Polyethylene glycol and caspase inhibitor emricasan alleviate cold injury in primary rat hepatocytes.

Current methods of storing explanted donor livers at 4 °C in University of Wisconsin (UW) solution result in loss of graft function and ultimately lead to less-than-ideal outcomes post transplantation. Our lab has previously shown that supplementing UW solution with 35-kilodalton polyethylene glycol (PEG) has membrane stabilizing effects for cold stored primary rat hepatocytes in suspension. Expanding on past studies, we here investigate if PEG has the same beneficial effects in an adherent primary rat hepatocyte cold storage model. In addition, we investigated the extent of cold-induced apoptosis through treating cold-stored hepatocytes with pan caspase inhibitor emricasan. In parallel to storage at the current cold storage standard of 4 °C, we investigated the effects of lowering the storage temperature to -4 °C, at which the storage solution remains ice-free due to the supercooling phenomenon. We show the addition of 5 % PEG to the storage medium significantly reduced the release of lactate dehydrogenase (LDH) in plated rat hepatocytes and a combinatorial treatment with emricasan maintains hepatocyte viability and morphology following recovery from cold storage. These results show that cold-stored hepatocytes undergo multiple mechanisms of cold-induced injury and that PEG and emricasan treatment in combination with supercooling may improve cell and organ preservation.

Polyethylene Glycol and Caspase Inhibitor Emricasan Alleviates Cold Injury in Primary Rat Hepatocytes.

Current methods of storing explanted donor livers at 4°C in University of Wisconsin (UW) solution result in loss of graft function and ultimately leads to less-than-ideal outcomes post transplantation. Our lab has previously shown that supplementing UW solution with 35-kilodalton polyethylene glycol (PEG) has membrane stabilizing effects for cold stored primary rat hepatocytes in suspension. Expanding on past studies, we here investigate if PEG has the same beneficial effects in an adherent primary rat hepatocyte cold storage model. In addition, we investigated the extent of cold-induced apoptosis through treating cold-stored hepatocytes with pan caspase inhibitor emricasan. In parallel to storage at the current cold storage standard of 4°C, we investigated the effects of lowering the storage temperature to -4°C, at which the storage solution remains ice-free due to the supercooling phenomenon. We show the addition of 5% PEG to the storage medium significantly reduced the release of lactate dehydrogenase (LDH) in plated rat hepatocytes and a combinatorial treatment with emricasan maintains hepatocyte viability and morphology following recovery from cold storage. These results show that cold-stored hepatocytes undergo multiple mechanisms of cold-induced injury and that PEG and emricasan treatment in combination with supercooling may improve cell and organ preservation.

Myocardial infarction from a tissue engineering and regenerative medicine point of view: A comprehensive review on models and treatments.

In the modern world, myocardial infarction is one of the most common cardiovascular diseases, which are responsible for around 18 million deaths every year or almost 32% of all deaths. Due to the detrimental effects of COVID-19 on the cardiovascular system, this rate is expected to increase in the coming years. Although there has been some progress in myocardial infarction treatment, translating pre-clinical findings to the clinic remains a major challenge. One reason for this is the lack of reliable and human representative healthy and fibrotic cardiac tissue models that can be used to understand the fundamentals of ischemic/reperfusion injury caused by myocardial infarction and to test new drugs and therapeutic strategies. In this review, we first present an overview of the anatomy of the heart and the pathophysiology of myocardial infarction, and then discuss the recent developments on pre-clinical infarct models, focusing mainly on the engineered three-dimensional cardiac ischemic/reperfusion injury and fibrosis models developed using different engineering methods such as organoids, microfluidic devices, and bioprinted constructs. We also present the benefits and limitations of emerging and promising regenerative therapy treatments for myocardial infarction such as cell therapies, extracellular vesicles, and cardiac patches. This review aims to overview recent advances in three-dimensional engineered infarct models and current regenerative therapeutic options, which can be used as a guide for developing new models and treatment strategies.

Human Heart Anoxia and Reperfusion Tissue (HEART) Model for the Rapid Study of Exosome Bound miRNA Expression As Biomarkers for Myocardial Infarction.

