Recombinant blood clotting proteins for hemophilia therapy

Trauma-Induced Coagulopathy: An Institution's 35 Year Perspective on Practice and Research

INTRODUCTION

Injury is the second leading cause of death worldwide, and as much as 40% of injury-related mortality is attributed to uncontrollable hemorrhage. This persists despite establishment of regionalized trauma systems and advances in the management of severely injured patients. Trauma-induced coagulopathy has been identified as the most common preventable cause of postinjury mortality.

METHODS

A review of the current literature was performed by collecting PUBMED references related to trauma-induced coagulopathy. Data were then critically analyzed and summarized based on the authors' clinical and research perspective, as well as that reported by other institutions and researchers interested in trauma-induced coagulopathy. A particular focus was placed on those aspects of coagulopathy in which agreement among clinical and basic scientists is currently lacking; these include, pathophysiology, the role of blood components and factor therapy, and goal-directed assessment and management.

RESULTS

Trauma-induced coagulopathy has been recognized in approximately one-third of trauma patients. There is a vast range of severity, and the emergence of viscoelastic assays, such as thrombelastography and rotational thromboelastogram, has refined its diagnosis and management, particularly through the establishment of goal-directed massive transfusion protocols. Despite advancements in the diagnosis and management of trauma-induced coagulopathy, much remains to be understood regarding its pathophysiology. The cell-based model of hemostasis has allowed for characterization of endothelial dysfunction, impaired thrombin generation, platelet dysfunction, fibrinolysis, endogenous anticoagulants such as protein-C, and antifibrinolytic proteins. These concepts collectively compose the contemporary, but still partial, understanding of trauma-induced coagulopathy.

CONCLUSION

Trauma-induced coagulopathy is a complex pathophysiological condition, of which some mechanisms have been characterized, but much remains to be understood in order to translate this knowledge into improved outcomes for the injured patient.

Congenital platelet disorder and type I von Willebrand disease presenting as prolonged bleeding after cleft lip and palate repair

Cleft lip and palate can be associated with coagulopathy. Here, we report the first known case of congenital platelet disorder and von Willebrand disease presenting as prolonged bleeding after cleft lip and palate repair. After identifying the underlying pathology, platelet infusions and aminocaproic acid were given to decrease bleeding from a second surgical procedure. Whole exome sequencing identified a von Willebrand factor gene mutation, an adenine to guanine substitution at the c.475A location. A high index of suspicion should be had for coagulopathy in patients with syndromic cleft lip and palate.

Update and new developments in the management of the exsanguinating patient

Definitive management of the exsanguinating patient continues to challenge providers in multiple specialties. Significant hemorrhage may be encountered in a variety of patient care circumstances. Over the past two decades, the vast majority of data and evidence regarding transfusion in the exsanguinating patient has been based upon the trauma literature, and a large amount of recent research has investigated this subject area. In addition to the care of trauma patients, the data which have emerged can also be extrapolated to the treatment of nontrauma patients undergoing transfusion for major hemorrhage. The concept of massive transfusion is an evolving paradigm, and numerous investigations have challenged old principles while creating new controversies. The current review will examine the latest developments in the management of patients with profound hemorrhage. The challenges of dealing with the "lethal triad" will be discussed, as will the various aspects of damage control and hemostatic resuscitation. The latest literature and controversy regarding massive transfusions and massive transfusion protocols will be elucidated with inclusion of data from recent military experiences. Finally, adjuncts including the most recent advances in hemorrhage control, identification of early predictors for massive transfusion, and utilization of pharmacologic and complementary factor agent therapy will be discussed.

