scholarly journals Engineering the Cellular Microenvironment of Post-infarct Myocardium on a Chip

2021 ◽  
Vol 8 ◽  
Author(s):  
Natalie N. Khalil ◽  
Megan L. McCain
Keyword(s):  
Disease Modeling ◽  
Cardiac Injury ◽  
Repair Process ◽  
Scar Tissue ◽  
Myocardial Infarctions ◽  
Cellular Microenvironment ◽  
Cell Culture Systems ◽  
Initial Injury ◽  
Organ On A Chip ◽  
Spatiotemporal Control

Myocardial infarctions are one of the most common forms of cardiac injury and death worldwide. Infarctions cause immediate necrosis in a localized region of the myocardium, which is followed by a repair process with inflammatory, proliferative, and maturation phases. This repair process culminates in the formation of scar tissue, which often leads to heart failure in the months or years after the initial injury. In each reparative phase, the infarct microenvironment is characterized by distinct biochemical, physical, and mechanical features, such as inflammatory cytokine production, localized hypoxia, and tissue stiffening, which likely each contribute to physiological and pathological tissue remodeling by mechanisms that are incompletely understood. Traditionally, simplified two-dimensional cell culture systems or animal models have been implemented to elucidate basic pathophysiological mechanisms or predict drug responses following myocardial infarction. However, these conventional approaches offer limited spatiotemporal control over relevant features of the post-infarct cellular microenvironment. To address these gaps, Organ on a Chip models of post-infarct myocardium have recently emerged as new paradigms for dissecting the highly complex, heterogeneous, and dynamic post-infarct microenvironment. In this review, we describe recent Organ on a Chip models of post-infarct myocardium, including their limitations and future opportunities in disease modeling and drug screening.

scholarly journals Single-cell transcriptomics following ischemic injury identifies a role for B2M in cardiac repair

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Bas Molenaar ◽  
Louk T. Timmer ◽  
Marjolein Droog ◽  
Ilaria Perini ◽  
Danielle Versteeg ◽  
...  
Keyword(s):  
Single Cell ◽  
Communication Networks ◽  
Cardiac Remodeling ◽  
Cardiac Injury ◽  
Ischemic Injury ◽  
Cell Types ◽  
Repair Process ◽  
Cardiac Repair ◽  
Cellular Heterogeneity ◽  
Intercellular Signaling

AbstractThe efficiency of the repair process following ischemic cardiac injury is a crucial determinant for the progression into heart failure and is controlled by both intra- and intercellular signaling within the heart. An enhanced understanding of this complex interplay will enable better exploitation of these mechanisms for therapeutic use. We used single-cell transcriptomics to collect gene expression data of all main cardiac cell types at different time-points after ischemic injury. These data unveiled cellular and transcriptional heterogeneity and changes in cellular function during cardiac remodeling. Furthermore, we established potential intercellular communication networks after ischemic injury. Follow up experiments confirmed that cardiomyocytes express and secrete elevated levels of beta-2 microglobulin in response to ischemic damage, which can activate fibroblasts in a paracrine manner. Collectively, our data indicate phase-specific changes in cellular heterogeneity during different stages of cardiac remodeling and allow for the identification of therapeutic targets relevant for cardiac repair.

Abstract 35: Enhanced Reprogramming of Human Fibroblasts into Cardiomyocytes Using Minimal Transcription Factors

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Yang Zhou ◽  
Sahar Alimohamadi ◽  
Jiandong Liu ◽  
Li Qian
Keyword(s):  
Transcription Factors ◽  
Disease Modeling ◽  
Human Fibroblasts ◽  
Cardiac Injury ◽  
Cardiac Regeneration ◽  
Clinical Applications ◽  
Significant Advance ◽  
Great Promise ◽  
Primary Fibroblasts ◽  
Core Components

