Head-to-head comparison of relevant cell sources of small extracellular vesicles for cardiac repair: Superiority of embryonic stem cells.

Small extracellular vesicles (sEV) derived from various cell sources have been demonstrated to enhance cardiac function in preclinical models of myocardial infarction (MI). The aim of this study was to compare different sources of sEV for cardiac repair and determine the most effective one, which nowadays remains limited. We comprehensively assessed the efficacy of sEV obtained from human primary bone marrow mesenchymal stromal cells (BM-MSC), human immortalized MSC (hTERT-MSC), human embryonic stem cells (ESC), ESC-derived cardiac progenitor cells (CPC), human ESC-derived cardiomyocytes (CM), and human primary ventricular cardiac fibroblasts (VCF), in in vitro models of cardiac repair. ESC-derived sEV (ESC-sEV) exhibited the best pro-angiogenic and anti-fibrotic effects in vitro. Then, we evaluated the functionality of the sEV with the most promising performances in vitro, in a murine model of MI-reperfusion injury (IRI) and analysed their RNA and protein compositions. In vivo, ESC-sEV provided the most favourable outcome after MI by reducing adverse cardiac remodelling through down-regulating fibrosis and increasing angiogenesis. Furthermore, transcriptomic, and proteomic characterizations of sEV derived from hTERT-MSC, ESC, and CPC revealed factors in ESC-sEV that potentially drove the observed functions. In conclusion, ESC-sEV holds great promise as a cell-free treatment for promoting cardiac repair following MI.

Phospholamban antisense oligonucleotides improve cardiac function in murine cardiomyopathy.

Heart failure (HF) is a major cause of morbidity and mortality worldwide, highlighting an urgent need for novel treatment options, despite recent improvements. Aberrant Ca2+ handling is a key feature of HF pathophysiology. Restoring the Ca2+ regulating machinery is an attractive therapeutic strategy supported by genetic and pharmacological proof of concept studies. Here, we study antisense oligonucleotides (ASOs) as a therapeutic modality, interfering with the PLN/SERCA2a interaction by targeting Pln mRNA for downregulation in the heart of murine HF models. Mice harboring the PLN R14del pathogenic variant recapitulate the human dilated cardiomyopathy (DCM) phenotype; subcutaneous administration of PLN-ASO prevents PLN protein aggregation, cardiac dysfunction, and leads to a 3-fold increase in survival rate. In another genetic DCM mouse model, unrelated to PLN (Cspr3/Mlp-/-), PLN-ASO also reverses the HF phenotype. Finally, in rats with myocardial infarction, PLN-ASO treatment prevents progression of left ventricular dilatation and improves left ventricular contractility. Thus, our data establish that antisense inhibition of PLN is an effective strategy in preclinical models of genetic cardiomyopathy as well as ischemia driven HF.

Biocompatible, Purified VEGF-A mRNA Improves Cardiac Function after Intracardiac Injection 1 Week Post-myocardial Infarction in Swine.

mRNA can direct dose-dependent protein expression in cardiac muscle without genome integration, but to date has not been shown to improve cardiac function in a safe, clinically applicable way. Herein, we report that a purified and optimized mRNA in a biocompatible citrate-saline formulation is tissue specific, long acting, and does not stimulate an immune response. In small- and large-animal, permanent occlusion myocardial infarction models, VEGF-A 165 mRNA improves systolic ventricular function and limits myocardial damage. Following a single administration a week post-infarction in mini pigs, left ventricular ejection fraction, inotropy, and ventricular compliance improved, border zone arteriolar and capillary density increased, and myocardial fibrosis decreased at 2 months post-treatment. Purified VEGF-A mRNA establishes the feasibility of improving cardiac function in the sub-acute therapeutic window and may represent a new class of therapies for ischemic injury.

Modification of gastric pH in the fasted dog.