Postinjury coagulopathy management: goal directed resuscitation via POC thrombelastography

Progressive postinjury coagulopathy remains the fundamental rationale for damage control surgery, but the decision to abort operative intervention must occur before laboratory confirmation of coagulopathy. Current massive transfusion protocols have embraced pre-emptive resuscitation strategies emphasizing administration of packed red blood cells, fresh frozen plasma, and platelets in ratios approximating 1:1:1 during the first 24 hours postinjury, based on US military retrospective experience and recent noncontrolled civilian data. This policy, termed "damage control resuscitation" assumes that patients presenting with life threatening hemorrhage at risk for postinjury coagulopathy should receive component therapy in rations approximating those found in whole blood during the first 24 hours. While we concur with the concept of pre-emptive coagulation factor replacement, and initially suggested this in 1982, we remain concerned for the continued unbridled administration of fresh frozen plasma and platelets without objective evidence of their specific requirement. A major limitation of current massive transfusion protocols is the lack of real time assessment of coagulation function to guide evolving blood component requirements. Existing laboratory coagulation testing was originally designed for evaluation of hemophilia and subsequently used for monitoring anticoagulation therapy. Consequently, the applicability of these tests in the trauma setting has never been proven and the time required to conduct these assays is incompatible with prompt correction of the coagulopathy in the trauma setting. This review examines the current approach to postinjury coagulopathy, including identification of patients at risk, resuscitation strategies, design and implementation of institutional massive transfusion protocols, and the potential benefits of goal-directed therapy by real time assessment of coagulation function via point of care rapid thromboelastography.

Management of bleeding disorders by prohemostatic therapy

Pro-hemostatic therapy aims at an improvement of hemostasis, which may be achieved by amelioration of primary hemostasis, stimulation of fibrin formation or inhibition of fibrinolysis. These treatment strategies may be applied to specifically correct a defect in one of the pathways of coagulation, but have in some situations also been shown to be effective in reducing bleeding in patients without a primary defect in coagulation. Besides the transfusion of platelets in case of thrombocytopenia or severe platelet disorders, a pharmacological improvement of primary hemostasis may be achieved by the administration of desmopressin. The administration of DDAVP results in a marked increase in the plasma concentration of Von Willebrand factor (and associated coagulation factor VIII) and (also by yet unexplained additional mechanisms) a remarkable potentiation of primary hemostasis as a consequence. DDAVP is used for the prevention and treatment of bleeding in patients with von Willebrand disease or mild hemophilia A, and further in patients with an impaired function of primary hemostasis, such as in patients with uremia, liver cirrhosis or in patients with aspirin-associated bleeding. Based on the current insight that activation of coagulation in vivo predominantly proceeds by the tissue factor/factor VII(a) pathway, recombinant factor VIIa has been developed as a prohemostatic agent and has recently become available for clinical use. Indeed, in uncontrolled clinical studies this compound has been shown to exert a potent procoagulant activity and appeared to be highly effective in the prevention and treatment of bleeding, although most experience so far has been obtained in patients with severe and complicated coagulation defects. At present, a more general use of this agent for bleeding patients without an apparent coagulation defect is the subject of a number of ongoing clinical trials. Agents that exert anti-fibrinolytic activity are aprotinin and the group of lysine analogues. The pro-hemostatic effect of these agents proceeds not only by the inhibition of fibrinolysis (thereby shifting the procoagulant/anticoagulant balance towards a more procoagulant state), but also due to a protective effect on platelets, as has been demonstrated at least for aprotinin. The mechanism of this platelet-protective effect has, besides a potential prevention of plasmin-mediated loss of platelet receptors not been elucidated. Whether the pro-hemostatic effect of the anti-fibrinolytic agents will eventually result in a higher incidence of thromboembolic complications is still a matter of debate (see further), however, this has so far not been shown in straightforward clinical trials.

Adenoviral vector-mediated expression of physiologic levels of human factor VIII in nonhuman primates

An E1-, E2a-, E3-deleted adenoviral vector (Av3H82) encoding an epitope-tagged B domain-deleted human factor VIII cDNA (flagged FVIII) was evaluated in nonhuman primates. Twelve cynomolgus monkeys received intravenous administration of Av3H82; 6 monkeys received 6 x 10(11) particles/kg and another 6 received 3 x 10(12) particles/kg. Adenoviral vector transduction of the liver was efficient, reproducible, and linearly dose dependent. Physiologic levels of flagged FVIII were readily detected in plasma samples obtained from monkeys that received the higher dose of vector and human FVIII mRNA was detected in their livers. Expression of transgene mRNA was restricted to the liver by the albumin promoter. Although vector DNA was readily detected in the liver of monkeys that received the lower dose, neither human FVIII mRNA nor flagged FVIII protein could be detected. Vector distribution was widespread, with the highest levels observed in liver and spleen. Histopathology, hematology, and serum chemistry analysis identified the liver and blood as major sites of toxicity. Transient mild serum elevations of liver enzymes were observed, along with a dose-dependent inflammatory response in the liver. In addition, mild lymphoid hyperplasia was observed in the spleen. Mild anemia and a transient decrease in platelet count were observed, as was marrow hyperplasia and extramedullary hematopoiesis.

