A bicuspid aortic valve (BAV) is a congenital heart defect in which the heart valve between the left ventricle and the aorta consists of two valve flaps instead of the normal three (tricuspid... Show moreA bicuspid aortic valve (BAV) is a congenital heart defect in which the heart valve between the left ventricle and the aorta consists of two valve flaps instead of the normal three (tricuspid aortic valve – TAV). In a large proportion of people with a BAV, calcification of the heart valves or a widening of the aorta occurs early in life. It is not yet clear why patients with a BAV are prone to develop valvular calcification and aortic dilatation. The aim of the research described in this thesis is to study the pathogenesis of aortic valve calcification and aortic dilatation in BAV patients with a focus on the role of endothelial cells in these processes. With the research described in this thesis, we have shown that endothelial cells from BAV patients respond differently than cells from people with a TAV. In addition, the endothelial cell activation in the vascular wall of BAV patients is different and dependent on the blood flow. We found two good tissue culture methods to study heart valve calcification and used them to study the role of the protein FHL2 in this process. Show less
Kruithof, B.P.T.; Pol, V. van de; T. los; Lodder, K.; Gourabi, B.M.; DeRuiter, M.C.; ... ; Marsan, N.A. 2021
Calcific aortic valve disease (CAVD) is a common progressive disease of the aortic valves, for which no medical treatment exists and surgery represents currently the only therapeutic solution. The... Show moreCalcific aortic valve disease (CAVD) is a common progressive disease of the aortic valves, for which no medical treatment exists and surgery represents currently the only therapeutic solution. The development of novel pharmacological treatments for CAVD has been hampered by the lack of suitable test-systems, which require the preservation of the complex valve structure in a mechanically and biochemical controllable system. Therefore, we aimed at establishing a model which allows the study of calcification in intact mouse aortic valves by using the Miniature Tissue Culture System (MTCS), an ex vivo flow model for whole mouse hearts. Aortic valves of wild-type mice were cultured in the MTCS and exposed to osteogenic medium (OSM, containing ascorbic acid, beta-glycerophosphate and dexamethasone) or inorganic phosphates (PI). Osteogenic calcification occurred in the aortic valve leaflets that were cultured ex vivo in the presence of PI, but not of OSM. In vitro cultured mouse and human valvular interstitial cells calcified in both OSM and PI conditions, revealing in vitro-ex vivo differences. Furthermore, endochondral differentiation occurred in the aortic root of ex vivo cultured mouse hearts near the hinge of the aortic valve in both PI and OSM conditions. Dexamethasone was found to induce endochondral differentiation in the aortic root, but to inhibit calcification and the expression of osteogenic markers in the aortic leaflet, partly explaining the absence of calcification in the aortic valve cultured with OSM. The osteogenic calcifications in the aortic leaflet and the endochondral differentiation in the aortic root resemble calcifications found in human CAVD. In conclusion, we have established an ex vivo calcification model for intact wild-type murine aortic valves in which the initiation and progression of aortic valve calcification can be studied. The in vitro-ex vivo differences found in our studies underline the importance of ex vivo models to facilitate pre-clinical translational studies. Show less
Pol, V. van de; Vos, M.; DeRuiter, M.C.; Goumans, M.J.; Vries, C.J.M. de; Kurakula, K. 2020
Despite the advent of new-generation drug-eluting stents, in-stent restenosis remains a significant problem in patients with coronary artery disease. In- stent restenosis is defined as the gradual... Show moreDespite the advent of new-generation drug-eluting stents, in-stent restenosis remains a significant problem in patients with coronary artery disease. In- stent restenosis is defined as the gradual re-narrowing of a stented coronary artery lesion due to arterial damage with subsequent local inflammation of the vessel wall and excessive growth of the vascular smooth muscle cells (vSMCs). Four-and-a-half LIM-domain protein 2 (FHL2) is a scaffold protein involved in regulating vSMC function and inflammation. Previously we have demonstrated that FHL2 prevents vSMC proliferation in a murine carotid artery ligation model. However, the effect of FHL2 on the inflammatory response of the vSMCs is not investigated. Therefore, we studied the inflammatory response in the vessel wall of FHL2-deficient (-KO) mice after carotid artery ligation. We found that circulating cytokines and local macrophage infiltration in the ligated carotid vessels were increased in FHL2-KO mice after carotid artery ligation. Moreover, FHL2-KO vSMCs showed increased secretion of cytokines such as SDF-1 alpha and RANTES, and enhanced activation of the NF kappa B pathway. Finally, we found that blocking the NF kappa B signalling pathway abrogated this pro-inflammatory state in FHL2-KO vSMCs. Taken together, our results demonstrate that FHL2 decreases the inflammatory response of vSMCs through inhibition of the NFkB-signalling pathway. Show less
