Cardioids reveal self-organizing principles of human cardiogenesis.

Organoids capable of forming tissue-like structures have transformed our ability to model human development and disease. With the notable exception of the human heart, lineage-specific self-organizing organoids have been reported for all major organs. Here, we established self-organizing cardioids from human pluripotent stem cells that intrinsically specify, pattern, and morph into chamber-like structures containing a cavity. Cardioid complexity can be controlled by signaling that instructs the separation of cardiomyocyte and endothelial layers and by directing epicardial spreading, inward migration, and differentiation. We find that cavity morphogenesis is governed by a mesodermal WNT-BMP signaling axis and requires its target HAND1, a transcription factor linked to developmental heart chamber defects. Upon cryoinjury, cardioids initiated a cell-type-dependent accumulation of extracellular matrix, an early hallmark of both regeneration and heart disease. Thus, human cardioids represent a powerful platform to mechanistically dissect self-organization, congenital heart defects and serve as a foundation for future translational research.

Dasatinib promotes muscle differentiation and disrupts normal muscle regeneration.

Dasatinib is one of the second-generation tyrosine kinase inhibitors used to treat chronic myeloid leukemia and has a broad target spectrum, including KIT, PDGFR, and SRC family kinases. Due to its broad drug spectrum, dasatinib has been reported at the basic research level to improve athletic performance by eliminating senescent cell removal and to have an effect on muscle diseases such as Duchenne muscular dystrophy, but its effect on myoblasts has not been investigated. In this study, we evaluated the effects of dasatinib on skeletal muscle both under normal conditions and in the regenerating state. Dasatinib suppressed the proliferation and promoted the fusion of C2C12 myoblasts. During muscle regeneration, dasatinib increased the gene expressions of myogenic-related genes (Myod, Myog, and Mymx), and caused abnormally thin muscle fibers on the CTX-induced muscle injury mouse model. From these results, dasatinib changes the closely regulated gene expression pattern of myogenic regulatory factors during muscle differentiation and disrupts normal muscle regeneration. Our data suggest that when using dasatinib, its effects on skeletal muscle should be considered, particularly at regenerating stages.

Who enrolls and why? Examining center-specific underlying patterns behind enrollment: a New York City-based traumatic brain injury model systems study.

BACKGROUND: To elucidate the sociodemographic and study factors involved in enrollment in the Traumatic Brain Injury Model System (TBIMS) database, this study examined the effect of a variety of variables on enrollment at a local TBIMS center. METHODS: A sample of 654 individuals from the local TBIMS center was studied examining enrollment by age, gender, race, ethnicity, homelessness status at date of injury, history of homelessness, health insurance status, presence of social support, primary language, consenting in hospital or after discharge, and the need for an interpreter. Binary logistic regression was conducted to identify variables that predict center-based enrollment into TBIMS. RESULTS: Results demonstrated that older age was associated with decreasing enrollment (OR = 0.99, p = 0.01), needing an interpreter made enrollment less likely (OR = 0.33, p < 0.01), being primarily Spanish speaking predicted enrollment (OR = 3.20, p = 0.02), Hispanic ethnicity predicted enrollment (OR = 7.31, p = 0.03), and approaching individuals in the hospital predicted enrollment (OR = 6.94, p < 0.01). Here, OR denotes the odds ratio estimate from a logistic regression model and P denotes the corresponding p-value. CONCLUSIONS: These results can be useful in driving enrollment strategies at this center for other similar TBI research, and to contribute a representative TBI sample to the national database.

Allantoin induces pruritus by activating MrgprD in chronic kidney disease.

Chronic kidney disease (CKD) is a disease with decreased, irreversible renal function. Pruritus is the most common skin symptom in patients with CKD, especially in end-stage renal disease. The underlying molecular and neural mechanism of CKD-associated pruritus (CKD-aP) remains obscure. Our data show that the level of allantoin increases in the serum of CKD-aP and CKD model mice. Allantoin could induce scratching behavior in mice and active DRG neurons. The calcium influx and action potential reduced significantly in DRG neurons of MrgprD KO or TRPV1 KO mice. U73122, an antagonist of phospholipase C, could also block calcium influx in DRG neurons induced by allantoin. Thus, our results concluded that allantoin plays an important role in CKD-aP, mediated by MrgprD and TrpV1, in CKD patients.

