Biomimetic electrical stimulation for cardiac tissue engineering

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.Includes bibliographical references (leaves 66-69).A major challenge of tissue engineering is directing cells to establish the physiological structure and function of the tissue being replaced. Electrical stimulation has been used to induce synchronous contractions of cultured cardiac constructs. The hypothesis adopted for this study is that functional cardiac constructs can be engineered by "mimicking" the conditions present during cardiac development, and in particular, electrical stimulation using supra-threshold signals. For this Master's Thesis research, I have compared the material properties and charge-transfer characteristics at the electrode-electrolyte interface of various biocompatible materials, including carbon, stainless steel, titanium and titanium nitride, for use as electrodes in a biomimetic system for cardiac tissue engineering. I have also designed and implemented an electrical stimulator which is capable of modulating several important parameters of electrical stimulation, including stimulus amplitude and frequency.(cont.) In addition, I have built an experimental setup incorporating this electrical stimulator and used it for experiments with C2C12 mouse myoblast cells and neonatal rat cardiomyocytes. Lastly, I have analyzed cell morphology as well as functional performance of engineered tissue by assessing excitation thresholds and maximum capture rates.by Nina Tandon.S.M

Surface-Patterned Electrode Bioreactor for Electrical Stimulation

We present a microscale cell culture system with an interdigitated microarray of excimer-laser-ablated indium tin oxide electrodes for electrical stimulation of cultured cells. The system has been characterized in a range of geometeries and stimulation regimes via electrochemical impedance spectroscopy and used to culture primary cardiomyocytes and human adipose derived stem cells. Over 6 days of culture with electrical stimulation (2 ms duration, 1 Hz, 180 μm wide electrodes with 200 μm spacing), both cell types exhibited enhanced proliferation, elongation and alignment, and adipose derived stem cells exhibited higher numbers of Connexin-43-composed gap junctions

Increased deep sleep in a medication-free, detoxified female offender with schizophrenia, alcoholism and a history of attempted homicide: Case report

BACKGROUND: Psychiatric sleep research has attempted to identify diagnostically sensitive and specific sleep patterns associated with particular disorders. Both schizophrenia and alcoholism are typically characterized by a severe sleep disturbance associated with decreased amounts of slow wave sleep, the physiologically significant, refreshing part of the sleep. Antisocial behaviour with severe aggression, on the contrary, has been reported to associate with increased deep sleep reflecting either specific brain pathology or a delay in the normal development of sleep patterns. The authors are not aware of previous sleep studies in patients with both schizophrenia and antisocial personality disorder. CASE PRESENTATION: The aim of the present case-study was to characterize the sleep architecture of a violent, medication-free and detoxified female offender with schizophrenia, alcoholism and features of antisocial personality disorder using polysomnography. The controls consisted of three healthy, age-matched women with no history of physical violence. The offender's sleep architecture was otherwise very typical for patients with schizophrenia and/or alcoholism, but an extremely high amount of deep sleep was observed in her sleep recording. CONCLUSIONS: The finding strengthens the view that severe aggression is related to an abnormal sleep pattern with increased deep sleep. The authors were able to observe this phenomenon in an antisocially behaving, violent female offender with schizophrenia and alcohol dependence, the latter disorders previously reported to be associated with low levels of slow wave sleep. New studies are, however, needed to confirm and explain this preliminary finding

Basic science232. Certolizumab pegol prevents pro-inflammatory alterations in endothelial cell function

Background: Cardiovascular disease is a major comorbidity of rheumatoid arthritis (RA) and a leading cause of death. Chronic systemic inflammation involving tumour necrosis factor alpha (TNF) could contribute to endothelial activation and atherogenesis. A number of anti-TNF therapies are in current use for the treatment of RA, including certolizumab pegol (CZP), (Cimzia ®; UCB, Belgium). Anti-TNF therapy has been associated with reduced clinical cardiovascular disease risk and ameliorated vascular function in RA patients. However, the specific effects of TNF inhibitors on endothelial cell function are largely unknown. Our aim was to investigate the mechanisms underpinning CZP effects on TNF-activated human endothelial cells. Methods: Human aortic endothelial cells (HAoECs) were cultured in vitro and exposed to a) TNF alone, b) TNF plus CZP, or c) neither agent. Microarray analysis was used to examine the transcriptional profile of cells treated for 6 hrs and quantitative polymerase chain reaction (qPCR) analysed gene expression at 1, 3, 6 and 24 hrs. NF-κB localization and IκB degradation were investigated using immunocytochemistry, high content analysis and western blotting. Flow cytometry was conducted to detect microparticle release from HAoECs. Results: Transcriptional profiling revealed that while TNF alone had strong effects on endothelial gene expression, TNF and CZP in combination produced a global gene expression pattern similar to untreated control. The two most highly up-regulated genes in response to TNF treatment were adhesion molecules E-selectin and VCAM-1 (q 0.2 compared to control; p > 0.05 compared to TNF alone). The NF-κB pathway was confirmed as a downstream target of TNF-induced HAoEC activation, via nuclear translocation of NF-κB and degradation of IκB, effects which were abolished by treatment with CZP. In addition, flow cytometry detected an increased production of endothelial microparticles in TNF-activated HAoECs, which was prevented by treatment with CZP. Conclusions: We have found at a cellular level that a clinically available TNF inhibitor, CZP reduces the expression of adhesion molecule expression, and prevents TNF-induced activation of the NF-κB pathway. Furthermore, CZP prevents the production of microparticles by activated endothelial cells. This could be central to the prevention of inflammatory environments underlying these conditions and measurement of microparticles has potential as a novel prognostic marker for future cardiovascular events in this patient group. Disclosure statement: Y.A. received a research grant from UCB. I.B. received a research grant from UCB. S.H. received a research grant from UCB. All other authors have declared no conflicts of interes

