Explore the vast range of titles available.

Hypertrophic cardiomyopathy (HCM) is a leading cause of sudden cardiac death that often goes undetected in the general population. HCM is also prevalent in patients with cardio-facio-cutaneous syndrome (CFCS), which is a genetic disorder characterized by aberrant signaling in the RAS/MAPK signaling cascade. Understanding the mechanisms of HCM development in such RASopathies may lead to novel therapeutic strategies, but relevant experimental models of the human condition are lacking. Therefore, the objective of this study was to develop the first 3D human engineered cardiac tissue (hECT) model of HCM. The hECTs were created using human cardiomyocytes obtained by directed differentiation of induced pluripotent stem cells derived from a patient with CFCS due to an activating BRAF mutation. The mutant myocytes were directly conjugated at a 3:1 ratio with a stromal cell population to create a tissue of defined composition. Compared to healthy patient control hECTs, BRAF-hECTs displayed a hypertrophic phenotype by culture day 6, with significantly increased tissue size, twitch force, and atrial natriuretic peptide (ANP) gene expression. Twitch characteristics reflected increased contraction and relaxation rates and shorter twitch duration in BRAF-hECTs, which also had a significantly higher maximum capture rate and lower excitation threshold during electrical pacing, consistent with a more arrhythmogenic substrate. By culture day 11, twitch force was no longer different between BRAF and wild-type hECTs, revealing a temporal aspect of disease modeling with tissue engineering. Principal component analysis identified diastolic force as a key factor that changed from day 6 to day 11, supported by a higher passive stiffness in day 11 BRAF-hECTs. In summary, human engineered cardiac tissues created from BRAF mutant cells recapitulated, for the first time, key aspects of the HCM phenotype, offering a new in vitro model for studying intrinsic mechanisms and screening new therapeutic approaches for this lethal form of heart disease.

The Targeted HealthcaRe InnoVation & Entrepreneurship (THRIVE) Fellowship was created to bridge the gap between healthcare professionals, who often lack experience in technology development and entrepreneurship, and engineers or technology experts, who may not fully understand clinical needs. This eight-month extracurricular program introduces medical and graduate students to the process of health technology innovation. Fellows form multidisciplinary teams to identify and address an unmet clinical need, following Biodesign principles. The program consists of three phases: (1) introduction to healthcare innovation and foundational skills; (2) team formation, mentor selection, and customer discovery; and (3) solution prototyping, pitching, and business plan development. A retrospective analysis of the 2022–2023 cohort evaluated participant demographics, subjective outcomes (Likert-scale surveys on skill acquisition and program satisfaction), and objective metrics (e.g., milestones completed, funds raised, technology disclosures). Descriptive statistics and paired t-tests for pre-post comparisons were used in the analysis. Of the 56 applicants, 29 were accepted, and 20 completed the program. Fellows rated overall satisfaction at 4.45/5, with 85% planning to incorporate healthcare innovation into their future careers. On average, teams met 10.4 of 12 milestones, raised$10,250 in additional funds (in addition to the $ 5,000 fellowship grant), and filed multiple technology disclosures. Fellows reported significant gains in key innovation skills (p = 1.3E-5) and spent an average of 7.4 hours per week on their projects. The THRIVE Fellowship fosters interdisciplinary collaboration, practical skill development, and a heightened commitment to healthcare innovation. Early successes include strong participant satisfaction, measurable skill acquisition, and substantial external funding. Future program refinements will focus on expanded mentor engagement, enhanced skill-building resources, and long-term tracking of career outcomes. This model may serve as a scalable approach to training future clinicians and researchers in healthcare technology innovation.