Current biomarkers for myocardial infarction (MI) diagnosis are typically late markers released upon cell death, incapable of distinguishing between ischemic and reperfusion injury and can be symptoms of other pathologies. Circulating microRNAs (miRNAs) have recently been proposed as alternative biomarkers for MI diagnosis; however, detecting the changes in the human cardiac miRNA profile during MI is extremely difficult. Here, to study the changes in miRNA levels during acute MI, a heart-on-chip model with a cardiac channel, containing human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes in human heart decellularized matrix and collagen, and a vascular channel, containing hiPSC-derived endothelial cells, is developed. This model is exposed to anoxia followed by normoxia to mimic ischemia and reperfusion, respectively. Using a highly sensitive miRNA biosensor that the authors developed, the exact same increase in miR-1, miR-208b, and miR-499 levels in the MI-on-chip and the time-matched human blood plasma samples collected before and after ischemia and reperfusion, is shown. That the surface marker profile of exosomes in the engineered model changes in response to ischemic and reperfusion injury, which can be used as biomarkers to detect MI, is also shown. Hence, the MI-on-chip model developed here can be used in biomarker discovery.

A Recombinant Dimethylarginine Dimethylaminohydrolase-1-Based Biotherapeutics to Pharmacologically Lower Asymmetric Dimethyl Arginine, thus Improving Postischemic Cardiac Function and Cardiomyocyte Mitochondrial Activity.

High serum levels of asymmetric dimethyl arginine (ADMA) are associated with cardiovascular disease and mortality. Pharmacological agents to specifically lower ADMA and their potential impact on cardiovascular complications are not known. In this study, we aimed to investigate the effect of specific lowering of ADMA on myocardial response to ischemia-reperfusion injury (I/R) and direct effects on cardiomyocyte function. Effects of recombinant dimethylarginine dimethylaminohydrolase (rDDAH)-1 on I/R injury were determined using isolated mouse heart preparation. Respiration capacity and mitochondrial reactive oxygen species (ROS) generation were determined on mouse cardiomyocytes. Our results show that lowering ADMA by rDDAH-1 treatment resulted in improved recovery of cardiac function and reduction in myocardial infarct size in mouse heart response to I/R injury (control 22.24 ±4.60% versus rDDAH-1 15.90 ±4.23%, P < 0.01). In mouse cardiomyocytes, rDDAH-1 treatment improved ADMA-induced dysregulation of respiration capacity and decreased mitochondrial ROS. Furthermore, in human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes with impaired contractility under hypoxia and high ADMA, rDDAH-1 treatment improved recovery and beating frequency (P < 0.05). rDDAH-1 treatment selectively modified I/R-induced myocardial cytokine expression, resulting in reduction in proinflammatory cytokine IL-17A (P < 0.001) and increased expression of anti-inflammatory cytokines IL-10 and IL-13 (P < 0.01). Further in vitro studies showed that IL-17A was the predominant and common cytokine modulated by ADMA-DDAH pathway in heart, cardiomyocytes, and endothelial cells. These studies show that lowering ADMA by pharmacological treatment with rDDAH-1 reduced I/R injury, improved cardiac function, and ameliorated cardiomyocyte bioenergetics and beating activity. These effects may be attributable to ADMA lowering in cardiomyocytes and preservation of cardiomyocyte mitochondrial function. SIGNIFICANCE STATEMENT: The pathological role of asymmetric dimethyl arginine (ADMA) has been demonstrated by its association with cardiovascular disease and mortality. Currently, pharmacological drugs to specifically lower ADMA are not available. The present study provides the first evidence that lowering of ADMA by recombinant recombinant dimethylarginine dimethylaminohydrolase (rDDAH)-1 improved postischemic cardiac function and cardiomyocyte bioenergetics and beating activity. Our studies suggest that lowering of ADMA by pharmacologic treatment offers opportunity to develop new therapies for the treatment of cardiovascular and renal disease.

Focal Prostate Stereotactic Body Radiation Therapy With Correlative Pathological and Radiographic-Based Treatment Planning.