Urolithin A alleviates neuropathic pain and activates mitophagy.

Neuropathic pain (NP) occurs frequently in the general population and has a negative impact on the quality of life. There is no effective therapy available yet owing to the complex pathophysiology of NP. In our previous study, we found that urolithin A (UA), a naturally occurring microflora-derived metabolite, could relieve NP in mice by inhibiting the activation of microglia and release of inflammation factors. Here in this study, we sought to investigate whether mitophagy would be activated when UA alleviated NP in mice. We showed that the autophagy flow was blocked in the spinal dorsal horn of the chronic constriction injury (CCI) mice when the most obvious pain behavior occurs. Intraperitoneal injection of UA markedly activated the mitophagy mediated by PTEN-induced kinase 1/Parkin, promoted mitobiogenesis in both neurons and microglia, and alleviated NP in the CCI mice. In summary, our data suggest that UA alleviates NP in mice and meanwhile induces mitophagy activation, which highlights a therapeutic potential of UA in the treatment of NP.

Comparison of veterans affairs and NIDILRR traumatic brain injury model systems participants with disorders of consciousness.

OBJECTIVE: To characterize demographic, pre-injury, and outcome data within the National Institute on Disability, Independent Living, and Rehabilitation Research (NIDILRR) and Veterans Affairs (VA) Traumatic Brain Injury Model Systems (TBIMS) cohorts with severe traumatic brain injury (TBI) with no command-following ability at time of admission to acute rehabilitation. DESIGN: Retrospective cohort. SETTING: NIDILRR and VA TBI Model Systems (TBIMS) centers. PARTICIPANTS: 396 NIDILRR and 72 VA participants without command-following ability who experienced TBI with subsequent Disorder of Consciousness (DoC). MAIN OUTCOME MEASURE: Pre-injury and injury characteristics, rehabilitation outcomes, and 1-year self-reported outcomes. RESULTS: VA TBIMS cohort included individuals who were active duty or had military service before their injury. The VA cohort were more likely to be re-hospitalized at 1-year follow-up or residing in a long-term care or rehab setting. The NIDILRR TBIMS cohort had higher FIM and DRS scores at rehabilitation discharge, while the VA participants saw longer lengths of stay and higher numbers of "violent" injury types. CONCLUSIONS: This study allows for a better understanding of the comparability between VA and NIDILRR DoC cohorts providing guidance on how veteran and civilian samples might be merged in future TBIMS studies to explore predictors of recovery from a DoC.

The effect of cilostazol on the platelet-derived growth factor-beta/beta isoform reduction on venous hyperplasia in an experimental balloon-induced injury model.

BACKGROUND: Intimal hyperplasia is the response to endothelial injury. Platelet-derived growth factor is released early and favors the formation of intimal hyperplasia. Although multiple treatments, from open surgery to endovascular techniques, have been used they remain controversial. There is currently interest in developing pharmacological strategies to address this pathology. Local vascular inflammation induced by vessel barotrauma generates intimal hyperplasia due to mechanical stress over the venous endothelium. Cilostazol is a selective phosphodiesterase type 3 (PDE3) selective inhibitor with a regulatory effect over intimal hyperplasia. The objective was to investigate cilostazol's role in inhibiting smooth muscle cell proliferation due to changes in the expression and release of PDGF-BB isoform and the effect on developing IH using an experimental model of vascular barotrauma (balloon-induced injury model). METHODS: We included 12 New Zealand rabbits. The balloon-induced injury model (BIIM) and experimental group cilostazol (20 mg/kg/day) included 6 rabbits each. Contralateral veins from 6 rabbits used in BIIM model has been taken as control group. We measured and compared the expression of PDGF-BB and the development of IH. A pathologist board chooses a PDGFRα antibody to localized its expression by immunohistochemistry analysis. Subsequently, using an automated immunohistochemical staining machine, the PDGFR expression was evaluated using a Zeiss Primo Star 4 light microscope. RESULTS: The measurement obtained in the intimal layer was: 126.12 µm2 in the CG, 232 µm2 in the BIIM group, and 178 µm2 in the EG. A statistically significant difference was observed. Baseline serum concentrations of PDGF-BB in the BIIM group were 0.22 pg/mL. At 12 h 0.42 pg/mL, and 0.17 pg/mL at seven days. In the experimental group, the basal levels were 0.33 pg/mL. With the use of cilostazol, a lower peak was obtained at 12 h (0.08 pg/mL). This difference was statistically significant. CONCLUSIONS: Cilostazol induced a significant reduction of IH caused by barotrauma in the venous endothelium, which correlates with decrease in the PDGF-BB in serum. This could be attributed to the pharmacologic effect on PDGFR expression.

