Vascular diseases pose a significant burden on society, mainly due to the lack of effective treatment methods. A major reason for this is the shortcomings of current preclinical model systems. In... Show moreVascular diseases pose a significant burden on society, mainly due to the lack of effective treatment methods. A major reason for this is the shortcomings of current preclinical model systems. In this study, we have taken steps toward developing a more complex and relevant model system for (brain) blood vessels to address this issue. We used human induced pluripotent stem cells (hiPSCs) in the lab as a cellular source to generate the different types of cells needed for stable blood vessels. These cells were then combined in 3D microscopic culture environments (so-called vessel-on-chip systems) to closely mimic physiological conditions. Using this model, we were able to demonstrate specific abnormalities in a hereditary vascular disease, which was not possible with more 'traditional' culture methods. Additionally, we included brain cells to better investigate brain-specific disorders in the future. This work lays the essential foundation for a better understanding and treatment of complex vascular diseases, while potentially reducing the number of animal models needed. Show less
Complexity is not necessarily expected from monogenic diseases but for many cardiovascular diseases (CVD), simple genotype-phenotype relationship may be far from reality. As millions of people... Show moreComplexity is not necessarily expected from monogenic diseases but for many cardiovascular diseases (CVD), simple genotype-phenotype relationship may be far from reality. As millions of people globally die of CVD, it is important to find models to study CVD that recapitulate the conditions as manifest in humans, most importantly for these cases of unexpected complexity. For these, simple gene mutation or deletion in mice has often failed. Combining human induced pluripotent stem cell (hiPSC) with genetic editing technologies is providing new opportunities to bridge the gap, with many hPSC-CM models now showing promising results for testing drugs, discovering molecular pathways associated with disease and other types of (gene) therapies. The work in this thesis contributes to this area of research. Show less
Gartner, T.C.L.B.; Wang, Y.; Leiteris, L.; Adrichem, I. van; Marsman, J.; Goumans, M.J.; ... ; Hjortnaes, J. 2023
In cardiac fibrosis, in response to stress or injury, cardiac fibroblasts deposit excessive amounts of collagens which contribute to the development of heart failure. The biochemical stimuli in... Show moreIn cardiac fibrosis, in response to stress or injury, cardiac fibroblasts deposit excessive amounts of collagens which contribute to the development of heart failure. The biochemical stimuli in this process have been extensively studied, but the influence of cyclic deformation on the fibrogenic behavior of cardiac fibroblasts in the ever-beating heart is not fully understood. In fact, most investigated mechanotransduction pathways in cardiac fibroblasts seem to ultimately have profibrotic effects, which leaves an important question in cardiac fibrosis research unanswered: how do cardiac fibroblasts stay quiescent in the ever-beating human heart? In this study, we developed a human cardiac fibrosis-on-a-chip platform and utilized it to investigate if and how cyclic strain affects fibrogenic signaling. The pneumatically actuated platform can expose engineered tissues to controlled strain magnitudes of 0–25% – which covers the entire physiological and pathological strain range in the human heart – and to biochemical stimuli and enables high-throughput screening of multiple samples. Microtissues of human fetal cardiac fibroblasts (hfCF) embedded in gelatin methacryloyl (GelMA) were 3D-cultured on this platform and exposed to strain conditions which mimic the healthy human heart. The results provide evidence of an antifibrotic effect of the applied strain conditions on cardiac fibroblast behavior, emphasizing the influence of biomechanical stimuli on the fibrogenic process and giving a detailed overview of the mechanosensitive pathways and genes involved, which can be used in the development of novel therapies against cardiac fibrosis. Show less
The aim of this thesis was to combine transcriptomics, genetics and human disease modelling to obtain further insight into molecular processes underlying osteoarthritis. More specifically, we aimed... Show moreThe aim of this thesis was to combine transcriptomics, genetics and human disease modelling to obtain further insight into molecular processes underlying osteoarthritis. More specifically, we aimed to elucidate the role of long noncoding RNAs expression changes as aberrant epigenetic mechanism in regulating gene expression in chondrocytes. We identified previously unknown long noncoding RNAs associated with the osteoarthritic process and showed enrichment for cis¬-regulation of these long noncoding RNAs with target messenger RNAs.To provide insight in the etiology of osteoarthritis, causal pathways can be identified by unravelling the substantial genetic component. To this end, we investigated the biological functionality of the high-impact, pathogenic mutation identified in the gene fibronectin1 in an early-onset osteoarthritis family. We demonstrated that the identified causal missense mutation in the gelatin-binding domain of the extracellular matrix protein fibronectin resulted in significant decreased binding capacity to collagen type II.Finally, the common function of fibronectin1 was investigated in cartilage and what changes occur at the transcript level of fibronectin1 with osteoarthritis. Down-regulation of full-length fibronectin was unbeneficial for in vitro chondrogenesis, we hypothesize that this was caused by decreased availability of the classical integrin binding site of fibronectin. Show less
One of the main challenges in the clinical management of patients with monogenic cardiac disease patients is the clinical heterogeneity in disease severity. Clinical manifestation of congenital... Show moreOne of the main challenges in the clinical management of patients with monogenic cardiac disease patients is the clinical heterogeneity in disease severity. Clinical manifestation of congenital long QT syndrome type 2 (LQT2) can range from the absence of symptoms to life-threatening arrhythmia episodes. Insight into the genetic etiology could advance clinical-decision making and guide the development of tailored medicine strategies. The focus of this thesis was twofold, 1) to validate technical procedures to store hiPSC-CMs and 2) to investigate genetic variant pathogenicity and unravel variable disease expressivity in genetically-matched hiPSC-CM models with LQT2-associated variants. First we established cryopreservation as an opportune method to store hiPSC-CMs with molecular and functional characteristics being retained after thaw and recovery. Second, we demonstrate the potential of hiPSC-CMs to reveal the inherent severity of KCNH2 mutations when using genetically-matched lines with KCNH2 mutations either located in different regions of the affected cardiac ion channel, in conjunction with a common single nucleotide, or a compound heterozygous mutation. Show less