The adult human heart has limited regenerative capacity and is thus an important target for novel regenerative approaches to replenish lost cardiomyocytes after cardiac injury. Cardiac reprogramming that converts fibroblasts to contractile induced cardiomyocytes (iCMs) by overexpressing cardiac lineage specific transcription factors holds great promise as an alternative approach for cardiac regeneration and disease modeling. Significant advance has been made to generate mouse iCMs; however, human iCM (hiCM) generation remains challenging and the yield is low for clinical applications. Here, we leveraged the knowledge that we learned from studying mouse iCM reprogramming to define the optimal condition for hiCM induction. We titrated the dosage of the human reprogramming factors systematically and surprisingly found the minimal core components GATA4, MEF2C and TBX5 were sufficient to induce cardiac fate in human primary fibroblasts. This is in sharp contrast to what has been reported in the literature. Subsequently, we cloned these three factors into a polycistronic vector separated by 2A peptides for defined ratio of protein expression. By optimizing the growth condition, we further improved the efficiency of hiCM reprogramming. Mechanistically, we found the balanced expression of this minimal combination of transcription factors with tailored microenvironment enhanced the establishment of cardiac program in non-myocytes. In sum, our study demonstrates that the use of a single vector with only three transcription factors simplifies generation and improves the yield of hiCMs for potential future clinical applications.

scholarly journals Emerging Roles for Immune Cells and MicroRNAs in Modulating the Response to Cardiac Injury

2019 ◽  
Vol 6 (1) ◽  
pp. 5 ◽  
Author(s):  
Adriana Rodriguez ◽  
Viravuth Yin
Keyword(s):  
Immune Cells ◽  
Cardiac Tissue ◽  
Heart Function ◽  
Cardiac Injury ◽  
Scar Tissue ◽  
Acute Injury ◽  
Heart Regeneration ◽  
Cardiomyocyte Proliferation ◽  
Cardiac Damage ◽  
Dynamic Interplay

Stimulating cardiomyocyte regeneration after an acute injury remains the central goal in cardiovascular regenerative biology. While adult mammals respond to cardiac damage with deposition of rigid scar tissue, adult zebrafish and salamander unleash a regenerative program that culminates in new cardiomyocyte formation, resolution of scar tissue, and recovery of heart function. Recent studies have shown that immune cells are key to regulating pro-inflammatory and pro-regenerative signals that shift the injury microenvironment toward regeneration. Defining the genetic regulators that control the dynamic interplay between immune cells and injured cardiac tissue is crucial to decoding the endogenous mechanism of heart regeneration. In this review, we discuss our current understanding of the extent that macrophage and regulatory T cells influence cardiomyocyte proliferation and how microRNAs (miRNAs) regulate their activity in the injured heart.

Decreasing Troponin Redraws by Validating Tiered Hemolysis Thresholds

2019 ◽  
Vol 152 (Supplement_1) ◽  
pp. S11-S12
Author(s):  
Katherine Turner ◽  
Tanya Harnish ◽  
Zahra Madani ◽  
Erin Kaleta ◽  
Christine Snozek
Keyword(s):  
High Risk ◽  
Troponin T ◽  
Cardiac Injury ◽  
Significant Risk ◽  
Myocardial Infarctions ◽  
H Index ◽  
High Risk Patients ◽  
Risk Patients ◽  
The Mean ◽  
Serial Measurements

