Comparison of High Purity Factor IX Concentrates and a Prothrombin Complex Concentrate in a Canine Model of Thrombogenicity

A non-stasis canine model of thrombogenicity has been used to evaluate batches of high purity factor IX concentrates from 4 manufacturers and a conventional prothrombin complex concentrate (PCC). Platelets, activated partial thromboplastin time (APTT), fibrinogen, fibrin(ogen) degradation products and fibrinopeptide A (FPA) were monitored before and after infusion of concentrate. Changes in FPA were found to be the most sensitive and reproducible indicator of thrombogenicity after infusion of batches of the PCC at doses of between 60 and 180 IU/kg, with a dose related delayed increase in FPA occurring. Total FPA generated after 100-120 IU/kg of 3 batches of PCC over the 3 h time course was 9-12 times that generated after albumin infusion. In contrast the amounts of FPA generated after 200 IU/kg of the 4 high purity factor IX products were in all cases similar to albumin infusion. It was noted that some batches of high purity concentrates had short NAPTTs indicating that current in vitro tests for potential thrombogenicity may be misleading in predicting the effects of these concentrates in vivo.

Human plasma-derived immunoglobulin G fractionated by an aqueous two-phase system, caprylic acid precipitation, and membrane chromatography has a high purity level and is free of detectable in vitro thrombogenic activity

BACKGROUND AND OBJECTIVES

Instituto Clodomiro Picado has developed an immunoglobulin G (IgG) plasma fractionation process combining a polyethylene glycol/phosphate aqueous two-phase system (ATPS), caprylic acid precipitation and anion-exchange membrane chromatography. We evaluated the purity and in vitro thrombogenicity of such IgG, in line with current international requirements.

MATERIALS AND METHODS

Contributions of the different production steps to reduce thrombogenicity were assessed at 0·2 l-scale, and then the methodology was scaled-up to a 10 l-scale and final products (n = 3) were analysed. Purity, immunoglobulin composition, and subclass distribution were determined by electrophoretic and immunochemical methods. The in vitro thrombogenic potential was determined by a thrombin generation assay (TGA) using a Technothrombin fluorogenic substrate. Prekallikrein activator (PKA), plasmin, factor Xa, thrombin and thrombin-like activities were assessed using S-2302, S-2251, S-2222, S-2238 and S-2288 chromogenic substrates, respectively, and FXI by an ELISA.

RESULTS

The thrombogenicity markers were reduced mostly during the ATPS step and were found to segregate mostly into the discarded liquid upper phase. The caprylic acid precipitation eliminated the residual procoagulant activity. The IgG preparations made from the 10 l-batches contained 100% gamma proteins, low residual IgA and undetectable IgM. The IgG subclass distribution was not substantially affected by the process. TGA and amidolytic activities revealed an undetectable in vitro thrombogenic risk and the absence of proteolytic enzymes in the final product.

CONCLUSIONS

Fractionating human plasma by an ATPS combined with caprylic acid and membrane chromatography resulted in an IgG preparation of high purity and free of a detectable in vitro thrombogenic risk.

Quantifying the thrombogenic potential of human plasma-derived immunoglobulin products

Polyvalent immunoglobulin G (IgG) products obtained by fractionation of human plasma are used to treat a broad range of conditions, including immunodeficiency syndromes and autoimmune, inflammatory, and infectious diseases. Recent incidences of increased thromboembolic events (TEEs) associated with intravenous (IV) IgG (IVIG) led to recalls of some products and increased regulatory oversight of manufacturing processes in order to ensure that products are essentially free of procoagulant/thrombogenic plasma protein contaminants. Laboratory investigations have now identified activated factor XI (FXIa) as the likely causative agent of IVIG-related TEEs. Quantification of the thrombogenic potential is becoming a requirement made to fractionators (a) to validate the capacity of IVIG and subcutaneous IgG manufacturing processes to remove procoagulant contaminants and (b) to establish the safety of the final products. However, in the absence of a recommended test by the main regulatory authorities, several analytical approaches have been evaluated by fractionators, regulators, and university groups. This review focuses on the scientific rationale, merits, and applications of several analytical methods of quantifying the thrombogenic potential of IgG products and intermediates to meet the latest regulatory requirements.

Dengue virus inactivation by minipool TnBP/Triton X-45 treatment of plasma and cryoprecipitate

BACKGROUND AND OBJECTIVES

A minipool solvent/detergent (S/D; 1% TnBP/1% Triton X-45; 31°C) process was developed for viral inactivation of plasma and cryoprecipitate used for transfusion. The goal of this study was to determine the rate and extent of inactivation of dengue virus (DENV) during this process.

