Quality assurance of hematopoietic stem cells by macrophages determines stem cell clonality

Wattrus et al. establish that hematopoietic stem and progenitor cells (HSPC) are quality assured for stress levels during development. Calreticulin is revealed as an “eat-me” molecule that initiates macrophage-HSPC interaction and leads to programmed cell clearance or stem cell expansion. They used SORT-seq to characterize the macrophage and HSPC subpopulations involved.

A pendulum of induction between the epiblast and extra-embryonic endoderm supports post-implantation progression

Vrij et al. aim to elucidate the principles of epiblast and extraembryonic endoderm co-development in mice. SORT-seq and immunofluorescence microscopy analysis indicate a process of lineage bifurcation and the two layers sequentially inducing developmental progression in each other.

Molecular signatures and cellular diversity during mouse habenula development

The authors performed SORT-seq on mouse habenular neurons at critical developmental stages, instructed by detailed 3D anatomical data. The data reveal cellular and molecular trajectories during embryonic and postnatal development, leading to different habenular subtypes. Among these, the Cartpt+ neuron subtype was studied in-depth and successfully linked to specific molecular and functional properties.

Inflammatory response in hematopoietic stem and progenitor cells triggered by activating SHP2 mutations evokes blood defects

Hematopoietic stem and progenitor cells (HSPCs) are the disease-propagating cells of juvenile myelomonocytic leukemia (JMML). A SHP2 mutation is common in these patients, and Solman et al. reproduced it in zebrafish. Single-cell mRNA sequencing of HSPCs from mutant zebrafish embryos and bulk sequencing of HSPCs from JMML patients revealed an overlapping inflammatory gene expression pattern. Pharmacological inhibition of the inflammatory response positively impacted mutant zebrafish, suggesting therapeutic possibilities in JMML patients.

Hand2 delineates mesothelium progenitors and is reactivated in mesothelioma

Prummel et al. studied the early embryonic origins of mesothelia in zebrafish, mice, and humans. Single-cell RNA sequencing of zebrafish early lateral plate mesoderm revealed a heterogeneous progenitor pool. Hand2 was found as a marker for mesothelial progenitors. These progenitors form visceral and parietal mesothelium.

LGR6 marks nephron progenitor cells

Nephron progenitor cells develop into all mature structures of the kidney through a stepwise process called mesenchymal to epithelial transition. Van Ineveld et al. identify protein LGR6 as a marker specific to nephron progenitor cells by combining single-cell RNA sequencing and in vivo lineage tracing techniques.