title: Temporal and pharmacological characterization of angiostatin release and generation by human platelets: implications for endothelial cell migration.
abstract: Platelets play an important role in thrombosis and in neo-vascularisation as they release and produce factors that both promote and suppress angiogenesis. Amongst these factors is the angiogenesis inhibitor angiostatin, which is released during thrombus formation. The impact of anti-thrombotic agents and the kinetics of platelet angiostatin release are unknown. Hence, our objectives were to characterize platelet angiostatin release temporally and pharmacologically and to determine how angiostatin release influences endothelial cell migration, an early stage of angiogenesis. We hypothesized anti-platelet agents would suppress angiostatin release but not generation by platelets. Human platelets were aggregated and temporal angiostatin release was compared to vascular endothelial growth factor (VEGF). Immuno-gold electron microscopy and immunofluorescence microscopy identified α-granules as storage organelles of platelet angiostatin. Acetylsalicylic acid, MRS2395, GPIIb/IIIa blocking peptide, and aprotinin were used to characterize platelet angiostatin release and generation. An endothelial cell migration assay was performed under hypoxic conditions to determine the effects of pharmacological platelet and angiostatin inhibition. Compared to VEGF, angiostatin generation and release from α-granules occurred later temporally during platelet aggregation. Consequently, collagen-activated platelet releasates stimulated endothelial cell migration more potently than maximally-aggregated platelets. Platelet inhibitors prostacyclin, S-nitroso-glutathione, acetylsalicylic acid, and GPIIb/IIIa blocking peptide, but not a P2Y12 inhibitor, suppressed angiostatin release but not generation. Suppression of angiostatin generation in the presence of acetylsalicylic acid enhanced platelet-stimulated endothelial migration. Hence, the temporal and pharmacological modulation of platelet angiostatin release may have significant consequences for neo-vascularization following thrombus formation.
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Aneta
authors.initials: A
authors.lastname: Radziwon-Balicka
authors.forename: Cesar
authors.initials: C
authors.lastname: Moncada de la Rosa
authors.forename: Barbara
authors.initials: B
authors.lastname: Zielnik
authors.forename: Adrian
authors.initials: A
authors.lastname: Doroszko
authors.forename: Paul
authors.initials: P
authors.lastname: Jurasz
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D043168:Angiostatins / Q000494:pharmacology*; D001241:Aspirin / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D015687:Cell Hypoxia; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects*; D003094:Collagen / Q000494:pharmacology; D017077:Culture Media, Conditioned / Q000494:pharmacology; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects; D011464:Epoprostenol / Q000494:pharmacology; D006801:Humans; D010455:Peptides / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000037:antagonists & inhibitors; D026422:S-Nitrosoglutathione / Q000494:pharmacology; D014631:Valerates / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology
chemical_list: C528918:2,2-dimethylpropionic acid 3-(2-chloro-6-methylaminopurin-9-yl)-2-(2,2-dimethylpropionyloxymethyl)propyl ester; D020533:Angiogenesis Inhibitors; D017077:Culture Media, Conditioned; D010455:Peptides; D010975:Platelet Aggregation Inhibitors; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; C467484:VEGFA protein, human; D014631:Valerates; D042461:Vascular Endothelial Growth Factor A; D026422:S-Nitrosoglutathione; D043168:Angiostatins; D003094:Collagen; D011464:Epoprostenol; D000225:Adenine; D001241:Aspirin
references.citation: J Natl Cancer Inst. 1987 May;78(5):961-9
references.pmid: 3553692
references.citation: Proc Natl Acad Sci U S A. 1998 May 26;95(11):6367-72
references.pmid: 9600971
references.citation: FASEB J. 1998 Dec;12(15):1731-8
references.pmid: 9837863
references.citation: Platelets. 1999;10(5):285-92
references.pmid: 16801104
references.citation: Blood. 2011 Aug 4;118(5):1370-3
references.pmid: 21622648
references.citation: J Thorac Cardiovasc Surg. 2013 Jan;145(1):234-40
references.pmid: 22889481
references.citation: Lancet. 1987 Nov 7;2(8567):1057-8
references.pmid: 2889967
references.citation: Cancer Res. 2003 Jul 15;63(14):4275-80
references.pmid: 12874037
references.citation: J Thromb Haemost. 2006 May;4(5):1095-106
references.pmid: 16689764
references.citation: Blood. 2011 Aug 4;118(5):1359-69
references.pmid: 21680800
references.citation: Cell. 1994 Oct 21;79(2):315-28
references.pmid: 7525077
references.citation: Angiogenesis. 2011 May;14(2):199-207
references.pmid: 21318419
references.citation: Can J Physiol Pharmacol. 2012 Jun;90(6):679-88
references.pmid: 22512504
references.citation: Proc Natl Acad Sci U S A. 2001 May 22;98(11):6470-5
references.pmid: 11353854
references.citation: Proc Natl Acad Sci U S A. 2005 Jan 4;102(1):216-20
references.pmid: 15615851
references.citation: Vascul Pharmacol. 2013 Apr;58(4):280-91
references.pmid: 23220260
references.citation: Cancer Res. 1996 Nov 1;56(21):4887-90
references.pmid: 8895739
references.citation: J Cell Biochem. 2004 Feb 1;91(2):398-409
references.pmid: 14743398
references.citation: Proc Natl Acad Sci U S A. 1997 Jan 21;94(2):663-8
references.pmid: 9012841
references.citation: Blood. 2008 Feb 1;111(3):1227-33
references.pmid: 17962514
references.citation: J Biol Chem. 1998 Nov 20;273(47):31480-5
references.pmid: 9813061
references.citation: Platelets. 1999;10(6):382-90
references.pmid: 16801117
references.citation: Cancer Res. 2004 May 15;64(10):3679-86
references.pmid: 15150128
references.citation: Proc Natl Acad Sci U S A. 1998 May 12;95(10):5579-83
references.pmid: 9576925
references.citation: J Biol Chem. 2000 Jan 21;275(3):1521-4
references.pmid: 10636838
references.citation: Br J Pharmacol. 1987 Sep;92(1):181-7
references.pmid: 3311265
references.citation: N Engl J Med. 2008 May 29;358(22):2319-31
references.pmid: 18480196
references.citation: J Cell Biol. 2001 Mar 19;152(6):1247-54
references.pmid: 11257124
references.citation: Blood. 2012 Jul 24;:
references.pmid: 22829627
references.citation: Thromb Res. 2010 Jan;125(1):53-60
references.pmid: 19427678
references.citation: Blood. 2003 Nov 1;102(9):3217-23
references.pmid: 12855585
references.citation: Br J Pharmacol. 2002 Dec;137(8):1330-8
references.pmid: 12466243