Stability of VIII:C in plasma: the dependence on protease activity and calcium

Calcium Prevents Enhanced Degradation of Factor VIII in the Condition of Motion

Background: Hemophilia A and B induce recurrent bleeding episodes, mainly in skeletal muscles and joints that are in intermittent motion. We have previously demonstrated that intermittent motion contributes to increased degradation of factors VIII and IX. Objectives: Given that calcium ions are known to enhance factor VIII-von Willebrand factor (vWF) interaction, the present study has investigated the role of these ions on factors VIII and IX in the condition of motion. Methods: The effects of calcium ions were assessed using purified proteins via Western blot, factor VIII activity, immunocytochemistry, and in Institute of Cancer Research (ICR) mice with no specific genetic background. Results: Calcium was found to prevent degradation of plasma-derived factor VIII but not that of factor IX, during intermittent motion. Calcium levels in the microcirculation of mouse striated muscles were elevated following movement, enabling prevention of factor VIII degradation in normal physiology. Calcium supplementation in drinking water increased factor VIII levels in blood and striated muscles of ICR mice during movement. Conclusions: calcium ions decrease factor VIII degradation in the condition of motion. Further research on the impact of calcium salt oral supplementation on hemophilia patients is warranted.

Solving the Measurement Problem and then Steppin' Out over the Line Riding the Rarest Italian: Crossing the Streams to Retrieve Stable Bioactivity in Majorana Bound States of Dialy zed Human Platelet Lysates

Exhaustive dialysis (ED) of lysed human platelets against dilute HCl yields stable angiogenic activity. Dialysis against a constrained external volume, with subsequent relaxation of the separation upon opening the dialysis bag, produces material able to maintain phenotypes and viability of human cells in culture better than ED material. Significant graded changes in MTT viability measurement tracked with external volume. The presence of elements smaller than the MW cutoff, capable of setting up cycling currents initiated by oriented flow of HCl across the membrane, suggests that maturation of bioactivity occurred through establishment of a novel type of geometric phase. These information-rich bound states fit recent descriptions of topological order and Majorana fermions, suggesting relevance in testing Penrose and Hameroff's theory of Orchestrated Objective Reduction, under conditions more general, and on finer scales, than those dependent on tubulin protein. The Berry curvature appears to be a good tool for building a general field theory of physiologic stress dependent on the quantum Hall effect. A new form of geometric phase, and an associated "geometric" quantum Hall effect underlying memory retrieval, dependent on the rate of path traversal and reduction from more than two initial field influences is described.

Cryoprecipitate production: the use of additives to enhance the yield

Cryoprecipitate is still widely used to treat hemophilia A in developing countries. However, the yield of factor VIII is relatively low averaging, i.e. only 50%. We have attempted to enhance the yield by adding sodium citrate to the plasma following the method of Shanbrom and Owens (Blood 98, 2001, 60a). Fresh-frozen plasma (FFP) units were processed either as control plasma or after the addition of 10% sodium citrate. Cryoprecipitate was produced from both. After resuspension, calcium chloride was added to the citrated cryoprecipitate to correct for excess citrate prior to testing. The levels of FVIII and fibrinogen were determined in both preparations. The citrated cryoprecipitates had varying yields of fibrinogen and FVIII in the cryoprecipitate. The FVIII levels varied from 34% to 215% recovery. Fibrinogen ranged from 55.5% to 121.4%. We found that the addition of increasing amounts of CaCl2 to normal plasma raised the FVIII values from 1.0 to 4 U/ml. To determine the possibility of assay influence we added different quantities of CaCl2 to control plasma and measured the FVIII and activated partial thromboplastin time levels. Addition of citrate to plasma resulted in an increased total amount of cryoprecipitate much of which was citrate. Assays showed considerable ranges in the quantity of FVIII and fibrinogen. Activation of FVIII can be caused by addition of excess calcium.

The influence of citrate concentration on the quality of plasma obtained by automated plasmapheresis: a prospective study

BACKGROUND

There is a need for more comprehensive work dealing with the quality of plasma collected by automated plasmapheresis using different final concentrations of citrate anticoagulant. A prospective study was performed to examine the influence of three concentrations of sodium citrate on the levels of clotting factors and markers of activated hemostasis and fibrinolysis.

