title: Infusible platelet membrane microvesicles: a potential transfusion substitute for platelets.
abstract: BACKGROUND
  Several substitutes for intact, viable platelets have been used for transfusion, both to people and in animal models, with varied success. Infusible platelet membrane (IPM) is prepared from human platelets. IPM retains the glycoprotein (GP)lb receptor and has platelet factor 3 activity (procoagulant activity). However, factor V, serotonin, a cytoplasmic marker enzyme (purine nucleotide phosphorylase), GPIIb/IIIa complex, and HLA class I and II antigens are all absent in IPM.
  
  
  METHODS
  IPM is prepared from outdated platelets. The platelets were disrupted by freezing and thawing; they were washed and heated to inactivate possible viral contaminants, and then the sonicated membrane microvesicle fraction was separated and lyophilized. The hemostatic activity of IPM was measured by its ability to reduce the prolonged bleeding time in thrombocytopenic rabbits.
  
  
  RESULTS
  Administration of IPM at a dose of 2 mg per kg results in a substantial reduction in the bleeding time. In a series of 23 experiments, a median preinjection bleeding time of 15 minutes was reduced to 6 minutes within 4 hours after IPM administration. Administration of IPM did show a mild enhancement in the thrombogenicity index, as measured in the Wessler rabbit model. This enhancement is, however, not significant, as a thrombogenicity index value of up to 0.6 is clinically acceptable.
  
  
  CONCLUSIONS
  IPM may have clinical potential as a substitute for platelets in the treatment of bleeding due to thrombocytopenia.
authors.affiliation: PRP, Inc., Watertown, Massachusetts, USA.
authors.forename: F C
authors.initials: FC
authors.lastname: Chao
authors.forename: B K
authors.initials: BK
authors.lastname: Kim
authors.forename: A M
authors.initials: AM
authors.lastname: Houranieh
authors.forename: F H
authors.initials: FH
authors.lastname: Liang
authors.forename: M W
authors.initials: MW
authors.lastname: Konrad
authors.forename: S N
authors.initials: SN
authors.lastname: Swisher
authors.forename: J L
authors.initials: JL
authors.lastname: Tullis
mesh_terms: D000818:Animals; D001760:Bleeding Time; D001792:Blood Platelets / Q000648:ultrastructure*; D002462:Cell Membrane / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D003593:Cytoplasm / Q000737:chemistry; D003594:Cytoplasmic Granules / Q000737:chemistry; D006487:Hemostasis; D006801:Humans; D008081:Liposomes / Q000737:chemistry; D008297:Male; D008854:Microscopy, Electron; D008970:Molecular Weight; D010743:Phospholipids / Q000032:analysis; D017713:Platelet Transfusion; D011817:Rabbits
chemical_list: D008081:Liposomes; D010743:Phospholipids