MATERIALS AND METHODS

DENV-1 was propagated using C6/36 mosquito cells to an infectivity titre close to 9 log and spiked (10% v/v) into individual plasma and cryoprecipitate samples from two distinct donors. Samples were taken right after spiking and during viral inactivation treatment by 1% TnBP-1% Triton X-45 at 31°C. DENV-1 infectivity was assessed on Vero E6 cells by a focus-forming assay (FFA). Culture medium and complement-inactivated plasma were used as experimental controls. Experiments were done in duplicate.

RESULTS

DENV-1 infectivity was 7·5 log in spiked plasma and 7·1 and 7·3 log in spiked cryoprecipitate. There was no loss of DENV-1 infectivity in the spiked materials, nor in the controls not subjected to S/D treatment. No infectivity was found in plasma and cryoprecipitate subjected to S/D treatment at the first time-point evaluated (10 min).

CONCLUSION

DENV-1 was strongly inactivated in plasma and cryoprecipitate, respectively, within 10 min of 1% TnBP/1% Triton X-45 treatment at 31°C. These data provide a reassurance of the safety of such S/D-treated plasma and cryoprecipitate with regard to the risk of transmission of all DENV serotypes and other flaviviruses.

Impact of solvent/detergent treatment of plasma on transfusion-relevant bacteria

BACKGROUND

A solvent/detergent (S/D) treatment in a medical device has been developed for pathogen reduction of plasma for transfusion. Impact of S/D on bacterial growth and on the capacity of complement to kill bacteria has been investigated in this study.

STUDY DESIGN AND METHODS

A pool of apheresis plasma from four donors was spiked with eight transfusion-relevant bacteria. Plasma was treated with 1% tri(n-butyl) phosphate and 1% Triton X-45 at 31°C for 90 min and then extracted by oil at 31°C for 70 min. Decomplemented plasma and Phosphate Buffer Saline were used as controls. Bacterial count was determined in samples taken immediately after spiking, or after S/D and oil treatment. Similar experiments were conducted using three individual recovered plasma donations. Bacteria growth inhibition tests were performed using discs soaked with plasma samples whether containing the S/D agents or not.

RESULTS

The mean reduction factors of Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae due to complement during S/D treatment were >8·75, 4·71, and 4·18 log in pooled plasma and >7·42, 2·24 and >6·08 log in individual plasmas, respectively. Bacillus cereus and Bacillus subtilis were inactivated by S/D (>7·04 and 1·60 log in pooled, and >6·06 and 2·39 in individual plasmas, respectively). Staphylococcus aureus, Staphylococcus epidermidis and Enterobacter cloacae did not multiply during S/D treatment of plasma. Growth inhibition tests revealed an inhibition of three gram-negative bacteria by complement and all gram-positive by S/D.

CONCLUSION

The S/D treatment of plasma does not alter the bactericidal activity of complement, and inactivates some gram-positive bacteria.

Pharmacokinetic study of minipooled solvent/detergent-filtered cryoprecipitate factor VIII

Eighteen cryoprecipitate minipools, each made of 30 units of low volume, concentrated cryoprecipitate, have been treated by solvent-detergent and filtration (S/D-F) in a single-use CE-marked bag system. The S/D-F cryoprecipitate contained a mean of 10.5 IU mL⁻¹ factor VIII (FVIII), 17 mg mL⁻¹ clottable fibrinogen, and >10 IU mL⁻¹ von Willebrand factor ristocetin co-factor, and anti-A and anti-B isoagglutinins were undetectable. The products have been infused in 11 severe (FVIII <1%) haemophilia A patients (mean age: 17.4 years; mean weight: 57.6 kg) at a dose close to 40 IU kg⁻¹. Patients were hospitalized for at least 36 h to determine FVIII recovery, half-life and clearance. They were also closely monitored for possible adverse events. None of the infused patients demonstrated reactions or adverse events even though they did not receive anti-allergic drugs or corticosteroids prior to infusion. The mean recovery of FVIII 10 min postinfusion was 69.7%. Mean FVIII half-life was 14.2 h and clearance was 2.6 mL h⁻¹ kg⁻¹. All patients had a bleeding-free interval of 8-10 days postS/D-F cryoprecipitate infusion. The data show that S/D-F cryoprecipitate FVIII presents a normal pharmacokinetics profile, and support that it could be safely used for the control of acute and chronic bleeding episodes in haemophilia A patients.