Synaptamide Ameliorates Hippocampal Neurodegeneration and Glial Activation in Mice with Traumatic Brain Injury.

Traumatic brain injury (TBI) is a major concern for public health worldwide, affecting 55 million people and being the leading cause of death and disability. To improve the outcomes and effectiveness of treatment for these patients, we conducted a study on the potential therapeutic use of N-docosahexaenoylethanolamine (synaptamide) in mice using the weight-drop injury (WDI) TBI model. Our study focused on exploring synaptamide's effects on neurodegeneration processes and changes in neuronal and glial plasticity. Our findings showed that synaptamide could prevent TBI-associated working memory decline and neurodegenerative changes in the hippocampus, and it could alleviate decreased adult hippocampal neurogenesis. Furthermore, synaptamide regulated the production of astro- and microglial markers during TBI, promoting the anti-inflammatory transformation of the microglial phenotype. Additional effects of synaptamide in TBI include stimulating antioxidant and antiapoptotic defense, leading to the downregulation of the Bad pro-apoptotic marker. Our data suggest that synaptamide has promising potential as a therapeutic agent to prevent the long-term neurodegenerative consequences of TBI and improve the quality of life.

Human engineered heart tissue transplantation in a guinea pig chronic injury model.

Myocardial injury leads to an irreversible loss of cardiomyocytes (CM). The implantation of human engineered heart tissue (EHT) has become a promising regenerative approach. Previous studies exhibited beneficial, dose-dependent effects of human induced pluripotent stem cell (hiPSC)-derived EHT patch transplantation in a guinea pig model in the subacute phase of myocardial injury. Yet, advanced heart failure often results from a chronic remodeling process. Therefore, from a clinical standpoint it is worthwhile to explore the ability to repair the chronically injured heart. In this study human EHT patches were generated from hiPSC-derived CMs (15 × 106 cells) and implanted epicardially four weeks after injury in a guinea pig cryo-injury model. Cardiac function was evaluated by echocardiography after a follow-up period of four weeks. Hearts revealed large transmural myocardial injuries amounting to 27% of the left ventricle. EHT recipient hearts demonstrated compact muscle islands of human origin in the scar region, as indicated by a positive staining for human Ku80 and dystrophin, remuscularizing 5% of the scar area. Echocardiographic analysis demonstrated no significant functional difference between animals that received EHT patches and animals in the cell-free control group (fractional area change 36% vs. 34%). Thus, EHT patches engrafted in the chronically injured heart but in contrast to the subacute model, grafts were smaller and EHT patch transplantation did not improve left ventricular function, highlighting the difficulties for a regenerative approach.

Prophylactic treatment with CN-105 improves functional outcomes in a murine model of closed head injury.