gamma-Carboxyglutamic acids 36 and 40 do not contribute to human factor IX function

The gamma-carboxyglutamic acid (Gla) domains of the vitamin K-dependent blood coagulation proteins contain 10 highly conserved Gla residues within the first 33 residues, but factor IX is unique in possessing 2 additional Gla residues at positions 36 and 40. To determine their importance, factor IX species lacking these Gla residues were isolated from heterologously expressed human factor IX. Using ion-exchange chromatography, peptide mapping, mass spectrometry, and N-terminal sequencing, we have purified and identified two partially carboxylated recombinant factor IX species; factor IX/gamma 40E is uncarboxylated at residue 40 and factor IX/gamma 36,40E is uncarboxylated at both residues 36 and 40. These species were compared with the fully gamma-carboxylated recombinant factor IX, unfractionated recombinant factor IX, and plasma-derived factor IX. As monitored by anti-factor IX:Ca (II)-specific antibodies and by the quenching of intrinsic fluorescence, all these factor IX species underwent the Ca(II)-induced conformational transition required for phospholipid membrane binding and bound equivalently to phospholipid vesicles composed of phosphatidylserine, phosphatidylcholine, and phosphatidylethanolamine. Endothelial cell binding was also similar in all species, with half-maximal inhibition of the binding of 125I-labeled plasma-derived factor IX at concentrations of 2-6 nM. Functionally, factor IX/gamma 36,40E and factor IX/gamma 40E were similar to fully gamma-carboxylated recombinant factor IX and plasma-derived factor IX in their coagulant activity and in their ability to participate in the activation of factor X in the tenase complex both with synthetic phospholipid vesicles and activated platelets. However, Gla 36 and Gla 40 represent part of the epitope targeted by anti-factor IX:Mg(II)-specific antibodies because these antibodies bound factor IX preferentially to factor IX/gamma 36,40E and factor IX/gamma 40E. These results demonstrate that the gamma-carboxylation of glutamic acid residues 36 and 40 in human factor IX is not required for any function of factor IX examined.

Purification of recombinant human coagulation factors II and IX and protein S expressed in recombinant Vaccinia virus-infected Vero cells

Recombinant human coagulation factors II and IX and recombinant human protein S were expressed by the Vaccinia virus expression system in Vero cells and isolated from the serum-free media. All three recombinant proteins were purified by the same universal strategy. After concentration by anion exchange chromatography, recombinant coagulation factors were purified by anion exchange filtration in the presence of Ca2+. The addition of Ca2+ to the vitamin K-dependent coagulation factors modified their physico-chemical behavior during anion exchange chromatography and resulted in the separation of the recombinant coagulation proteins from contaminating proteins.

Treating hemophilia

Hemophilias A and B are inherited disorders of clotting-factor production that are characterized by low levels of factor VIII- or IX-coagulant activity. The clinical course of patients with hemophilia is marked by episodes of hemorrhage, some spontaneous and some related to trauma or medical procedures. The physical well-being of patients with hemophilia is maintained by the prevention of bleeding when possible and by prompt, effective treatment of bleeding when it occurs. Factor-replacement therapy continues to be the mainstay of hemophilia treatment, but like pharmacotherapy for other disease states, it is most effective when provided within the framework of a well-designed, individualized therapeutic plan. Currently available factor concentrates have a much greater safety profile than older products, but they are not free of adverse effects. Patients with inhibitors continue to present a challenge in restoring hemostasis. Pharmacists can play an important role in the pharmaceutical care of patients with hemophilia.