Thrombospondin exerts an antiangiogenic effect on cord formation by endothelial cells in vitro

M. L. Iruela-Arispe, P. Bornstein, H. Sage*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

256 Scopus citations


The response of endothelial cells to angiogenic stimuli has been shown to be influenced by the extracellular microenvironment. We tested whether thrombospondin an extracellular matrix protein, modulated the spontaneous formalin of cords by endothelial cells in vitro. Despite continued proliferation, a decrease in secreted thrombospondin was detected in cord-containing, as compared with subconfluent, cultures of both aortic and microvascular endothelial cells Consistent with this trend, mRNA levels of thrombospondin decreased by factors of 16 in aortic and 60 in microvascular cultures that contained endothelial cords. Since thrombospondin was immunolocalized to fibrillar arrays that appeared to be associated with endothelial cords, we added anti-thrombospondin IgG to cord-forming cultures to limit the availability of the protein during this process. In the presence of anti-thrombospondin antibodies, there was a 33-50% increase in cord formation. These results suggest that thrombospondin is an inhibitor of angiogenesis in vitro and are consistent with its proposed roles as a destabilizer of endothelial cell focal contacts and as an inhibitor of endothelial cell proliferation.

Original languageEnglish (US)
Pages (from-to)5026-5030
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number11
StatePublished - Jun 1 1991


  • Angiogenesis
  • Extracellular matrix

ASJC Scopus subject areas

  • General


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