Summary
Blood platelets contain angiopoietin-1, a growth factor essential for blood vessel
development via stabilization of proliferating endothelial cells. It has recently
been reported that angiopoietin-1 can act as a vascular stability factor (Nature Medicine
6:460, 2000). In investigating the normal tissue distribution of angiopoietin-1 from
surgically-removed frozen specimens by RT-PCR, we found it consistently present in
platelets and megakaryocytes, usually absent in relatively non-vascular tissue: breast,
colon, lung, skin, kidney, thyroid, testicle, cervix and occasionally present in tissue
enriched with vasculature: prostate, endometrium, ovary, under conditions in which
mRNA stability was verified by the positive detection of internal control, actin mRNA.
The consistent distribution in platelets and relatively absent distribution in non-vascular
normal tissue suggested that the well-known role of platelets in maintaining vascular
stability, may in part be due to platelet release of angiopoietin-1 following platelet
activation. In this communication we report the incidence of Ang-1 in various normal
tissues and demonstrate that thrombin-treated human platelets release angiopoietin-1
in vitro.
Keywords
Angiopoietin-1 - platelets - thrombin - vascular stability