Intravenous immunoglobulin G: trends in production methods, quality control and quality assurance

Intravenous immunoglobulin G (IVIG) is now the leading product obtained by fractionation of human plasma. It is the standard replacement therapy in primary and acquired humoral deficiency, and is also used for immunomodulatory therapy in various autoimmune disorders and transplantation. Over the last 30 years, the production processes of IVIG have evolved dramatically, gradually resulting in the development of intact IgG preparations safe to administer intravenously, with normal half-life and effector functions, prepared at increased yield, and exhibiting higher pathogen safety. This article reviews the developments that have led to modern IVIG preparations, the current methods used for plasma collection and fractionation, the safety measures implemented to minimize the risks of pathogen transmission and the major quality control tests that are available for product development and as part of mandatory batch release procedures.

A virally inactivated functional growth factor preparation from human platelet concentrates

BACKGROUND

Human platelet growth factors (HPGF) are essential for tissue regeneration and may replace fetal bovine serum (FBS) in cell therapy. No method for the manufacture of standardized virally inactivated HPGF has been developed yet.

STUDY DESIGN AND METHODS

Platelet concentrates (PC) were subjected to solvent/detergent (S/D) treatment (1% TnBP/1% Triton X-45), oil extraction, hydrophobic interaction chromatography and sterile filtration. Platelet-derived growth factor (PDGF)-AB, -BB and -AA, transforming growth factor-beta1 (TGF-beta1), epidermal growth factor (EGF), insulin-like growth factor-1 (IGF-1) and vascular endothelium growth factor (VEGF) were measured by ELISA. Composition in proteins and lipids was determined, protein profiles were obtained by SDS-PAGE, and TnBP and Triton X-45 were assessed by gas chromatography and high-performance liquid chromatography, respectively. Cell growth promoting activity of HPGF was evaluated by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay using human embryonic kidney (HEK293A) fibroblast and Statens Seruminstitute rabbit corneal (SIRC) epithelial cell lines.

RESULTS

The GF preparation contained a mean of 16.66, 2.04, 1.53, 72.19, 0.33, 48.59 and 0.44 ng/ml of PDGF-AB, -BB, -AA, TGF-beta1, EGF, IGF-1 and VEGF, respectively. The protein profile was typical of platelet releasates and had less than 2 p.p.m. of residual S/D agents. MTS assay of HEK293A and SIRC cultures showed that the GF preparation at 10% and 0.1% (v/v), respectively, could successfully replace 10% FBS for cell proliferation. Cell-stimulating activity of HPGF on HEK293A was over twice that of PC releasates.

CONCLUSION

STANDARDIZED and functional virally inactivated HPGF can be prepared from human PC for possible applications in cell therapy and regenerative medicine.

[Plasma fractionation in the world: current status]

From 22 to 25 million liters of plasma are fractionated yearly in about 70 fractionation plants, either private or government-owned, mainly located in industrialized countries, and with a capacity ranging from 50000 to three million liters. In an increasingly global environment, the plasma industry has recently gone through a major consolidation phase that has seen mergers and acquisitions, and has led to the closure of a number of small plants in Europe. Currently, some fifteen countries are involved into contract plasma fractionation programs to ensure a supply of plasma-derived medicinal products. The majority of the plasma for fractionation is obtained by automated plasmapheresis, the remaining (recovered plasma) being prepared from whole blood as a by-product of red cell production. Plasma for fractionation should be produced, and controlled following well established procedures to meet the strict quality requirements set by regulatory authorities and fractionators. The plasma fractionation technology still relies heavily on the cold ethanol fractionation process, but has been improved by the introduction of modern chromatographic purification methods, and efficient viral inactivation and removal treatments, ensuring quality and safety to a large portfolio of fractionated plasma products. The safety of these products with regards to the risk of transmission of variant Creutzfeldt-Jakob disease seems to be provided, based on current scientific data, by extensive removal of the infectious agent during certain fractionation steps. The leading plasma product is now the intravenous immunoglobulin G, which has replaced factor VIII and albumin in this role. The supply of plasma products (most specifically coagulation products and immunoglobulin) at an affordable price and in sufficient quantity remains an issue; the problem is particularly acute in developing countries, as the switch to recombinant factor VIII in rich countries has not solved the supply issue and has even led to an increase of the mean price of plasma-derived factor VIII to the developing world. In the last few years, the plasma fractionation industry has improved greatly, and should remain essential in the years to come for the procurement of many essential medicines.

