Abstract

Abstract Funding Acknowledgements None. Heart failure with preserved ejection fraction (HFpEF) continues to pose a significant challenge with a bleak prognosis and a rising incidence, particularly among the aging population in Western countries. An in-depth comprehension of cellular-level pathogenesis, with a specific emphasis on the pivotal role of cellular senescence in endothelial dysfunction, is imperative for the evolution of innovative therapeutic interventions. Many previous approaches to investigate the genesis of HFpEF are based only on HFpEF-mouse models, which cannot directly be transferred to humans. The isolation of circulating endothelial cells from peripheral blood samples represents a more translatable, feasible, less invasive way to study endothelial dysfunction, a central component of HFpEF-pathogenesis, in human material for the identification of new therapeutical targets. This study focuses on establishing a new protocol for isolating circulating endothelial cells (CEC) in HFpEF patients to address endothelial dysfunction and pinpoint novel therapeutic targets through a comprehensive whole transcriptome analysis. Methodologically, CEC isolation from whole blood samples was achieved using a newly established Fluorescence-Activated Cell Sorting (FACS) panel. HFpEF patients were recruited based on their HFA-PEFF score, with non-diseased controls comprising both young and old subjects meticulously matched for sex and age. Subsequently, the isolated CECs were subjected to transcriptome analysis. Our new protocol is based on red blood cell lysis followed by magnetic cell sorting to deplete CD45+ cells. This is followed by staining with fluorescent-conjugated monoclonal antibodies. This FACS panel includes known endothelial-specific markers including CD11b- and CD45-, CD146+, CD34+ and CD31+ as well as DAPI- as a nucleus marker. The prepared CECs were sorted using FACS and a specially developed gating. We isolated the RNA in preparation for sequencing. Our protocol was validated by immunofluorescence staining of isolated CECs (markers: CD31, vWF, CD146, Phalloidin) and PCR analysis (markers: CD31, CD146 and vWF). In summary, we have successfully established a new, robust and highly targeted workflow for consistently isolating circulating endothelial cells from blood and performing RNA sequencing on the collected samples. This is a key advance towards a deeper understanding of the pathophysiology of HFpEF. The application of our methodology may enable the characterization of patients with HFpEF at the transcriptome level. The whole transcriptome analyses provide potential starting points for further in vitro and in vivo studies. As we extend our investigations to larger patient cohorts in the future, there is potential for the identification of novel therapeutic targets.