Cell transplantation studies have shown that injection of progenitor cells can improve cardiac function after myocardial infarction (MI). Transplantation of human cardiac progenitor cells (hCPCs)... Show moreCell transplantation studies have shown that injection of progenitor cells can improve cardiac function after myocardial infarction (MI). Transplantation of human cardiac progenitor cells (hCPCs) results in an increased ejection fraction, but survival and integration are low. Therefore, paracrine factors including extracellular vesicles (EVs) are likely to contribute to the beneficial effects. We investigated the contribution of EVs by transplanting hCPCs with reduced EV secretion. Interestingly, these hCPCs were unable to reduce infarct size post-MI. Moreover, injection of hCPC-EVs did significantly reduce infarct size. Analysis of EV uptake showed cardiomyocytes and endothelial cells primarily positive and a higher Ki67 expression in these cell types. Yes-associated protein (YAP), a proliferation marker associated with Ki67, was also increased in the entire infarcted area. In summary, our data suggest that EV secretion is the driving force behind the short-term beneficial effect of hCPC transplantation on cardiac recovery after MI. Show less
Unfortunately cardiovascular disease is very common, which makes it important to gain a better understanding of how we can restore the 'broken' heart after injury . Progenitor cells can serve as... Show moreUnfortunately cardiovascular disease is very common, which makes it important to gain a better understanding of how we can restore the 'broken' heart after injury . Progenitor cells can serve as the 'building blocks ' for cardiac repair. Cardiac progenitor cells, which are the focus of t his thesis, can be derived from either the myocardial (CPCs) or epicardial (EPDCs) layer of the heart. Based on the idea that we want to isolate CPCs and EPDCs from the human heart and eventually use these cells for cardiac regeneration, in this thesis the f ollowing questions were investigated: • Which marker scan recognize CPCs within human cardiac tissue and how can we efficiently isolate EPDCs? ( Pa r t 1) • Which factors play a role in CPC and EPDC behavior? (Part 2) In Chapter 3, 4 and 5 novel antibodies for the isolation of CPCs are introduced and a new method to isolate and expand EPDCs is presented in Chapter 6. We studied human CPC to cardiomyocyte differentiation in Chapter 7 and questioned, in Chapter 8, whether extraembryonic endoderm-derived cells can support human cardiomyocyte differ entiation in vitro. Finally, we studied the TGFbet a signaling pathway, including its co-receptor Endoglin, in regulating EPDC behavior in Chapter 9 and 10. Show less
The aim of stem cell therapy after cardiac injury is to replace damaged cardiac tissue. Human cardiac progenitor cells (CPCs) represent an interesting cell population for clinical strategies to... Show moreThe aim of stem cell therapy after cardiac injury is to replace damaged cardiac tissue. Human cardiac progenitor cells (CPCs) represent an interesting cell population for clinical strategies to treat cardiac disease and human CPC-specific antibodies would aid in the clinical implementation of cardiac progenitor based cell therapy. However, the field of CPC biology suffers from the lack of human CPC-specific markers. Therefore, we raised a panel of monoclonal antibodies (mAb) against CPCs Of this panel of antibodies, we show that mAb C1096 recognizes a progenitor-like population in the fetal and adult human heart and partially co-localize with reported CPC populations in vitro. Furthermore, mAb C1096 can be used to isolate a multipotent progenitor population from human heart tissue. Interestingly, the two lead candidates, mAb C1096 and mAb C19, recognize glycosylated residues on PECAM1 and GRP78, respectively, and de-N-glycosylation significantly abolishes their binding. Thereby, this report describes new clinical applicable antibodies against human CPCs, and for the first time demonstrates the importance of glycosylated residues as CPCs specific markers. Show less
AIMS:Cardiac progenitor cells (CPCs) have been isolated from adult and developing hearts using an anti-mouse Sca-1 antibody. However, the absence of a human Sca-1 homologue has hampered the... Show moreAIMS:Cardiac progenitor cells (CPCs) have been isolated from adult and developing hearts using an anti-mouse Sca-1 antibody. However, the absence of a human Sca-1 homologue has hampered the clinical application of the CPCs. Therefore, we generated novel monoclonal antibodies (mAbs) specifically raised against surface markers expressed by resident human CPCs. Here, we explored the suitability of one of these mAbs, mAb C19, for the identification, isolation and characterization of CPCs from fetal heart tissue and differentiating cultures of human embryonic stem cells (hESCs).METHODS & RESULTS:Using whole-cell immunization, mAbs were raised against Sca-1+ CPCs and screened for reactivity to various CPC lines by flow cytometry. mAb C19 was found to be specific for Sca-1+ CPCs, with high cell surface binding capabilities. mAb C19 stained small stem-like cells in cardiac tissue sections. Moreover, during differentiation of hESCs towards cardiomyocytes, a transient population of cells with mAb C19 reactivity was identified and isolated using magnetic-activated cell sorting. Their cell fate was tracked and found to improve cardiomyocyte purity from hESC-derived cultures. mAb C19+ CPCs, from both hESC differentiation and fetal heart tissues, were maintained and expanded in culture, while retaining their CPC-like characteristics and their ability to further differentiate into cardiomyocytes by stimulation with TGFβ1. Finally, gene expression profiling of these mAb C19+ CPCs suggested a highly angiogenic nature, which was further validated by cell-based angiogenesis assays.CONCLUSION:mAb C19 is a new surface marker for the isolation of multipotent CPCs from both human heart tissues and differentiating hESCs. Show less
Cardiac cushion formation is crucial for both valvular and septal development. Disruption in this process can lead to valvular and septal malformations, which constitute the largest part of... Show moreCardiac cushion formation is crucial for both valvular and septal development. Disruption in this process can lead to valvular and septal malformations, which constitute the largest part of congenital heart defects. One of the signaling pathways that is important for cushion formation is the TGFβ superfamily. The involvement of TGFβ and BMP signaling pathways in cardiac cushion formation has been intensively studied using chicken in vitro explant assays and in genetically modified mice. In this review, we will summarize and discuss the role of TGFβ and BMP signaling components in cardiac cushion formation. Show less
