Inner mitochondrial membrane structure and fusion dynamics are altered in senescent human iPSC-derived and primary rat cardiomyocytes.

Dysfunction of the aging heart is a major cause of death in the human population. Amongst other tasks, mitochondria are pivotal to supply the working heart with ATP. The mitochondrial inner membrane (IMM) ultrastructure is tailored to meet these demands and to provide nano-compartments for specific tasks. Thus, function and morphology are closely coupled. Senescent cardiomyocytes from the mouse heart display alterations of the inner mitochondrial membrane. To study the relation between inner mitochondrial membrane architecture, dynamics and function is hardly possible in living organisms. Here, we present two cardiomyocyte senescence cell models that allow in cellular studies of mitochondrial performance. We show that doxorubicin treatment transforms human iPSC-derived cardiomyocytes and rat neonatal cardiomyocytes in an aged phenotype. The treated cardiomyocytes display double-strand breaks in the nDNA, have ß-galactosidase activity, possess enlarged nuclei, and show p21 upregulation. Most importantly, they also display a compromised inner mitochondrial structure. This prompted us to test whether the dynamics of the inner membrane was also altered. We found that the exchange of IMM components after organelle fusion was faster in doxorubicin-treated cells than in control cells, with no change in mitochondrial fusion dynamics at the meso-scale. Such altered IMM morphology and dynamics may have important implications for local OXPHOS protein organization, exchange of damaged components, and eventually the mitochondrial bioenergetics function of the aged cardiomyocyte.

Emerging role of mitophagy in cardiovascular physiology and pathology.

Healthy mitochondrial function is imperative for most tissues, but especially those with a high energy demand. Robust evidence linking mitochondrial dysfunction with cardiovascular disease has demonstrated that mitochondrial activity is highly relevant to cardiac muscle performance. Mitochondrial homeostasis is maintained through coordination among the processes that comprise the so-called mitochondrial dynamics machinery. The most-studied elements of cardiac mitochondrial dynamics are mitochondrial fission and fusion, biogenesis and degradation. Selective autophagic removal of mitochondria (mitophagy) is essential for clearing away defective mitochondria but can lead to cell damage and death if not tightly controlled. In cardiovascular cells such as cardiomyocytes and cardiac fibroblasts, mitophagy is involved in metabolic activity, cell differentiation, apoptosis and other physiological processes related to major phenotypic changes. Modulation of mitophagy has detrimental and/or beneficial outcomes in various cardiovascular diseases, suggesting that a deeper understanding of the mechanisms underlying mitochondrial degradation in the heart could provide valuable clinical insights. Here, we discuss current evidence supporting the role of mitophagy in cardiac pathophysiology, with an emphasis on different research models and their interpretations; basic concepts related to this selective autophagy; and the most commonly used experimental approaches for studying this mechanism. Finally, we provide a comprehensive literature analysis on the role of mitophagy in heart failure, ischemia/reperfusion, diabetic cardiomyopathy and other cardiovascular diseases, as well as its potential biomedical applications.

A Reliable Preclinical Model to Study the Impact of Cigarette Smoke in Development and Disease.

The World Health Organization has estimated that, worldwide, cigarette smoking has caused more than 100 million deaths in the last century, a number that is expected to increase in the future. Understanding cigarette smoke toxicity is key for research and development of proper public health policies. The current challenge is to establish a reliable preclinical model to evaluate the effects of cigarette smoke. In this work, we describe a simple method that allows for quantifying the toxic effects of cigarette smoke using zebrafish. Here, viability of larvae and adult fish, as well as the effects of cigarette smoke extracts on vascular development and tissue regeneration, can be easily assayed. © 2019 by John Wiley & Sons, Inc.

A Novel In Vivo Model to Study Impaired Tissue Regeneration Mediated by Cigarette Smoke.

Cigarette smoke is associated with several pathologies including chronic respiratory diseases and cancer. In addition, exposure to cigarette smoke is correlated with impaired wound healing, where a significant decrease in the regenerative capacity of smokers is well documented and broadly considered a negative risk factor after trauma or surgery. So far, some in vitro and in vivo models have been described to study how exposure to cigarette smoke diminishes the regenerative potential in different organisms. However, although useful, many of these models are difficult and expensive to implement and do not allow high-throughput screening approaches. In order to establish a reliable and accessible model, we have evaluated the effects of cigarette smoke extract (CSE) on zebrafish development and regeneration. In this work, zebrafish embryos and larvae were exposed to low doses of aqueous CSE showing severe developmental abnormalities in a dose-dependent manner. Furthermore, when adult zebrafish were subjected to caudal fin amputation, we observed a significant decrease in the regenerative capacity of animals exposed to CSE. The effect was exacerbated in male and aged fish compared to female or young organisms. The establishment of a zebrafish model to assess the consequences of cigarette smoke and its effects on animal physiology could provide a new tool to study the underlying mechanisms involved in impaired tissue regeneration, and aid the development of novel approaches to treat complications associated with cigarette smoke toxicity.