INTRODUCTION: Advances in multiparametric MRI (mpMRI) combining anatomic and functional imaging can accurately identify foci of adenocarcinoma within the prostate, offering the possibility of partial gland therapy. We performed tandem prospective pilot trials to investigate the feasibility of focal prostate SBRT (f-SBRT) based on correlating diagnostic mpMRI and biopsies with confirmatory pathology in treatment planning. MATERIALS AND METHODS: Patients with pathologic focal Gleason 6-7 disease and a corresponding PIRADS 4-5 lesion on mpMRI underwent targeted and comprehensive biopsies using MRI/ultrasound fusion under electromagnetic sensor navigation. After rigorous analysis for imaging biopsy concordance, five of 18 patients were eligible to proceed to f-SBRT. Chi-squared test was used for differences from expected outcomes, and concordance was estimated with binomial distribution theory and Wilson's method. RESULTS: Six patients had Gleason 6 and 12 had Gleason 3 + 4 disease (mean PSA: 5.8 ng/ml, range: 2.2-8.4). Absolute concordance was 43.8% (95% CI: 0.20, 0.64). Patterns of discordance included additional sites of ipsilateral disease, bilateral disease, and negative target. Five were upstaged to a new NCCN risk category necessitating treatment escalation. The five patients with concordant pathology completed three-fraction f-SBRT with sparing of the surrounding normal structures (including contralateral neurovascular bundle), with no reported grade 2+ toxicities and favorable PSA responses (mean: 41% decrease). CONCLUSIONS: On our pilot trials of f-SBRT planning using rigorous imaging and pathology concordance, image-guided confirmatory biopsies frequently revealed additional disease, suggesting the need for caution in partial-gland therapy. For truly focal disease, f-SBRT provided excellent dosimetry, minimal toxicity, and encouraging biochemical response. Clinical Trial Registration: www.clinicaltrials.gov, NCT02681614; NCT02163317.

A multiplexed ion-exchange membrane-based miRNA (MIX·miR) detection platform for rapid diagnosis of myocardial infarction.

Micro RNAs (miRNAs) have shown great potential as rapid and discriminating biomarkers for acute myocardial infarction (AMI) diagnosis. We have developed a multiplexed ion-exchange membrane-based miRNA (MIX·miR) preconcentration/sensing amplification-free platform for quantifying in parallel a panel of miRNAs, including miR-1, miR-208b, and miR-499, from the same plasma samples from: 1) reference subjects with no evident coronary artery disease (NCAD); 2) subjects with stable coronary artery disease (CAD); and 3) subjects experiencing ST-elevation myocardial infarction (STEMI) prior to (STEMI-pre) and following (STEMI-PCI) percutaneous coronary intervention. The picomolar limit of detection from raw plasma and 3-decade dynamic range of MIX·miR permits detection of the miRNA panel in untreated samples from disease patients and its precise standard curve, provided by large 0.1 to 1 V signals and eliminates individual sensor calibration. The use of molecular concentration feature reduces the assay time to less than 30 minutes and increases the detection sensitivity by bringing all targets close to the sensors. miR-1 was low for NCAD patients but more than one order of magnitude above the normal value for all samples from three categories (CAD, STEMI-pre, and STEMI-PCI) of patients with CAD. In fact, miR-1 expression levels of stable CAD, STEMI-pre and STEMI-PCI are each more than 10-fold higher than the previous class, in that order, well above the 95% confidence level of MIX·miR. Its overexpression estimate is significantly higher than the PCR benchmark. This suggests that, in contrast to protein biomarkers of myocardial injury, miR-1 appears to differentiate ischemia from both reperfusion injury and non-AMI CAD patients. The battery-operated MIX·miR can be a portable and low-cost AMI diagnostic device, particularly useful in settings where cardiac catheterization is not readily available to determine the status of coronary reperfusion.

Correction: Constant-potential environment for activating and synchronizing cardiomyocyte colonies with on-chip ion-depleting perm-selective membranes.

Correction for 'Constant-potential environment for activating and synchronizing cardiomyocyte colonies with on-chip ion-depleting perm-selective membranes' by Vivek Yadav et al., Lab Chip, 2020, 20, 4273-4284, DOI: 10.1039/D0LC00809E.

Tunable Human Myocardium Derived Decellularized Extracellular Matrix for 3D Bioprinting and Cardiac Tissue Engineering.

