Beating Activity Research Articles

Aspirin inhibits growth and enhances cardiomyocyte differentiation of bone marrow mesenchymal stem cells

This study aimed to examine the effects of aspirin on the growth and cardiomyocyte differentiation grade of bone marrow mesenchymal stem cells (BMMSCs). BMMSCs were divided into five differentiation groups with different concentrations of aspirin (0 mM, 0.5 mM, 1 mM, 2 mM, or 5 mM), and a undifferentiated control group. Cell growth was measured by cell proliferation, apoptosis assays and DNA cycle analysis. The differentiation grade of BMMSC-derived cardiomyocyte-like cells was examined by measuring the levels of cardiac-specific proteins with cyto-immunofluorescence staining, flow cytometry, and Western blotting. Electrophysiological analyses were performed by patch-clamp experiments and calcium transients were measured by a laser scanning confocal microscope. Cell proliferation decreased as the concentration of aspirin increased. Cell apoptosis increased with increasing aspirin concentration. DNA replication was inhibited in the high dose-aspirin group compared to the low dose- or non-aspirin groups. The number of α-myosin heavy chain (α-MHC) and cardiac troponin I (cTnI) positive cells, cardiac troponin T (cTnT) and connexin 43 (Cx43) positive rates, expression levels of Cx43, Nkx2.5, GATA4 and β1 adrenoceptor increased with increasing aspirin concentration. No sarcomeric cross-striations, spontaneous or induced beating activity or action potentials was observed in each group. Calcium transients were measured in small number cells in 2 mM aspirin group, but the features are atypical. Consequently, aspirin inhibits proliferation and survival of BMMSCs and enhances cardiomyocyte differentiation of BMMSCs.

Does Heating up Saline for Nasal Irrigation Improve Mucociliary Function in Chronic Rhinosinusitis?

Background Mucociliary function is affected by temperature. Exposure to cold air may impair ciliary beat frequency. While saline nasal irrigation improves in ciliary beat activity, there is no evidence supporting the use of heated saline irrigation in treating patients with chronic rhinosinusitis. Objective To compare the effects of heated saline to room-temperature saline nasal irrigation on mucociliary clearance in chronic rhinosinusitis patients. Methods Adult patients with chronic rhinosinusitis were randomized into two groups receiving either heated saline or room-temperature saline nasal irrigation. Healthy subjects were included as control. Saccharin transit time was measured before and after nasal irrigation. Nasal patency was assessed by peak nasal inspiratory flow, anterior rhinomanometry, acoustic rhinometry, nasal obstruction score, and breathe-comfort score. Any adverse events were reported. Results Twenty-three patients with chronic rhinosinusitis and nine healthy subjects were enrolled. Saccharin transit time was decreased after nasal irrigation in both heated saline subgroup (baseline 12.3 ± 4.5 min vs. postirrigation 8.4 ± 4.9 min, p = 0.05) and room-temperature subgroup (baseline 12.8 ± 5.0 min vs. postirrigation 8.9 ± 4.2 min, p = 0.01). The saccharin transit time improvement was not different between heated saline (3.8 ± 6.2 min) and room-temperature saline (3.8 ± 4.0 min), p = 0.13. Postheated saline irrigation saccharin transit time of chronic rhinosinusitis patients (8.4 ± 4.9 min) was not different to healthy subjects (9.2 ± 3.7 min), p = 0.69. Nasal patency was not different between groups. There was no adverse event reported. Conclusion Nasal saline irrigation is beneficial to patients with chronic rhinosinusitis on mucociliary improvement. Warming saline is not necessary and adds no additional benefit to room-temperature saline irrigation.

A temporal comparison of sex-aggregation pheromone gland content and dynamics of release in three members of theLutzomyia longipalpis(Diptera: Psychodidae) species complex.