Current strategies to prevent transmission of prions by human plasma derivatives

Protein products prepared from pooled human plasma are an essential class of therapeutics used mostly to control bleeding and/or immunological disorders. Because of the human origin of the starting material, there is a risk that these products may possibly transmit prions causing variant Creutzfeldt-Jakob disease (vCJD). No case of transmission of prions by plasma products has been observed. Case-by-case measures implemented in various countries, and several technical factors may contribute, to various degrees, to the prevention of the risk of transmission of prions by plasma products. Those measures include (a) the epidemiological surveillance of population in countries with cases of vCJD and/or bovine spongiform encephalopathies (BSE), (b) the deferral of blood donors who traveled or resided, for specific periods of time, to countries with BSE, or who received transfusion or tissue transplant, (c) the removal of leucocytes in plasma used for fractionation, and, last but not least, (d) the removal of the prion agents during the complex industrial fractionation process used to prepare plasma products. Numerous experimental infectivity studies, involving the spiking of brain-derived infectious materials, have demonstrated that several fractionation steps, in particular ethanol fractionation, depth filtration, and chromatography, can remove several logs of prions. Removal is explained by the distinct hydrophobic and aggregative properties of the prion proteins. In addition, nanofiltration using multi-layer membranes of 75 nm or smaller, which is commonly used for removing viruses from coagulation factors and immunoglobulins products, can remove more than 3-5 logs of spiked prions, presumably by size-exclusion and trapping mechanisms. Therefore, the risk of transmission of vCJD by human plasma products appears remote, but caution should prevail since the biochemical nature of the infectious agent in human blood is still unknown.

A minipool process for solvent-detergent treatment of cryoprecipitate at blood centres using a disposable bag system

BACKGROUND AND OBJECTIVES

Single-donor or small-pool cryoprecipitates are produced by blood establishments, mostly in developing countries, for substitute therapy in haemophilia A, von Willebrand disease and fibrinogen deficiency, as well as for the manufacture of fibrin sealant. As cryoprecipitate may be contaminated with pathogenic plasma-borne viruses, there is an urgent need to develop a simple method for the viral inactivation of cryoprecipitate.

MATERIALS AND METHODS

Cryoprecipitate was obtained according to standard procedures. Ten minipools of five or six donations of cryoprecipitate were prepared and subjected, in sterile closed bags, to a viral inactivation treatment using either 2% tri(n-)butyl phosphate (TnBP) for 4 h at 37 degrees C or the combination of 1% TnBP and 1% Triton X-45 for 4 h at 31 degrees C. The cryoprecipitates were subsequently extracted three times in their processing bags by mixing and decantation using 7.5% sterile ricinus oil. The TnBP-treated cryoprecipitates were further subjected to a clarifying centrifugation step at 3800 g for 30 min. The final products were dispensed into individual bags and frozen at -30 degrees C or lower.

RESULTS

The cryoprecipitates treated with either 2% TnBP or 1% TnBP + 1% Triton X-45 showed excellent (> 93%) mean recovery of coagulant factor VIII (FVIII), ristocetin cofactor Von Willebrand factor (VWF:RCo), and clottable fibrinogen activity. Prothrombin time, international normalized ratio and activated partial thromboplastin time increased during solvent-detergent treatment but returned to initial values after oil extractions. The final content of TnBP and Triton X-45 was < 10 and 50 ppm, indicating excellent removal by the oil-extraction procedure.

CONCLUSIONS

Viral inactivation treatment by TnBP, with or without Triton X-45, can be applied to minipools of cryoprecipitate, with good recovery of FVIII, VWF and fibrinogen. The viral inactivation and solvent-detergent removal process can be performed in a closed bag system and using simple blood establishment techniques and equipment. This technology could be considered for the improved viral safety of cryoprecipitate which is used to treat haemophilia A, von Willebrand disease or fibrinogen deficiency, or to prepare fibrin sealant.

Content and functional activity of von Willebrand factor in apheresis plasma

BACKGROUND AND OBJECTIVES

Von Willebrand Factor (VWF) is a complex high-molecular-weight (HMW) plasma glycoprotein playing a critical role in primary and secondary haemostasis. Owing to its multimeric structure and sensitivity to proteolysis, VWF can be used as a marker of the impact of collection procedures on the characteristics of plasma for transfusion and for fractionation. We studied VWF content, functional activity and HMW multimers in plasmas collected by five different automated apheresis collection procedures.

