Paula Barlabé

Highlights • Heart- and vascular-deficient mouse embryos are generated by selective cell ablation • Intraspecies blastocyst complementation generates functional cardiovascular system • Rat hearts are generated in mice, and complemented chimeras survive until E10.5 • Single-cell RNA-seq suggests unexplored interspecies barriers Summary Generating organs from stem cells through blastocyst complementation is a promising approach to meet the clinical need for transplants.

Analysis of defined TE-associated markers showed heterogeneous expression within cells of the TE-like cluster ( Figures 2 A and 2B and 3 A ). Accordingly, an unsupervised subclustering analysis revealed three subpopulations (5_0, 5_1, and 5_2; Figure 3 B). Trajectory analysis using CytoTRACE ( Figure 3 C) and monocle 3 ( Figure 3 D) showed that, within the TE-like cluster, the 5_0 subcluster corresponds to less differentiated cells, while the most differentiated subcluster is 5_2.