Zebrafish as an Emerging Model Organism to Study Angiogenesis in Development and Regeneration.

Angiogenesis is the process through which new blood vessels are formed from preexisting ones and plays a critical role in several conditions including embryonic development, tissue repair and disease. Moreover, enhanced therapeutic angiogenesis is a major goal in the field of regenerative medicine and efficient vascularization of artificial tissues and organs is one of the main hindrances in the implementation of tissue engineering approaches, while, on the other hand, inhibition of angiogenesis is a key therapeutic target to inhibit for instance tumor growth. During the last decades, the understanding of cellular and molecular mechanisms involved in this process has been matter of intense research. In this regard, several in vitro and in vivo models have been established to visualize and study migration of endothelial progenitor cells, formation of endothelial tubules and the generation of new vascular networks, while assessing the conditions and treatments that either promote or inhibit such processes. In this review, we address and compare the most commonly used experimental models to study angiogenesis in vitro and in vivo. In particular, we focus on the implementation of the zebrafish (Danio rerio) as a model to study angiogenesis and discuss the advantages and not yet explored possibilities of its use as model organism.

[Association between serotonin transporter and monoamine oxidase A gene polymorphisms and depression]. / Asociación entre los polimorfismos 5HTTLPR, uMAOA y depresión en una cohorte de pacientes de atención primaria.

BACKGROUND: Serotonin plays a central role regulating mood and on the development of depressive disorders. AIM: To study whether 5HTTLPR functional polymorphisms in the serotonin transporter gene or the Monoamine oxidase A gene (uMAOA) were risk markers for depression. MATERIAL AND METHODS: The Composite International Diagnostic Interview (CIDI) was applied to 1,062 consultants in primary health care centers aged between 18 and 75 years to establish the diagnosis of depression. A sample of saliva was obtained for DNA extraction and genetic analyses. RESULTS: No association between the presence of depressive disorders and 5HTTLPR (ss) or uMAOA (3/3) risk genotypes was found. Psychological abuse and the presence of two or more life events were found to be predictors of depression in the studied sample. CONCLUSIONS: In this study, 5HTTLPR and uMAOA polymorphisms were not risk factors for depression. However, psychological abuse and the presence of two or more life events were risk factors for depressive disorders.

Asociación entre los polimorfismos 5HTTLPR, uMAOA y depresión en una cohorte de pacientes de atención primaria / Association between serotonin transporter and monoamine oxidase A gene polymorphisms and depression

Background: Serotonin plays a central role regulating mood and on the development of depressive disorders. Aim: To study whether 5HTTLPR functional polymorphisms in the serotonin transporter gene or the Monoamine oxidase A gene (uMAOA) were risk markers for depression. Material and Methods: The Composite International Diagnostic Interview (CIDI) was applied to 1,062 consultants in primary health care centers aged between 18 and 75 years to establish the diagnosis of depression. A sample of saliva was obtained for DNA extraction and genetic analyses. Results: No association between the presence of depressive disorders and 5HTTLPR (ss) or uMAOA (3/3) risk genotypes was found. Psychological abuse and the presence of two or more life events were found to be predictors of depression in the studied sample. Conclusions: In this study, 5HTTLPR and uMAOA polymorphisms were not risk factors for depression. However, psychological abuse and the presence of two or more life events were risk factors for depressive disorders.

Generation of Viable Plant-Vertebrate Chimeras.

The extreme dependence on external oxygen supply observed in animals causes major clinical problems and several diseases are related to low oxygen tension in tissues. The vast majority of the animals do not produce oxygen but a few exceptions have shown that photosynthetic capacity is physiologically compatible with animal life. Such symbiotic photosynthetic relationships are restricted to a few aquatic invertebrates. In this work we aimed to explore if we could create a chimerical organism by incorporating photosynthetic eukaryotic cells into a vertebrate animal model. Here, the microalgae Chlamydomonas reinhardtii was injected into zebrafish eggs and the interaction and viability of both organisms were studied. Results show that microalgae were distributed into different tissues, forming a fish-alga chimera organism for a prolonged period of time. In addition, microscopic observation of injected algae, in vivo expression of their mRNA and re-growth of the algae ex vivo suggests that they survived to the developmental process, living for several days after injection. Moreover microalgae did not trigger a significant inflammatory response in the fish. This work provides additional evidence to support the possibility that photosynthetic vertebrates can be engineered.