Background/Aims: Our previous studies demonstrated that intrinsic aortic smooth muscle cell (VSMC) stiffening plays a pivotal role in aortic stiffening in aging and hypertension. However, the underlying molecular mechanisms remain largely unknown. We here hypothesized that Rho kinase (ROCK) acts as a novel mediator that regulates intrinsic VSMC mechanical properties through the serum response factor (SRF) /myocardin pathway and consequently regulates aortic stiffness and blood pressure in hypertension. Methods: Four-month old male spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were studied. Aortic stiffness was measured by echography. Intrinsic mechanical properties of VSMCs were measured by atomic force microscopy (AFM) in vitro. Results: Compared to WKY rats, SHR showed a significant increase in aortic stiffness and blood pressure, which is accompanied by a remarkable cell stiffening and ROCK activation in thoracic aortic (TA) VSMCs. Theses alterations in SHR were abolished by Y-27632, a specific inhibitor of ROCK. Additionally, boosted filamentous/globular actin ratio was detected in TA VSMCs from SHR versus WKY rats, resulting in an up-regulation of SRF and myocardin expression and its downstream stiffness-associated genes including α-smooth muscle actin, SM22, smoothelin and myosin heavy chain 11. Reciprocally, these alterations in SHR TA VSMCs were also suppressed by Y-27632. Furthermore, a specific inhibitor of SRF/myocardin, CCG-100602, showed a similar effect to Y-27632 in SHR in both TA VSMCs stiffness in vitro and aorta wall stiffness in vivo. Conclusion: ROCK is a novel mediator modulating aortic VSMC stiffness through SRF/myocardin signaling which offers a therapeutic target to reduce aortic stiffening in hypertension.

Nanoparticle-based delivery of nucleotides offers an alternative to viral vectors for gene therapy. We report highly efficient in vivo delivery of modified mRNA (modRNA) to rat and pig myocardium using formulated lipidoid nanoparticles (FLNP). Direct myocardial injection of FLNP containing 1–10 μg eGFPmodRNA in the rat (n = 3 per group) showed dose-dependent enhanced green fluorescent protein (eGFP) mRNA levels in heart tissue 20 hours after injection, over 60-fold higher than for naked modRNA. Off-target expression, including lung, liver, and spleen, was <10% of that in heart. Expression kinetics after injecting 5 μg FLNP/eGFPmodRNA showed robust expression at 6 hours that reduced by half at 48 hours and was barely detectable at 2 weeks. Intracoronary administration of 10 μg FLNP/eGFPmodRNA also proved successful, although cardiac expression of eGFP mRNA at 20 hours was lower than direct injection, and off-target expression was correspondingly higher. Findings were confirmed in a pilot study in pigs using direct myocardial injection as well as percutaneous intracoronary delivery, in healthy and myocardial infarction models, achieving expression throughout the ventricular wall. Fluorescence microscopy revealed GFP-positive cardiomyocytes in treated hearts. This nanoparticle-enabled approach for highly efficient, rapid and short-term mRNA expression in the heart offers new opportunities to optimize gene therapies for enhancing cardiac function and regeneration.

Knowledge of brain tissue mechanical properties may be critical for formulating hypotheses about traumatic brain injury (TBI) mechanisms and for accurate TBI simulations. To determine the local mechanical properties of anatomical subregions within the rat hippocampus, the atomic force microscope (AFM) was adapted for use on living brain tissue. The AFM provided advantages over alternative methods for measuring local mechanical properties of brain because of its high spatial resolution, high sensitivity, and ability to measure live samples under physiologic conditions. From AFM indentations, a mean pointwise or depth-dependent apparent elastic modulus, Ě, was determined for the following hippocampal subregions: CA1 pyramidal cell layer (CA1P) and stratum radiatum (CA1SR), CA3 pyramidal cell layer (CA3P) and stratum radiatum (CA3SR), and the dentate gyrus (DG). For all regions, Ě was indentation-depth-dependent, reflecting the nonlinearity of brain tissue. At an indentation depth of 3 μm, Ě was 234 ± 152 Pa for CA3P, 308 ± 184 Pa for CA3SR, 137 ± 97 Pa for CA1P, 169 ± 52 Pa for CA1SR, and 201 ± 133 Pa for DG (mean ± SD). Our results demonstrate for the first time that the hippocampus is mechanically heterogeneous. Based on our findings, we discuss hypotheses accounting for experimentally observed patterns of hippocampal cell death, which can be tested with biofidelic finite element models of TBI.