MATERIALS AND METHODS

Five series of 30 plasma units were obtained from volunteer donors at two collection sites using Haemonetics PCS2 machines with Revision (Rev) F, Rev G, high-separation core (HSC), or filter core (FC) procedures, or Baxter-Fenwall Autopheresis-C (Auto-C). VWF antigen (VWF:Ag), ristocetin cofactor (VWF:RCo) activity and HMW multimers were first determined in 10 randomly selected plasma donations collected with Rev G, HSC, FC and Auto-C procedures. Then, the same analyses and the collagen binding (VWF:CB) activity were determined in the pools of 30 donations from each of the five procedures and compared with two normal plasma pools (NPP1 and NPP2). A reference plasma (RP) was used to calibrate each assay.

RESULTS

There were a greater number of group O individuals in the Rev F, Rev G and FC donors than in the HSC and Auto-C donors. The mean VWF:Ag level was > 100 IU/dl, VWF:RCo activity was > 90 U/dl, the VWF:RCo/Ag ratio was close to 1, and the percentage of 11-15 mers was above 100% of RP in the 10 individual plasma units from Rev G, HSC, FC, and Auto-C and in their respective pools. The mean percentage of multimers > 15 mers, relative to RP, was significantly less in Rev G plasmas (48 +/- 17%; range 32-91%), compared with Auto-C, HSC and FC plasmas (P = 0.0211; 0.0257; and 0.0376, respectively). The VWF:CB activity of the 30-donation pools was 61 and 60 U/dl in Auto C and HSC, 50 U/dl in Rev F and FC, and 43 U/dl in the Rev G pool. The VWF:CB/Ag ratio was 0.54 (Auto-C), 0.49 (HSC), 0.46 (Rev F), 0.45 (FC) and 0.37 (Rev G), compared with 0.81and 0.92 in NPPs. The percentage of VWF multimers of 11-15 mers in apheresis plasma and NPP was normal. VWF multimers > 15 mers ranged from 38 to 64% of that of RP plasma, and was 111 and 112% in NPPs.

CONCLUSIONS

The VWF:Ag, VWF:RCo activity and 11-15 mer VWF multimers were well preserved in all plasma units from each of the five apheresis procedures. The VWF:CB activity and the percentage of multimers > 15 mers in apheresis plasma was less than in normal plasma pools and differed slightly among procedures.

WHO Expert Committee on Biological Standardization

This report presents the recommendations of a WHO Expert Committee commissioned to coordinate activities leading to the adoption of international requirements for the production and control of vaccines and other biologicals and the establishment of international biological reference materials. The report starts with a discussion of general issues brought to the Committee's attention and provides information on the status and development of reference materials for various antibodies, antigens, blood products and related substances, cytokines, growth factors, and endocrinological substances. The second part of the report, of particular relevance to manufacturers and national regulatory authorities, contains recommendations for the production and quality control of meningococcal group C conjugate vaccines, guidelines for regulatory expectations for clinical evaluation of vaccines, guidelines for the production and quality control of inactivated oral cholera vaccines and guidelines on viral inactivation and removal procedures intended to assure the viral safety of human blood plasma products.

Chromatographic purification and properties of a therapeutic human protein C concentrate

Protein C deficiency (inherited and acquired) has a relatively high incidence rate in the general population worldwide. For many years, protein C deficient patients have been treated with fresh frozen plasma, prothrombin complex concentrates, heparin or oral anticoagulants, which all have clinical drawbacks. We report the production process of a highly purified human protein C concentrate from 1500 l of cryo-poor plasma by a four-step chromatographic procedure. After DEAE-Sephadex adsorption, protein C was separated from clotting factors II, VII and IX by DEAE-Sepharose FF and further purified, using a new strategy, by an on-line chromatographic system combining DMAE-Fractogel and heparin-Sepharose CL-6B. In addition, the product was treated against viral risks by solvent-detergent and nanofiltration on 15-nm membranes. The protein C concentrate was essentially free of other vitamin K-dependent proteins. Proteolytic activity was undetectable. Neither activated protein C, prekallikrein activator, nor activated vitamin K-dependent clotting factors were found resulting in good stability of the protein C activity. In vitro and in vivo animal tests did not reveal any sign of potential thrombogenicity. The final freeze-dried product had a mean protein C concentration of 58 IU/ml and a mean specific activity of 215 IU/mg protein, corresponding to over 12000-fold purification from plasma. Therefore, this concentrate appears to be of potential benefit for the treatment of protein C deficiency.

