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Improved hemostasis in hemophilia mice by means of an engineered factor Va mutant.

ABSTRACT: Factor (F)VIIa-based bypassing not always provides sufficient hemostasis in hemophilia.To investigate the potential of engineered activated factor V (FVa) variants as bypassing agents in hemophilia A.Activity of FVa variants was studied in vitro using prothrombinase assays with purified components and in FV- and FVIII-deficient plasma using clotting and thrombin generation assays. In vivo bleed reduction after the tail clip was studied in hemophilia A mice.FVa mutations included a disulfide bond connecting the A2 and A3 domains and ones that rendered FVa resistant to inactivation by activated protein C (APC). '(super) FVa,' a combination of the A2-A3 disulfide (A2-SS-A3) to stabilize FVa and of APC-cleavage site mutations (Arg506/306/679Gln), had enhanced specific activity and complete APC resistance compared with wild-type FVa, FVL eiden (Arg506Gln), or FVaL eiden (A2-SS-A3). Furthermore, (super) FVa potently increased thrombin generation in vitro in FVIII-deficient plasma. In vivo, (super) FVa reduced bleeding in FVIII-deficient mice more effectively than wild-type FVa. Low-dose (super) FVa, but not wild-type FVa, decreased early blood loss during the first 10 min by more than two-fold compared with saline and provided bleed protection for the majority of mice, similar to treatments with FVIII. During the second 10 min after tail cut, (super) FVa at high dose, but not wild-type FVa, effectively reduced bleeding. These findings suggest that (super) FVa enhances not only clot formation but also clot stabilization. Thus, (super) FVa efficiently improved hemostasis in hemophilia in vitro and in vivo and may have potential therapeutic benefits as a novel bypassing agent in hemophilia.

SUBMITTER: von Drygalski A

PROVIDER: S-EPMC4161283 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature

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Improved hemostasis in hemophilia mice by means of an engineered factor Va mutant.

von Drygalski A A Cramer T J TJ Bhat V V Griffin J H JH Gale A J AJ Mosnier L O LO

Journal of thrombosis and haemostasis : JTH 20140101 3

<h4>Background</h4>Factor (F)VIIa-based bypassing not always provides sufficient hemostasis in hemophilia.<h4>Objectives</h4>To investigate the potential of engineered activated factor V (FVa) variants as bypassing agents in hemophilia A.<h4>Methods</h4>Activity of FVa variants was studied in vitro using prothrombinase assays with purified components and in FV- and FVIII-deficient plasma using clotting and thrombin generation assays. In vivo bleed reduction after the tail clip was studied in hem ...[more]

PMID: 24818532

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Project description:BackgroundHemostasis and repair are two essential processes in wound healing, yet early hemostasis and following vascularization are challenging to address in an integrated manner.ResultsIn this study, we constructed a hemostatic sponge OBNC-DFO by fermentation of Komagataeibacter xylinus combined with TEMPO oxidation to obtain oxidized bacterial nanocellulose (OBNC). Then angiogenetic drug desferrioxamine (DFO) was grafted through an amide bond, and it promoted clot formation and activated coagulation reaction by rapid blood absorption due to the high total pore area (approximately 42.429 m2/g measured by BET). The further release of DFO stimulated the secretion of HIF-1α and the reconstruction of blood flow, thus achieving rapid hemostasis and vascularization in damaged tissue. This new hemostatic sponge can absorb water at a rate of approximate 1.70 g/s, rapidly enhancing clot formation in the early stage of hemostasis. In vitro and in vivo coagulation experiments (in rat tail amputation model and liver trauma model) demonstrated superior pro-coagulation effects of OBNC and OBNC-DFO to clinically used collagen hemostatic sponges (COL). They promoted aggregation and activation of red blood cells and platelets with shorter whole blood clotting time, more robust activation of endogenous coagulation pathways and less blood loss. In vitro cellular assays showed that OBNC-DFO prevailed over OBNC by promoting the proliferation of human umbilical vein endothelial cells (HUVECs). In addition, the release of DFO enhanced the secretion of HIF-1α, further strengthening vascularization in damaged skin. In the rat skin injury model, 28 days after being treated with OBNC-DFO, skin appendages (e.g., hair follicles) became more intact, indicating the achievement of structural and functional regeneration of the skin.ConclusionThis hemostatic and vascularization-promoting oxidized bacterial nanocellulose hemostatic sponge, which rapidly activates coagulation pathways and enables skin regeneration, is a highly promising hemostatic and pro-regenerative repair biomaterial.

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Improved hemostasis in hemophilia mice by means of an engineered factor Va mutant.

Publications

Improved hemostasis in hemophilia mice by means of an engineered factor Va mutant.

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