Stefan Braam

Stefan Braam

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58
Publications
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2,792
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Publications

Publications (58)
Article
Full-text available
Novel studies conducting cardiac safety assessment using human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are promising but might be limited by their specificity and predictivity. It is often challenging to correctly classify ion channel blockers or to sufficiently predict the risk for Torsade de Pointes (TdP). In this study,...
Article
Full-text available
Aims: Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have proven valuable for studies in drug discovery and safety, although limitations regarding their structural and electrophysiological characteristics persist. In this study, we investigated the electrophysiological properties of Pluricyte® CMs, a commercially available...
Article
Full-text available
Safety pharmacology is an essential part of drug development aiming to identify, evaluate and investigate undesirable pharmacodynamic properties of a drug primarily prior to clinical trials. In particular, cardiovascular adverse drug reactions (ADR) have halted many drug development programs. Safety pharmacology has successfully implemented a scree...
Conference Paper
Safety pharmacology studies that evaluate drug candidates for potential cardiovascular liabilities remain a critical component of drug development. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have recently emerged as a new and promising tool for preclinical hazard identification and risk assessment of drugs. Recently, Plu...
Article
Full-text available
Multi electrode arrays (MEAs) are increasingly used to detect external field potentials in electrically active cells. Recently, in combination with cardiomyocytes derived from human (induced) pluripotent stem cells they have started to become a preferred tool to examine newly developed drugs for potential cardiac toxicity in pre-clinical safety pha...
Article
Full-text available
Differentiated derivatives of human pluripotent stem cells (hPSCs) are often considered immature because they resemble foetal cells more than adult, with hPSC-derived cardiomyocytes (hPSC-CMs) being no exception. Many functional features of these CMs, such as their cell morphology, electrophysiological characteristics, sarcomere organization and co...
Article
Full-text available
Cardiomyocytes Under…?>Human embryonic stem cells (hESCs) and induced pluripotent stem cells (hiPSCs) can differentiate to cardiomyocytes in vitro, offering unique opportunities to investigate cardiac development and disease as well as providing a platform to perform drug and toxicity tests. Initial cardiac differentiation methods were based on eit...
Article
Full-text available
It has been known for over 20 years that foetal calf serum can induce hypertrophy in cultured cardiomyocytes but this is rarely considered when examining cardiomyocytes derived from pluripotent stem cells (PSC). Here, we determined how serum affected cardiomyocytes from human embryonic- (hESC) and induced pluripotent stem cells (hiPSC) and hiPSC fr...
Chapter
In this chapter we outline a basic protocol for the differentiation of hESCs into cardiomyocytes. The method is based on the formation of aggregates of a standard size using a fixed number of undifferentiated cells in each aggregate. The aggregates are formed by centrifugation of the cells into embryoid body (EB)-like structures and are referred to...
Article
Unexpected induction of arrhythmias in the heart is still one of the major risks of new drugs despite recent improvements in cardiac safety assays. Here we address this in a novel emerging assay system. Eleven reference compounds were administrated to spontaneously beating clusters of cardiomyocytes from human pluripotent stem cells (hPSC-CM) and t...
Conference Paper
In this paper we present a “polymer-last” approach for the fabrication of (partly) flexible and stretchable sensors assemblies. The “Flex-to-Rigid” (F2R) platform is based on this approach and especially designed for the fabrication of very small sensor systems which can be folded into, or around the tip of minimal invasive instruments such as lapa...
Conference Paper
Full-text available
A platform for the batch fabrication of pneumatically actuated Stretchable Micro-Electrode Arrays (SMEAs) by using state-of-the-art micro-fabrication techniques and materials is demonstrated. The proposed fabrication process avoids the problems normally associated with processing of thin film structures on polydimethylsiloxane (PDMS), by first fabr...
Chapter
Drugs are substances that when absorbed into the body of a living organism alter cellular behavior and correct abnormal body function. Natural and synthetic drugs have been developed for their ability to treat a wide variety of diseases. They must interact at the molecular level with either a component of the body or with an infectious micro-organi...
Article
Full-text available
NKX2-5 is expressed in the heart throughout life. We targeted eGFP sequences to the NKX2-5 locus of human embryonic stem cells (hESCs); NKX2-5(eGFP/w) hESCs facilitate quantification of cardiac differentiation, purification of hESC-derived committed cardiac progenitor cells (hESC-CPCs) and cardiomyocytes (hESC-CMs) and the standardization of differ...
Article
Introduction: The field of cardiac safety pharmacology has been experiencing exciting changes over the recent years. Drug induced arrhythmia of the torsade des pointes types has been the reason for the denial of approval of novel drug candidates. The aim of cardiac safety pharmacology is to detect undesirable pharmacodynamic drug effects within an...
Article
Recent advances in pluripotent stem cell biology now make it possible to generate human cardiomyocytes in vitro from both healthy individuals and from patients with cardiac abnormalities. This offers unprecedented opportunities to study cardiac disease development 'in a dish' and establish novel platforms for drug discovery, either to prevent disea...
Article
Full-text available
A novel stretchable Micro-Electrode Array (MEA) for biomedical applications with robust spiraled interconnects and radial micro-grooves for cell alignment is presented, enabling the unique combination of alignment, mechanical stimulation, and electrical characterization of living cells. Many of the problems normally associated with the fabrication...