OBJECTIVES: The aim was to compare the ability of pretreatments to consistently adjust gastric conditions to low or high pH in the fasted state in dogs. METHODS: Four male Labrador/Labrador-cross dogs weighing 25-35 kg were surgically equipped with a ventricle fistula cannula in the stomach and a jejunal nipple valve stoma. Dogs were fasted overnight before the experiments, with free access to water. The pH in the dogs' stomach was modified either orally with buffers (0.1 mol/l HCl-KCl, 0.05 mol/l glycine-HCl, 0.1 mol/l citrate or 0.1 mol/l BIS-TRIS) or intravenously with pharmacological agents (pentagastrin 4-6 microg/kg, ranitidine 50 mg or omeprazole 1 mg/kg). Intragastric pH was recorded continuously for 2 h with an electrode connected to an ambulatory pH meter. Chyme was collected simultaneously from the jejunal stoma as an approximate measure of gastric emptying. KEY FINDINGS: 0.1 mol/l HCl-KCl buffer p.o. and 1 mg/kg omeprazole i.v. attained low and high gastric pH more reproducibly (11/11 and 6/7 experiments met target values of pH < 3 and > 4, respectively) and for a longer duration (average time exceeding target value 90 and 103 min, respectively) than the other buffers and pharmacological pretreatments. The starting pH did not alter the modifiers' capacity to increase or decrease the pH. However, the lag time before chyme appeared at the jejunal stoma appeared to be longer when the pH was low and shorter when the pH was high. CONCLUSIONS: To achieve a consistently low gastric pH in fasting dogs, 0.1 mol/l HCl-KCl buffer should be administered orally, 15 min before the dosage form. To elevate the gastric pH reproducibly, omeprazole 1 mg/kg should be administered intravenously at least 90 min before oral administration of the dosage form.

The delayed dissolution of paracetamol products in the canine fed stomach can be predicted in vitro but it does not affect the onset of plasma levels.

Although it is generally believed that paracetamol can be used as a marker of gastric emptying, there have been reports in the literature that show delayed dissolution of immediate release paracetamol tablets using standard in vitro setups and food-simulating media, delayed disintegration of paracetamol products in the fed stomach, and no correlation of paracetamol absorption with gastric emptying in the fed state. In this study, we confirmed that dissolution of Panodil and Apotel tablets is delayed in food-simulating media regardless of the in vitro hydrodynamics and on a formulation dependent manner. Further, we assessed the usefulness of in vitro dissolution data in the prediction of delayed disintegration time in the fed stomach and we examined the importance of delayed gastric disintegration on the onset of plasma levels using the canine model. In vitro dissolution data in cow's milk reflected the delayed disintegration of Panodil tablets in the fed stomach. In vitro dissolution of Apotel tablets in milk was delayed less than of Panodil and the effect of dosing conditions on the in vivo disintegration was not apparent. However, for the products tested in this study, there was no correlation between intragastric disintegration and onset of plasma levels probably because gastric emptying in also delayed in the fed state.

Food effects on tablet disintegration.

The aims of the present study was to investigate if food components, as represented by a multi-component nutritional drink for tube feeding, could affect tablet disintegration of standard tablets in vitro as well as in vivo and propose a mechanism for potential food effects on tablet disintegration. The tablet disintegration was delayed between 5 min and more than 1h in the simulated gastric fed medium compared to a simple buffer. This effect was dependent on the tablet composition. A similar delay in tablet disintegration was also found in vivo after administration of the nutritional drink to three Labradors as observed by removing the tablet from the stomach at different times through a gastric fistula. The delay in tablet disintegration appeared to be caused by precipitation of a film, mainly consisting of protein, on the tablet surface as indicated by disintegration studies with pure nutrients, identification by IR spectroscopy of contents of precipitates obtained in a model study were the nutrients were incubated with different tablet excipients and visual observations of tablets exposed to the simulated fed medium. The drug dissolution of a soluble compound, metoprolol tartrate, from a standard tablet was also strongly delayed in the simulated fed medium. In conclusion, food, could significantly delay tablet disintegration and drug dissolution in the stomach by formation of a film around the tablets. This effect could be monitored by a simple in vitro disintegration test using a test medium based on a nutritional drink. More studies are needed to investigate the significance of the slow tablet disintegrations on bioavailability and for which types of food the present effect occurs.