BackgroundLutzomyia longipalpis is the South American vector of Leishmania infantum, the etiologic agent of visceral leishmaniasis (VL). Male L. longipalpis produce a sex-aggregation pheromone that is critical in mating, yet very little is known about its accumulation over time or factors involved in release. This laboratory study aimed to compare accumulation of pheromone over time and determine factors that might influence release in three members of the L. longipalpis species complex.Methodology/Principal findingsWe investigated male sex-aggregation pheromone gland content at different ages and the release rate of pheromone in the presence or absence of females under different light conditions by gas chromatography-mass spectrometry (GC-MS). Pheromone gland content was determined by extraction of whole males and pheromone release rate was determined by collection of headspace volatiles. Pheromone gland content appeared age-related and pheromone began to accumulate between 6 to 12 h post eclosion and gradually increased until males were 7–9 days old. The greatest amount was detected in 9-day old Campo Grande males ((S)-9-methylgermacrene-B; X ± SE: 203.5 ± 57.4 ng/male) followed by Sobral 2S males (diterpene; 199.9 ± 34.3) and Jacobina males ((1S,3S,7R)-3-methyl-α-himachalene; 128.8 ± 30.3) at 7 days old. Pheromone release was not continuous over time. During a 4-hour period, the greatest quantities of pheromone were released during the first hour, when wing beating activity was most intense. It was then substantially diminished for the remainder of the time. During a 24 h period, 4–5 day old male sand flies released approximately 63 ± 11% of the pheromone content of their glands, depending on the chemotype. The presence of females significantly increased pheromone release rate. The light regime under which the sand flies were held had little influence on pheromone release except on Sobral 2S chemotype.Conclusions/SignificanceAccumulation of pheromone appears to occur at different rates in the different chemotypes examined and results in differing amounts being present in glands over time. Release of accumulated pheromone is not passive, but depends on biotic (presence of females) and abiotic (light) circumstances. There are marked differences in content and release between the members of the complex suggesting important behavioural, biosynthetic and ecological differences between them.

Carbon nanotubes embedded in embryoid bodies direct cardiac differentiation.

We embedded carbon nanotubes (CNTs) in mouse embryoid bodies (EBs) for modulating mechanical and electrical cues of the stem cell niche. The CNTs increased the mechanical integrity and electrical conductivity of the EBs. Measured currents for the unmodified EBs (hereafter, EBs) and the EBs-0.25mg/mL CNTs were 0.79 and 26.3mA, respectively, at voltage of 5V. The EBs had a Young's modulus of 20.9±6.5kPa, whereas the Young's modulus of the EB-0.1mg/mL CNTs was 35.2±5.6kPa. The EB-CNTs also showed lower proliferation and greater differentiation rates compared with the EBs as determined by the expression of pluripotency genes and the analysis of EB sizes. Interestingly, the cardiac differentiation of the EB-CNTs was significantly greater than that of the EBs, as confirmed by high-throughput gene analysis at day 5 of culture. Applying electrical stimulation to the EB-CNTs specifically enhanced the cardiac differentiation and beating activity of the EBs.

Surface acoustic waves induced micropatterning of cells in gelatin methacryloyl (GelMA) hydrogels

Acoustic force patterning is an emerging technology that provides a platform to control the spatial location of cells in a rapid, accurate, yet contactless manner. However, very few studies have been reported on the usage of acoustic force patterning for the rapid arrangement of biological objects, such as cells, in a three-dimensional (3D) environment. In this study, we report on a bio-acoustic force patterning technique, which uses surface acoustic waves (SAWs) for the rapid arrangement of cells within an extracellular matrix-based hydrogel such as gelatin methacryloyl (GelMA). A proof-of-principle was achieved through both simulations and experiments based on the in-house fabricated piezoelectric SAW transducers, which enabled us to explore the effects of various parameters on the performance of the built construct. The SAWs were applied in a fashion that generated standing SAWs (SSAWs) on the substrate, the energy of which subsequently was transferred into the gel, creating a rapid, and contactless alignment of the cells (<10 s, based on the experimental conditions). Following ultraviolet radiation induced photo-crosslinking of the cell encapsulated GelMA pre-polymer solution, the patterned cardiac cells readily spread after alignment in the GelMA hydrogel and demonstrated beating activity in 5–7 days. The described acoustic force assembly method can be utilized not only to control the spatial distribution of the cells inside a 3D construct, but can also preserve the viability and functionality of the patterned cells (e.g. beating rates of cardiac cells). This platform can be potentially employed in a diverse range of applications, whether it is for tissue engineering, in vitro cell studies, or creating 3D biomimetic tissue structures.