Abstract Cardiac troponin T (cTnT) assays are used for the diagnosis of acute myocardial infarctions and require serial measurements. Hemolysis is a common analytical interference for cTnT immunoassays, causing a false decrease in analyte concentration. Recollection of specimens that do not meet the recommended hemolysis threshold (H-index = 100) causes reporting delays and mistiming of serial measurements. This has been particularly disruptive to our emergency department and creates significant risk for patients whose diagnosis could be delayed by recollection due to hemolysis. Here we aimed to reevaluate the limits for acceptable hemolysis by determining the magnitude of cTnT concentration depression from hemolysis to evaluate whether more detailed thresholds could be established. To quantify the effects of hemolysis on cTnT, patient pools were prepared from residual serum with cTnT concentrations ranging from 10 to 100 ng/L and spiked with hemolysate prepared from lysed red blood cells to create H-indices ranging from 120 to 200. Samples were run in triplicate by the Elecsys Troponin T Gen. 5 STAT assay. Results demonstrated consistent percent decreases in cTnT across all concentrations tested for each level of hemolysis. The mean percent changes in cTnT concentrations in the presence of hemolysis for H-indices of 120, 140, 160, 180, and 200 were –3.4 ± 1.3%, –4.1 ± 1.2%, –6.3 ± 1.2%, –8.0 ± 1.7%, and –10.7 ± 1.22%, respectively. The observed decrease in cTnT was linearly related to the H index; predicted differences at higher H-indices (>200) agreed well with prior publications evaluating greater degrees of hemolysis. In our practice, a 2-hour delta ≥10 ng/L is considered significant for acute cardiac injury, <4 ng/L is a nonsignificant delta, and a delta of 4 to 9 ng/L is considered indeterminate. Baseline cTnT results of ≥100 ng/L result in immediate triage to cardiology. Approximately one-third of our patients with cTnT testing have baseline results within the reference range (≤15 ng/L males, ≤10 ng/L females). Based on the spiking data, H-index cutoffs were chosen to minimize recollections for low-risk and high-risk patients. Cutoffs for intermediate cTnT results were more restrictive to ensure delta interpretation would not change significantly. This resulted in a H-index of 300 for samples ≤8 ng/L, 200 for 9 to 40 ng/L, 160 for 41 to 70 ng/L, 140 for 71 to 99 ng/L, and 300 for ≥100 ng/L. These data quantify the percent change for cTnT in the presence of varying levels of hemolysis. At lower cTnT values, a larger degree of hemolysis can be tolerated because the percentage of depression results in a small absolute change, thus leading to less impact on the delta. The tiered H-index cutoffs allow minimal disruption to patient care for low- and high-risk patients, while maintaining the integrity of serial measurements for those with intermediate cTnT concentrations. Therefore, laboratories may consider releasing some hemolyzed cTnT specimens with a comment to decrease redraws and mistiming of serial measurements.

scholarly journals A Review of the Evidence for and against a Role for Mast Cells in Cutaneous Scarring and Fibrosis

2020 ◽  
Vol 21 (24) ◽  
pp. 9673
Author(s):  
Traci A. Wilgus ◽  
Sara Ud-Din ◽  
Ardeshir Bayat
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Cell Activation ◽  
Social Issues ◽  
Critical Role ◽  
Large Body ◽  
Repair Process ◽  
Scar Tissue ◽  
Mast Cell Activation

Scars are generated in mature skin as a result of the normal repair process, but the replacement of normal tissue with scar tissue can lead to biomechanical and functional deficiencies in the skin as well as psychological and social issues for patients that negatively affect quality of life. Abnormal scars, such as hypertrophic scars and keloids, and cutaneous fibrosis that develops in diseases such as systemic sclerosis and graft-versus-host disease can be even more challenging for patients. There is a large body of literature suggesting that inflammation promotes the deposition of scar tissue by fibroblasts. Mast cells represent one inflammatory cell type in particular that has been implicated in skin scarring and fibrosis. Most published studies in this area support a pro-fibrotic role for mast cells in the skin, as many mast cell-derived mediators stimulate fibroblast activity and studies generally indicate higher numbers of mast cells and/or mast cell activation in scars and fibrotic skin. However, some studies in mast cell-deficient mice have suggested that these cells may not play a critical role in cutaneous scarring/fibrosis. Here, we will review the data for and against mast cells as key regulators of skin fibrosis and discuss scientific gaps in the field.

scholarly journals Modeling Living Cells Within Microfluidic Systems Using Cellular Automata Models

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Julia Ballesteros Hernando ◽  
Milagros Ramos Gómez ◽  
Andrés Díaz Lantada
Keyword(s):  
Cellular Automata ◽  
Growth Rates ◽  
Computational Models ◽  
Disease Modeling ◽  
Petri Dish ◽  
Microfluidic System ◽  
Microfluidic Systems ◽  
Cell Behaviors ◽  
Cad Models ◽  
Organ On A Chip