The treatment of traumatic brain injury (TBI) in military populations is hindered by underreporting and underdiagnosis. Clinical symptoms and outcomes may be mitigated with an effective pre-injury prophylaxis. This study evaluates whether CN-105, a 5-amino acid apolipoprotein E (ApoE) mimetic peptide previously shown to modify the post-traumatic neuroinflammatory response, would maintain its neuroprotective effects if administered prior to closed-head injury in a clinically relevant murine model. CN-105 was synthesized by Polypeptide Inc. (San Diego, CA) and administered to C57-BL/6 mice intravenously (IV) and/or by intraperitoneal (IP) injection at various time points prior to injury while vehicle treated animals received IV and/or IP normal saline. Animals were randomized following injury and behavioral observations were conducted by investigators blinded to treatment. Vestibulomotor function was assessed using an automated Rotarod (Ugo Basile, Comerio, Italy), and hippocampal microglial activation was assessed using F4/80 immunohistochemical staining in treated and untreated mice 7 days post-TBI. Separate, in vivo assessments of the pharmacokinetics was performed in healthy CD-1. IV CN-105 administered prior to head injury improved vestibulomotor function compared to vehicle control-treated animals. CN-105 co-administered by IP and IV dosing 6 h prior to injury also improved vestibulomotor function up to 28 days following injury. Microglia counted in CN-105 treated specimens were significantly fewer (P = 0.03) than in vehicle specimens. CN-105 improves functional outcomes and reduces hippocampal microglial activation when administered prior to injury and could be adapted as a pre-injury prophylaxis for soldiers at high risk for TBI.

Real-time dynamic simulation for highly accurate spatiotemporal brain deformation from impact.

Real-time dynamic simulation remains a significant challenge for spatiotemporal data of high dimension and resolution. In this study, we establish a transformer neural network (TNN) originally developed for natural language processing and a separate convolutional neural network (CNN) to estimate five-dimensional (5D) spatiotemporal brain-skull relative displacement resulting from impact (isotropic spatial resolution of 4 mm with temporal resolution of 1 ms). Sequential training is applied to train (N = 5184 samples) the two neural networks for estimating the complete 5D displacement across a temporal duration of 60 ms. We find that TNN slightly but consistently outperforms CNN in accuracy for both displacement and the resulting voxel-wise four-dimensional (4D) maximum principal strain (e.g., root mean squared error (RMSE) of ~1.0% vs. ~1.6%, with coefficient of determination, R 2 >0.99 vs. >0.98, respectively, and normalized RMSE (NRMSE) at peak displacement of 2%-3%, based on an independent testing dataset; N = 314). Their accuracies are similar for a range of real-world impacts drawn from various published sources (dummy, helmet, football, soccer, and car crash; average RMSE/NRMSE of ~0.3 mm/~4%-5% and average R 2 of ~0.98 at peak displacement). Sequential training is effective for allowing instantaneous estimation of 5D displacement with high accuracy, although TNN poses a heavier computational burden in training. This work enables efficient characterization of the intrinsically dynamic brain strain in impact critical for downstream multiscale axonal injury model simulation. This is also the first application of TNN in biomechanics, which offers important insight into how real-time dynamic simulations can be achieved across diverse engineering fields.

Data-driven Uncertainty Quantification in Computational Human Head Models.

Computational models of the human head are promising tools for estimating the impact-induced response of the brain, and thus play an important role in the prediction of traumatic brain injury. The basic constituents of these models (i.e., model geometry, material properties, and boundary conditions) are often associated with significant uncertainty and variability. As a result, uncertainty quantification (UQ), which involves quantification of the effect of this uncertainty and variability on the simulated response, becomes critical to ensure reliability of model predictions. Modern biofidelic head model simulations are associated with very high computational cost and high-dimensional inputs and outputs, which limits the applicability of traditional UQ methods on these systems. In this study, a two-stage, data-driven manifold learning-based framework is proposed for UQ of computational head models. This framework is demonstrated on a 2D subject-specific head model, where the goal is to quantify uncertainty in the simulated strain fields (i.e., output), given variability in the material properties of different brain substructures (i.e., input). In the first stage, a data-driven method based on multi-dimensional Gaussian kernel-density estimation and diffusion maps is used to generate realizations of the input random vector directly from the available data. Computational simulations of a small number of realizations provide input-output pairs for training data-driven surrogate models in the second stage. The surrogate models employ nonlinear dimensionality reduction using Grassmannian diffusion maps, Gaussian process regression to create a low-cost mapping between the input random vector and the reduced solution space, and geometric harmonics models for mapping between the reduced space and the Grassmann manifold. It is demonstrated that the surrogate models provide highly accurate approximations of the computational model while significantly reducing the computational cost. Monte Carlo simulations of the surrogate models are used for uncertainty propagation. UQ of the strain fields highlights significant spatial variation in model uncertainty, and reveals key differences in uncertainty among commonly used strain-based brain injury predictor variables.