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors

Background Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. Methods We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors. Results Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged. Conclusions Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.Peer reviewe

Live imaging of stem cells in the germarium of the Drosophila ovary using a reusable gas-permeable imaging chamber

Live imaging of stem cells and their support cells can be used to visualize cellular dynamics and fluctuations of intracellular signals, proteins, and organelles in order to better understand stem cell behavior in the niche. We describe a simple protocol for imaging stem cells in the Drosophila ovary that improves on alternative protocols in that flies of any age can be used, dissection is simplified because the epithelial sheath that surrounds each ovariole need not be removed, and ovarioles are imaged in a closed chamber with a large volume of medium that buffers oxygen, pH, and temperature. We also describe how to construct the imaging chamber, which can be easily modified and used to image other tissues and non-adherent cells. Imaging is limited by follicle cells moving out of the germarium in culture around the time of egg chamber budding; however, the epithelial sheath delays this abnormal cell migration. This protocol requires an hour to prepare the ovarioles, followed by half an hour on the confocal microscope to locate germaria and set z limits. Successful imaging time depends on germarial morphology at the time of dissection, but we suggest 10-11 h to encompass all specimens

Electrical stimulation of human embryonic stem cells: Cardiac differentiation and the generation of reactive oxygen species.

none7Exogenous electric fields have been implied in cardiac differentiation of mouse embryonic stem cells and the generation of reactive oxygen species (ROS). In this work, we explored the effects of electrical field stimulation on ROS generation and cardiogenesis in embryoid bodies (EBs) derived from human embryonic stern cells (hESC, line H13), using a custom-built electrical stimulation bioreactor. Electrical properties of the bioreactor system were characterized by electrochemical impedance spectroscopy (EIS) and analysis of electrical currents. The effects of the electrode material (stainless steel, titanium-nitride-coated titanium, titanium), length of stimulus ( 1 and 90 s) and age of EBs at the onset of electrical stimulation (4 and 8 days) were investigated with respect to ROS generation. The amplitude of the applied electrical field was 1 V/mm. The highest rate of ROS generation was observed for stainless steel electrodes, for signal duration of 90 s and for 4-day-old EBs. Notably, comparable ROS generation was achieved by incubation of EBs with 1 nM H(2)O(2). Cardiac differentiation in these EBs was evidenced by spontaneous contractions, expression of troponin T and its sarcomeric organization. These results imply that electrical stimulation plays a role in cardiac differentiation of hESCs, through mechanisms associated with the intracellular generation of ROS.mixedE SERENA; E FIGALLO; N TANDON; C CANNIZZARO; S GERECHT; ELVASSORE N.; G VUNJAK-NOVAKOVICSerena, Elena; Figallo, Elisa; N., Tandon; C., Cannizzaro; S., Gerecht; Elvassore, Nicola; G., VUNJAK NOVAKOVI

Electrical stimulation via a biocompatible conductive polymer directs retinal progenitor cell differentiation

The goal of this study was to simulate in vitro the spontaneous electrical wave activity associated with retinal development and investigate if such biometrically designed signals can enhance differentiation of mouse retinal progenitor cells (mRPC). To this end, we cultured cells on an electroconductive transplantable polymer, polypyrrole (PPy) and measured gene expression and morphology of the cells. Custom-made 8-well cell culture chambers were designed to accommodate PPy deposited onto indium tin oxide-coated (ITO) glass slides, with precise control of the PPy film thickness. mRPCs were isolated from post-natal day 1 (P1) green fluorescent protein positive (GFP+) mice, expanded, seeded onto PPY films, allowed to adhere for 24 hours, and then subjected to electrical stimulation (100 μA pulse trains, 5 s in duration, once per minute) for 4 days. Cultured cells and non-stimulated controls were processed for immunostaining and confocal analysis, and for RNA extraction and quantitative PCR. Stimulated cells expressed significantly higher levels of the early photoreceptor marker cone-rod homebox (CRX, the earliest known marker of photoreceptor identity), and protein kinase-C (PKC), and significantly lower levels of the glial fibrillary acidic protein (GFAP). Consistently, stimulated cells developed pronounced neuronal morphologies with significantly longer dendritic processes and larger cell bodies than non-stimulated controls. Taken together, the experimental evidence shows that the application of an electrical stimulation designed based on retinal development can be implemented to direct and enhance retinal differentiation of mRPCs, suggesting a role for biomimetic electrical stimulation in directing progenitor cells toward neural fates