Human embryonic stem cell-derived cardiomyocytes restore function in infarcted hearts of non-human primates.

Pluripotent stem cell-derived cardiomyocyte grafts can remuscularize substantial amounts of infarcted myocardium and beat in synchrony with the heart, but in some settings cause ventricular arrhythmias. It is unknown whether human cardiomyocytes can restore cardiac function in a physiologically relevant large animal model. Here we show that transplantation of ∼750 million cryopreserved human embryonic stem cell-derived cardiomyocytes (hESC-CMs) enhances cardiac function in macaque monkeys with large myocardial infarctions. One month after hESC-CM transplantation, global left ventricular ejection fraction improved 10.6 ± 0.9% vs. 2.5 ± 0.8% in controls, and by 3 months there was an additional 12.4% improvement in treated vs. a 3.5% decline in controls. Grafts averaged 11.6% of infarct size, formed electromechanical junctions with the host heart, and by 3 months contained ∼99% ventricular myocytes. A subset of animals experienced graft-associated ventricular arrhythmias, shown by electrical mapping to originate from a point-source acting as an ectopic pacemaker. Our data demonstrate that remuscularization of the infarcted macaque heart with human myocardium provides durable improvement in left ventricular function.

Bronchoscopic thermal vapor ablation in a canine model of emphysema.

Clinical studies indicate the potential of bronchoscopic thermal vapor ablation to result in clinically relevant improvements in severe chronic obstructive pulmonary disease patients with upper lobe-predominant emphysema. However, the mechanisms by which vapor ablation results in lung volume reduction are not fully known. This study determined the 3-month safety and efficacy of vapor ablation in a canine model of emphysema and described the histopathological changes in the lung. The cranial lobes of papain-exposed dogs were treated with a vapor dose of ten calories per gram of lung tissue (n = 8) or were sham treated (n = 3). Safety was monitored peri- and postoperatively for 3 months. Animals were then sacrificed, estimates of lung volume reduction performed, and the lungs processed for histology. Vapor ablation was associated with an average of 20% volume reduction of the treated lobes and an absence of serious adverse events. The amount of lobar volume reduction was correlated with the amount of fibrosis and atelectasis in the treated lobe. Bronchoscopic thermal vapor ablation at a dose of 10 cal/g results in lobar volume reduction associated with remodeling of the targeted tissue characterized by mature collagen formation in the absence of major adverse events.

Time course of airway remodelling after an acute chlorine gas exposure in mice.

Accidental chlorine (Cl2) gas inhalation is a common cause of acute airway injury. However, little is known about the kinetics of airway injury and repair after Cl2 exposure. We investigated the time course of airway epithelial damage and repair in mice after a single exposure to a high concentration of Cl2 gas. Mice were exposed to 800 ppm Cl2 gas for 5 minutes and studied from 12 hrs to 10 days post-exposure. The acute injury phase after Cl2 exposure (< or = 24 hrs post-exposure) was characterized by airway epithelial cell apoptosis (increased TUNEL staining) and sloughing, elevated protein in bronchoalveolar lavage fluid, and a modest increase in airway responses to methacholine. The repair phase after Cl2 exposure was characterized by increased airway epithelial cell proliferation, measured by immunoreactive proliferating cell nuclear antigen (PCNA), with maximal proliferation occurring 5 days after Cl2 exposure. At 10 days after Cl2 exposure the airway smooth muscle mass was increased relative to controls, suggestive of airway smooth muscle hyperplasia and there was evidence of airway fibrosis. No increase in goblet cells occurred at any time point. We conclude that a single exposure of mice to Cl2 gas causes acute changes in lung function, including pulmonary responsiveness to methacholine challenge, associated with airway damage, followed by subsequent repair and airway remodelling.

Gob-5 is not essential for mucus overproduction in preclinical murine models of allergic asthma.

Overexpression of Gob-5 has previously been linked to goblet cell metaplasia and mucin overproduction in both in vitro and in vivo model systems. In this study, Gob-5 knockout mice were generated and their phenotype was evaluated in two established preclinical models of allergic asthma. We sought to determine whether the Gob-5-null animals could produce less mucus in response to allergic challenge, and whether this would have any impact on reducing goblet cell metaplasia and airway inflammation. We found that in the absence of a proinflammatory stimulus we could not detect an overt phenotypic difference between age and sex-matched knockout and wild-type animals. Allergic challenge with ovalbumin or intranasal administration of interleukin-13 produced a robust allergic response that was similar regardless of genotype. In addition, siRNA-mediated knockdown of CLCA-1 in cultured lung epithelial cells failed to reduce mucin expression in vitro. Thus, in contrast to previously published reports, our findings show that Gob-5 expression is not essential for mucin overproduction in vitro or in murine models of allergic asthma. Furthermore, we have also exploited the use of gene expression array analysis to investigate the possibility that a compensatory mechanism, involving other genes, may act to override the requirement for Gob-5-mediated mucus overproduction.

Preferential diaphragmatic weakness during sustained Pseudomonas aeruginosa lung infection.

Infection with Pseudomonas aeruginosa plays a major role in the pulmonary inflammation and injury associated with cystic fibrosis. Lung inflammation may also lead to more widespread systemic effects on other organs. We tested the following hypotheses: (1) ongoing P. aeruginosa lung infection produces diaphragmatic and limb muscle weakness and (2) such muscle dysfunction is directly correlated with the level of pulmonary inflammation. Chronic bronchopulmonary infection with mucoid P. aeruginosa was induced in C57BL/6 mice. At Day 2 after infection, diaphragmatic force was decreased (37%) only in mice infected with a high dose of 1 x 10(6) cfu, whereas by Day 7 after infection, diaphragmatic force was similarly reduced (36%) even at a fivefold lower inoculating dose. No significant correlations were found between diaphragmatic weakness and pulmonary inflammation, as assessed by the number of neutrophils, macrophages, and lymphocytes in bronchoalveolar lavage fluid. Moreover, in marked contrast to the diaphragm, no effects of P. aeruginosa infection on contractile function were observed in prototypical slow- and fast-twitch hindlimb muscles. We conclude that sustained lung infection with P. aeruginosa induces preferential weakness of the diaphragm, which is not directly correlated with the degree of pulmonary inflammation induced under these conditions.