STUDY DESIGN AND METHODS

Fifty-one experienced plasma donors were recruited for subsequent 750-mL plasmapheresis procedures using 4-percent (wt/vol) sodium citrate. Anticoagulant-to-blood ratios of 1:16.6, 1:14.2, and 1:12.5 were used, corresponding to sodium citrate concentrations of 6 percent, 7 percent, and 8 percent (vol/vol), respectively. Between two plasmapheresis procedures, there was a washout period of 7 days. Determinations were made of the plasma levels of fibrinogen and factors V, VII, VIII, and IX, as well as antithrombin, tissue-type plasminogen activator, and several markers of activated hemostasis and fibrinolysis: activated factor VII, prothrombin splits products, D-dimers, and beta-thromboglobulin.

RESULTS

The plasma samples anticoagulated with 6-percent citrate contained significantly higher levels of factors V, VIII, and IX than the samples anticoagulated with 8-percent citrate (p<0.0001, p< or =0.0001 and p = 0.009, respectively). The citrate concentration had no influence on the levels of fibrinogen, factor VII, antithrombin, or tissue-type plasminogen activator. There was no evidence that the plasma samples containing lower citrate concentrations were more prone to activation of hemostasis or fibrinolysis.

CONCLUSION

A reduction in the final citrate concentration of plasma collected by automated plasmapheresis results in higher yields of factors V, VIII, and IX without activation of hemostasis. More comprehensive studies should confirm previous work dealing with the establishment of the lowest citrate concentration acceptable in plasma used as therapeutic fresh-frozen plasma or as starting material for the manufacture of plasma derivatives.

Isolation of the factor VIII-von Willebrand factor complex directly from plasma by gel filtration

A high capacity gel filtration system was developed with the purpose of isolating factor VIII (FVIII) and von Willebrand factor (vWF) directly from plasma in significantly higher yields than obtained by cryoprecipitation, the technique most commonly used to recover FVIII-vWF from human plasma. After laboratory-scale gel filtration of plasma, a FVIII-containing fraction was collected containing about 90% of FVIII in the applied plasma and with almost tenfold higher purity than that obtained by cryoprecipitation. The gel filtration step has been scaled up for use as the initial step in the manufacturing process for a FVIII preparation (Nordiate).

Stability of blood coagulation factors and inhibitors in blood drawn into half-strength citrate anticoagulant

Drawing of blood into a citrate-phosphate-dextrose (CPD) solution with a reduced citrate concentration has been shown to improve the maintenance of coagulation factor VIII (F VIII) in plasma and to give possibilities to improve erythrocyte preservation. We studied the quality of plasma obtained from whole blood drawn under continuous mixing into CPD in which the citrate concentration was reduced by 50% (0.5CPD). The blood was stored at room temperature for 8 h before component preparation. We confirmed improved stability of F VIII by 0.5CPD. We found no clinically significant changes in inhibitors to the coagulation and kallikrein systems, and no signs of activation of these systems, during the 8-hour holding time. In control blood drawn into CPD, F VIII and coagulation factor IX decreased by 0.09 IU/ml (8%) and 0.07 U/ml (7%), respectively, otherwise we found no significant differences between 0.5CPD plasma and CPD plasma.

Characterization of factors affecting the stability of frozen heparinized plasma

The use of heparin rather than citrate as primary anticoagulant has been shown to significantly improve the initial activity, stability and recovery of factor VIII:C from human plasma, cryoprecipitates or factor VIII concentrates if the plasma was initially frozen at -80 degrees C and subsequently stored at this temperature. If frozen and stored at progressively warmer temperatures however, increasing amounts of insoluble protein aggregates, termed storage precipitates (SPs), were recovered in the thawed plasma and cryoprecipitate fractions. Plasma recovery by centrifugation at 7,000 g for 7 min [Method I (MI)], 2 x 10 min (MII) or 15 min (MIII) had little effect on SP formation after 1 month at any storage temperature. After 4 months at -20 degrees C, more SP was recovered from MIII plasma whereas at -40 degrees C, more SP was recovered from MI plasma. Also, the preparation method had little or no effect on factor VIII:C activity at equivalent storage times or temperatures. A trend towards improved factor VIII recoveries was noted at lower freezing and storage temperatures however. SP formation was associated with reduced fibrinogen levels in the recovered plasma without loss of antithrombin-III or increased fibrinopeptide-A. Western blots showed polymerization of A alpha or gamma-chains of fibrinogen. SP formation was reduced or eliminated with factor XIII inhibitors, antibody to the active factor XIII a subunit or adjustment of heparinized plasma to 5-10 mM sodium citrate before initial freezing and storage. Although plasma factor VIII:C recoveries were only slightly affected at these citrate concentrations under most conditions, its recovery in cryoprecipitates was substantially improved owing to the reduction or absence of SPs.