Nanofiltration of single plasma donations: feasibility study

BACKGROUND AND OBJECTIVES

Major technical developments have been made in recent years to improve the quality and safety of human plasma for transfusion and fractionation. The present study was performed to assess, for the first time, the feasibility of applying a nanofiltration process, using 75-nm and 35-nm mean pore size membranes (Planova) 75N and Planova 35N), to human plasma.

MATERIALS AND METHODS

Ten apheresis plasma units were obtained from 10 plasma donors. Within 4 h of collection, plasma was subjected to leucoreduction and filtration (using 75-nm and 35-nm mean pore size membranes) at 35 degrees C, at less than 1 bar pressure. Aliquots of plasma were taken at all steps of the filtration procedure and numerous plasma quality parameters were measured. In addition, six hepatitis C virus (HCV)-positive plasma donations were experimentally subjected to the same filtration sequence and subsequently assessed by RNA polymerase chain reaction (PCR) and branched-chain DNA-quantification assays.

RESULTS

Leucoreduced plasma can be reproducibly nanofiltered onto a sequence of 75-nm and 35-nm membranes, at a flow rate of 450 ml/h and a temperature of 35 +/- 0.5 degrees C. Some protein dilution, or loss, was found during filtration, but the plasma filtered through membranes with a mean pore size of 75 nm and 35 nm met in vitro specifications for use in transfusion or fractionation. There were no signs of activation of the coagulation system. HCV-positive plasma donations became negative, as judged by PCR and branched-chain DNA assay results, after filtration through the 35-nm membrane.

CONCLUSIONS

It is possible to apply a 75 + 35-nm filtration process to leucoreduced human plasma. This technology may have important future benefits in improving the quality and safety of plasma, by removing blood cell debris and infectious agents.

Nanofiltration of plasma-derived biopharmaceutical products

This review presents the current status on the use and benefits of viral removal filtration systems--known as nanofiltration--in the manufacture of plasma-derived coagulation factor concentrates and other biopharmaceutical products from human blood origin. Nanofiltration of plasma products has been implemented at a production scale in the early 1990s to improve margin of viral safety, as a complement to the viral reduction treatments, such as solvent-detergent and heat treatments, already applied for the inactivation of human immunodeficiency virus, hepatitis B and hepatitis C virus. The main reason for the introduction of nanofiltration was the need to improve product safety against non-enveloped viruses and to provide a possible safeguard against new infectious agents potentially entering the human plasma pool. Nanofiltration has gained quick acceptance as it is a relatively simple manufacturing step that consists in filtering protein solution through membranes of a very small pore size (typically 15-40 nm) under conditions that retain viruses by a mechanism largely based on size exclusion. Recent large-scale experience throughout the world has now established that nanofiltration is a robust and reliable viral reduction technique that can be applied to essentially all plasma products. Many of the licensed plasma products are currently nanofiltered. The technology has major advantages as it is flexible and it may combine efficient and largely predictable removal of more than 4 to 6 logs of a wide range of viruses, with an absence of denaturing effect on plasma proteins. Compared with other viral reduction means, nanofiltration may be the only method to date permitting efficient removal of enveloped and non-enveloped viruses under conditions where 90-95% of protein activity is recovered. New data indicate that nanofiltration may also remove prions, opening new perspectives in the development and interest of this technique. Nanofiltration is increasingly becoming a routine step in the manufacture of biopharmaceutical products.

Passive transfer of scrub typhus plasma to patients with AIDS: a descriptive clinical study

We examined the HIV-inhibitory effects previously found to be associated with scrub typhus infection. Individual 500 ml units of plasma from donors with mild scrub typhus were safety-tested, subjected to virucidal heat treatment, and administered to 10 HIV-1-infected recipients who were not receiving antiretroviral drugs. HIV-1 copy number fell three-fold or more in two recipients, and virus burden was reduced for 8 weeks in 70% (7/10) of recipients of a single plasma infusion, compared with the mean of three pre-infusion measurements. Scrub typhus donor plasma inhibited HIV-1 in vitro compared with normal human plasma and media controls. In the clearest in vivo response, reduction in viral load was accompanied by clinical improvement, a switchback from the syncytia-inducing to the non-syncytia-inducing phenotype, and decreases in CD8 cells and IL-6 levels. Scrub typhus infections can generate heat-stable, transferable plasma factors that exert prolonged anti-HIV effects. Whether variability in the results is due to different scrub typhus infections, different HIV infections or different individual responses, is unclear.