The generation of 3D tissue constructs with multiple cell types and matching mechanical properties remains a challenge in cardiac tissue engineering. Recently, 3D bioprinting has become a powerful tool to achieve these goals. Decellularized extracellular matrix (dECM) is a common scaffold material due to providing a native biochemical environment. Unfortunately, dECM's low mechanical stability prevents usage for bioprinting applications alone. In this study, we developed bioinks composed of decellularized human heart ECM (dhECM) with either gelatin methacryloyl (GelMA) or GelMA-methacrylated hyaluronic acid (MeHA) hydrogels dual crosslinked with UV light and microbial transglutaminase (mTGase). We characterized the bioinks' mechanical, rheological, swelling, printability, and biocompatibility properties. Composite GelMA-MeHA-dhECM (GME) hydrogels demonstrated improved mechanical properties by an order of magnitude compared to the GelMA-dhECM (GE) hydrogels. All hydrogels were extrudable and compatible with human induced pluripotent stem cell derived cardiomyocytes (iCMs) and human cardiac fibroblasts (hCFs). Tissue-like beating of the printed constructs with striated sarcomeric alpha-actinin and connexin 43 expression was observed. The order of magnitude difference between the elastic modulus of these hydrogel composites offers applications in in vitro modeling of the myocardial infarct boundary. Here, as a proof of concept, we created an infarct boundary region with control over the mechanical properties along with the cellular and macromolecular content through printing iCMs with GE bioink and hCFs with GME bioink.

Adipose stem cell secretome markedly improves rodent heart and human induced pluripotent stem cell-derived cardiomyocyte recovery from cardioplegic transport solution exposure.

Heart transplantation is a life-saving therapy for end-stage organ failure. Organ deterioration during transportation limits storage to 4 hours, limiting hearts available. Approaches ameliorating organ damage could increase the number of hearts acceptable for transplantation. Prior studies show that adipose-derived stem/stromal cell secretome (ASC-S) rescues tissues from postischemic damage in vivo. This study tested whether ASC-S preserved the function of mouse hearts and human induced pluripotent stem cell-derived cardiomyocytes (iCM) exposed to organ transportation and transplantation conditions. Hearts were subjected to cold University of Wisconsin (UW) cardioplegic solution ± ASC-S for 6 hours followed by analysis using the Langendorff technique. In parallel, the effects of ASC-S on the recovery of iCM from UW solution were examined when provided either during or after cold cardioplegia. Exposure of hearts and iCM to UW deteriorated contractile activity and caused cell apoptosis, worsening in iCM as a function of exposure time; these were ameliorated by augmenting with ASC-S. Silencing of superoxide dismutase 3 and catalase expression prior to secretome generation compromised the ASC-S cardiomyocyte-protective effects. In this study, a novel in vitro iCM model was developed to complement a rodent heart model in assessing efficacy of approaches to improve cardiac preservation. ASC-S displays strong cardioprotective activity on iCM either with or following cold cardioplegia. This effect is associated with ASC-S-mediated cellular clearance of reactive oxygen species. The effect of ASC-S on the temporal recovery of iCM function supports the possibility of lengthening heart storage by augmenting cardioplegic transport solution with ASC-S, expanding the pool of hearts for transplantation.

Constant-potential environment for activating and synchronizing cardiomyocyte colonies with on-chip ion-depleting perm-selective membranes.

In this study, an ion depleted zone created by an ion-selective membrane was used to impose a high and uniform constant extracellular potential over an entire ∼1000 cell rat cardiomyocyte (rCM) colony on-a-chip to trigger synchronized voltage-gated ion channel activities while preserving cell viability, thus extending single-cell voltage-clamp ion channel studies to an entire normalized colony. Image analysis indicated that rCM beating was strengthened and accelerated (by a factor of ∼2) within minutes of ion depletion and the duration of contraction and relaxation phases was significantly reduced. After the initial synchronization, the entire colony responds collectively to external potential changes such that beating over the entire colony can be activated or deactivated within 0.1 s. These newly observed collective dynamic responses, due to simultaneous ion channel activation/deactivation by a uniform constant-potential extracellular environment, suggest that perm-selective membrane modules on cell culture chips can facilitate studies of extracellular cardiac cell electrical communication and how ion-channel related pathologies affect cardiac cell synchronization. The future applications of this new technology can lead to better drug screening platforms for cardiotoxicity as well as platforms that can facilitate synchronized maturation of pluripotent stem cells into colonies with high electrical connectivity.

