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CaMKII over stimulation in engineered heart tissues (EHTs) made from human induced pluripotent stem cells (hiPSCs): a parameter involved in the immaturity of hiPSC EHTs cardiomyocytes?

Periodic Reporting for period 1 - EHT-CaMKII (CaMKII over stimulation in engineered heart tissues (EHTs) made from human induced pluripotent stem cells (hiPSCs): a parameter involved in the immaturity of hiPSC EHTs cardiomyocytes?)

Reporting period: 2016-04-01 to 2018-03-31

In Europe, as observed in other parts of the world, cardiovascular diseases represent the leading cause of death. The engineering of 3 dimensions (3D) heart tissues (EHTs) technology may represent a promising technique to treat pathologies characterised by a decrease/loss of cardiac function. Taking advantage of the recent availability of human induced pluripotent stem cells (hiPSCs), our laboratory developed a protocol to produce contractile human cardiac tissue (hEHT) from hiPSC-differentiated cardiomyocytes (CMs) (Breckwoldt et al., 2017). If their use is source of hope for numerous applications among which patient cardiac repair, and despite the major advances in EHT technology, CMs still do not acquire a fully mature phenotype. The objective of the project was focused on EHT technology improvement, with particular attention to improving the degree of maturation of CMs (see image attached to the summary).
First, we could precise maturation default characteristics of EHT cardiomyocytes (CMs) and determine reliable read-outs for CMs maturation assessment. By measuring CaMKII protein activity, we could show that CaMKII was both present and active in EHT constitutive CMs. Unfortunately, the pharmacological inhibition of CaMKII did not show any sign of EHT-CMs maturation level improvement but, on the contrary, showed signs of a worsened maturation compared to the control group. Despite many attempts to solve this problem, we were not able to overcome it as these maturation defects may be linked with the emerging role of this protein kinase in physiological heart development during embryogenesis and particularly in regulating cardiac gene expression to insure a correct cardiac differentiation and maturation. These negative results forced us to reorient the project onto another interesting way to develop the EHT technology: the study of CMs proliferation within EHTs. This project arose from data obtained during the development of a new protocol to isolate CMs from EHTs as part of the initial project.
Potential impacts are based on the results which will follow from the ongoing projects. This encompass a technical project directly ensuing the initial project and centred on the development of a new protocol to isolate CMs from EHTs, and a project resulting from the reorientation of the EHT-CaMKII project which is focused on CMs proliferation within EHTs. These new project axis should give new opportunities for results dissemination by giving rise to the publication of both the new methods developped and the results obtained. They should also give new opportunities for their exploitation to improve hEHT engraftment and consequently heart remuscularization, the long-term final objective being to pursue the technology improvement towards a first human engraftment of hiPSC-EHTs.
hiPSC-EHT-CMs maturation: Picture of an EHT (A), CMs IF pictures 4 (B) and 50 (C) days after casting