Regular Article The procoagulant properties of purified fibrinogen concentrate are enhanced by carbon monoxide releasing molecule-2 ☆ Kelly A. Machovec a , Deepu S. Ushakumari a , Ian J. Welsby b , Vance G. Nielsen a, ⁎ a Department of Anesthesiology and Perioperative Medicine, Drexel University College of Medicine b Department of Anesthesiology and Critical Care, Duke University School of Medicine abstract article info Article history: Received 4 May 2011 Received in revised form 21 June 2011 Accepted 2 August 2011 Available online 26 August 2011 Keywords: Fibrinogen concentrate Carbon monoxide releasing molecule Hemodilution Thrombelastography Introduction: Fibrinogen concentrate has been demonstrated to enhance coagulation in vitro and in several clinical settings of coagulopathy. We have recently demonstrated that carbon monoxide releasing molecule-2 (tricarbonyldichlororuthenium (II) dimer; CORM-2) enhances fibrinogen as a substrate for thrombin via an attached heme. The objective of this study was to determine if CORM-2 modified fibrinogen concentrate would enhance coagulation more effectively than CORM-2 naïve fibrinogen concentrate. Materials and Methods: In the first series of experiments, fibrinogen concentrate (final concentration 300 mg/dl) was exposed to 0, 50 or 100 μM CORM-2 for 5 min at 37 °C prior to being added to citrated, fibrinogen depleted plasma. In another series of experiments, citrated plasma obtained from 12 normal subjects was 50% diluted with crystalloid to which was added fibrinogen concentrate (final concentration 300 mg/dl) exposed to 0 or 100 μM CORM-2. Coagulation was activated with tissue factor (n = 8 per condition). Thrombus growth was monitored with thrombelastography for 15 min. Results and Conclusions: CORM-2 modification of fibrinogen concentrate significantly enhanced the velocity of clot formation (30-50%) and strength (15-31%) in fibrinogen deficient plasma. Similarly, while diluted plasma-derived thrombi demonstrated a marked decrease in velocity of formation (54%) and strength (61%), fibrinogen concentrate significantly enhanced velocity (217%) and strength (171%); however, CORM-2 modified fibrinogen concentrate significantly increased velocity (303%) and strength (205%) to a greater extent. Additional in vitro investigation and in vivo preclinical assessments of the hemostatic efficacy of CORM-2 modified fibrinogen concentrate are warranted. © 2011 Elsevier Ltd. All rights reserved. Introduction The continuing need for quickly accessible, durable blood components to treat coagulopathy in surgical/military settings is the focus of several investigators worldwide. One such therapeutic that is well established in Europe and recently approved in the United States is human fibrinogen concentrate (RiaSTAP®, CSL Behring GmbH, Marburg, Germany), a product derived from cryoprecipitate that is stable at room temperature (range 2-25 °C) for up to 30 months. Fibrinogen concentrate has been demonstrated to improve clot strength in human blood diluted with either crystalloid or colloidal volume expanders [1,2]. In a preclinical, porcine model of dilutional coagulopathy, fibrinogen concentrate improved the velocity of thrombus formation and strength [3]. Retrospective studies of severe hemorrhage [4,5] and cardiopulmonary bypass [5,6] demonstrated reduced need for red blood cell (RBC), fresh frozen plasma (FFP) and platelet transfusion and reduced bleeding following administration of fibrinogen concentrate; however, no untreated patients with hemor- rhage were used for comparison. Finally, in a prospective investiga- tion with patients undergoing coronary artery bypass surgery [7], prophylactic administration of fibrinogen concentrate decreased bleeding without significant postoperative hypercoagulability (e.g., vein graft occlusion). In sum, fibrinogen concentrate provides a quickly employable, effective treatment of congenital or acquired hypofibrinogenemia-associated coagulopathy. While fibrinogen concentrate administration is an effective therapeutic intervention, recent observation concerning fibrinogen biochemistry raised the possibility that this product could be further enhanced. We recently reported that of carbon monoxide releasing molecule-2 (tricarbonyldichlororuthenium (II) dimer; CORM-2) enhances plasmatic coagulation [8], primarily by enhancing fibrino- gen as a substrate [9]. Electron microscopy revealed that CORM-2 exposure changed the micromorphology of thrombi, resulting in a decrease in thick fibrin polymer formation in favor of thin fiber production [10]. Finally, we recently determined that the molecular mechanism by which carbon monoxide modifies fibrinogen is via an Thrombosis Research 129 (2012) 793–796 ☆ Grant Support: This investigation was supported by both the Departments. ⁎ Corresponding author at: Hahnemann University Hospital, Drexel University College of Medicine, Broad & Vine Streets, Mail Stop 310, Philadelphia, PA 19102. Tel.: +1 215 762 8936; fax: +1 215 762 8656. E-mail address: vance.nielsen@drexelmed.edu (V.G. Nielsen). 0049-3848/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.thromres.2011.08.005 Contents lists available at ScienceDirect Thrombosis Research journal homepage: www.elsevier.com/locate/thromres