Atrial myocytes are continuously exposed to mechanical forces including shear stress. However, in atrial myocytes, the effects of shear stress are poorly understood, particularly with respect to its effect on ion channel function. Here, we report that shear stress activated a large outward current from rat atrial myocytes, with a parallel decrease in action potential duration. The main ion channel underlying the increase in current was found to be Kv1.5, the recruitment of which could be directly observed by total internal reflection fluorescence microscopy, in response to shear stress. The effect was primarily attributable to recruitment of intracellular pools of Kv1.5 to the sarcolemma, as the response was prevented by the SNARE protein inhibitor N -ethylmaleimide and the calcium chelator BAPTA. The process required integrin signaling through focal adhesion kinase and relied on an intact microtubule system. Furthermore, in a rat model of chronic hemodynamic overload, myocytes showed an increase in basal current despite a decrease in Kv1.5 protein expression, with a reduced response to shear stress. Additionally, integrin beta1d expression and focal adhesion kinase activation were increased in this model. This data suggests that, under conditions of chronically increased mechanical stress, the integrin signaling pathway is overactivated, leading to increased functional Kv1.5 at the membrane and reducing the capacity of cells to further respond to mechanical challenge. Thus, pools of Kv1.5 may comprise an inducible reservoir that can facilitate the repolarization of the atrium under conditions of excessive mechanical stress.

Marfan syndrome (MFS) is an autosomal dominant disease of the connective tissue due to mutations in the fibrillin-1 gene (FBN1). This study aimed at characterizing microelastic properties of the ascending aortic wall and lung parenchyma tissues from wild type (WT) and age-matched Fbn1 hypomorphic mice (Fbn1 mgR/mgR mice) to identify tissue-specific biomechanical effects of aging and disease in MFS. Atomic force microscopy was used to indent lung parenchyma and aortic wall tissues, using Hybrid Eshelby Decomposition analysis to extract layer-specific properties of the intima and media. The intima stiffened with age and was not different between WT and Fbn1 mgR/mgR tissues, whereas the media layer of MFS aortas showed progressive structural and mechanical degradation with a modulus that was 50% softer than WT by 3.5 months of age. Similarly, MFS mice displayed progressive structural and mechanical deterioration of lung tissue, which was over 85% softer than WT by 3.5 months of age. Chronic treatment with the angiotensin type I receptor antagonist, losartan, attenuated the aorta and lung tissue degradation, resulting in structural and mechanical properties not significantly different from age-matched WT controls. By revealing micromechanical softening of elastin-rich aorta and lung tissues with disease progression in fibrillin-1 deficient mice, our findings support the use of losartan as a prophylactic treatment that may abrogate the life-threatening symptoms of MFS.

Human mesenchymal stem cell (hMSC) delivery has demonstrated promise in preclinical and clinical trials for myocardial infarction therapy; however, broad acceptance is hindered by limited understanding of hMSC-human cardiomyocyte (hCM) interactions. To better understand the electrophysiological consequences of direct heterocellular connections between hMSCs and hCMs, three original mathematical models were developed, representing an experimentally verified triad of hMSC families with distinct functional ion channel currents. The arrhythmogenic risk of such direct electrical interactions in the setting of healthy adult myocardium was predicted by coupling and fusing these hMSC models to the published ten Tusscher midcardial hCM model. Substantial variations in action potential waveform-such as decreased action potential duration (APD) and plateau height-were found when hCMs were coupled to the two hMSC models expressing functional delayed rectifier-like human ether à-go-go K+ channel 1 (hEAG1); the effects were exacerbated for fused hMSC-hCM hybrid cells. The third family of hMSCs (Type C), absent of hEAG1 activity, led to smaller single-cell action potential alterations during coupling and fusion, translating to longer tissue-level mean action potential wavelength. In a simulated 2-D monolayer of cardiac tissue, re-entry vulnerability with low (5%) hMSC insertion was approximately eight-fold lower with Type C hMSCs compared to hEAG1-functional hMSCs. A 20% decrease in APD dispersion by Type C hMSCs compared to hEAG1-active hMSCs supports the claim of reduced arrhythmogenic potential of this cell type with low hMSC insertion. However, at moderate (15%) and high (25%) hMSC insertion, the vulnerable window increased independent of hMSC type. In summary, this study provides novel electrophysiological models of hMSCs, predicts possible arrhythmogenic effects of hMSCs when directly coupled to healthy hCMs, and proposes that isolating a subset of hMSCs absent of hEAG1 activity may offer increased safety as a cell delivery cardiotherapy at low levels of hMSC-hCM coupling.