Multi-parametric assessment of cardiomyocyte excitation-contraction coupling using impedance and field potential recording: A tool for cardiac safety assessment

IntroductionThe ICH S7B guidelines recommend that all new chemical entities should be subjected to hERG repolarization screening due to its association with life-threatening “Torsades de Pointes” (TdP) arrhythmia. However, it has become evident that not all hERG channel inhibitors result in TdP and not all compounds that induce QT prolongation and TdP necessarily inhibit hERG. In order to address the limitations of the S7B/E14 guidelines, the FDA through a public/private partnership initiated the Comprehensive in vitro Proarrhythmia Assay (CiPA) initiative to examine the possible modification and refinement of the ICH E14/S7B guidelines. One of the main components of the CiPA initiative is to utilize a predictive assay system together with human cardiomyocytes for risk assessment of arrhythmia. MethodIn this manuscript we utilize the xCELLigence® CardioECR system which simultaneously measures excitation-contraction coupling together with human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) to assess the effect of 8 reference compounds across 3 different independent sites. These 8 compounds were part of Phase I CiPA validation study. ResultsOur data demonstrate that hERG channel blockers, such as E4031 and moxifloxacin, prolonged field potential duration (FPD) at low concentration and induced arrhythmic beating activity as measured by field potential (FP) recording and impedance (IMP) recordings at higher concentrations. On the contrary, nifedipine, an inhibitor of calcium channel, didn't disrupt the periodicity of cell beating and weakened cell contractile activity and shortened FPD. Multichannel inhibitors, such as flecainide, quinidine and mexiletine, not only increased FPD and induced arrhythmia but also significantly reduced the amplitude of FP spike. JNJ303, an IKs inhibitor, only affected FPD. Comparison of the compound effect on FPD across the 3 different sites is consistent in terms of trend of the effect with observed 3–10 fold differences in minimal effective concentration at which a minimum of 10% response is detected. In addition, pentamidine, a hERG trafficking inhibitor which induced irregular beating activity over a more prolonged duration of time was readily flagged in this assay system. Taken together, this multi-parameter assay using hiPSC-CMs in conjunction with simultaneous measurement of ion channel activity and contractility can be a reliable approach for risk assessment of proarrhythmic compounds.

Graphene induces spontaneous cardiac differentiation in embryoid bodies.

Graphene was embedded into the structure of mouse embryoid bodies (EBs) using the hanging drop technique. The inclusion of 0.2 mg per mL graphene in the EBs did not affect the viability of the stem cells. However, the graphene decreased the stem cell proliferation, probably by accelerating cell differentiation. The graphene also enhanced the mechanical properties and electrical conductivity of the EBs. Interestingly, the cardiac differentiation of the EB-graphene was significantly greater than that of the EBs at day 5 of culture, as confirmed by high-throughput gene analysis. Electrical stimulation (voltage, 4 V; frequency, 1 Hz; and duration, 10 ms for 2 continuous days) further enhanced the cardiac differentiation of the EBs, as demonstrated by analyses of the cardiac protein and gene expression and the beating activity of the EBs. Taken together, the results demonstrated that graphene played a major role in directing the cardiac differentiation of EBs, which has potential cell therapy and tissue regeneration applications.

