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Cardiomyocytes derived from patient-specific induced pluripotent stem cells (iPSC-CMs) successfully reproduce the mechanisms of several channelopathies. However, this approach involve cell reprogramming from somatic tissue biopsies or genomic editing in healthy iPSCs for every mutation found and to be investigated. We aim to knockout (KO) Na V 1.5, the cardiac sodium channel, in a healthy human iPSC line, characterize the model and then, use it to express variants of Na V 1.5. We develop a homozygous Na V 1.5 KO iPSC line able to differentiate into cardiomyocytes with CRISPR/Cas9 tool. The Na V 1.5 KO iPSC-CMs exhibited an organized contractile apparatus, spontaneous contractile activity, and electrophysiological recordings confirmed the major reduction in total Na + currents. The action potentials (APs) exhibited a reduction in their amplitude and in their maximal rate of rise. Voltage optical mapping recordings revealed that the conduction velocity Ca 2+ transient waves propagation velocities were slow. A wild-type (WT) Na V 1.5 channel expressed by transient transfection in the KO iPSC-CMs restored Na + channel expression and AP properties. The expression of Na V 1.5/delQKP, a long QT type 3 (LQT3) variant, in the Na V 1.5 KO iPSC-CMs showed that dysfunctional Na + channels exhibited a persistent Na + current and caused prolonged AP duration that led to arrhythmic events, characteristics of LQT3.

Generating atrial-like cardiomyocytes derived from human induced pluripotent stem cells (hiPSCs) is crucial for modeling and treating atrial-related diseases, such as atrial arrythmias including atrial fibrillations. However, it is essential to obtain a comprehensive understanding of the electrophysiological properties of these cells. The objective of the present study was to investigate the molecular, electrical, and biophysical properties of several ion channels, especially Na V 1.5 channels, in atrial hiPSC cardiomyocytes. Atrial cardiomyocytes were obtained by the differentiation of hiPSCs treated with retinoic acid (RA). The quality of the atrial specification was assessed by qPCR, immunocytofluorescence, and western blotting. The electrophysiological properties of action potentials (APs), Ca 2+ dynamics, K +  and Na + currents were investigated using patch-clamp and optical mapping approaches. We evaluated mRNA transcript and protein expressions to show that atrial cardiomyocytes expressed higher atrial- and sinoatrial-specific markers ( MYL7 , CACNA1D ) and lower ventricular-specific markers ( MYL2 , CACNA1C , GJA1 ) than ventricular cardiomyocytes. The amplitude, duration, and steady-state phase of APs in atrial cardiomyocytes decreased, and had a shape similar to that of mature atrial cardiomyocytes. Interestingly, Na V 1.5 channels in atrial cardiomyocytes exhibited lower mRNA transcripts and protein expression, which could explain the lower current densities recorded by patch-clamp. Moreover, Na + currents exhibited differences in activation and inactivation parameters. These differences could be explained by an increase in SCN2B regulatory subunit expression and a decrease in SCN1B and SCN4B regulatory subunit expressions. Our results show that a RA treatment made it possible to obtain atrial cardiomyocytes and investigate differences in Na V 1.5 channel properties between ventricular- and atrial-like cells.

The use of human derived induced pluripotent stem cells (hiPSCs) differentiated to dopaminergic (DA) neurons offers a valuable experimental model to decorticate the cellular and molecular mechanisms of Parkinson’s disease (PD) pathogenesis. However, the existing approaches present with several limitations, notably the lengthy time course of the protocols and the high variability in the yield of DA neurons. Here we report on the development of an improved approach that combines neurogenin-2 programming with the use of commercially available midbrain differentiation kits for a rapid, efficient, and reproducible directed differentiation of hiPSCs to mature and functional induced DA (iDA) neurons, with minimum contamination by other brain cell types. Gene expression analysis, associated with functional characterization examining neurotransmitter release and electrical recordings, support the functional identity of the iDA neurons to A9 midbrain neurons. iDA neurons showed selective vulnerability when exposed to 6-hydroxydopamine, thus providing a viable in vitro approach for modeling PD and for the screening of small molecules with neuroprotective proprieties.

