title: Phospholipids released from activated platelets improve platelet aggregation and endothelial cell migration.
abstract: This study was undertaken to isolate phospholipids released from activated platelets and to investigate their biological activities. Freshly washed platelets were activated with freezing/thawing, thrombin, ionophore 23187, and arachidonic acid. Thrombin was incubated with platelet-rich plasma to promote synthesis and release of phospholipids from platelets. Phospholipids in supernatants of activated platelets were extracted with butanol and separated by thin-layer chromatography. Release of phosphatidylserine (PS) and phosphatidic acid (PA) increased when platelets were treated with freezing/thawing, ionophore, and thrombin. The lysophosphatidyl ethanolamine (LPE) appeared not to be induced with freezing/thawing, but increased significantly by thrombin, ionophore, and arachidonic acid. The effects of platelet phospholipids on hemostasis and angiogenesis were studied with platelet aggregation and endothelium chemotaxis. Phospholipids isolated from thrombin-stimulated platelet-rich/platelet-poor plasmas were used as synergistic agonists in platelet aggregation and as chemotactic agents in endothelial cell migration. Several phospholipids increased chemotaxis and platelet aggregation; these were PS, PA, LPE, and sphingosine-1-phosphate. Also, chemotaxis of those phospholipids increased when combined with charcoal-stripped fetal bovine serum, suggesting that cofactors in serum enhanced phospholipid-induced cell migration. These observations suggest that activated platelets release biologically active phospholipids into the blood stream, where they may play an important role in thrombosis and angiogenesis.
authors: The Methodist Research Institute, Clarian Health Partners, Inc., Indianapolis 46202, IN, USA.
authors: H
authors: H
authors: Xiao
authors: R A
authors: RA
authors: Siddiqui
authors: M H
authors: MH
authors: Al-Hassani
authors: D
authors: D
authors: Sliva
authors: R J
authors: RJ
authors: Kovacs
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000378:metabolism; D002417:Cattle; D002465:Cell Movement / Q000187:drug effects; D002633:Chemotaxis / Q000187:drug effects*; D002855:Chromatography, Thin Layer; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects*; D006801:Humans; D007700:Kinetics; D010743:Phospholipids / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology*; D015539:Platelet Activation / Q000187:drug effects; D010974:Platelet Aggregation / Q000187:drug effects*; D013917:Thrombin / Q000494:pharmacology
chemical_list: D010743:Phospholipids; D013917:Thrombin