Matrix metalloproteinase-2 enhances platelet deposition on collagen under flow conditions.
Platelets contain and release matrix metalloproteinase-2 (MMP-2) that in turn potentiates platelet aggregation. Platelet deposition on a damaged vascular wall is the first, crucial, step leading to thrombosis. Little is known about the effects of MMP-2 on platelet activation and adhesion under flow conditions. We studied the effect of MMP-2 on shear-dependent platelet activation using the O'Brien filtration system, and on platelet deposition using a parallel-plate perfusion chamber. Preincubation of human whole blood with active MMP-2 (50 ng/ml, i.e. 0.78 nM) shortened filter closure time (from 51.8 ± 3.6 sec to 40 ± 2.7 sec, p<0.05) and increased retained platelets (from 72.3 ± 2.3% to 81.1 ± 1.8%, p<0.05) in the O'Brien system, an effect prevented by a specific MMP-2 inhibitor. High shear stress induced the release of MMP-2 from platelets, while TIMP-2 levels were not significantly reduced, therefore, the MMP-2/TIMP-2 ratio increased significantly showing enhanced MMP-2 activity. Preincubation of whole blood with active MMP-2 (0.5 to 50 ng/ml, i.e 0.0078 to 0.78 nM) increased dose-dependently human platelet deposition on collagen under high shear-rate flow conditions (3000 sec⁻¹) (maximum +47.0 ± 11.9%, p<0.05, with 50 ng/ml), while pre-incubation with a MMP-2 inhibitor reduced platelet deposition. In real-time microscopy studies, increased deposition of platelets on collagen induced by MMP-2 started 85 sec from the beginning of perfusion, and was abolished by a GPIIb/IIIa antagonist, while MMP-2 had no effect on platelet deposition on fibrinogen or VWF. Confocal microscopy showed that MMP-2 enhances thrombus volume (+20.0 ± 3.0% vs control) rather than adhesion. In conclusion, we show that MMP-2 potentiates shear-induced platelet activation by enhancing thrombus formation.
Giuseppe
G
Guglielmini
Viviana
V
Appolloni
Stefania
S
Momi
Philip G
PG
De Groot
Monica
M
Battiston
Luigi
L
De Marco
Emanuela
E
Falcinelli
Paolo Gresele, MD, PhD, Section of Internal and Cardiovascular Medicine, Department of Medicine, University of Perugia, Via E. Dal Pozzo, 06126 Perugia, Italy, Tel.: +39 075 5783989, Fax: +39 075 5716083, E-mail: paolo.gresele@unipg.it.
Paolo
P
Gresele
D000818:Animals; D001792:Blood Platelets / Q000166:cytology; D003094:Collagen / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005340:Fibrinogen / Q000737:chemistry; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D008853:Microscopy; D018613:Microscopy, Confocal; D015539:Platelet Activation; D010973:Platelet Adhesiveness; D010974:Platelet Aggregation; D011994:Recombinant Proteins / Q000378:metabolism; D033081:Shear Strength; D013314:Stress, Mechanical; D013927:Thrombosis / Q000378:metabolism*; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism; D014841:von Willebrand Factor / Q000378:metabolism
D011994:Recombinant Proteins; C560823:TIMP2 protein, human; D014841:von Willebrand Factor; D019716:Tissue Inhibitor of Metalloproteinase-2; D005340:Fibrinogen; D003094:Collagen; C522361:MMP2 protein, human; D020778:Matrix Metalloproteinase 2; C522362:Mmp2 protein, mouse
Matrix metalloproteinases; TIMP-2; platelet adhesion; shear stress