Abstract Several computational models, both continuum and discrete, allow for the simulation of collective cell behaviors in connection with challenges linked to disease modeling and understanding. Normally, discrete cell modelling employs quasi-infinite or boundary-less 2D lattices, hence modeling collective cell behaviors in Petri dish-like environments. The advent of lab- and organ-on-a-chip devices proves that the information obtained from 2D cell cultures, upon Petri dishes, differs importantly from the results obtained in more biomimetic micro-fluidic environments, made of interconnected chambers and channels. However, discrete cell modelling within lab- and organ-on-a-chip devices, to our knowledge, is not yet found in the literature, although it may prove useful for designing and optimizing these types of systems. Consequently, in this study we focus on the establishment of a direct connection between the computer-aided designs (CAD) of microfluidic systems, especially labs- and organs-on-chips (and their multi-chamber and multi-channel structures), and the lattices for discrete cell modeling approaches aimed at the simulation of collective cell interactions, whose boundaries are defined directly from the CAD models. We illustrate the proposal using a quite straightforward cellular automata model, apply it to simulating cells with different growth rates, within a selected set of microsystem designs, and validate it by tuning the growth rates with the support of cell culture experiments and by checking the results with a real microfluidic system.

scholarly journals Specific macrophage populations promote both cardiac scar deposition and subsequent resolution in adult zebrafish

2019 ◽  
Vol 116 (7) ◽  
pp. 1357-1371 ◽  
Author(s):  
Laura Bevan ◽  
Zhi Wei Lim ◽  
Byrappa Venkatesh ◽  
Paul R Riley ◽  
Paul Martin ◽  
...  
Keyword(s):  
Inflammatory Response ◽  
Inflammatory Cell ◽  
Inflammatory Responses ◽  
Tissue Injury ◽  
Cardiac Injury ◽  
Repair Process ◽  
Adult Zebrafish ◽  
Cardiac Damage ◽  
Scar Resolution ◽  
Macrophage Subsets

Abstract Aims A robust inflammatory response to tissue injury is a necessary part of the repair process but the deposition of scar tissue is a direct downstream consequence of this response in many tissues including the heart. Adult zebrafish not only possess the capacity to regenerate lost cardiomyocytes but also to remodel and resolve an extracellular scar within tissues such as the heart, but this scar resolution process remains poorly understood. This study aims to characterize the scarring and inflammatory responses to cardiac damage in adult zebrafish in full and investigate the role of different inflammatory subsets specifically in scarring and scar removal. Methods and results Using stable transgenic lines, whole organ imaging and genetic and pharmacological interventions, we demonstrate that multiple inflammatory cell lineages respond to cardiac injury in adult zebrafish. In particular, macrophage subsets (tnfα+ and tnfα−) play prominent roles with manipulation of different phenotypes suggesting that pro-inflammatory (tnfα+) macrophages promote scar deposition following cardiac injury whereas tnfα− macrophages facilitate scar removal during regeneration. Detailed analysis of these specific macrophage subsets reveals crucial roles for Csf1ra in promoting pro-inflammatory macrophage-mediated scar deposition. Additionally, the multifunctional cytokine Osteopontin (Opn) (spp1) is important for initial scar deposition but also for resolution of the inflammatory response and in late-stage ventricular collagen remodelling. Conclusions This study demonstrates the importance of a correctly balanced inflammatory response to facilitate scar deposition during repair but also to allow subsequent scar resolution, and full cardiac regeneration, to occur. We have identified Opn as having both pro-fibrotic but also potentially pro-regenerative roles in the adult zebrafish heart, driving Collagen deposition but also controlling inflammatory cell resolution.