Addressing the climate change and biodiversity loss crises while ensuring livelihoods are not negatively affected is a matter that requires urgent action. A recently published Evidence Gap Map (EGM) identified no recent systematic reviews on land management interventions. Drawing from this EGM, the review aims to examine and synthesise the latest evidence on what works, how, and at what cost to improve environmental and human welfare outcomes in land management in low‐ and middle‐income countries. We will address the following research questions: (1) What are the effects of protected areas, land rights and decentralisation interventions on environmental and poverty outcomes? Do effects vary by population, location, or other factors? (2) What are the barriers and enablers that impact the effectiveness of these interventions? (3) What is the cost‐effectiveness of these interventions? The set of interventions will be based on the studies identified in the EGM, and we will search, appraise and synthesise additional evidence on influencing factors and cost data.

Background An estimated two billion people do not have sufficient access to nutritious food, and nearly half are dependent on small‐scale and subsistence farming. Projections show that the global population is not on track to reach the Sustainable Development Goals. With this in mind, development actors are increasingly seeking to better integrate rural farmers into agricultural markets. This synthesis of the literature can help to inform policy decisions to improve outcomes for smallholder farmers in low‐ and middle‐income countries, and to enable the realization of the Sustainable Development Goals. This work is the most comprehensive and up‐to‐date review synthesizing evidence from 262 interventions. Objectives The purpose of this systematic review is to appraise and synthesize evidence of the effects of five types of interventions facilitating farmers' access to output markets in low‐ and middle‐income countries. We examine how these effects vary across contexts and subgroups. We also identify evidence on program costs and evidence gaps in the literature. Search Methods The search of included studies was based on nine major databases/search engines and 25 institutional websites, using a set of English search terms. We also conducted forward and backward citation tracking of literature, published a public call for papers, and contacted key experts. Selection Criteria We included studies on the effects of five types of output market access interventions, focusing on participants residing in low‐ and middle‐income countries: (1) Farm‐to‐market transport infrastructure interventions; (2) Access to output market information interventions; (3) New marketplaces or alternative marketing opportunities interventions; (4) Contract farming interventions; (5) Improved storage infrastructure and technologies interventions. We included published and unpublished studies from 2000 onwards, with experimental and quasi‐experimental study designs focusing on relevant outcomes. Data Collection and Analysis We screened 52,366 studies, identifying a total of 439 papers representing 289 unique studies on the effects of 262 interventions in 53 countries. Data extraction and risk of bias assessments were completed by two independent reviewers. Main Results All five types of output market access interventions resulted in small‐to‐moderate positive effects on almost all measures of market participation, agricultural production, and welfare outcomes. These improvements occurred through a reduction in transaction costs, adoption of improved practices, greater farm investment, access to higher prices for farmers, greater volume sold, and increased farm income. Effects vary by intervention type. However, the body of evidence is comprised of a large share of included studies with a high risk of bias. Few studies have information on the cost of interventions, and there are gaps in the available evidence. Authors' Conclusions Output market access interventions are effective in reducing transaction costs and addressing market failures, thereby leading to higher income levels. Evidence of effects on food security and nutrition is sparse and has not provided conclusive findings. We also found that multi‐component interventions are not necessarily more effective than single component interventions. The specific needs and dynamics of each context should inform the choice of the intervention and approach. Investments in additional research with low risk of selection bias and confounding effects will improve the evidence base, especially for outcomes that constitute gaps in the literature. For example, the effects on quality of agricultural products and group participation are under‐researched, and we did not find any included studies focusing on North Africa or the Middle East. Collecting and reporting information on interventions' cost‐effectiveness will help decision‐makers to prioritize limited resources.