Article
Derivation of heart and vascular endothelial cells from human pluripotent stem cells (embryonic stem cells or HESCs and induced pluripotency stem cells or hiPS cells) is an area of growing interest both as a route to cell therapy for the heart and as a platform for drug discovery and toxicity. Understanding the underlying developmental mechanisms t...
Article
Full-text available
The Publisher regrets that this article is an accidental duplication of an article that has already been published, doi:10.1016/j.scr.2010.04.004. The duplicate article has therefore been withdrawn.
Article
The absence of identified cell surface proteins and corresponding antibodies to most differentiated derivatives of human embryonic stem cells (hESCs) has largely limited selection of specific cell types from mixed cell populations to genetic approaches. Here, we describe the use of mass spectrometry (MS)-based proteomics on cell membrane proteins i...
Article
Recent withdrawals of prescription drugs from clinical use because of unexpected side effects on the heart have highlighted the need for more reliable cardiac safety pharmacology assays. Block of the human Ether-a-go go Related Gene (hERG) ion channel in particular is associated with life-threatening arrhythmias, such as Torsade de Pointes (TdP). H...
Article
In recent years the differentiation efficiency of human embryonic stem cells (hESCs) to cardiomyocytes has improved considerably. In general, hESC-derived cardiomyocytes are formed in aggregates, which require dissociation for follow-up experimental analyses and (clinical) applications. Here, we show that inhibition of the Rho-associated kinase (RO...
Article
Generic methods for genetic manipulation of human embryonic stem cells (hESCs) are important for both present research and future commercial applications. To date, differences in cell derivation and culture have required independent optimization of transfection and transduction protocols and some lines have remained refractile to all methods. Here...
Article
Full-text available
Human embryonic stem cells (hESC) hold great potential as a model for human development, disease pathology, drug discovery and safety pharmacology. All these applications will depend on comprehensive knowledge of their biology and control of their signaling mechanisms and fate choices. To begin to address this, we developed a standardized feeder-fr...
Article
Stem cells derived from pre-implantation human embryos or from somatic cells by reprogramming are pluripotent and self-renew indefinitely in culture. Pluripotent stem cells are unique in being able to differentiate to any cell type of the human body. Differentiation towards the cardiac lineage has attracted significant attention, initially with a s...
Article
Pluripotent stem cells self-renew indefinitely and possess characteristic protein-protein networks that remodel during differentiation. How this occurs is poorly understood. Using quantitative mass spectrometry, we analyzed the (phospho)proteome of human embryonic stem cells (hESCs) during differentiation induced by bone morphogenetic protein (BMP)...
Article
Full-text available
Human embryonic stem cells (hESCs) are often cocultured on mitotically inactive fibroblast feeder cells to maintain their undifferentiated state. Under these growth conditions, hESCs form multilayered colonies of morphologically heterogeneous cells surrounded by flattened mesenchymal cells. In contrast, hESCs grown in feeder cell-conditioned medium...
Article
Full-text available
Defined growth conditions are essential for many applications of human embryonic stem cells (hESC). Most defined media are presently used in combination with Matrigel, a partially defined extracellular matrix (ECM) extract from mouse sarcoma. Here, we defined ECM requirements of hESC by analyzing integrin expression and ECM production and determine...
Article
Human embryonic stem cells (hESCs) are of immense interest in regenerative medicine as they can self-renew indefinitely and can give rise to any adult cell type. Human embryonal carcinoma cells (hECCs) are the malignant counterparts of hESCs found in testis tumors. hESCs that have acquired chromosomal abnormalities in culture are essentially indist...
Article
Full-text available
Low efficiency of transfection limits the ability to genetically manipulate human embryonic stem cells (hESCs), and differences in cell derivation and culture methods require optimization of transfection protocols. We transiently transferred multiple independent hESC lines with different growth requirements to standardized feeder-free culture, and...
Article
Human embryonic stem cells (hESC) can differentiate to cardiomyocytes in vitro but with generally poor efficiency. Here, we describe a novel method for the efficient generation of cardiomyocytes from hESC in a scalable suspension culture process. Differentiation in serum-free medium conditioned by the cell line END2 (END2-CM) readily resulted in di...
Article
Full-text available
Realizing the potential of human embryonic stem cells (hESCs) in research and commercial applications requires generic protocols for culture, expansion and genetic modification that function between multiple lines. Here we describe a feeder-free hESC culture protocol that was tested in 13 independent hESC lines derived in five different laboratorie...
Article
Full-text available
Chemotherapy, including microtubule (MT)-interacting agents, can enhance the tumor-eradicating activity of replication-competent adenoviruses. The purpose of this study was to obtain more insight into the mechanism underlying this enhancement that may be exploited for the development of improved therapy. Two MT-interacting agents with opposite acti...
Article
Oncolytic adenoviruses are exploited as possible anticancer agents in clinical trails. To monitor adenoviral gene expression, a real-time RT-PCR method with a LightCycler was developed that allows the rapid and easy quantification of a number of early and late adenoviral genes in infected tumor cells. Primers were designed that can amplify the spli...
Article
Almost 7 years after their first derivation from human embryos, a pressing urgency to deliver the promises of therapies based on human embryonic stem cells (hESC) has arisen. Protocols have been developed to support long-term growth of undifferentiated cells and partially direct differentiation to specific cell lineages. The stage has almost been s...

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