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

Platelet storage media

Present platelet storage media often designated platelet additive solutions (PAS) basically contain acetate, citrate and phosphate and recently also potassium and magnesium. However, there seems to be an increasing interest in developing PASs that can be used also after further reduction of residual plasma content below 15-20% plasma. Inclusion of glucose but also calcium and bicarbonate in such solutions have been suggested to improve platelet (PLT) storage, especially when plasma content is reduced to very low levels. Results from a limited number of studies using novel PAS alternatives have been presented during the last years, such as InterSol-G, PAS-5, M-sol, PAS-G and SAS. Most of them are experimental solutions. The combined results presented in those studies suggest that presence of glucose may be necessary during PLT storage, primarily to maintain ATP at acceptable levels. At plasma inclusion below 15-20%, the content of glucose will generally be too low to support PLT metabolism for more than a few days making glucose addition in PAS necessary. Significant effects associated with presence of calcium was observed in PLTs stored in PAS with 5% inclusion but not with 20-35% plasma inclusion, suggesting that the content of plasma could be of importance. Bicarbonate only seems to be of importance for pH regulation, primarily when plasma inclusion is reduced to about 5%. Reduction in rate of glycolysis was observed in some PAS alternatives containing potassium and magnesium but not in others. Differences in pH or in concentrations of the various compounds included in PAS may be possible explanations. Additionally, novel PAS containing glucose, calcium and bicarbonate does not seem to be associated with improved in vitro results as compared to SSP+ or CompoSol when PLTs are stored with 35% plasma inclusion. The results would then also suggest that excess of glucose in novel PAS environment may not be associated with additional positive effects on PLT metabolism. This review is based on the few publications on novel PAS available, and additional studies would be needed in the future.

Factor VIII and fibrinogen recovery in plasma after Theraflex methylene blue-treatment: effect of plasma source and treatment time

BACKGROUND

The quality of fresh-frozen plasma is affected by different factors. Factor VIII is sensitive to blood component storage processes and storage as well as pathogen-reduction technologies. The level of fibrinogen in plasma is not affected by the collection processes but it is affected by preparation and pathogen-reduction technologies.

MATERIALS AND METHODS

The quality of plasma from whole blood and apheresis donations harvested at different times and treated with a pathogen-reduction technique, methylene blue/light, was investigated, considering, in particular, fibrinogen and factor VIII levels and recovery.

RESULTS

The mean factor VIII level after methylene blue treatment exceeded 0.5 IU/mL in all series. Factor VIII recovery varied between 78% and 89% in different series. The recovery of factor VIII was dependent on plasma source as opposed to treatment time. The interaction between the two factors was statistically significant. Mean levels of fibrinogen after methylene blue/light treatment exceeded 200 mg/dL in all arms. The level of fibrinogen after treatment correlated strongly with the level before treatment. There was a negative correlation between fibrinogen level before treatment and recovery. Pearson's correlation coefficient between factor VIII recovery and fibrinogen recovery was 0.58.

DISCUSSION

These results show a difference in recovery of factor VIII and fibrinogen correlated with plasma source. The recovery of both factor VIII and fibrinogen was higher in whole blood plasma than in apheresis plasma. Factor VIII and fibrinogen recovery did not appear to be correlated.

Warm storage of whole blood for 72 hours

BACKGROUND

In field emergency medicine, fresh whole-blood units are stored at room temperature up to 24 hours or occasionally longer. Few data exist on the integrity and in vitro functional properties of whole blood stored warm beyond 24 hours.

STUDY DESIGN AND METHODS

Ten citrate phosphate dextrose solution whole-blood units were collected and divided into two equal volumes. One-half of each unit was stored at 19 degrees C and the other half was stored at 25 degrees C, encompassing the accepted range for room temperature storage. At 6, 24, 48, and 72 hours, aliquots were collected from each unit and whole blood analyzed for cell counts, gases, and clotting function with thromboelastography, red cells for intracellular analytes, platelet (PLT)-rich plasma for aggregometry, and the supernatant for hemoglobin, potassium, glucose, lactate, and plasma clotting studies.