Pol, V. van de; Bons, L.R.; Lodder, K.; Kurakula, K.B.; Sanchez Duffhues, G.; Siebelink, H.M.J.; ... ; Goumans, M.J. 2019
Bicuspid aortic valve (BAV), the most common congenital heart defect, is associated with an increased prevalence of aortic dilation, aortic rupture and aortic valve calcification. Endothelial cells... Show moreBicuspid aortic valve (BAV), the most common congenital heart defect, is associated with an increased prevalence of aortic dilation, aortic rupture and aortic valve calcification. Endothelial cells (ECs) play a major role in vessel wall integrity. Little is known regarding EC function in BAV patients due to lack of patient derived primary ECs. Endothelial colony forming cells (ECFCs) have been reported to be a valid surrogate model for several cardiovascular pathologies, thereby facilitating an in vitro system to assess patient-specific endothelial dysfunction. Therefore, the aim of this study was to investigate cellular functions in ECFCs isolated from BAV patients. Outgrowth and proliferation of ECFCs from patients with BAV (n = 34) and controls with a tricuspid aortic valve (TAV, n = 10) were determined and related to patient characteristics. Interestingly, we were only able to generate ECFCs from TAV and BAV patients without aortic dilation, and failed to isolate ECFC colonies from patients with a dilated aorta. Analyzing EC function showed that while proliferation, cell size and endothelial-to-mesenchymal transition were similar in TAV and BAV ECFCs, migration and the wound healing capacity of BAV ECFCs is significantly higher compared to TAV ECFCs. Furthermore, calcification is blunted in BAV compared to TAV ECFCs. Our results reveal ECs dysfunction in BAV patients and future research is required to unravel the underlying mechanisms and to further validate ECFCs as a patient-specific in vitro model for BAV. Show less
Sanchez Duffhues, G.; Vinuesa, A.G. de; Pol, V. van de; Geerts, M.E.; Vries, M.R. de; Janson, S.G.T.; ... ; Dijke, P. ten 2019
Bicuspid aortic valve (BAV), the most common congenital heart defect, is associated with an increased prevalence of aortic dilation, aortic rupture and aortic valve calcification. Endothelial cells... Show moreBicuspid aortic valve (BAV), the most common congenital heart defect, is associated with an increased prevalence of aortic dilation, aortic rupture and aortic valve calcification. Endothelial cells (ECs) play a major role in vessel wall integrity. Little is known regarding EC function in BAV patients, due to lack of patient derived primary ECs. Endothelial colony forming cells (ECFCs) have been reported to be a valid surrogate model for several cardiovascular pathologies, thereby facilitating an in vitro system to assess patient-specific endothelial dysfunction. Therefore, the aim of this study was to investigated cellular functions in ECFCs isolated from BAV patients. Outgrowth and proliferation of ECFCs from patients with BAV (n=34) and controls with a tricuspid aortic valve (TAV, n=10) was determined and related to patient characteristics. Interestingly, we were only able to generate ECFCs from TAV and BAV patients without aortic dilation and failed to isolate ECFC colonies from patients with a dilated aorta. Analyzing EC function showed that while proliferation, cell size and endothelial-to-mesenchymal transition were similar in TAV and BAV ECFCs, migration and the wound healing capacity of BAV ECFCs is significantly higher compared to TAV ECFCs. Furthermore, calcification is blunted in BAV compared to TAV ECFCs. Our results reveal ECs dysfunction in BAV patients and future research is required to unravel the underlying mechanisms and to further validate ECFCs as a patient-specific in vitro model for BAV. Show less
Akintola, A.A.; Pol, V. van de; Bimmel, D.; Maan, A.C.; Heemst, D. van 2016
Maximizing baseline function of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) is essential for their effective application in models of cardiac toxicity and disease. Here, we aimed... Show moreMaximizing baseline function of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) is essential for their effective application in models of cardiac toxicity and disease. Here, we aimed to iden- tify factors that would promote an adequate level of function to permit robust single-cell contractility measurements in a human induced pluripotent stem cell (hiPSC) model of hypertrophic cardiomyop- athy (HCM). A simple screen revealed the collabora- tive effects of thyroid hormone, IGF-1 and the glucocorticoid analog dexamethasone on the elec- trophysiology, bioenergetics, and contractile force generation of hPSC-CMs. In this optimized condi- tion, hiPSC-CMs with mutations in MYBPC3, a gene encoding myosin-binding protein C, which, when mutated, causes HCM, showed significantly lower contractile force generation than controls. This was recapitulated by direct knockdown of MYBPC3 in control hPSC-CMs, supporting a mechanism of hap- loinsufficiency. Modeling this disease in vitro using human cells is an important step toward identifying therapeutic interventions for HCM Show less
Kooijman, S.; Boon, M.R.; Parlevliet, E.T.; Geerling, J.J.; Pol, V. van de; Romijn, J.A.; ... ; Rensen, P.C.N. 2014