Breast cancer models: Engineering the tumor microenvironment.

The mechanisms behind cancer initiation and progression are not clear. Therefore, development of clinically relevant models to study cancer biology and drug response in tumors is essential. In vivo models are very valuable tools for studying cancer biology and for testing drugs; however, they often suffer from not accurately representing the clinical scenario because they lack either human cells or a functional immune system. On the other hand, two-dimensional (2D) in vitro models lack the three-dimensional (3D) network of cells and extracellular matrix (ECM) and thus do not represent the tumor microenvironment (TME). As an alternative approach, 3D models have started to gain more attention, as such models offer a platform with the ability to study cell-cell and cell-material interactions parametrically, and possibly include all the components present in the TME. Here, we first give an overview of the breast cancer TME, and then discuss the current state of the pre-clinical breast cancer models, with a focus on the engineered 3D tissue models. We also highlight two engineering approaches that we think are promising in constructing models representative of human tumors: 3D printing and microfluidics. In addition to giving basic information about the TME in the breast tissue, this review article presents the state-of-the-art tissue engineered breast cancer models. STATEMENT OF SIGNIFICANCE: Involvement of biomaterials and tissue engineering fields in cancer research enables realistic mimicry of the cell-cell and cell-extracellular matrix (ECM) interactions in the tumor microenvironment (TME), and thus creation of better models that reflect the tumor response against drugs. Engineering the 3D in vitro models also requires a good understanding of the TME. Here, an overview of the breast cancer TME is given, and the current state of the pre-clinical breast cancer models, with a focus on the engineered 3D tissue models is discussed. This review article is useful not only for biomaterials scientists aiming to engineer 3D in vitro TME models, but also for cancer researchers willing to use these models for studying cancer biology and drug testing.

Distinct glycosylation in membrane proteins within neonatal versus adult myocardial tissue.

Mammalian hearts have regenerative potential restricted to early neonatal stage and lost within seven days after birth. Carbohydrates exclusive to cardiac neonatal tissue may be key regulators of regenerative potential. Although cell surface and extracellular matrix glycosylation are known modulators of tissue and cellular function and development, variation in cardiac glycosylation from neonatal tissue to maturation has not been fully examined. In this study, glycosylation of the adult rat cardiac ventricle showed no variability between the two strains analysed, nor were there any differences between the glycosylation of the right or left ventricle using lectin histochemistry and microarray profiling. However, in the Sprague-Dawley strain, neonatal cardiac glycosylation in the left ventricle differed from adult tissues using mass spectrometric analysis, showing a higher expression of high mannose structures and lower expression of complex N-linked glycans in the three-day-old neonatal tissue. Man6GlcNAc2 was identified as the main high mannose N-linked structure that was decreased in adult while higher expression of sialylated N-linked glycans and lower core fucosylation for complex structures were associated with ageing. The occurrence of mucin core type 2 O-linked glycans was reduced in adult and one sulfated core type 2 O-linked structure was identified in neonatal tissue. Interestingly, O-linked glycans from mature tissue contained both N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc), while all sialylated N-linked glycans detected contained only Neu5Ac. As glycans are associated with intracellular communication, the specific neonatal structures found may indicate a role for glycosylation in the neonatal associated regenerative capacity of the mammalian heart. New strategies targeting tissue glycosylation could be a key contributor to achieve an effective regeneration of the mammalian heart in pathological scenarios such as myocardial infarction.

Quantitative Real-Time PCR Analysis of Individual Flue-Cured Tobacco Seeds and Seedlings Reveals Seed Transmission of Tobacco Mosaic Virus.