Affinity chromatography in the industrial purification of plasma proteins for therapeutic use

Affinity chromatography is a powerful technique for the purification of many proteins in human plasma. Applications cover the isolation of proteins for research purposes but also, to a large extent, for the production of therapeutic products. In industrial plasma fractionation, affinity chromatography has been found to be particularly advantageous for fine and rapid capture of plasma proteins from industrial plasma fractions pre-purified by ethanol fractionation or by ion-exchange chromatography. To date, affinity chromatography is being used in the production of various licensed therapeutic plasma products, such as the concentrates of Factor VIII, Factor IX, von Willebrand Factor, Protein C, Antithrombin III, and Factor XI. Most commonly used ligands are heparin, gelatin, murine antibodies, and, to a lesser extent, Cu(2+). Possible development of the use of affinity chromatography in industrial plasma fractionation should be associated to the current development of phage display and combinatorial chemistry. Both approaches may lead to the development of tailor-made synthetic ligands that would allow implementation of protein capture technology, providing improved productivity and yield for plasma products.

Evaluation of a fibrin sealant free of bovine-derived components in an experimental vas anastomosis study

OBJECTIVES

The risk of transmission of bovine spongiform encephalopathy cannot be excluded from the use of bovine-derived products. The present study was undertaken to evaluate the performance of a new fibrin glue free of bovine-derived components in vas anastomosis and to compare this product to conventional vas anastomosis with fibrin glue.

METHODS

Bilateral delayed vas anastomosis was performed in 40 Sprague-Dawley rats. All animals underwent a fibrin glue-assisted vas anastomosis with three transmural sutures tied prior to fibrin glue application. The composition and preparation of fibrin glue was similar for all vas anastomoses except the fibrinolysis inhibitor component which was aprotinin (3,000 KUI/ml) in group 1 and tranexamic acid (10 mg/ml) in group 2. The animals (20 rats in both groups) were sacrificed 7 weeks postoperatively and evaluated for gross patency, presence of sperm granuloma and tensile strength measurements at the anastomosis site.

RESULTS

No difference was found between the 2 groups for all parameters evaluated whether a bovine-derived or a synthetic fibrinolysis inhibitor component was used.

CONCLUSION

This study showed that tranexamic acid, a fibrinolysis inhibitor, can be substituted for conventional fibrin glue thereby avoiding the risks of bovine products.

Purification of human ceruloplasmin as a by-product of C1-inhibitor

Human ceruloplasmin (Cp) has been purified from cryoprecipitate-poor plasma as a by-product of the C1-inhibitor production chain. Highly purified Cp was obtained by subsequent ion-exchange chromatography on sulfate-Fractogel EMD and TMAE-Fractogel EMD. Treatments for viral safety included application of the solvent-detergent method and two nanofiltration steps using 35- and 15-nm pore size filters at the end of the process. Overall antigen yield was 95 (+/-5) %. Purified human ceruloplasmin was studied by electron spin resonance (ESR) to characterize its different types of copper complexes and to check its antioxidant properties. We distinguished three types of complexes: one type-2 Cu(II) with g// = 2.25 and A// = 180 G and two type-I Cu(II) exhibiting different narrow hyperfine splitting (A// = 72 G and A// = 90 G) with close g// (2.20 and 2.21). Purified Cp has a specific activity of 24.5+/-0.2 mU/mg of proteins. This process provides a method for Cp purification that could be easily integrated into modern plasma fractionation.

Virucidal heat-treatment of single plasma units: a potential approach for developing countries

