Thrombospondin-1: a unique marker to identify in vitro platelet activation when monitoring in vivo processes

J Thromb Haemost. 2010 Aug;8(8):1809-19. doi: 10.1111/j.1538-7836.2010.03908.x. Epub 2010 May 12.


Background: Measuring platelet activation in patients has become a potent method to investigate pathophysiological processes. However, the commonly applied markers are sensitive to detrimental influences by in vitro platelet activation during blood analysis.

Objectives: Protein isoforms of platelet-derived thrombospondin-1 (TSP-1) were investigated for their potential to identify in vitro platelet activation when monitoring in vivo processes.

Methods: TSP-1 was determined in plasma, serum or supernatant of purified platelets by ELISA and immunoblotting and was compared with standard markers of platelet activation. A collective of 20 healthy individuals and 30 cancer patients was analyzed.

Results: While in vitro platelet degranulation led to a selective increase in the 200-kDa full-length molecule, an in vivo process involving platelet activation such as wound healing resulted in the predominant rise of the 140-kDa TSP-1 protein. The physiological ratio of circulating TSP-1 variants was determined and a cut-off level at 1.0 was defined to identify plasma samples with artificial in vitro platelet activation exceeding the cut-off level. In contrast, cancer patients known to frequently exhibit increased in vivo activation of platelets presented with a significantly decreased ratio of TSP-1 variants as compared with healthy volunteers.

Conclusions: In comparison to standard platelet markers, TSP-1 constitutes a sensitive and stable parameter suited to monitor in vitro platelet activation. The analysis of TSP-1 protein isoforms further offers a valuable tool to reliably discriminate between in vitro and in vivo effects, to exclude variability introduced during blood processing and improve clinical monitoring.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Case-Control Studies
  • Female
  • Humans
  • In Vitro Techniques
  • Male
  • Middle Aged
  • Neoplasms / blood
  • Platelet Activation*
  • Protein Isoforms
  • Recombinant Proteins / chemistry
  • Temperature
  • Thrombospondin 1 / blood*
  • Thrombospondin 1 / chemistry
  • Time Factors
  • Wound Healing


  • Protein Isoforms
  • Recombinant Proteins
  • Thrombospondin 1