Protein encoded by the Angpt1 (angiopoietin 1) gene is expressed by hematopoietic stem cells of the bone marrow. It is believed that after cancer radiation treatment, this expression slows the regeneration of blood vessels in the surrounding niche, thus reducing their leakiness.
These knock-in/knock-out mice express a GFP reporter from the mouse Angpt1 promoter in hematopoietic stem cells and the surrounding stromal cells in bone marrow. GFP can be readily detected in KIT+ hematopoietic progenitor cells and bone marrow stromal cells by flow cytometry. For imaging on sections, one needs an anti-GFP antibody to make GFP visible. GFP is expressed by CD41+ megakaryocytes and KIT+ (c-kit+) hematopoietic progenitor cells throughout the bone marrow. Virtually all of the ANGPT1 expression by stromal cells is by LEPR+ cells which localize mainly around sinusoids, as well as near arterioles. Nearly all PDGFRA+ cells (indicative of mesenchymal stem/stromal cells) are GFP+. GFP expression is not detected in endothelial cells or osteopontin+ bone lining cells in the diaphysis or metaphysis.
Crosses of Angpt1GFP heterozygotes produce no viable homozygous progeny, suggesting this is a strong loss-of-function allele.
