds acquire a specialized pattern of electrical activation with the formation of the atrioventricular conduction system (AVCS), which coincides with the completion of ventricular septation. We investigated whether AVCS formation coincides with ventricular septation in developing Siamese crocodiles (Crocodylus siamensis). Comparisons were made with Amazon toadhead turtle (Mesoclemmys heliostemma) with a partial septum only and no AVCS (negative control) and with chicken (Gallus gallus) (septum and AVCS, positive control). Optical mapping of the electrical impulse in the crocodile and chicken showed a similar developmental specialization that coincided with full ventricular septation, whereas in the turtle the ventricular activation remained primitive. Co-localization of neural marker human natural killer-1 (HNK-1) and cardiomyocyte marker anti-myosin heavy chain (MF20) identified the AVCS on top of the ventricular septum in the crocodile and chicken only. AVCS formation is correlated with ventricular septation in both evolution and development.

a b s t r a c tConnexin40 (Cx40) is the main connexin expressed in the murine atria and ventricular conduction system. We assess here the developmental role of Cx40 in atrial conduction of the mouse. Cx40 deficiency significantly prolonged activation times in embryonic day 10.5, 12.5 and 14.5 atria during spontaneous activation; the severity decreased with increasing age. In a majority of Cx40 deficient mice the impulse originated from an ectopic focus in the right atrial appendage; in such a case the activation time was even longer due to prolonged activation. Cx40 has thus an important physiological role in the developing atria.

Tissue imaging in 3D using visible light is limited and various clearing techniques were developed to increase imaging depth, but none provides universal solution for all tissues at all developmental stages. In this review, we focus on different tissue clearing methods for 3D imaging of heart and vasculature, based on chemical composition (solvent-based, simple immersion, hyperhydration, and hydrogel embedding techniques). We discuss in detail compatibility of various tissue clearing techniques with visualization methods: fluorescence preservation, immunohistochemistry, nuclear staining, and fluorescent dyes vascular perfusion. We also discuss myocardium visualization using autofluorescence, tissue shrinking, and expansion. Then we overview imaging methods used to study cardiovascular system and live imaging. We discuss heart and vessels segmentation methods and image analysis. The review covers the whole process of cardiovascular system 3D imaging, starting from tissue clearing and its compatibility with various visualization methods to the types of imaging methods and resulting image analysis.

The nonsyndromic cleft is one of the most frequent congenital defects in humans. Clinical data demonstrated improved and almost scarless neonatal healing of reparative surgery. Based on our previous results on crosstalk between neonatal fibroblasts and adult keratinocytes, the present study focused on characterization of fibroblasts prepared from cleft lip tissue samples of neonates and older children, and compared them with samples isolated from normal adult skin (face and breast) and scars. Although subtle variances in expression profiles of children and neonates were observed, the two groups differed significantly from adult cells. Compared with adult cells, differences were observed in nestin and smooth muscle actin (SMA) expression at the protein and transcript level. Furthermore, fibroblast to myofibroblast differentiation drives effective wound healing and is largely regulated by the cytokine, transforming growth factor-β1 (TGF-β1). Dysregulation of the TGF-β signalling pathway, including low expression of the TGF-β receptor II, may contribute to reducing scarring in neonates. Fibroblasts of facial origin also exhibited age independent differences from the cells prepared from the breast, reflecting the origin of the facial cells from neural crest-based ectomesenchyme.

Epoxyeicosatrienoic acids (EETs) and their synthetic analogs have cardiovascular protective effects. Here, we investigated the action of a novel EET analog EET-B on the progression of post-myocardial infarction (MI) heart failure in spontaneously hypertensive rats (SHR). Adult male SHR were divided into vehicle- and EET-B (10 mg/kg/day; p.o., 9 weeks)-treated groups. After 2 weeks of treatment, rats were subjected to 30-min left coronary artery occlusion or sham operation. Systolic blood pressure (SBP) and echocardiography (ECHO) measurements were performed at the beginning of study, 4 days before, and 7 weeks after MI. At the end of the study, tissue samples were collected for histological and biochemical analyses. We demonstrated that EET-B treatment did not affect blood pressure and cardiac parameters in SHR prior to MI. Fractional shortening (FS) was decreased to 18.4 ± 1.0% in vehicle-treated MI rats compared with corresponding sham (30.6 ± 1.0%) 7 weeks following MI induction. In infarcted SHR hearts, EET-B treatment improved FS (23.7 ± 0.7%), markedly increased heme oxygenase-1 (HO-1) immunopositivity in cardiomyocytes and reduced cardiac inflammation and fibrosis (by 13 and 19%, respectively). In conclusion, these findings suggest that EET analog EET-B has beneficial therapeutic actions to reduce cardiac remodeling in SHR subjected to MI.