RESULTS

Whole-blood units stored at room temperature maintained cellular counts and coagulation activity for up to 72 hours. Units stored at 19 degrees C demonstrated greater RBC adenosine triphosphate and 2,3-diphosphoglycerate (DPG) content and stronger responses in PLT aggregation studies when compared with 25 degrees C storage. No significant hemolysis was observed, and no bacterial growth was detected.

CONCLUSION

Storage of whole blood at room temperature for 72 hours leads to marked reductions in pH and DPG, but the observed reduction in PLT function and plasma coagulation factor activity was surprisingly modest compared to literature values. These findings should prompt additional investigation, given their potential importance for whole blood processing and field-expedient transfusion.

The quality of plasma collected by automated apheresis and of recovered plasma from leukodepleted whole blood

BACKGROUND

There exists a current lack of information about the composition of the different types of plasma. No direct comparisons between apheresis plasma (AP) and recovered plasma (RP) derived from in-line-filtered whole blood (WB) have been published to date.

STUDY DESIGN AND METHODS

Sixty AP units, 100 RP units from in-line-filtered WB held for 3 hours at 20 degrees C between donation and freezing, and an additional 100 RP units held for 15 hours at 20 degrees C before freezing were analyzed for coagulation factors and inhibitors, total protein, immunoglobulin G (IgG), and hemostasis and proteolysis activation markers. The influence of twice freezing and thawing on clotting factors V, VIII, and XI was also examined.

RESULTS

AP contains substantially greater activities of factor (F) V, FVIII, F IX, and FXI than RP frozen within 3 hours after WB donation. Prolonged holding of RP at 20 degrees C for more than 15 hours caused an additional reduction in FVIII, FXI, and protein S activities. Significantly greater levels of prothrombin fragments 1 and 2, platelet factor 4, and neutrophil elastase were found in RP compared with AP. IgG was lower in AP compared with RP. Twice freezing and thawing caused a marked drop in FV, FVIII, and FXI activity.

CONCLUSION

Higher FVIII and F IX potencies in AP compared with RP can be expected to result in greater yields when used for purification of these clotting factors. AP is presumably more efficient than RP for treating coagulopathies. RP, however, may contain higher IgG levels than AP.

Defining the optimal storage conditions for the long-term storage of platelets

Aging of platelets after in vitro storage at 22 degrees C is significantly slower than aging of platelets in vivo at 37 degrees C, a situation that may make long-term storage of platelets possible. Three approaches appear to be of specific importance: (1) to reduce the activation of platelets during collection of blood and the preparation and storage of platelet concentrates, (2) to reduce the metabolic rate of glucose consumption and lactate production, and (3) to make sure that glucose is available in the storage medium during the entire storage period. The activation of platelets can be counteracted either by the addition of platelet activation inhibitors or the availability of certain components such as potassium and magnesium in the synthetic storage media. The use of synthetic media offers the possibility to include additional platelet-specific components in the storage environment. A number of effects have been observed that can be assigned to certain added components. Reducing platelet activation and the inclusion of key components in the platelet storage environment, such as glucose, acetate, citrate, phosphate, potassium, and magnesium, may optimize storage conditions for the long-term storage of platelets.

In vivo and in vitro comparison of platelets stored in either synthetic media or plasma

Since 1980, several synthetic media have been developed for the storage of platelets for transfusion. At present, platelets suspended in approximately 70% synthetic medium and 30% plasma can be stored for at least 5 days at very stable pH levels, generally pH 6.8-7.2. Present knowledge suggests that synthetic media should contain at least acetate, citrate, phosphate, potassium and magnesium. Future studies will probably result in the inclusion of other components to this list. Glucose for platelet metabolism will generally be supplied by carryover of plasma from the original platelet preparation. In addition, improved plastic containers for the storage of platelets will probably facilitate the introduction of new synthetic media. In six studies comparing synthetic media with plasma as the storage environment, and involving patients with intensive chemotherapy for haematological malignancies, the clinical outcome in terms of corrected count increments (CCI) generally indicated similar results. Three studies suggested significant reduction of the incidence of transfusion reactions of platelets suspended in synthetic media as compared with plasma. For future comparisons of platelet storage in either plasma or new synthetic media, additional platelet survival and recovery studies, as well as patient-transfusion studies, will be needed as in vitro data may not always reflect the clinical outcome. This will add further knowledge to data from the present few clinical studies available that compare storage of platelets in either synthetic media or plasma.