Effects of Metabolites of Bacteria Bacillus SP. from Permafrost on Speed Repair of Skin Wound

10.12737/7269 ◽  
2014 ◽  
Vol 21 (4) ◽  
pp. 53-61 ◽  
Author(s):  
Бажин ◽  
A. Bazhin ◽  
Калёнова ◽  
L. Kalenova ◽  
Новикова ◽  
...  
Keyword(s):  
Immune System ◽  
Repair Process ◽  
Scar Tissue ◽  
Skin Wound ◽  
Regenerative Process ◽  
Skin Defect ◽  
Bacillus Sp ◽  
Repair Processes ◽  
Stage Of Development ◽  
Cell Immunity

Fossil bacteria are evolutionarily valuable forms of life. In permafrost conditions for a very long time, bacteria can develop a unique repair mechanisms of structural and functional defects. In the experiment on mice of BALB/c it was revealed the presence of high reparative capacity in fossil bacteria strain MG8 Bacillus sp., isolated from samples of relict permafrost, and their metabolic products – metabolites that can be delegated to other living systems. Ability to regulate reparative processes in macroorganism shows in MG8 in the doses less than 20×1103 microbial cells and topically on the wound surface. The “thermal&#34; metabolites, produced by culturing the bacteria at 37°C, are leaders modulation of repair processes in healing skin blemishes. Local application on the wound ointment with &#34;heat&#34; metabolites allows to accelerate by 30% the process of reparation relative to placebo, by 20% – relative to the medicinal product &#34;Solcoseryl&#34; and by 10% – faster than under the influence of bacteria. Dynamics of morphogenetic processes in the healing of skin defect under MG8 bacteria effect and their metabolites is correlated with the dynamics of immune system activity. The sequence of changes in the activity of various components of the immune system (cellular factors inherent immunoresistance – cell immunity humoral immunity) corresponds to the stage of development of the repair process (damage – inflammation – recovery). Mechanisms of regulation of repair processes in the immune system consistent with the general laws regulating the inflammatory process and changes in waves: the predominant increase in the activity of pro-inflammatory mechanisms replaced predominant anti-inflammatory mechanisms of increased activity of the immune system. Using strain MG8 metabolites allows to optimize regenerative process, to reduce time of wound contraction and the formation of scar tissue, to full restore of the coat, so they can be modulators of the wound process, with a predominance of regeneration mechanisms

scholarly journals Vegfaa instructs cardiac muscle hyperplasia in adult zebrafish

2018 ◽  
Vol 115 (35) ◽  
pp. 8805-8810 ◽  
Author(s):  
Ravi Karra ◽  
Matthew J. Foglia ◽  
Wen-Yee Choi ◽  
Christine Belliveau ◽  
Paige DeBenedittis ◽  
...  
Keyword(s):  
Heart Development ◽  
Epithelial To Mesenchymal Transition ◽  
Cardiac Injury ◽  
Angiogenic Factor ◽  
Regulatory Sequences ◽  
Mesenchymal Transition ◽  
Epicardial Cells ◽  
Myocardial Wall ◽  
Tightly Coupled ◽  
Spatiotemporal Control

During heart development and regeneration, coronary vascularization is tightly coupled with cardiac growth. Although inhibiting vascularization causes defects in the innate regenerative response of zebrafish to heart injury, angiogenic signals are not known to be sufficient for triggering regeneration events. Here, by using a transgenic reporter strain, we found that regulatory sequences of the angiogenic factor vegfaa are active in epicardial cells of uninjured animals, as well as in epicardial and endocardial tissue adjacent to regenerating muscle upon injury. Additionally, we find that induced cardiac overexpression of vegfaa in zebrafish results in overt hyperplastic thickening of the myocardial wall, accompanied by indicators of angiogenesis, epithelial-to-mesenchymal transition, and cardiomyocyte regeneration programs. Unexpectedly, vegfaa overexpression in the context of cardiac injury enabled ectopic cardiomyogenesis but inhibited regeneration at the site of the injury. Our findings identify Vegfa as one of a select few known factors sufficient to activate adult cardiomyogenesis, while also illustrating how instructive factors for heart regeneration require spatiotemporal control for efficacy.

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