Background Delivery of stem cells to the failing heart is a promising therapeutic strategy. However, the improvement in cardiac function in animal studies has not fully translated to humans. To help bridge the gap between species, we investigated the effects of adult human cardiac stem cells (hCSCs) on contractile function of human engineered cardiac tissues (hECTs) as a species-specific model of the human myocardium. Methods Human induced pluripotent stem cell-derived cardiomyoctes (hCMs) were mixed with Collagen/Matrigel to fabricate control hECTs, with an experimental group of hCSC-supplemented hECT fabricated using a 9:1 ratio of hCM to hCSC. Functional testing was performed starting on culture day 6, under spontaneous conditions and also during electrical pacing from 0.25 to 1.0 Hz, measurements repeated at days 8 and 10. hECTs were then frozen and processed for gene analysis using a Nanostring assay with a cardiac targeted custom panel. Results The hCSC-supplemented hECTs displayed a twofold higher developed force vs. hCM-only controls by day 6, with approximately threefold higher developed stress and maximum rates of contraction and relaxation during pacing at 0.75 Hz. The spontaneous beat rate characteristics were similar between groups, and hCSC supplementation did not adversely impact beat rate variability. The increased contractility persisted through days 8 and 10, albeit with some decrease in the magnitude of the difference of the force by day 10, but with developed stress still significantly higher in hCSC-supplemented hECT; these findings were confirmed with multiple hCSC and hCM cell lines. The force-frequency relationship, while negative for both, control (− 0.687 Hz − 1 ; p  = 0.013 vs. zero) and hCSC-supplemented (− 0.233 Hz − 1 ; p  = 0.067 vs. zero) hECTs, showed a significant rectification in the regression slope in hCSC-supplemented hECT ( p  = 0.011 vs. control). Targeted gene exploration (59 genes) identified a total of 14 differentially expressed genes, with increases in the ratios of MYH7/MHY6 , MYL2/MYL7 , and TNNI3/TNNI1 in hCSC-supplemented hECT versus controls. Conclusions For the first time, hCSC supplementation was shown to significantly improve human cardiac tissue contractility in vitro, without evidence of proarrhythmic effects, and was associated with increased expression of markers of cardiac maturation. These findings provide new insights about adult cardiac stem cells as contributors to functional improvement of human myocardium.

Background Friedreich’s ataxia (FRDA) is an autosomal recessive disease caused by a non-coding mutation in the first intron of the frataxin ( FXN ) gene that suppresses its expression. Compensatory hypertrophic cardiomyopathy, dilated cardiomyopathy, and conduction system abnormalities in FRDA lead to cardiomyocyte (CM) death and fibrosis, consequently resulting in heart failure and arrhythmias. Murine models have been developed to study disease pathology in the past two decades; however, differences between human and mouse physiology and metabolism have limited the relevance of animal studies in cardiac disease conditions. To bridge this gap, we aimed to generate species-specific, functional in vitro experimental models of FRDA using 2-dimensional (2D) and 3-dimensional (3D) engineered cardiac tissues from FXN-deficient human pluripotent stem cell-derived ventricular cardiomyocytes (hPSC-hvCMs) and to compare their contractile and electrophysiological properties with healthy tissue constructs. Methods Healthy control and FRDA patient-specific hPSC-hvCMs were derived by directed differentiation using a small molecule-based protocol reported previously. We engineered the hvCMs into our established human ventricular cardiac tissue strip (hvCTS) and human ventricular cardiac anisotropic sheet (hvCAS) models, and functional assays were performed on days 7–17 post-tissue fabrication to assess the electrophysiology and contractility of FRDA patient-derived and FXN-knockdown engineered tissues, in comparison with healthy controls. To further validate the disease model, forced expression of FXN was induced in FXN-deficient tissues to test if disease phenotypes could be rescued. Results Here, we report for the first time the generation of human engineered tissue models of FRDA cardiomyopathy from hPSCs: FXN-deficient hvCTS displayed attenuated developed forces (by 70–80%) compared to healthy controls. High-resolution optical mapping of hvCAS with reduced FXN expression also revealed electrophysiological defects consistent with clinical observations, including action potential duration prolongation and maximum capture frequency reduction. Interestingly, a clear positive correlation between FXN expression and contractility was observed ( ρ  > 0.9), and restoration of FXN protein levels by lentiviral transduction rescued contractility defects in FXN-deficient hvCTS. Conclusions We conclude that human-based in vitro cardiac tissue models of FRDA provide a translational, disease-relevant biomimetic platform for the evaluation of novel therapeutics and to provide insight into FRDA disease progression.