Abstract 12435: Mitochondrial Calcium Flux Modulates Pacemaker Activity in Embryonic Stem Cell-Derived Cardiomyocytes

Introduction: Ca2+ release from the sarcoplasmic reticulum (SR) is known to contribute to spontaneous activity via the cytoplasmic Na+-Ca2+ exchanger (NCX). Mitochondria are known to participate in Ca2+ cycling. We studied the role of mitochondrial Ca2+ flux in spontaneously activity of embryonic stem cells (ESC)-derived CMs. Methods: CMs were derived from wild type (Wt) and ryanodine receptor type 2 knockout (RYR2-/-) mouse ESCs and differentiated for 19-21 days. Action potentials (APs) were recorded by perforated whole cell current-clamp. Cytoplasmic Ca2+ transients were determined by fluorescent imaging. Mitochondrial Ca2+ transients were monitored simultaneously with APs. Results: While If blocker, 10μM ivabradine, had no significant effect on the automaticity, SR Ca2+ handling inhibitors, 10 μM ryanodine and 2 μM 2-APB, reduced the spontaneous beating rate to 56% and 73% respectively in Wt CMs. Inhibition of mitochondrial Ca2+ flux by 10 μM Ru360 showed a similar inhibitory effect on the pacemaker activity.To isolate the contribution of mitochondrial Ca2+, we used RYR2-/- CMs. In RYR2-/- CMs, beating rate was dependent on SR Ca2+ uptake and release from IP3 and the Na+/Ca2+ exchange current but was independent of sarcolemmal Ca2+ influx through L-type Ca2+ channels. In these cells, MCU inhibition by pharmacological or molecular biological means reduced beating rate. Depolarizing mitochondria prevented spontaneous beating. The mitochondrial NCX blocker, 1 or 3μM CGP-37157, terminated AP firings. Conclusions: Mitochondrial Ca2+ cycling plays a role in spontaneous beating activity in embryonic stem (ES) cell-derived cardiomyocytes. Mitochondrial dysfunction may contribute to altered pacemaker activity in cardiomyopathy.

Electrophysiologic and cellular characteristics of cardiomyocytes after X-ray irradiation

The aim of this study was to investigate possible effects of ionizing irradiation on the electrophysiological functionality of cardiac myocytes in vitro. Primary chicken cardiomyocytes with spontaneous beating activity were irradiated with X-rays (dose range of 0.5–7Gy). Functional alterations of cardiac cell cultures were evaluated up to 7 days after irradiation using microelectrode arrays. As examined endpoints, cell proliferation, apoptosis, reactive oxygen species (ROS) and DNA damage were evaluated. The beat rate of the cardiac networks increased in a dose-dependent manner over one week. The duration of single action potentials was slightly shortened. Additionally, we observed lower numbers of mitotic and S-phase cells at certain time points after irradiation. Also, the number of cells with γH2AX foci increased as a function of the dose. No significant changes in the level of ROS were detected. Induction of apoptosis was generally negligibly low.This is the first report to directly show alterations in cardiac electrophysiology caused by ionizing radiation, which were detectable up to one week after irradiation.

Structural and functional screening in human induced-pluripotent stem cell-derived cardiomyocytes accurately identifies cardiotoxicity of multiple drug types

Safety pharmacology studies that evaluate new drug entities for potential cardiac liability remain a critical component of drug development. Current studies have shown that in vitro tests utilizing human induced pluripotent stem cell-derived cardiomyocytes (hiPS-CM) may be beneficial for preclinical risk evaluation. We recently demonstrated that an in vitro multi-parameter test panel assessing overall cardiac health and function could accurately reflect the associated clinical cardiotoxicity of 4 FDA-approved targeted oncology agents using hiPS-CM. The present studies expand upon this initial observation to assess whether this in vitro screen could detect cardiotoxicity across multiple drug classes with known clinical cardiac risks. Thus, 24 drugs were examined for their effect on both structural (viability, reactive oxygen species generation, lipid formation, troponin secretion) and functional (beating activity) endpoints in hiPS-CM. Using this screen, the cardiac-safe drugs showed no effects on any of the tests in our panel. However, 16 of 18 compounds with known clinical cardiac risk showed drug-induced changes in hiPS-CM by at least one method. Moreover, when taking into account the Cmax values, these 16 compounds could be further classified depending on whether the effects were structural, functional, or both. Overall, the most sensitive test assessed cardiac beating using the xCELLigence platform (88.9%) while the structural endpoints provided additional insight into the mechanism of cardiotoxicity for several drugs. These studies show that a multi-parameter approach examining both cardiac cell health and function in hiPS-CM provides a comprehensive and robust assessment that can aid in the determination of potential cardiac liability.