Tobacco mosaic virus (TMV) is an extensively studied RNA virus known to infect tobacco (Nicotiana tabacum) and other solanaceous crops. TMV has been classified as a seedborne virus in tobacco, with infection of developing seedlings thought to occur from contact with the TMV-infected seed coat. The mechanism of TMV transmission through seed was studied in seed of the K 326 cultivar of flue-cured tobacco. Cross pollinations were performed to determine the effect of parental tissue on TMV infection in seed. Dissection of individual tobacco seeds into seed coat, endosperm, and embryo was performed to determine TMV location within a seed, while germination tests and separation of the developing seedling into seed coat, roots, and cotyledons were conducted to estimate the percent transmission of TMV. A reverse-transcriptase quantitative PCR (RT-qPCR) assay was developed and used to determine TMV concentrations in individual seed harvested from pods that formed on plants from TMV-infected and noninfected crosses. The results showed maternal transmission of TMV to tobacco seed and seedlings that developed from infected seed, not paternal transmission. RT-qPCR and endpoint PCR assays were also conducted on the separated seed coat, endosperm, and embryo of individual seed and separated cotyledons, roots, and seed coats of individual seedlings that developed from infected tobacco seed to identify the location of the virus in the seed and the subsequent path the virus takes to infect the developing seedling. RT-qPCR and endpoint PCR assay results showed evidence of TMV infection in the endosperm and embryo, as well as in the developing seedling roots and cotyledons within 10 days of initiating seed germination. To our knowledge, this is the first report of TMV being detected in embryos of tobacco seed, demonstrating that TMV is seedborne and seed-transmitted in flue-cured tobacco.

HIV-Nef Protein Transfer to Endothelial Cells Requires Rac1 Activation and Leads to Endothelial Dysfunction Implications for Statin Treatment in HIV Patients.

RATIONALE: Even in antiretroviral therapy-treated patients, HIV continues to play a pathogenic role in cardiovascular diseases. A possible cofactor may be persistence of the early HIV response gene Nef, which we have demonstrated recently to persist in the lungs of HIV+ patients on antiretroviral therapy. Previously, we have reported that HIV strains with Nef, but not Nef-deleted HIV strains, cause endothelial proinflammatory activation and apoptosis. OBJECTIVE: To characterize mechanisms through which HIV-Nef leads to the development of cardiovascular diseases using ex vivo tissue culture approaches as well as interventional experiments in transgenic murine models. METHODS AND RESULTS: Extracellular vesicles derived from both peripheral blood mononuclear cells and plasma from HIV+ patient blood samples induced human coronary artery endothelial cells dysfunction. Plasma-derived extracellular vesicles from antiretroviral therapy+ patients who were HIV-Nef+ induced significantly greater endothelial apoptosis compared with HIV-Nef-plasma extracellular vesicles. Both HIV-Nef expressing T cells and HIV-Nef-induced extracellular vesicles increased transfer of cytosol and Nef protein to endothelial monolayers in a Rac1-dependent manner, consequently leading to endothelial adhesion protein upregulation and apoptosis. HIV-Nef induced Rac1 activation also led to dsDNA breaks in endothelial colony forming cells, thereby resulting in endothelial colony forming cell premature senescence and endothelial nitric oxide synthase downregulation. These Rac1-dependent activities were characterized by NOX2-mediated reactive oxygen species production. Statin treatment equally inhibited Rac1 inhibition in preventing or reversing all HIV-Nef-induction abnormalities assessed. This was likely because of the ability of statins to block Rac1 prenylation as geranylgeranyl transferase inhibitors were effective in inhibiting HIV-Nef-induced reactive oxygen species formation. Finally, transgenic expression of HIV-Nef in endothelial cells in a murine model impaired endothelium-mediated aortic ring dilation, which was then reversed by 3-week treatment with 5 mg/kg atorvastatin. CONCLUSIONS: These studies establish a mechanism by which HIV-Nef persistence despite antiretroviral therapy could contribute to ongoing HIV-related vascular dysfunction, which may then be ameliorated by statin treatment.

Elevated oxidative stress in the aortic media of patients with bicuspid aortic valve.

