Induced pluripotent stem cells from patients with hypoplastic left heart syndrome (HLHS) as a model to study functional contribution of endothelial-mesenchymal transition (EndMT) in HLHS

by Xiaopeng Liu
Cumulative thesis
Date of Examination:2016-11-28
Date of issue:2016-11-30
Advisor:Prof. Dr. Elisabeth Zeisberg
Referee:Prof. Dr. Kao Mei Guan
Referee:Prof. Dr. Frauke Alves
Persistent Address: http://dx.doi.org/10.53846/goediss-6004

 

 

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Abstract

English

Hypoplastic left heart syndrome (HLHS) is one of the most lethal congenital heart diseases (CHD) and its pathological mechanism remains unclear. Endocardial fibroelastosis (EFE) is a hallmark of HLHS which impairs myocardial growth. EFE tissue originates from aberrant EndMT. Thus, we hypothesized that potential disorders in endothelial cells of HLHS could facilitate the EndMT, which eventually lead to the EFE formation. Human induced pluripotent stem cells (hiPSCs) provide a new access for modeling HLHS because of their ability of differentiation into desired cell types. We developed a simple endothelial cells (ECs) differentiation protocol from hiPSCs by monolayer differentiation approach. Three different combinations of cytokines were confirmed to contribute towards endothelial cell generation in this protocol. Furthermore, stage-specific medium was optimized and simplified to increase the efficiency of endothelial cells differentiation. We also demonstrated that the endothelial cell growth medium was supportive for maintaining and expanding hiPSCs derived ECs (hiPSC-ECs). To explore the underlying molecular mechanisms of HLHS, patient-specific hiPSCs (HLHS-hiPSCs) were generated and characterized to be pluripotent. All the endothelial cells derived from the HLHS-hiPSC lines were generated based on this endothelial cell differentiation protocol. Endothelial cells derived from HLHS-hiPSCs (HLHS-hiPSC-ECs) showed similar morphological and genetic properties as the wild type control (WT-hiPSC-ECs). Thereafter, we investigated whether the HLHS-hiPSC-ECs were more susceptible to EndMT, induced by TGFβ1 treatment or hypoxia condition than WT-hiPSC-ECs. The expression of SNAIL (SNAIL1), and SLUG (SNAIL2), as key indicators of EndMT, implied no significant phenotypic and expression differences between HLHS-hiPSC-ECs and WT-hiPSC-ECs. In sum, it needs further optimization to study EndMT by using hiPSC-ECs, such as enrichment of specific subtype of endothelial cells.
Keywords: iPSC; endothelial cells; HLHS; EndMT
 
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