Factor VIII: Structure, function and analysis

Factor VIII is an important blood coagulation protein whose genetic deficiency leads to the serious bleeding disorder, classic haemophilia (haemophilia A). Here we review the structure, function and analysis of this protein for diagnostic and therapeutic applications. Because factor VIII is tightly associated with von Willebrand factor some recent work on the latter is also considered so as to clarify the relationship between them.

Definition of the affinity of binding between human von Willebrand factor and coagulation factor VIII

Factor VIII and von Willebrand factor are two plasma proteins essential for effective hemostasis. In vivo, they form a non-covalent complex whose association appears to be metal ion dependent. However, a precise definition of the nature of the molecular forces governing their association remains to be defined, as does their binding affinity. In this paper we have determined the dissociation constant and stoichiometry for Factor VIII binding to immobilized von Willebrand factor. The data demonstrate that these proteins interact saturably and with relatively high affinity. Computer assisted analyses of the Scatchard data favour a two site binding model. The higher affinity site was found to have a Kd of 62 (+/- 13) x 10(-12) M while that of the lower affinity site was 380 (+/- 92) x 10(-12) M. The density of Factor VIII binding sites (Bmax) present on von Willebrand factor was 31 (+/- 3) pM for the high affinity binding site and 46 (+/- 6) pM for the lower site, corresponding to a calculated Factor VIII: von Willebrand factor binding ratio of 1:33 and 1:23, respectively.

[Safety of donors, quality of products, how much to reduce the quantity of citrate]

We examined 1,053 blood samples from 48 donors, for the effect of gradual reduction of citrate. We observed that: 1--Platelet count does not show any significant variation between 1/8 to 1/18 ratio. 2--In 13.3% of the cases, platelet clumping starts at 1/18 ratio. 3--There was no significant variation of the thrombin plasma level between 1/8 to 1/16 ratio (by measuring thrombin/ATIII complex). Our results show clearly that we can reduce the citrate ratio to 1/14 without expecting any adverse effect. Therefore we designated 1/14 as the security ratio. Parallel to this we also found that the average level +/- SD of ionized calcium is 100 +/- 10 muMol at 1/14 ratio.

A simple plasma anticoagulant-exchange method to increase the recovery of factor VIII in therapeutic concentrates

Donor blood, primarily anticoagulated by acid citrate dextrose formula A (ACD-A), was separated by means of the HemaScience Autopheresis C plasmapheresis device. The citrated plasma was collected directly into a solution of heparin and calcium chloride to achieve a final plasma-ionised calcium concentration of approximately 2 mM, and a heparin concentration of 1.0 IU/ml. Heparin at this concentration provided adequate anticoagulation, and did not result in insoluble cryoprecipitates. Three pairs of donor-matched 4-kg plasma pools (anticoagulant-exchanged variant and ACD-A-anticoagulated control) were constructed and subsequently fractionated to an intermediate stage. The mean recovery of factor VIII from 3 anticoagulant-exchanged pools (394 IU/kg) was 23% greater than the mean recovery from the matched control pools (319 IU/kg). This increased recovery was not achieved at the expense of specific activity.

Studies on the stability of VIII:C during the manufacture of a factor VIII concentrate for clinical use

The stability of VIII:C was investigated by monitoring samples taken at different points from a routine process for the manufacture of factor VIII concentrate and by examining the stabilising influence of a number of product formulations. Loss of VIII:C over process-finishing procedures (formulation, 0.22 micron filtration, dispensing) was associated with a citrate-induced inactivation which could be prevented by controlling the ionised calcium concentration of the solution. These results were obtained using a one-stage clotting assay but were not observed using a two-stage assay. No evidence for activation was found in vitro (e.g. by FPA generation and VIII:C stability) and the yield increase suggested by the one-stage assay was supported by results from a controlled clinical evaluation.

Human factor VIII from heparinized plasma. Purification and characterization of a single-chain form

Human factor VIII was purified from heparinized blood by cryoprecipitation, poly(ethyleneglycol) precipitation, Affi-Gel blue, aminohexyl, polyelectrolyte E5 and immunoaffinity chromatography. A purification of 280,000-fold over plasma with a specific activity over 5300 units/mg was achieved. Analyses of factor VIII using HPLC indicated a molecular mass of 280-340 kDa. Variation in the native mass may reflect heterogeneity of the protein due to associated lipid since structural analysis confirmed that factor VIII contained variable amounts of free fatty acids and diglycerides and triglycerides, but no phospholipids. Additional characterization by denaturing polyacrylamide gel electrophoresis under reducing conditions, followed by silver staining, showed a major single-chain polypeptide of factor VIII with a mass of approximately 260 kDa. To determine whether proteolyzed forms of factor VIII were present during fractionation, we analysed earlier steps in purification. This revealed additional species of factor VIII eluting faster than the single-chain form during chromatography on polyelectrolyte E5. Gel electrophoresis showed that these species of factor VIII consisted of multiple polypeptide chains, and partial peptide mapping using Staphylococcus aureus V8 protease indicated that they were structurally related. Monoclonal and hemophilic antibodies were used in immunoadsorption experiments to demonstrate that the purified factor VIII was composed predominantly of the 260-kDa factor VIII chain.