Since HIV first burst onto the scene of transfusion medicine, the quest for viral inactivation processes for plasma and plasma products has not ceased. Sophisticated methods for improving viral safety are currently used in the industrial world. However, in developing countries, with no facilities for treating plasma, nonviral-inactivated fresh frozen plasma [FFP] continues to be used extensively, and as screening may not be optimal (or may even be absent), FFP still contributes to the spread of HIV and other infectious viruses. The feasibility of heat-treating FFP at the liquid state, in its collection bag, was explored by testing diverse conditions of temperature and duration, in the presence of biologically compatible stabilisers. Quality of the heat-treated plasma was evaluated by haematological, biochemical and animal assays. The efficiency of the method to inactivate viruses was validated using HIV and model viruses. The selected heating conditions are 50 degrees C for 3 h. The optimized combination of stabilizers is composed of 30 mM trisodium citrate, 10 g L-1 L-lysine, 12 mM calcium gluconate and 150 g L-1 sorbitol. Plasma coagulability is appropriately preserved as shown by the KCT ratio (1.4). Recovery of biological activity of most coagulation factors is higher than 70% (including fibrinogen & von Willebrand factor). Electrophoretic and immunoblotting studies did not evidence protein aggregation and/or degradation. Viral validation studies of this procedure have shown complete inactivation of HIV (> 6.6 log) in less than 1 h of treatment. A viral reduction of at least 4 log for various model viruses, including those of hepatitis A and C viruses, suggests a potential contribution of the method to diminish the risk from various blood-borne viruses. The selected formulation appears to preserve plasma protein integrity and properties. The procedure does not require sophisticated equipment but it is mandatory to monitor it carefully to ensure quality and reproducibility. If properly controlled and standardized, this approach offers an opportunity to reduce the risk of transmission of HIV and other viruses, particularly in poor countries with a high incidence of HIV.

Vasal reanastomosis using fibrin glue combined with sutures: which combination of sutures in a delayed protocol? Experimental study in rats

OBJECTIVES

The actual number of transmural sutures needed to ensure a successful fibrin-glued vasovasostomy is a key study parameter of the few experimental works already published. The present work was done to evaluate fibrin-glued vasovasostomy in rats in combination with only 2 transmural sutures. We compared the results to our previous study in which we demonstrated the efficiency of a combination of the use of fibrin glue with 3 sutures in comparison with a conventional microsurgical technique.

MATERIALS AND METHODS

Twenty Sprague-Dawley rats underwent bilateral vasectomy followed 2 weeks later by bilateral vasovasostomy using fibrin glue combined with 2 transmural sutures. Each animal was sacrificed 7 weeks postoperatively after a 3-week mating period with a Sprague-Dawley female rat, the vasal specimens were evaluated for sperm granuloma formation. Mean operative time and fertility rates were recorded.

RESULTS

The combination of fibrin glue with 2 transmural sutures gave evidence of less successful performances than the combination with 3 transmural sutures and the conventional microsurgical technique for all parameters evaluated but the mean operative time.

CONCLUSION

Our study underlines the need for a third transmural suture placed 120 degrees apart from the others when performing a fibrin glue delayed vasovasostomy. This allows a better vas lumen opening at the anastomotic site and therefore a more efficient vasal anastomosis in a delayed protocol.

Reducing the risk of infection from plasma products: specific preventative strategies

Collection and testing procedures of blood and plasma that are designed to exclude donations contaminated by viruses provide a solid foundation for the safety of all blood products. Plasma units may be collected from a selected donor population, contributing to the exclusion of individuals at risk of carrying infectious agents. Each blood/plasma unit is individually screened to exclude donations positive for a direct (e.g., viral antigen) or an indirect (e.g. anti-viral antibodies) viral marker. As infectious donations, if collected from donors in the testing window period, can still be introduced into manufacturing plasma pools, the production of pooled plasma products requires a specific approach that integrates additional viral reduction procedures. Prior to the large-pool processing, samples of each donation for fractionation are pooled ('mini-pool') and subjected to a nucleic acid amplification test (NAT) by, for example, the polymerase chain reaction (PCR) to detect viral genomes (in Europe: HCV RNA plasma pool testing is now mandatory). Any individual donation found PCR positive is discarded before the industrial pooling. The pool of eligible plasma donations (which may be 2000 litres or more) may be subjected to additional viral screening tests, and then undergoes a series of processing and purification steps that, for each product, comprise one or several reduction treatments to exclude HIV, HBV HCV and other viruses. Viral inactivation treatments most commonly used are solvent-detergent incubation and heat treatment in liquid phase (pasteurization). Nanofiltration (viral elimination by filtration), as well as specific forms of dry-heat treatments, have gained interest as additional viral reduction steps coupled with established methods. Viral reduction steps have specific advantages and limits that should be carefully balanced with the risks of loss of protein activity and enhancement of epitope immunogenicity. Due to the combination of these overlapping strategies, viral transmission events of HIV, HBV, and HCV by plasma products have become very rare. Nevertheless, the vulnerability of the plasma supply to new infectious agents requires continuous vigilance so that rational and appropriate scientific countermeasures against emerging infectious risks can be implemented promptly.