In vitro chronotropic effects of Erythrina senegalensis DC (Fabaceae) aqueous extract on mouse heart slice and pluripotent stem cell-derived cardiomyocytes

Ethnopharmacological relevanceErythrina senegalensis DC (Fabaceae) bark is commonly used in sub-Saharan traditional medicine for the treatment of many diseases including gastrointestinal disorders and cardiovascular diseases. In this study, we investigated the effect of the aqueous extract of the stem bark of Erythrina senegalensis on the contractile properties of mouse ventricular slices and human induced pluripotent stem (hiPS) cell-derived cardiomyocytes. We also investigated the cytotoxic effect of the extract on mouse embryonic stem (ES) cells differentiating into cardiomyocytes (CMs). Materials and methodsWe used well-established electrophysiological technologies to assess the effect of Erythrina senegalensis aqueous extract (ESAE) on the beating activity of mouse ventricular slices, mouse ES and hiPS cell-derived CMs. To study the cytotoxic effect of our extract, differentiating mouse ES cells were exposed to different concentrations of ESAE. EB morphology was assessed by microscopy at different stages of differentiation whereas cell viability was measured by flow cytometry, fluorometry and immunocytochemistry. The electrical activity of CMs and heart slices were respectively captured by the patch clamp technique and microelectrode array (MEA) method following ESAE acute exposure. ResultsOur findings revealed that ESAE exhibits a biphasic chronotropic activity on mouse ventricular slices with an initial low dose (0.001 and 0.01µg/mL) decrease in beating activity followed by a corresponding significant increase in chronotropic activity at higher doses above 10µg/mL. The muscarinic receptor blocker, atropine abolished the negative chronotropic activity of ESAE, while propranolol successfully blocked its positive chronotropic activity. ESAE showed a significant dose-dependent positive chronotropic activity on hiPS cell-derived CMs. Also, though not significantly, ESAE decreased cell viability and increased total caspase-3/7 activity of mouse ES cells in a concentration-dependent manner. ConclusionErythrina senegalensis aqueous extract exhibits a biphasic chronotropic effect on mouse heart and a positive chronotropic activity on hiPS cell-derived CMs, suggesting a possible mechanism through muscarinic and β-adrenergic receptor pathways. Also, ESAE is not cytotoxic on mouse ES cells at concentrations up to 100µg/mL.

Automatic solution for detection, identification and biomedical monitoring of a cow using remote sensing for optimised treatment of cattle

In this paper we show how a novel photonic remote sensing system assembled on a robotic platform can extract vital biomedical parameters from cattle including their heart beating, breathing and chewing activity. The sensor is based upon a camera and a laser using selfinterference phenomena. The whole system intends to provide an automatic solution for detection, identification and biomedical monitoring of a cow. The detection algorithm is based upon image processing involving probability map construction. The identification algorithms involve well known image pattern recognition techniques. The sensor is used on top of an automated robotic platform in order to support animal decision making. Field tests and computer simulated results are presented.

Water uptake in terrestrial hermit crabs: a morpho-functional analysis

Coenobita hermit crabs succeeded in their adaptation to land thanks to their shell and to the possibility of carrying water within it. Such a water reserve may play several roles: to compensate for dehydration, to keep the gills and abdomen surface sufficiently wet to allow gas exchange, to reduce temperature through evaporation and to facilitate osmoregulation. The mechanism through which water is absorbed and then imbibed or stored within the shell was studied using transparent shells and dyes. We were able to show that there are two pathways involving different organs. Drinking relies on setae on the 3rd maxillipeds while shell refilling involves the setae of both claws, as well as setae of the 3rd maxillipeds, and inverted scaphognatite beating activity. Shell refilling and drinking are alternated and both are interrupted by grooming activity. Thus, refilling the entire shell takes a variable period of time. The absorbing setae of both the maxilliped and the claw show a particular twisted shape, strongly resembling in both structure and density the absorbing setae at the base of the 3rd and 4th walking legs of the Ocypodidae.

