In vivo analysis of antithrombotic effectiveness of recombinant hirudin on microvascular thrombus formation and recanalization.
OBJECTIVE
This study was undertaken to evaluate in vivo the effect of recombinant hirudin (r-hirudin [HBW 023]), a potent thrombin inhibitor, on the process of microvascular thrombus formation and recanalization.


METHODS
Thrombosis was induced photochemically in distinct arterioles (n = 25) and venules (n = 30) of the ear of 16 hairless hr/hr mice (8 to 10 weeks old, 25 to 30 g of body weight). r-Hirudin (1 mg/kg of body weight) was administered intravenously directly before thrombus induction; saline-treated animals served as controls. Thrombus formation (i.e., first platelet deposition at the endothelial lining [FPD]; inner luminal diameter reduction to 50% [D/2]; complete vessel occlusion [CVO]), vessel recanalization, microcirculatory parameters, and leukocyte-endothelial cell interaction were analyzed by means of intravital fluorescence microscopy.


RESULTS
Hirudin significantly delayed the process of thrombus formation compared with saline-treated controls in both arterioles (FPD: 381 +/- 80 vs 137 +/- 25 seconds, P < 0.05; D/2: 627 +/- 49 vs 501 +/- 71 seconds; CVO: 925 +/- 78 vs 854 +/- 60 seconds) and venules (FPD: 173 +/- 11 vs 59 +/- 4 seconds; D/2: 342 +/- 54 vs 228 +/- 27 seconds; CVO: 541 +/- 85 vs 344 +/- 43 seconds; P < 0.05). In addition, r-hirudin-treated animals showed an increased rate of vessel recanalization at 24 hours after thrombus induction (arterioles: 54% [7 of 13] vs 0% [0 of 12], P < 0.05; venules: 77% [10 of 13] vs 53% [9 of 17]), whereas microcirculatory parameters and leukocyte-endothelial cell interaction were not affected.


CONCLUSIONS
Our data indicate that r-hirudin not only counteracts the process of thrombus formation but also promotes vessel recanalization, thus supporting its use in clinical microvascular surgery.
Roesken
F
F
Institute for Clinical and Experimental Surgery, University of Saarland, Homburg/Saar, Germany.
Vollmar
B
B
Rücker
M
M
Seiffge
D
D
Menger
M D
MD
D000818:Animals; D000991:Antithrombins / Q000627:therapeutic use*; D002465:Cell Movement / Q000187:drug effects; D024764:Hirudin Therapy; D007962:Leukocytes / Q000187:drug effects; D051379:Mice; D008812:Mice, Hairless; D008833:Microcirculation / Q000187:drug effects; D008856:Microscopy, Fluorescence; D011994:Recombinant Proteins / Q000627:therapeutic use; D013927:Thrombosis / Q000517:prevention & control*; D014654:Vascular Patency
D000991:Antithrombins; D011994:Recombinant Proteins