ReviewPost ScreenPreclinical assessment of cardiac toxicity
Section snippets
In vivo cardiac models
Before a potential drug candidate can be progressed into clinical studies, the regulatory guidelines require in vivo studies to be performed in animal models.
Toxicological studies are mainly performed in rodents (rat, mice and rabbit) but also have to be performed in non-rodent models if the rodent models lack relevance to humans (see: http://www.emea.europa.eu/pdfs/human/swp/2836707en.pdf).
To assess the potential of drugs to delay ventricular repolarization for safety pharmacology the draft of
Explanted hearts and cardiac tissue
Langendorff-perfused explanted hearts of guinea pig and rabbits 10, 11, 12, as well as preparations of cardiac tissue like papillary muscle or purkinje fibres from guinea pig or dog [13], are common models in cardiac safety pharmacology and belong to the ‘Gold Standard’ of test batteries for the investigation of new chemical entities prior to clinical trials [3].
Explanted rat hearts have been applied to investigate aspects of injuries induced by ischemic reperfusion [14], for example apoptosis
Engineered cardiac tissues
Several attempts have been made to generate three-dimensional cardiac tissues, mainly from the aspect of replacement therapy. Recent publications have described engineered tissues from dissociated embryonic chicken or neonatal rat hearts [17] and wild type embryonic stem cell-derived murine or human cardiomyocytes 18, 19, 20.
So far, strategies to introduce engineered cardiac tissues for long-term and chronic toxicity or electrophysiological screening of pharmaceutical compounds have not yet
Primary cardiomyocytes
Primary cardiomyocytes isolated from different species at different stages of development (neonatal, adult) represent established models in toxicological and physiological test systems.
The advantages of primary cells are manifold. All ion channels underlying the cardiac action potential can be measured functionally in their native cellular environment and state, and high-content physiological data can be obtained that predicts the complex interaction of ion channel activities [24].
Fetal
Cell lines
Several attempts to generate cardiomyocyte-like cell lines have been made to overcome the limitation of primary cell preparations. One of the first directed experiments was the transgenic expression of the viral large T-antigen under the control of the atrial natriuretic factor (ANF) promoter in the mouse, which led to the generation of the atrial tumor cell line AT-1 [28]. These cells were neither capable of serial passaging in culture, nor freezing and had to be propagated as a subcutaneous
Primary-like embryonic stem cell-derived cardiomyocytes
The first embryonic stem cell lines from mouse were described in 1981 40, 41 and generation of the well-known cell line D3 and its differentiation into cardiac myocytes was published in 1985 by Doetschman et al. [42]. Almost 20 years later, the generation of human ES cells and differentiation into cardiomyocytes were described 43, 44.
One disadvantage of these wild type ES cell-derived cardiomyocytes is that the remaining amount of undifferentiated ES cells, as well as other proliferative cell
Biomarkers of cardiac damage
To expand further the descriptive capacity of ES cell-derived cardiomyocytes, biomarker release has also been studied. The term ‘biomarker’ was standardized by an NIH working group in 2001 as ‘a characteristic that is both effectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacological response to a therapeutic intervention’ [52]. At present, there are only a few accepted biomarkers for cardiac damage that can be measured in biological
Conclusion
Taken together, there is growing evidence that ES cell-derived cardiomyocytes provide a highly relevant and robust system to detect accurately the cardiotoxic potential of compounds. Since ES cell-derived cardiomyocytes can be stored as pre-seeded multiwell plates and pre-seeded coverslips, the use of such a system for medium to high throughput screening at early stages of drug development is favorable. Even more, because of its high physiological relevance and clinical predictive qualities,
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