Effects of histamine on ciliary beat frequency of ciliated cells from guinea pigs nasal mucosa

We aimed to investigate the effect of histamine on ciliary beat frequency (CBF) through combining high-speed digital microscopy and patch-clamp technology. Ciliated cells were obtained from septum and turbinate of 90-120-day-old healthy male guinea pigs. Tight seal was formed by applying negative pressure on the glass electrode after the drawing and pushing progress. Then, we enrolled high-speed digital microscopy to measure CBF before and after treatment with histamine of different concentrations ranging from 10(-6) to 10(-1) mol/L in Hank's solution and D-Hank's solution as well as after administrating adenosine triphosphate. One-way ANOVA, Student's t test or Kruskal-Wallis test was used for statistical comparisons. Glass electrode fix up ciliated cell is available at tip diameter of 2-5 μm and negative pressure of 10-20 cmH2O column. The baseline CBF in Hank's solution was higher than in D-Hank's solution. Treatment with 10(-6)-l0(-3) mol/L histamine of concentrations can stimulate a rise of CBF. Nevertheless, CBF in all groups decreased to baseline CBF within 20 min. Generally, 10(-2) mol/L histamine can stimulate a rise of CBF; meanwhile, the high concentration of histamine killed 50% ciliated cell. Histamine at 10(-1) mol/L killed all ciliated cells. Ciliary beating activity decreased in Ca(2+)-free solution. Moreover, adenosine triphosphate could increase CBF effectively after the stimulation effect of histamine. We construct an effective technology integrating patch-clamp technique with CBF measurements on ciliated cells. Extracellular histamine stimulation could increase CBF effectively.

Abstract 3674: Targeted oncology therapeutics show unique cardiotoxic profiles: Ponatinib as a case study

Abstract Although tyrosine kinase inhibitors (TKI) have greatly improved the treatment and prognosis of multiple cancer types, unexpected clinical cardiotoxicity has occurred with some of these agents that was not predicted by standard preclinical toxicity assessment methods. Since cardiotoxicity with TKI are often caused by the inhibition of signaling pathways that are critical to cardiac cell function, multi-targeted TKI that block multiple pathways increase the likelihood for cardiac cell damage. We recently demonstrated that an in vitro multi-parameter test panel assessing the effect of drug treatment on overall cardiac health and function could accurately predict the cardiotoxicity of four FDA-approved TKI. The multi-targeted TKI that are clinically associated with cardiac adverse events (crizotinib, sunitinib, nilotinib) all proved to be cardiotoxic in our in vitro tests while a more targeted and relatively cardiac-safe drug, erlotinib, showed only minor changes in cardiac cell health. The present studies expand upon this initial observation using a broad panel of drugs such as TKI (including the recently withdrawn TKI ponatinib), chemotherapeutic agents, and non-oncology compounds, which were grouped based on their known clinical toxicity profiles ranging from cardiac safe to withdrawn. We assessed each compound's cardiotoxic potential by examining their effect on cell viability, reactive oxygen species (ROS) generation, lipid formation, troponin secretion and beating activity in a human induced pluripotent-derived cardiac stem (iPS) cell model. The results showed a unique cardiotoxic signature of oncology therapeutics that was significantly different from other drug classes. Oncology compounds, including ponatinib, induced metabolic stress (ROS generation and lipid formation) resulting in potent cardiac cell death and troponin secretion while other classes of drugs disrupted cardiac cell beating with minimal impact on cardiac cell health. In comparison, cardiac-safe drugs, including non-oncology compounds and more targeted TKI, did not impact any of the endpoints that assessed cardiac cell health and function. Our results demonstrate unique toxicity profiles for different drug classes which may reflect multiple mechanisms of cardiotoxicity. For oncology compounds specifically, multi-targeted TKI and chemotherapeutic agents show potent cardiac toxicity while more targeted agents are less cardiac toxic. These studies show that a multi-parameter approach provides a comprehensive and robust assessment of cardiotoxic potential by evaluating several parameters that are important to cardiac cell health and function in a more predictive adult cardiac cell model. A panel such as this aids in early risk assessment of cardiotoxic compounds and may reduce drug failure due to toxicity discovered in later phases of development or after drug approval such as that shown with ponatinib. Citation Format: Dominique Talbert, Kimberly Doherty, Patricia Trusk, Diarmuid Moran, Scott Shell, Sarah Bacus. Targeted oncology therapeutics show unique cardiotoxic profiles: Ponatinib as a case study. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3674. doi:10.1158/1538-7445.AM2014-3674