OBJECTIVE: Congenital bicuspid aortic valve (BAV) is distinctly associated with the development of ascending aortopathy in adulthood, portending risk of both ascending aortic aneurysm and dissection. Our previous work implicated deficiency in oxidative stress response as a mediator of the BAV-associated aortopathy. We hypothesize that reactive oxygen species generation invokes elevated local oxidative tissue damage in ascending aorta of patients with BAV. METHODS: Ascending aortic specimens were obtained from patients undergoing elective aortic replacement and/or aortic valve replacement and during heart transplant operations. Levels of superoxide anion were measured via high-pressure liquid chromatography-based detection of 2-hydroxyethidium in aortic specimens. Lipid peroxidation and enzymatic activity of superoxide dismutase and peroxidase were quantified in aortic specimens. RESULTS: Superoxide anion production was elevated in aortic specimens from patients with nonaneurysmal BAV (n = 59) compared with specimens from patients with the morphologically normal tricuspid aortic valve (TAV, n = 38). Total superoxide dismutase activity was similar among aortic specimens from patients with TAV versus BAV (n = 27 and 26, respectively), whereas peroxidase activity was increased in aortic specimens from patients with BAV compared with specimens from patients with TAV (n = 14 for both groups). Lipid peroxidation was elevated in aortic specimens from BAV patients compared with TAV patients (n = 14 and 11, respectively). CONCLUSIONS: Superoxide anion accumulation and increased lipid peroxidation demonstrate that, despite increased peroxidase activity, the ascending aortopathy of patients with BAV involves oxidative stress. In addition, the absence of increased superoxide dismutase activity in BAV specimens indicates a deficiency in antioxidant defense. This suggests that the characteristic smooth muscle cell loss observed in BAV aortopathy may be a consequence of superoxide-mediated cell damage.

Classification and Functional Characterization of Vasa Vasorum-Associated Perivascular Progenitor Cells in Human Aorta.

In the microcirculation, pericytes are believed to function as mesenchymal stromal cells (MSCs). We hypothesized that the vasa vasorum harbor progenitor cells within the adventitia of human aorta. Pericytes, endothelial progenitor cells, and other cell subpopulations were detected among freshly isolated adventitial cells using flow cytometry. Purified cultured pericytes were enriched for the MSC markers CD105 and CD73 and depleted of the endothelial markers von Willebrand factor and CD31. Cultured pericytes were capable of smooth muscle lineage progression including inducible expression of smooth muscle myosin heavy chain, calponin, and α-smooth muscle actin, and adopted a spindle shape. Pericytes formed spheroids when cultured on Matrigel substrates and peripherally localized with branching endothelial cells in vitro. Our results indicate that the vasa vasorum form a progenitor cell niche distinct from other previously described progenitor populations in human adventitia. These findings could have important implications for understanding the complex pathophysiology of human aortic disease.

Human iPSC-derived myocardium-on-chip with capillary-like flow for personalized medicine.

The heart wall tissue, or the myocardium, is one of the main targets in cardiovascular disease prevention and treatment. Animal models have not been sufficient in mimicking the human myocardium as evident by the very low clinical translation rates of cardiovascular drugs. Additionally, current in vitro models of the human myocardium possess several shortcomings such as lack of physiologically relevant co-culture of myocardial cells, lack of a 3D biomimetic environment, and the use of non-human cells. In this study, we address these shortcomings through the design and manufacture of a myocardium-on-chip (MOC) using 3D cell-laden hydrogel constructs and human induced pluripotent stem cell (hiPSC) derived myocardial cells. The MOC utilizes 3D spatially controlled co-culture of hiPSC derived cardiomyocytes (iCMs) and hiPSC derived endothelial cells (iECs) integrated among iCMs as well as in capillary-like side channels, to better mimic the microvasculature seen in native myocardium. We first fully characterized iCMs using immunostaining, genetic, and electrochemical analysis and iECs through immunostaining and alignment analysis to ensure their functionality, and then seeded these cells sequentially into the MOC device. We showed that iECs could be cultured within the microfluidic device without losing their phenotypic lineage commitment, and align with the flow upon physiological level shear stresses. We were able to incorporate iCMs within the device in a spatially controlled manner with the help of photocrosslinkable polymers. The iCMs were shown to be viable and functional within the device up to 7 days, and were integrated with the iECs. The iCMs and iECs in this study were derived from the same hiPSC cell line, essentially mimicking the myocardium of an individual human patient. Such devices are essential for personalized medicine studies where the individual drug response of patients with different genetic backgrounds can be tested in a physiologically relevant manner.