Community Research and Development Information Service - CORDIS



Project ID: 323182
Funded under: FP7-IDEAS-ERC
Country: Netherlands

Mid-Term Report Summary - STEMCARDIOVASC (Human Pluripotent Stem Cells: the new heart patient?)

Increases in life expectancy are being paralleled by increased prevalence of chronic, age- and lifestyle-associated disorders of the cardiovascular system. This has not been met by commensurate development of new drugs, in part because diseases like heart failure have been difficult to model in laboratory assays. 10 years ago, the advent of cellular reprogramming that turns somatic cells of the body into induced pluripotent stem cell (iPSC) with the ability to divide indefinitely and form any cell of the body, so that heart, brain or vascular cells can be generated from individuals of any ethnic background with any disease. STEMCARDIOVASC is exploiting iPSC technology to create cardiovascular disease models that will reveal underlying mechanisms of cardiac arrhythmia, fibrosis and hypertrophy, and vascular failure, allowing the identification new drug targets for treatment. At the outset, it was clear that these applications would require new methods to derive the appropriate cell types from iPSC and a new level of sophistication in bioassays to monitor disease phenotypes. The aims of STEMCARDIOVASC were (1) to develop protocols for differentiating all cells of the heart from hPSC (2) to engineer synthetic human myocardium that can model healthy tissue and measure common disease states and (3) generate hPSC representing different disease states on sets of standardized genetic backgrounds. Several of these aims have been achieved and published; others are on track to be complete by the end of the project or better “fit for purpose” alternatives have emerged. Specific outcomes are as follows:
In aim (1): we have generated a set of hPSC lines by gene targeting that express fluorescent reporters (GFP, mCherry, Turq) in various combinations in the Nkx2.5, Mesp1, CoupTFII, Etv2 and Pax3 loci (den Hartogh 2015, and in prep). Using the principles of heart development, these “rainbow lines” have allowed us to direct differentiation specificlly to atrial- (Devalla 2015) and pacemaker-like (Birket 2015a) cardiomycytes for the first time, in addition to ventricular cells (Davis 2012; Bellin 2013). Ongoing work shows that we can also derive cardiac fibroblsts and epicardium: the principle cellular components of the heart have thus been generated. Further, we have used these reporter lines to identify cell surface proteins that allow antibody-based selection of these cardiomyocyte subtypes and blood vessel cells from mixed differentiated cell population in the absence of transgenic reporters (Orlova 2014,a, b; van den Berg 2014, 2015). Finally, we have developed a unique method to expand cardiac progenitor cells from hPSC for the first time (Birket 2015a), facilitating use of screening platforms and creating new cell therapy opportunities.
In aim (2): we have created multiple cardiovascular disease models for cardiac arrhythmias (Davis 2012; Bellin 2013; Zhang 2015), cardiac hypertrophy (Birket 2015b) and vascular disease (Orlova 2014a). We have introduced the vascular endothelial cells and pericytes into microfluidic devices (van der Meer 2013) and demonstrated their functionality (Orlova 2014a, b). The generation of hiPSC models for the vascular hemorrhaging disease HHT has lead to new insight into its mechanism (defective interaction between endothelial cells and pericytes causing vessel wall weakness, enhanced vascularity) and thus indications of potential new drugs. For cardiac arrhythmia, we have generated 4 isogenic pairs of mutated (Long QT) and genetically repaired hiPSC lines and use these to examine the effects of novel allosteric drugs for disease correction. This has provided exciting opportunities to collaborate in drug development with medicinal chemists and illustrated the importance of isogenic controls (Sala, 2016, in revision).
These results extend into aim (3), where we have developed new assays for simultaneous measurement of voltage, action potential, calcium transient and force of contraction in hPSC cardiomyocytes (Ribeiro 2015, and unpublished). We have used this to demonstrate increased maturation of hPSC cardiomycoytes in the presence of small molecules (Birket 2015b) but as importantly, this new platform has allowed us to demonstrate cardiac hypertrophy as reduced force of contraction in hiPSC derived cardiomyocytes from a youth who collapsed during exercise. Neither he nor his (carrier) father knew they had a mutation in an important cardiac contraction protein.
Finally, we have made significant progress in developing 3-dimensional cardiac microtissues as complex cellular mixtures which may replace the decellularized primary heart tissue originally planned. We can simultaneously derive cardiomyocytes and endothelium in hPSC and produce matured myocardium with stable vasculature. This is now being used as an improved assay to measure force of contraction of cardiomyocytes by vector analysis and reveal drug responses and disease phenotypes, as hypothesized in the STEMCARDIOVASC proposal. The project as a whole is on track.

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