title: A method to assess the migration properties of cell-derived microparticles within a living tissue.
abstract: BACKGROUND
  Cells undergoing activation or apoptosis exhibit plasma membrane changes, leading to the formation of shed vesicles (microparticles, MP). Although their effects on recipient cells in vitro, and their ability to support inflammatory or thrombotic events in the circulation have been studied, the spreading of such vesicles in tissues is still elusive. Our aim was to set up a method to examine the behavior of these vesicles in vivo.
  
  
  METHODS
  We examined the persistence of green-fluorescent microparticles (fMP), prepared after Ca2+ ionophore activation (iono-fMP) or apoptogenic treatment (eto-fMP) of human Jurkat T lymphoblastic or non-hematopoietic embryonic kidney (HEK) cell lines, following injection in zebrafish embryos 2h after egg fertilization.
  
  
  RESULTS
  One hour post-injection, iono-fMP issued from both cell types formed a fluorescent dispersal in the intercellular space of embryos. In contrast, eto-fMP or MP deprived of sialic acid at their membrane, gathered together at the site of injection.
  
  
  CONCLUSIONS
  We propose a method characterizing the abilities of MP to spread in the intercellular space. We showed that MP produced by apoptosis of T cells and those deprived of sialic acid at their membrane do not diffuse within the living cells. On the contrary, MP shed upon calcium induced activation of T and HEK cells, diffuse at a distance and spread in the intercellular space.
  
  
  CONCLUSIONS
  The fate of injected MP relies on the type of induction rather than the cell species and results provide a model to test the ability of vesicles to interact locally or to spread outside of the site of production.
authors: INSERM U770, 80 rue du Général Leclerc, Université Paris-Sud, Faculté de Médecine, Hôpital de Bicêtre, 94276 Le Kremlin-Bicêtre, France. ac_baresi@yahoo.com
authors: Thang Q
authors: TQ
authors: Hoang
authors: Christine
authors: C
authors: Rampon
authors: Jean-Marie
authors: JM
authors: Freyssinet
authors: Sophie
authors: S
authors: Vriz
authors: Danièle
authors: D
authors: Kerbiriou-Nabias