Studies on the procurement of blood coagulation factor VIII in vitro studies on blood components prepared in half-strength citrate anticoagulant

The effect of replacing a standard citrate anticoagulant with one containing half the amount of citrate on the in vitro properties of components prepared from blood donations was investigated. This resulted in a significant improvement in factor VIII stability such that there was little loss during overnight storage, and this was reflected in the factor VIII yield in cryoprecipitate. The quality of cellular components in red cell units stored up to 35 days or platelet concentrates stored up to 7 days was not adversely affected. Although initial levels were similar to those in standard anticoagulant, the extent of fibrinopeptide A generation and complement C3 breakdown in red cell units stored for 35 days in half-strength citrate was somewhat increased.

Molecular pathology and immunology of factor VIII (hemophilia A and factor VIII inhibitors)

Factor VIII is a large procoagulant glycoprotein that circulates in plasma in a noncovalent complex with von Willebrand factor. It is essential for the efficient cleavage of coagulation factor X by factor IXa, and its absence causes a severe bleeding disorder. Plasma factor VIII is reduced from the normal range of approximately 100 to 200 ng/ml in patients with the hereditary coagulation defect, hemophilia A, as well as in patients who develop autoantibodies that inactivate factor VIII. The understanding of factor VIII structure has been enhanced by recent studies that have characterized the X chromosome gene responsible for its synthesis, and preliminary information is now available about specific genetic defects. The basis for antibody formation in approximately 15 per cent of repeatedly transfused hemophilic patients is less clear at this time, however, for these individuals appear to have a variety of genetic defects that are not characteristically different from the patients who do not develop inhibitors. Although the antibodies cause a serious problem for affected individuals, they have been very useful in characterizing normal factor VIII and nonfunctional factor VIII-like protein that is found in the plasmas of 10 per cent of patients with mild hemophilia. Moreover, they are very useful reagents that can be used for immunoassay of factor VIII that has been modified in ways that have destroyed its procoagulant function.

Small-pool high-yield factor VIII production

Hemophilia care depends on several factors for the production of purified FVIII: plasma procurement, plasma logistics, production method, and efficacy. The latter two are restrictive factors, both for the supply and the safety of FVIII preparations. Conventional production methodology unavoidably recovers only 10 to 20% of usable protein, therefore requiring large pools of source plasma. Related to pool size is the transmission of diseases, which poses unnecessary risks for patients. The development of new technologies to better recover FVIII allows reduction of the pool size: crush-thaw, controlled pore-glass chromatography, and heparin double-cold precipitation techniques. This review will reflect on current production methods, pool size concept, small-pool approaches in FVIII production, and future developments.

Influence of heparin and calcium chloride on assay, stability, and recovery of factor VIII

The influence of heparin alone or in conjunction with calcium chloride on the coagulation assay for factor VIII, on the stability of factor VIII in blood and in plasma, and on the recovery of factor VIII in cryoprecipitate and in an intermediate purity concentrate was investigated. A stabilizing effect of heparin and calcium on factor VIII activity in blood and plasma could be confirmed. We were, however, unable to make use of the higher activity that can, under certain circumstances, be recovered in the cryoprecipitates; this was mainly due to the poor solubility of cryoprecipitates prepared from heparinized blood. Heparin (or the absence of a calcium chelator) also interferes with the recovery of plasma components other than factor VIII.

The relationship of biological and immunological activities of factor VIII

Factor VIII is an essential blood clotting factor which consists of two protein moieties, each with distinct biological functions and antigenic determinants. The immunological markers were originally seen as indicators of the biological activities; however this view has been increasingly challenged. We have investigated the biological and immunological properties of Factor VIII to clarify these relationships. Plasma stored at room temperature for 21 days lost biological activity, but retained immunological activity: The procoagulant activity was reduced to 35% and the ristocetin cofactor activity to 75.4% of their original levels; but the reactivities of both procoagulant antigen and Factor VIII related antigen were maintained. A dissociation of activities was also demonstrated in serum, in which the procoagulant activity was 10% and the procoagulant antigen 72% of corresponding plasma values. These results indicate that the antigenic reactivities are not appropriate markers for Factor VIII biological activity.