Cardiac injury of the newborn mammalian heart accelerates cardiomyocyte terminal differentiation.

After birth cardiomyocytes undergo terminal differentiation, characterized by binucleation and centrosome disassembly, rendering the heart unable to regenerate. Yet, it has been suggested that newborn mammals regenerate their hearts after apical resection by cardiomyocyte proliferation. Thus, we tested the hypothesis that apical resection either inhibits, delays, or reverses cardiomyocyte centrosome disassembly and binucleation.

Towards regenerating the mammalian heart: challenges in evaluating experimentally induced adult mammalian cardiomyocyte proliferation.

In recent years, there has been a dramatic increase in research aimed at regenerating the mammalian heart by promoting endogenous cardiomyocyte proliferation. Despite many encouraging successes, it remains unclear if we are any closer to achieving levels of mammalian cardiomyocyte proliferation for regeneration as seen during zebrafish regeneration. Furthermore, current cardiac regenerative approaches do not clarify whether the induced cardiomyocyte proliferation is an epiphenomena or responsible for the observed improvement in cardiac function.

Spatially Resolved Genome-wide Transcriptional Profiling Identifies BMP Signaling as Essential Regulator of Zebrafish Cardiomyocyte Regeneration.

In contrast to mammals, zebrafish regenerate heart injuries via proliferation of cardiomyocytes located near the wound border. To identify regulators of cardiomyocyte proliferation, we used spatially resolved RNA sequencing (tomo-seq) and generated a high-resolution genome-wide atlas of gene expression in the regenerating zebrafish heart. Interestingly, we identified two wound border zones with distinct expression profiles, including the re-expression of embryonic cardiac genes and targets of bone morphogenetic protein (BMP) signaling.

Persistent scarring and dilated cardiomyopathy suggest incomplete regeneration of the apex resected neonatal mouse myocardium--A 180 days follow up study.

Heart damage in mammals is generally considered to result in scar formation, whereas zebrafish completely regenerate their hearts following an intermediate and reversible state of fibrosis after apex resection (AR). Recently, using the AR procedure, one-day-old mice were suggested to have full capacity for cardiac regeneration as well. In contrast, using the same mouse model others have shown that the regeneration process is incomplete and that scarring still remains 21 days after AR.

Developmental alterations in centrosome integrity contribute to the post-mitotic state of mammalian cardiomyocytes.

Mammalian cardiomyocytes become post-mitotic shortly after birth. Understanding how this occurs is highly relevant to cardiac regenerative therapy. Yet, how cardiomyocytes achieve and maintain a post-mitotic state is unknown.

Poly(glycerol sebacate)/poly(butylene succinate-butylene dilinoleate) fibrous scaffolds for cardiac tissue engineering.

The present article investigates the use of a novel electrospun fibrous blend of poly(glycerol sebacate) (PGS) and poly(butylene succinate-butylene dilinoleate) (PBS-DLA) as a candidate for cardiac tissue engineering. Random electrospun fibers with various PGS/PBS-DLA compositions (70/30, 60/40, 50/50, and 0/100) were fabricated. To examine the suitability of these fiber blends for heart patches, their morphology, as well as their physical, chemical, and mechanical properties were measured before examining their biocompatibility through cell adhesion.

The cardiomyocyte cell cycle in hypertrophy, tissue homeostasis, and regeneration.

Mammalian cardiomyocytes withdraw from the cell cycle shortly after birth. Although the adult heart is unable to regenerate, numerous reports have shown that adult cardiomyocytes exhibit a dynamic range of cell cycle activity under various physiological and pathological conditions. Reason and consequence of cardiomyocyte cell cycle activity remain unclear and have led to a number of misconceptions.

A simple method for isolating disomic strains of Saccharomyces cerevisiae.

A simple method to select disomic (N + 1) strains that should be applicable for almost any chromosome in Saccharomyces cerevisiae is presented. A diploid heterozygous for a KanMX knock-out mutation in an essential gene is sporulated and viable geneticin (G418)-resistant colonies selected. Disomic products of a missegregation or non-disjunction event containing a copy of both the wild-type essential gene and its complementary KanMX knock-out allele make up most of the viable colonies.

Caspase-3 mediated cleavage of MEKK1 promotes p53 transcriptional activity.

Myocardial ischemia/reperfusion (IR) induces myocyte apoptosis, and the pro-apoptotic/tumor suppressor protein p53 may contribute to this process. However, the signaling mechanism by which IR induces p53 activation remains largely unknown. Here, we show that MEKK1 undergoes proteolytic cleavage in a caspase-3 dependent manner in both in vivo and in vitro models of ischemic injury.