Background Severe ventricular rhythm disturbances are the hallmark of arrhythmogenic cardiomyopathy (ACM), and are often explained by structural conduction abnormalities. However, comprehensive investigations of ACM cell electrical instability are lacking. This study aimed to elucidate early electrical myogenic signature of ACM. Methods We investigated a 41‐year‐old ACM patient with a missense mutation (c.394C>T) in the DSC2 gene, which encodes desmocollin 2. Pathogenicity of this variant was confirmed using a zebrafish DSC2 model system. Control and DSC2 patient‐derived pluripotent stem cells were reprogrammed and differentiated into cardiomyocytes (hiPSC‐CM) to examine the specific electromechanical phenotype and its modulation by antiarrhythmic drugs (AADs). Samples of the patient's heart and hiPSC‐CM were examined to identify molecular and cellular alterations. Results A shortened action potential duration was associated with reduced Ca2+ current density and increased K+ current density. This finding led to the elucidation of previously unknown abnormal repolarization dynamics in ACM patients. Moreover, the Ca2+ mobilised during transients was decreased, and the Ca2+ sparks frequency was increased. AAD testing revealed the following: (1) flecainide normalised Ca2+ transients and significantly decreased Ca2+ spark occurrence and (2) sotalol significantly lengthened the action potential and normalised the cells’ contractile properties. Conclusions Thorough analysis of hiPSC‐CM derived from the DSC2 patient revealed abnormal repolarization dynamics, prompting the discovery of a short QT interval in some ACM patients. Overall, these results confirm a myogenic origin of ACM electrical instability and provide a rationale for prescribing class 1 and 3 AADs in ACM patients with increased ventricular repolarization reserve. Thorough analysis of hiPSC‐CM derived from a DSC2 patient, zebrafish and patient cohort, we identified abnormal repolarization dynamicity, prompting the discovery of a short QT interval in some ACM patients. By normalizing the increased repolarization reserve of ACM myocytes, class 3 AADs are likely to be the drugs of first choice for DSC2 patients. These findings may encourage randomized trials to evaluate class 3 antiarrhythmic drugs, alone or in combination with class I medications in ACM patients.

Myotonic dystrophy, or dystrophia myotonica type 1 (DM1), is a multi-systemic disorder and is the most common adult form of muscular dystrophy. It affects not only muscles but also many organs, including the brain. Cerebral impairments include cognitive deficits, daytime sleepiness, and loss of visuospatial and memory functions. The expression of mutated transcripts with CUG repeats results in a gain of toxic mRNA function. The antisense oligonucleotide (ASO) strategy to treat DM1 brain deficits is limited by the fact that ASOs do not cross the blood–brain barrier after systemic administration, indicating that other methods of delivery should be considered. ASO technology has emerged as a powerful tool for developing potential new therapies for a wide variety of human diseases, and its potential has been proven in a recent clinical trial. Targeting DMPK mRNA in neural cells derived from human induced pluripotent stem cells obtained from a DM1 patient with the IONIS 486178 ASO abolished CUG-expanded foci, enabled nuclear redistribution of MBNL1/2, and corrected aberrant splicing. Intracerebroventricular injection of the IONIS 486178 ASO in DMSXL mice decreased the levels of mutant DMPK mRNAs by up to 70% throughout different brain regions. It also reversed behavioral abnormalities following neonatal administration. The present study indicated that the IONIS 486178 ASO targets mutant DMPK mRNAs in the brain and strongly supports the feasibility of a therapy for DM1 patients based on the intrathecal injection of an ASO.

Generating atrial-like cardiomyocytes derived from human induced pluripotent stem cells (hiPSCs) is crucial for modeling and treating atrial-related diseases, such as atrial arrythmias including atrial fibrillations. However, it is essential to obtain a comprehensive understanding of the electrophysiological properties of these cells. The objective of the present study was to investigate the molecular, electrical, and biophysical properties of several ion channels, especially Na 1.5 channels, in atrial hiPSC cardiomyocytes. Atrial cardiomyocytes were obtained by the differentiation of hiPSCs treated with retinoic acid (RA). The quality of the atrial specification was assessed by qPCR, immunocytofluorescence, and western blotting. The electrophysiological properties of action potentials (APs), Ca dynamics, K  and Na currents were investigated using patch-clamp and optical mapping approaches. We evaluated mRNA transcript and protein expressions to show that atrial cardiomyocytes expressed higher atrial- and sinoatrial-specific markers (MYL7, CACNA1D) and lower ventricular-specific markers (MYL2, CACNA1C, GJA1) than ventricular cardiomyocytes. The amplitude, duration, and steady-state phase of APs in atrial cardiomyocytes decreased, and had a shape similar to that of mature atrial cardiomyocytes. Interestingly, Na 1.5 channels in atrial cardiomyocytes exhibited lower mRNA transcripts and protein expression, which could explain the lower current densities recorded by patch-clamp. Moreover, Na currents exhibited differences in activation and inactivation parameters. These differences could be explained by an increase in SCN2B regulatory subunit expression and a decrease in SCN1B and SCN4B regulatory subunit expressions. Our results show that a RA treatment made it possible to obtain atrial cardiomyocytes and investigate differences in Na 1.5 channel properties between ventricular- and atrial-like cells.