Osteoporosis in Light of a New Mechanism Theory of Delayed Onset Muscle Soreness and Non-Contact Anterior Cruciate Ligament Injury.

Osteoporosis is a disorder, with a largely unknown pathomechanism, that is often marked as a "silent thief", because it usually only becomes undisguised when fractures occur. This implies that the pathological damage occurs earlier than the sensation of pain. The current authors put forward a non-contact injury model in which the chronic overloading of an earlier autologously microinjured Piezo2 ion channel of the spinal proprioceptor terminals could lead the way to re-injury and earlier aging in a dose-limiting and threshold-driven way. As a result, the aging process could eventually lead the way to the metabolic imbalance of primary osteoporosis in a quad-phasic non-contact injury pathway. Furthermore, it is emphasised that delayed onset muscle soreness, non-contact anterior cruciate injury and osteoporosis could have the same initiating proprioceptive non-contact Piezo2 channelopathy, at different locations, however, with different environmental risk factors and a different genetic predisposition, therefore producing different outcomes longitudinally. The current injury model does not intend to challenge any running pathogenic theories or findings, but rather to highlight a principal injury mechanism.

The optimization conditions of establishing an H9c2 cardiomyocyte hypoxia/reoxygenation injury model based on an AnaeroPack System.

Ischemia-reperfusion (I/R) injury is a major cause of cardiomyocyte apoptosis after vascular recanalization, which was mimicked by a hypoxia/reoxygenation (H/R) injury model of cardiomyocytes in vitro. In this study, we explored an optimal H/R duration procedure using the AnaeroPack System. To study the H/R procedure, cardiomyocytes were exposed to the AnaeroPack System with sugar and serum-free medium, followed by reoxygenation under normal conditions. Cell injury was detected through lactate dehydrogenase (LDH) and cardiac troponin (c-Tn) release, morphological changes, cell apoptosis, and expression of apoptosis-related proteins. The results showed that the damage to H9c2 cells increased with prolonged hypoxia time, as demonstrated by increased apoptosis rate, LDH and c-Tn release, HIF-1α expression, as well as decreased expression of Bcl-2. Furthermore, hypoxia for 10 h and reoxygenation for 6 h exhibited the highest apoptosis rate and damage and cytokine release; in addition, cells were deformed, small, and visibly round. After 12 h of hypoxia, the majority of the cells were dead. Taken together, this study showed that subjecting H9c2 cells to the AnaeroPack System for 10 h and reoxygenation for 6 h can achieve a practicable and repeatable H/R injury model.

Displacement Error Propagation From Embedded Markers to Brain Strain.

Head injury model validation has evolved from against pressure to relative brain-skull displacement, and more recently, against marker-based strain. However, there are concerns on strain data quality. In this study, we parametrically investigate how displacement random errors and synchronization errors propagate into strain. Embedded markers from four representative configurations are used to form unique and nonoverlapping tetrahedrons, triangles, and linear elements. Marker displacements are then separately subjected to up to ±10% random displacement errors and up to ±2 ms synchronization errors. Based on 100 random trials in each perturbation test, we find that smaller strain errors relative to the baseline peak strains are significantly associated with larger element sizes (volume, area, or length; p < 0.05). When displacement errors are capped at the two extreme levels, the earlier "column" and "cluster" configurations provide few usable elements with relative strain error under an empirical threshold of 20%, while about 30-80% of elements in recent "repeatable" and "uniform" configurations are considered otherwise usable. Overall, denser markers are desired to provide exhaustive pairwise linear elements with a range of sizes to balance the need for larger elements to minimize strain error but smaller elements to increase the spatial resolution in strain sampling. Their signed strains also provide unique and unambiguous information on tissue tension and compression. This study may provide useful insights into the scrutinization of existing experimental data for head injury model strain validation and to inform how best to design new experiments in the future.

Proteomic Modulation in the Dorsal Spinal Cord Following Spinal Cord Stimulation Therapy in an In Vivo Neuropathic Pain Model.