Dry powder formulation of simvastatin

Objectives: This study focuses on the development of a dry powder inhaler (DPI) formulation of simvastatin (SV), and the effects of SV on the respiratory epithelium.Methods: Micronised SV samples were prepared by dry jet-milling. The long-term chemical stability and physicochemical properties of the formulations were characterised in terms of particles size, morphology, thermal and moisture responses. Furthermore, in vitro aerosol depositions were performed. The formulation was evaluated for cell viability and its effect on cilia beat activity, using ciliated nasal epithelial cells in vitro. The formulation transport across an established air interface Calu-3 bronchial epithelial cells and its ability to reduce mucus secretion was also investigated.Results: The particle size of the SV formulation and its aerosol performance were appropriate for inhalation therapy. Moreover, the formulation was found to be non-toxic to pulmonary epithelia cells and cilia beat activity up to a concentration of 10−6 M. Transport studies revealed that SV has the ability to penetrate into airway epithelial cells and is converted into its active SV hydroxy acid metabolite. Single dose of SV DPI also decreased mucus production after 4 days of dosing.Conclusion: This therapy could potentially be used for the local treatment of diseases like chronic obstructive pulmonary disease, cystic fibrosis, and bronchiectasis given its anti-inflammatory effects and ability to reduce mucus production.

IPS cell-derived cardiogenicity is hindered by sustained integration of reprogramming transgenes.

Nuclear reprogramming inculcates pluripotent capacity by which de novo tissue differentiation is enabled. Yet, introduction of ectopic reprogramming factors may desynchronize natural developmental schedules. This study aims to evaluate the effect of imposed transgene load on the cardiogenic competency of induced pluripotent stem (iPS) cells. Targeted inclusion and exclusion of reprogramming transgenes (c-MYC, KLF4, OCT4, and SOX2) was achieved using a drug-inducible and removable cassette according to the piggyBac transposon/transposase system. Pulsed transgene overexpression, before iPS cell differentiation, hindered cardiogenic outcomes. Delayed in counterparts with maintained integrated transgenes, transgene removal enabled proficient differentiation of iPS cells into functional cardiac tissue. Transgene-free iPS cells generated reproducible beating activity with robust expression of cardiac α-actinin, connexin 43, myosin light chain 2a, α/β-myosin heavy chain, and troponin I. Although operational excitation-contraction coupling was demonstrable in the presence or absence of transgenes, factor-free derivatives exhibited an expedited maturing phenotype with canonical responsiveness to adrenergic stimulation. A disproportionate stemness load, caused by integrated transgenes, affects the cardiogenic competency of iPS cells. Offload of transgenes in engineered iPS cells ensures integrity of cardiac developmental programs, underscoring the value of nonintegrative nuclear reprogramming for derivation of competent cardiogenic regenerative biologics.

Abstract 2: Automated Dissociation Of Neonatal Hearts And Immunomagnetic Purification Of Cardiomyocytes, Cardiac Fibroblasts And Endothelial Cells

