This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Ratajska, A. Search for Related Content PubMed PubMed Citation Articles by Ratajska, A.

(Circulation Research. 2006;98:e72.)
© 2006 American Heart Association, Inc.

Letters to the Editor

Is the Fetal Heart a Hematopoietic Organ?

Anna Ratajska

Department of Pathological Anatomy, The Medical University of Warsaw, Poland

An extract of the first 250 words of the full text is provided, because this article has no abstract.

To the Editor:

The article by Tomanek et al¹ presents well the in vivo data on the requirement of VEGF family members for tubulogenesis and coronary artery formation. The authors observed that VEGF-Trap (a chimera of R1 and R2), apart from precluding formation of coronary arteries, causes a massive accumulation of erythrocytes in the subepicardium and in the interventricular septum. The important finding of this study was that erythrocytes that are components of blood islands derive from epicardial-derived precursors. The authors assume that proepicardial cells include a hemangioblast population. From this observation a conclusion can be drawn that either the proepicardium or the fetal heart exhibits a hematopoietic activity.

Considering the topic of blood island derivation in the embryonic heart I would like to comment that although the derivation of the endothelial cell component in these structures has been proven, the origin of erythrocytes is ambiguous and has not yet been resolved. Quail-chicken chimera and retrovirus-infected proepicardial organ studies revealed that endothelial cells of coronary vasculature derive from the proepicardium and subsequently from the epicardium.^1,2,3 Angiogenic potential of the proepicardium has been confirmed several times.⁴ With regard to derivation of the blood cell component, one of the theories implies that fetal heart hematoblasts (erythroblasts) derive in situ from migrating angioblasts or hemangioblasts.⁵ This situation would be similar to that seen in developing yolk sac, indicative of the presence of a presumptive hemangioblast.⁶ An article by Kattan et al⁷ indicates that commitment to the hematopoietic lineage appears to precede the formation . . . [Full Text of this Article]