Since the adult heart has minimal capacity to repair itself, myocardial infarction often leads to pathological remodeling and ultimately to the development of fatal heart failure. Upon ischemic... Show moreSince the adult heart has minimal capacity to repair itself, myocardial infarction often leads to pathological remodeling and ultimately to the development of fatal heart failure. Upon ischemic injury, the epicardium, the outer layer of the heart which is essential for cardiac development, becomes re-activated and displays reparative potential. In this process, epicardial epithelial-to-mesenchymal transition (epiMT) is an essential step. We hypothesize that the reparative capacity of the heart can be improved by enhancing the participation of the epicardium to cardiac repair, particularly by stimulating the occurrence of epiMT. Therefore, the aim of my thesis is to find ways to boost epiMT in the injured heart. In this thesis, we describe a cell culture model which allows us to study epiMT. Using this model, we identify novel epiMT regulators. Because EMT is also involved in pathological remodeling, application of an epiMT stimulator should be transient and local. Therefore, we describe a method to locally administer these factors to the injured mouse heart. Show less
This thesis describes the potential use of these cardiac progenitor-derived extracellular vesicles (EVs) for cardiac repair and focused on translational aspects that could accelerate clinical... Show moreThis thesis describes the potential use of these cardiac progenitor-derived extracellular vesicles (EVs) for cardiac repair and focused on translational aspects that could accelerate clinical implementation of EV-based therapeutics. The first steps have been made in optimizing EV production processes such as EV isolation and storage. Furthermore, this thesis described a potential method for sustained EV release and to prolong therapeutic exposure by using a hydrogel. Ultimately, this could contribute to improved efficacy upon local delivery of EV therapeutics. Together, this thesis potentially contributes to fasten clinical adoption of EV-based therapeutics for patients with heart failure. Show less
General aim of this thesis, entitled Guide to the heart, was to explore the generation of multiple human pluripotent stem cell (hPSC)-derived cardiac subtypes and their application for selective... Show moreGeneral aim of this thesis, entitled Guide to the heart, was to explore the generation of multiple human pluripotent stem cell (hPSC)-derived cardiac subtypes and their application for selective pharmacology, understanding human cardiac development and cardiac repair.Approaches for the differentiation of hPSCs to cardiomyocytes (CMs) followed by purification from heterogeneous cultures are described. To generate subtype specific CMs, a protocol for the derivation and characterization of hPSC-derived CMs with atrial identity was developed. HPSC-derived atrial CMs have proven successful as pre-clinical pharmacological tool. The development of a human atrial reporter by CRISPR/Cas9-mediated knockin of red fluorescent mCherry into the genomic locus of atrial-enriched COUP-TFII allowed the selection of atrial and ventricular CMs. In addition, we evaluated the importance of COUP-TFII for atrial differentiation of hPSC and identified that COUP-TFII is dispensable for atrial differentiation of hPSCs. Importantly, hPSC-derived cardiac progenitors (CPCs) alleviated ventricular remodeling and fibrosis after transplantation to the heart in an acute myocardial infarction model in mice. This thesis ends with a review of the native cardiac environment during development, as well as the adult heart in health and disease. This was used to describe current knowledge regarding extracellular matrix preferences for engineering cardiac tissues from hPSC-CMs. Show less
Hereditary hemorrhagic telangiectasia (HHT) or Rendu-Osler-Weber disease, is a rare genetic disorder, known for its endothelial dysplasia causing vessel malformations, severe nose bleeds and... Show moreHereditary hemorrhagic telangiectasia (HHT) or Rendu-Osler-Weber disease, is a rare genetic disorder, known for its endothelial dysplasia causing vessel malformations, severe nose bleeds and internal bleedings. In the majority of patients mutations are found in genes belonging to the TGFβ superfamily, causing a disbalance in the TGFβ signaling pathway by haploinsufficiency of the remaining functional protein. In this thesis we studied different aims and approaches to influence HHT1-MNC homing and differentiation to restore their contribution to tissue repair. In various experimental methods inducing ischemic and/or direct tissue damage, we aimed to improve tissue repair in the Eng+/- mice. Using DPP4 inhibition, we increased the SDF1-CXCR4 homing mechanism, to restore the impaired homing capacity of the HHT1-MNCs. Furthermore, we focused on correcting the M1/M2 differentiation in Eng+/- mice. Via use of the BMP receptor inhibitor LDN we aimed to restore the skewed BMP/TGFβ signaling; stimulating the TGFβ pathway signaling to induce M2 differentiation. We concluded that DPP4 inhibition can be used to improve the HHT1 immune system and tissue repair, and is best used in concert with other drugs or therapies that stimulate cardiac or tissue repair, like anti-coagulants or cell therapy. Show less
