Extracellular matrix stimulation of guinea pig megakaryocyte proplatelet formation in vitro is mediated through the vitronectin receptor

R. M. Leven, Fern Tablin

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


We have used an in vitro culture system to study the role of extracellular matrix (ECM) in the fragmentation of guinea pig bone marrow megakaryocytes (MK) and the formation of proplatelet fragments from these cells. Proplatelet formation is stimulated by culturing the cells on a hydrated type I collagen gel in the presence of serum. MK express integrin proteins alpha5, alpha6, beta1, and the alpha(v) beta3 complex as demonstrated by immunofluorescence. A monoclonal antibody, LM 609, to the alpha(v) beta3 vitronectin receptor blocked proplatelet formation, whereas the monoclonal antibodies to the beta1, alpha5, and alpha6 integrin proteins did not inhibit proplatelet formation. The tetrapeptide Arg-Gly-Asp-Ser (RGDS) inhibits proplatelet formation; however, there was no inhibition by the fibronectin receptor-specific peptide GRGDdSP. The fibrinogen gamma chain peptide HHLGGAKQAGDV, which binds to the platelet membrane glycoprotein complex IIb-IIIa but not to the vitronectin receptor (VnR), did not inhibit proplatelet formation, nor did two different laminin peptides. In the absence of serum, 5.7% of MK spontaneously formed processes or fragmented. The addition of 50 μg/ml of vitronectin to serum-free cultures increased proplatelet formation to 21.5% of the MK, equal to cultures with 10% serum. Stimulation of proplatelet formation by vitronectin in serum-free cultures was inhibited by LM 609. Antibody staining with anti-bovine vitronectin antibody showed that MK contain intracellular vitronectin. These data show that guinea pig MK express alpha5, alpha6, beta1, and alpha(v) beta3 integrins. However, only the MK vitronectin receptor and its interaction with vitronectin plays an essential role in proplatelet formation in vitro.

Original languageEnglish (US)
Pages (from-to)1316-1322
Number of pages7
JournalExperimental Hematology
Issue number11
StatePublished - 1992
Externally publishedYes


  • extracellular matrix
  • integrin proteins
  • megakaryocytes
  • vitronectin receptor

ASJC Scopus subject areas

  • Cancer Research
  • Cell Biology
  • Genetics
  • Hematology
  • Oncology
  • Transplantation


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