title: In vivo imaging analysis of the interaction between unusually large von Willebrand factor multimers and platelets on the surface of vascular wall.
abstract: To elucidate how unusually large von Willebrand factor (UL-VWF) multimers facilitate thrombus formation, their behavior was analyzed together with that of platelets in living mice deficient in the gene encoding the protease that cleaves UL-VWF, a disintegrin-like and metalloprotease with thrombospondin type 1 motif 13 (ADAMTS13-/-). By crossing ADAMTS13-/- mice with green fluorescent protein-expressing transgenic mice (GFP mice), GFP-ADAMTS13-/- mice were obtained. The dynamics of GFP-expressing platelets were monitored employing intravital confocal fluorescent microscopy. Administration of a vasopressin derivative, DDAVP, a secretagogue of VWF increased the number of platelets adhered to vascular endothelial cells (VECs) on mesentery at sites recognized by an anti-VWF antibody. Some of these platelets were interconnected and aligned as beads on a string. They reached their maximum length at 5 min and were longer in GFP-ADAMTS13-/- mice than in GFP mice (5.3 ± 4.3, N = 6 vs 2.9 ± 2.1 μm, N = 4) (mean±SE). Focal injury of VECs by topical application of FeCl(3) developed longer (25, 3-50 vs 10, 2-25 μm, P < 0.01) (mean, 10th-90th percentile) and more stable (1.3, 0.3-6.3 vs 0.3, 0.2-1.3 s, P < 0.01) connected platelets in GFP-ADAMTS13-/- mice than in GFP mice. This study revealed that ADAMTS13 cleaves platelet-bound UL-VWF multimers, both during their secretion from VECs and after their adherence to injured vascular walls in veins. UL-VWF multimers either being secreted from VECs or circulating in plasma of ADAMTS13-/- mice appeared to facilitate the accumulation of longer and more stable VWF strings with more associated platelets on injured vascular walls.
authors.affiliation: Department of Physiology, Hamamatsu University School of Medicine, Handa-yama, Higashi-ku, Hamamatsu, Japan.
authors.forename: Miroslaw
authors.initials: M
authors.lastname: Rybaltowski
authors.forename: Yuko
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Hideo
authors.initials: H
authors.lastname: Mogami
authors.forename: Iwona
authors.initials: I
authors.lastname: Chlebinska
authors.forename: Tomasz
authors.initials: T
authors.lastname: Brzoska
authors.forename: Aki
authors.initials: A
authors.lastname: Tanaka
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Banno
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Miyata
authors.forename: Tetsumei
authors.initials: T
authors.lastname: Urano
mesh_terms: D000071120:ADAMTS13 Protein; D000818:Animals; D001792:Blood Platelets / Q000378:metabolism*; D003894:Deamino Arginine Vasopressin / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism* / Q000528:radiation effects; D007834:Lasers; D008666:Metalloendopeptidases / Q000172:deficiency / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D010973:Platelet Adhesiveness; D055503:Protein Multimerization; D013927:Thrombosis / Q000209:etiology; D014841:von Willebrand Factor / Q000378:metabolism*
chemical_list: D014841:von Willebrand Factor; C502939:ADAMTS13 protein, mouse; D008666:Metalloendopeptidases; D000071120:ADAMTS13 Protein; D003894:Deamino Arginine Vasopressin