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Zimmer, S.

Publications and source records attributed to Zimmer, S..

3 recordsLinked to original sources
bioRxiv2022

Porcine and human aortic valve endothelial and interstitial cell isolation and characterization

BackgroundCalcific aortic valve stenosis is defined by pathological changes in the aortic valve and their predominant cell types: valvular interstitial (VICs) and endothelial cells (VECs). Understanding the cellular and molecular mechanisms of this disease is a prerequisite to identify potential pharmacological treatment strategies. In this study, we present a unique aortic valve cell isolation technique to acquire specific human and porcine cell populations and compared VICs and VECs of these species with each other for the first time. Methods and ResultsAortic valve cells were isolated from human explants from patients undergoing surgical aortic valve replacement or porcine valvular tissue. Pure VEC and VIC populations could be verified by gene expression analysis and immunofluorescence staining showing a highly significant upregulation of endothelial markers in VECs and mesenchymal markers in VICs, respectively. Further analysis and comparison of cells in in vitro experiments revealed that endothelial-to-mesenchymal transition could be induced in hVECs, leading to significant increase of mesenchymal markers. In vitro calcification experiments of VICs induced by osteogenic medium or pro-calcifying medium demonstrated a pronounced calcification marker expression and visible calcific deposition in Alizarin red staining in both species. ConclusionThis study aims to initiate a first step towards standardization of a reproducible isolation technique for pure human and porcine VEC and VIC populations. Comparison of human and porcine aortic valve cells demonstrated that porcine cells might serve as an alternative cellular model system, in settings, where human tissues are difficult to obtain. Statements and DeclarationsThe authors declare no relevant financial or non-financial interests to disclose.

cell biology↗
bioRxiv2022

Aortic valve disease augments vesicular microRNA-145-5p to regulate the calcification of valvular interstitial cells via cellular crosstalk

RationaleAortic valve stenosis (AVS) is a major contributor to cardiovascular death in the elderly population worldwide. MicroRNAs (miRNAs) are highly dysregulated in patients with AVS undergoing surgical aortic valve replacement (SAVR). However, miRNA-dependent mechanisms regulating inflammation and calcification or miRNA-mediated cell-cell crossstalk during the pathogenesis of AVS are still poorly understood. Here, we explored the role of extracellular vesicles (EV)-associated miR-145-5p, which we showed to be highly upregulated upon valvular calcification in AVS in mice and humans. MethodsHuman TaqMan miRNA arrays identified dysregulated miRNAs in aortic valve tissue explants from AVS patients compared to non-calcified valvular tissue explants of patients undergoing SAVR. Echocardiographic parameters were measured in association with the quantification of dysregulated miRNAs in a murine AVS model. In vitro calcification experiments were performed to explore the effects of EV-miR-145-5p on calcification and crosstalk in valvular cells. To dissect molecular miRNA signatures and their effect on signaling pathways, integrated OMICS analyses were performed. RNA sequencing (RNA-seq), high-throughput transcription factor (TF) and proteome arrays showed that a number of genes, miRNAs, TFs, and proteins are crucial for calcification and apoptosis, which are involved in the pathogenesis of AVS. ResultsAmong several miRNAs dysregulated in valve explants of AVS patients, miR-145-5p was the most highly gender-independently dysregulated miRNA (AUC, 0.780, p-value, 0.01). MiRNA arrays utilizing patient-derived- and murine aortic-stenosis samples demonstrated that the expression of miR-145-5p is significantly upregulated and correlates positively with cardiac function based on echocardiography. In vitro experiments confirmed that miR-145-5p is encapsulated into EVs and shuttled into valvular interstitial cells. Based on the integrated OMICs results, miR-145-5p interrelates with markers of inflammation, calcification, and apoptosis. In vitro calcification experiments demonstrated that miR-145-5p regulates the ALPL gene, a hallmark of calcification in vascular and valvular cells. EV-mediated shuttling of miR-145-5p suppressed the expression of ZEB2, a negative regulator of the ALPL gene, by binding to its 3 untranslated region to inhibit its translation, thereby diminishing the calcification of target valvular interstitial cells. ConclusionElevated levels of pro-calcific and pro-apoptotic EV-associated miR-145-5p contribute to the progression of AVS via the ZEB2-ALPL axis, which could potentially be therapeutically targeted to minimize the burden of AVS. Clinical SignificanceO_ST_ABSWhat is known?C_ST_ABSO_LIAortic valve stenosis (AVS) is the most prevalent structural heart valve disease requiring surgical or interventional valve replacement. Currently, no medical treatment option is available to slow, halt, or reverse the progression of the disease. C_LIO_LIAVS induces pressure overload on the left ventricle (LV), resulting in concentric hypertrophy and LV dysfunction. C_LIO_LIAVS is not an exclusively degenerative disease that leads to fibrosis and calcification of the valve cusps but rather a chronic inflammatory disease, in which mechanical strain and shear stress lead to endothelial dysfunction and immune cell infiltration, which induces chronic inflammation, apoptosis and differentiation of valvular interstitial cells into osteoblast-like cells. C_LIO_LIIncreasing osteoblastic differentiation and the formation of macrocalcifications are hallmarks of the later stages of AVS. C_LI What is the new information we provide?O_LIDuring aortic valve stenosis, expression pattern of vesicle-associated regulatory miRNAs is altered. C_LIO_LIPatient-derived aortic valve tissue demonstrated an increased expression of miR-145-5p in humans, as well as in aortic valve explants from an experimental murine AVS model. C_LIO_LIMiR145-5p contributes to calcification of the aortic valve through ZEB2, a transcriptional repressor of ALPL, in valvular interstitial cells. C_LIO_LIExtracellular vesicular shuttling of miR-145-5p contributes to valvular cell-cell crosstalk and plays a role in the pathogenesis of AVS. C_LI

cell biology↗
bioRxiv2021

Chemical-induced Gene Expression Ranking and its Application to Pancreatic Cancer Drug Repurposing

Chemical-induced gene expression profiles provide critical information on the mode of action, off-target effect, and cellar heterogeneity of chemical actions in a biological system, thus offer new opportunities for drug discovery, system pharmacology, and precision medicine. Despite their successful applications in drug repurposing, large-scale analysis that leverages these profiles is limited by sparseness and low throughput of the data. Several methods have been proposed to predict missing values in gene expression data. However, most of them focused on imputation and classification settings which have limited applications to real-world scenarios of drug discovery. Therefore, a new deep learning framework named chemical-induced gene expression ranking (CIGER) is proposed to target a more realistic but more challenging setting in which the model predicts the rankings of genes in the whole gene expression profiles induced by de novo chemicals. The experimental results show that CIGER significantly outperforms existing methods in both ranking and classification metrics for this prediction task. Furthermore, a new drug screening pipeline based on CIGER is proposed to select approved or investigational drugs for the potential treatments of pancreatic cancer. Our predictions have been validated by experiments, thereby showing the effectiveness of CIGER for phenotypic compound screening of precision drug discovery in practice.

bioinformatics↗