Open Access

Lukas Tombor, David John, Simone F. Glaser, Guillermo Luxán, Elvira Forte, Milena Furtado, Nadia Rosenthal, Nina Baumgarten, Marcel Holger Schulz, Janina Wittig, Eva-Maria Rogg, Yosif Manavski, Ariane Fischer, Marion Muhly-Reinholz, Kathrin Klee, Mario Looso, Carmen Selignow, Till Acker, Sofia Iris Bibli, Ingrid Fleming, Ralph Patrick, Richard P. Harvey, Wesley Tyler Abplanalp, Stefanie Dimmeler

• Endothelial cells play a critical role in the adaptation of tissues to injury. Tissue ischemia induced by infarction leads to profound changes in endothelial cell functions and can induce transition to a mesenchymal state. Here we explore the kinetics and individual cellular responses of endothelial cells after myocardial infarction by using single cell RNA sequencing. This study demonstrates a time dependent switch in endothelial cell proliferation and inflammation associated with transient changes in metabolic gene signatures. Trajectory analysis reveals that the majority of endothelial cells 3 to 7 days after myocardial infarction acquire a transient state, characterized by mesenchymal gene expression, which returns to baseline 14 days after injury. Lineage tracing, using the Cdh5-CreERT2;mT/mG mice followed by single cell RNA sequencing, confirms the transient mesenchymal transition and reveals additional hypoxic and inflammatory signatures of endothelial cells during early and late states after injury. These data suggest that endothelial cells undergo a transient mes-enchymal activation concomitant with a metabolic adaptation within the first days after myocardial infarction but do not acquire a long-term mesenchymal fate. This mesenchymal activation may facilitate endothelial cell migration and clonal expansion to regenerate the vascular network.