Binding of Factor VIII to Lipid Nanodiscs Increases its Clotting Function in a Mouse Model of Hemophilia A

An overview on the investigation of nanomaterials' effect on plasma components: immunoglobulins and coagulation factor VIII, 2010-2020 review

FVIII and immunoglobulins (Igs) are the most prominent plasma proteins, which play a vital role in plasma hemostasis. These proteins have been implemented frequently in protein therapy. Therefore, their maintenance, durability, and stability are highly essential. Herein, various approaches to improve protein functions have been investigated, such as using recombinant protein replacement. In comparison, advances in nanotechnology have provided adequate context to boost biomaterial utilization. In this regard, the applications of various nanoparticles such as polymeric nanomaterials (PEG and PLGA), metal nanoparticles, dendrimers, and lipid based nanomaterials (liposomes and lipid nanoparticles) in stability and the functional improvement of antibodies and coagulation factor VIII (FVIII) have been reviewed from 2010 to 2020. Reviewing related articles has shown that not only can nanomaterials adequately protect the structure of proteins, but have also improved proteins' functions in some cases. For example, the high rate of FVIII instability has been successfully enhanced by bio-PEGylation. Also, utilizing PEGylated liposomes, using the PEG-lip technique for coating nanostructures, leads to FIIIV half-life prolongation. Hence, PEGylation had most impact on the stability of FVIII. Likewise, PEG-coated liposome nano-carriers also presented such a good effect on stability improvements for FVIII due to their ability to tune the immune system by reducing FVIII immunogenicity. Similarly, Ig PEGylation and conjugation to magnetic nanoparticles resulted in increased half-life and better purification of Igs, respectively, without any loss in structural or functional features. Consequently, metal-organic frameworks and recent hybrid systems have been introduced as promising nanomaterials in biomedical applications. As far as we know, this is the first study in this field, which considers the applications of nanoparticles for improving the storage and stability of antibodies and coagulation FVIII.

Factor VIII and Factor V Membrane Bound Complexes

The formation of membrane-bound complexes between specific coagulation factors at different cell surfaces is required for effective blood clotting. The most important of these complexes, the intrinsic Tenase and Prothrombinase complexes, are formed on the activated platelet surface during the propagation phase of coagulation. These two complexes are highly specific in their assembly mechanism and function modulated by anionic membranes, thus offering desirable targets for pharmaceutical interventions. Factor V (FV) and factor VIII (FVIII) are highly homologous non-enzymatic proteins. In their active state, FVa and FVIIIa serve as cofactors for the respective serine proteases factor Xa (FXa) and factor IXa (FIXa), significantly increasing their catalytic activity. This is achieved by forming well organized membrane-bound complexes at the phosphatidylserine rich activated platelet membrane in the presence of Ca²⁺ ions. The tenase (FVIIIa/FIXa) complex, catalyzes the proteolytic conversion of FX to FXa. Subsequently the prothrombinase (FVa/FXa) complex catalyzes the conversion of prothrombin to thrombin, required for efficient blood clotting. Although significant knowledge of FV and FVIII biochemistry and regulation has been achieved, the molecular mechanisms of their function are yet to be defined. Understanding the geometric assembly of the tenase and prothrombinase complexes is paramount in defining the structural basis of bleeding and thrombotic disorders. Such knowledge will enable the design of efficient pro- and anticoagulant therapies critical for regulating abnormal hemostasis. In this chapter, we will summarize the findings to date, showing our achievement in the field and outlining the future findings required to grasp the complexity of these proteins.