OBJECTIVES: Spinal cord stimulation (SCS) provides relief for patients suffering from chronic neuropathic pain although its mechanism may not be as dependent on electrical interference as classically considered. Recent evidence has been growing regarding molecular changes that are induced by SCS as being a key player in reversing the pain process. Here, we observed the effect of SCS on altering protein expression in spinal cord tissue using a proteomic analysis approach. METHODS: A microlead was epidurally implanted following induction of an animal neuropathic pain model. After the model was established, stimulation was applied for 72 hours continuously followed by tissue collection and proteomic analysis via tandem mass spectroscopy. Identified proteins were run through online data bases for protein identification and classification of biological processes. RESULTS: A significant improvement in mechanical sensitivity was observed following 48 hours of SCS therapy. Proteomic analysis identified 5840 proteins, of which 155 were significantly affected by SCS. Gene ontology data bases indicated that a significant number of proteins were associated to stress response, oxidation/reduction, or extracellular matrix pathways. Additionally, many of the proteins identified also play a role in neuron-glial interactions and are involved in nociception. CONCLUSIONS: The development of an injury unbalances the proteome of the local neural tissue, neurons, and glial cells, and shifts the proteomic profile to a pain producing state. This study demonstrates the reversal of the injury-induced proteomic state by applying conventional SCS therapy. Additional studies looking at variations in electrical parameters are needed to optimize SCS.

[Research progress on in vitro models of cardiomyocyte injury].

Cardiovascular diseases seriously endanger human health and life. The accompanying myocardial injury has been a focus of attention in society. Chinese medicine,serving as a natural and precious reservoir for the research and development of new drugs,is advantageous in resisting myocardial injury due to its multi-component,multi-pathway,and multi-target characteristics. In recent years,with the extensive application of culture method for isolated cardiomyocytes,a cost-effective,controllable in vitro model of cardiomyocyte injury with uniform samples is becoming a key tool for mechanism research on cardiomyocyte injury and drug development.A good in vitro model can reduce experimental and manpower cost,and also accurately stimulate clinical changes to reveal the mechanism. Therefore,the selection and establishment of in vitro model are crucial for the in-depth research. This study summarized the modeling principles,evaluation indicators,and application of more than ten models reflecting different clinical conditions,such as injuries induced by hypoxia-reoxygenation,hypertrophy,oxidative stress,inflammation,internal environmental disturbance,and toxicity. Furthermore,we analyzed advantages and technical difficulties,aiming to provide a reference for in-depth research on myocardial injury mechanism and drug development.

Development of a human cardiac organoid injury model reveals innate regenerative potential.

The adult human heart possesses a limited regenerative potential following an ischemic event, and undergoes a number of pathological changes in response to injury. Although cardiac regeneration has been documented in zebrafish and neonatal mouse hearts, it is currently unknown whether the immature human heart is capable of undergoing complete regeneration. Combined progress in pluripotent stem cell differentiation and tissue engineering has facilitated the development of human cardiac organoids (hCOs), which resemble fetal heart tissue and can be used to address this important knowledge gap. This study aimed to characterize the regenerative capacity of immature human heart tissue in response to injury. Following cryoinjury with a dry ice probe, hCOs exhibited an endogenous regenerative response with full functional recovery 2 weeks after acute injury. Cardiac functional recovery occurred in the absence of pathological fibrosis or cardiomyocyte hypertrophy. Consistent with regenerative organisms and neonatal human hearts, there was a high basal level of cardiomyocyte proliferation, which may be responsible for the regenerative capacity of the hCOs. This study suggests that immature human heart tissue has an intrinsic capacity to regenerate.

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Cardiomyocytes injury model has been widely used in the study for the molecular mechanism of cardiovascular diseases and drug action. It is very important to select the appropriate model due to the different formation mechanisms for various models. Clinical cardiovascular pathological change is relatively complex. Currently used models according to the characteristics of clinical cardiovascular diseases mainly include hydrogen peroxide-induced myocardial cell damage model, hypoxia reoxygenation injury model, adriamycin-induced myocardial cell damage model, high sugar high fat-induced myocardial cell damage model, and isoprenaline-induced myocardial cell damage model. Every model has its advantages as well as its disadvantages. The suitable model of myocardial cell injury can be selected according to the research purpose.