Thrombospondins deployed by thrombopoietic cells determine angiogenic switch and extent of revascularization
J. Clin. Invest. Hans-Georg Kopp, et al. 116:3277 doi:10.1172/JCI29314 [Go to this article.]

Figure 1
In the bone marrow, TSP1 is expressed in megakaryocytes and platelets and on endosteal surfaces. An antibody raised against citrullinated proteins results in robust and specific megakaryocyte staining. (A) Megakaryocytes (red arrows) are highly immunoreactive for TSPs. Representative images of WT bone marrow at steady state are shown. Sections were stained for TSPs. Original magnification, ×400. Inset provides a lower magnification overview of WT bone marrow; original magnification, ×200. Sections shown in A and B were counterstained with hematoxylin. (B) In addition, TSP immunoreactivity was demonstrated on endosteal osseous surfaces (green arrows) and platelets (black arrow). This would be in line with previous reports in which TSP1 has been shown to be a cytoadhesive molecule for hematopoietic stem cells. On the other hand, hematopoietic cells other than megakaryocytes and platelets did not stain with the same antibody. Frozen bone marrow section at steady state is shown. Original magnification, ×1,000. (C) WT murine steady state bone marrow was stained with an antibody against CD41 and the anti-citrulline antibody. While anti-CD41 binding was visualized with a Cy2-labeled secondary antibody (green), the anti-citrulline antibody was detected with a Cy3-labeled secondary antibody (red). It is obvious that both antibodies bind to megakaryocytes. However, the anti-citrulline antibody results in more robust and stronger staining results. Original magnification, ×100. (D) Murine megakaryocytes differentiated in culture costained with anti-CD41a and anti-citrulline as above. The merged view shows that both antibodies bind to megakaryocytes. Cytospin from in vitro–differentiated lineage negative murine bone marrow cells is shown. Original magnification, ×1,000.