Pure cardiovascular cell lineages are a requisite for an unbiased and cell-type specific investigation of (patho-) physiological mechanisms involved in heart failure. Moreover, pure heart cells are needed as building blocks for cardiac tissue engineering. Therefore, we developed a rapid and automated heart dissociation protocol followed by an immunomagnetic enrichment of the three major heart cell types, namely cardiomyocytes (CMs), cardiac fibroblasts (Fibs) and endothelial cells (Endos) from both, mouse and rat neonatal hearts. First, we developed an enzyme mix optimal for the dissociation of neonatal mouse and rat hearts by screening our enzyme library. Next, we optimized the dissociation by utilizing our gentleMACS technology resulting in a fast (1 h), robust, and fully automated heart dissociation protocol. Analysis of the dissociated heart cells prior to cell purification showed: (i) high cell vitalities (&gt;90%), (ii) high frequencies of α-actinin-positive CMs (ca. 60%) and (iii) vimentin-positive non-CMs with a frequency of ca. 40%. In order to selectively enrich various cell-types from these heterogenous cell populations, we performed a cell-surface marker screen. We identified several candidates for the composition of antibody cocktails enabling selective enrichment of mouse and rat CMs, Fibs or Endos with purities of up to 97%. CMs grown in 2D cultures showed spontaneous beating activity and the expression of sarcomeric proteins. Additionally, heart cells were cultured on decellularized mouse heart slices. Analysis of the slice cultures after recellularization showed (i) partial restoration of synchronous contractions and (ii) orientated and elongated heart cells. Purified Fibs were highly proliferative and could be expanded 34-fold over an analyzed culture period of 15 days. Finally, functionality of the purified endothelial cells was proven by Dil-LDL endocytosis. In summary, we established an automated protocol for the dissociation of neonatal hearts, enabling the subsequent immunomagnetic enrichment of CMs, Fibs and Endos which can readily be utilized for 2D cell culture assays or to generate in vitro heart muscle models and surrogate tissue for myocardial repair.

Functional improvement and maturation of rat and human engineered heart tissue by chronic electrical stimulation

Spontaneously beating engineered heart tissue (EHT) represents an advanced in vitro model for drug testing and disease modeling, but cardiomyocytes in EHTs are less mature and generate lower forces than in the adult heart. We devised a novel pacing system integrated in a setup for videooptical recording of EHT contractile function over time and investigated whether sustained electrical field stimulation improved EHT properties. EHTs were generated from neonatal rat heart cells (rEHT, n=96) or human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (hEHT, n=19). Pacing with biphasic pulses was initiated on day 4 of culture. REHT continuously paced for 16–18 days at 0.5Hz developed 2.2× higher forces than nonstimulated rEHT. This was reflected by higher cardiomyocyte density in the center of EHTs, increased connexin-43 abundance as investigated by two-photon microscopy and remarkably improved sarcomere ultrastructure including regular M-bands. Further signs of tissue maturation include a rightward shift (to more physiological values) of the Ca2+-response curve, increased force response to isoprenaline and decreased spontaneous beating activity. Human EHTs stimulated at 2Hz in the first week and 1.5Hz thereafter developed 1.5× higher forces than nonstimulated hEHT on day 14, an ameliorated muscular network of longitudinally oriented cardiomyocytes and a higher cytoplasm-to-nucleus ratio. Taken together, continuous pacing improved structural and functional properties of rEHTs and hEHTs to an unprecedented level. Electrical stimulation appears to be an important step toward the generation of fully mature EHT.

Chaperones and Cardiac Misfolding Protein Diseases

Cardiomyocytes are best known for their spontaneous beating activity, large cell size, and low regenerative capacity during adulthood. The mechanical activity of cardiomyocytes depends on a sophisticated contractile apparatus comprised of sarcomeres whose rhythmic contraction relies on Ca(2+) transients with a high level of energy consumption. Hence the proper folding and assembly of the sarcomeric and other accessory proteins involved in those diverse functions (i.e., structural, mechanical, energy exchange and production) is critical for muscle mechanics. Chaperone proteins assist other polypeptides to reach their proper conformation, activity and/or location. Consequently, chaperone-like functions are important for the healthy heart but assume greater relevance during cardiac diseases when such chaperone proteins are recruited: 1) to protect cardiac cells against adverse effects during the pathological transition, and 2) to mitigate certain pathogenic mechanisms per se. Protein misfolding is observed as a consequence of inappropriate intracellular environment with acquired conditions (e.g., ischemia/reperfusion and redox imbalance) or because of mutations, which can modify primary to quaternary protein structures. In this review, we discuss the importance of cardiac chaperones while emphasizing the genetic origin (modification of gene/protein sequence) of cardiac protein misfolding and their consequences on the cardiomyocytes leading to organ dysfunction and failure.