Manufacture and composition of fresh frozen plasma and virus-inactivated therapeutic plasma preparations: correlation between composition and therapeutic efficacy

The clinical efficacy of the therapeutic plasma used in the treatment of congenital and acquired severe coagulopathy depends on the potency of clotting factor and inhibitor activities. The composition of plasma strongly depends on the conditions under which it is produced. A low citrate anticoagulant-to-blood ratio, short intervals between donation and plasma separation and rapid freezing markedly improve the preservation of unstable coagulation factors. The influence of different leukocyte reduction filters on plasma quality still requires clarification. Recent trials on long-term storage conditions suggest that keeping plasma at -30 degrees C or colder over a period of 24-36 months prevents substantial decrease in clotting factor activities including factor VIII (FVIII). Three types of therapeutic plasma are currently available. Quarantine-stored fresh frozen plasma (FFP) contains physiological activities of therapeutically relevant plasma proteins, but carries a risk of transmitting blood-borne viruses that cannot be detected by human immunodeficiency virus (HIV) and hepatitis B and C screening. In contrast, solvent/detergent-treated plasma (SDP) and methylene blue/light-treated plasma (MBP) is virtually free of HIV and hepatitis C virus (HCV) subtypes. Virus inactivation procedures can have the consequence of reducing several clotting factors and inhibitors in SDP and MBP to varying degrees. However, pooling of plasma units before solvent/detergent (SD) treatment results in well-standardized protein levels of SDP. At least five prospective trials and four observational studies covering different clinical settings suggest that SDP and FFP do not substantially differ in their clinical efficacy or in their tolerance. By way of contrast, there is a lack of data about the clinical efficacy and tolerance of MBP compared to FFP.

Platelet storage media

Platelet additive solutions (PASs) can be used as a substitute for plasma for the storage of platelet concentrates (PCs) in order to recover plasma for other purposes, to avoid transfusion of large volumes of plasma to patients, to improve storage conditions, and to make possible photochemical treatment for viral inactivation of PCs. The effects on platelet metabolism associated with different factors and compounds in PAS are only partly known. Available studies suggest that: (1) The presence of glucose in the platelet storage medium during the entire storage period is necessary for platelet metabolism. (2) Acetate is used as a substrate for platelet metabolism reducing production of lactate by platelets. By formation of bicarbonate, it maintains stable pH levels during storage. (3) The fall in pH can be rapid in PAS-containing media, due to the very limited buffering capacity of PAS compared with that of plasma. (4) Platelets stored in PAS at a citrate concentration of 8 mmol/l produce only half the quantity of lactate as that of platelets at 14-26 mmol/l of citrate. (5) Free fatty acids from plasma can be used as substrate for platelet metabolism and are supposed to be made available by the hydrolysis of plasma triglycerides. (6) For apheresis PCs with ACD anticoagulant, the presence of phosphate in PAS seems to be a critical factor to avoid low adenine nucleotide levels during storage. The results of available studies suggest that PAS for storing platelets has a great potential for wide use in transfusion medicine. A number of interesting questions regarding the effects of different compounds in PAS are still to be answered. It is expected that answers to these questions will be provided over the next few years.

Automated blood-mixing devices still fail to mix at low bleeding rates

BACKGROUND AND OBJECTIVES

The study evaluated mixing performance for various commercial blood-mixing devices at different flow rates.

MATERIALS AND METHODS

A glycerol solution with a density equal to blood was pumped into a blood bag (mounted on a mixer) that contained 70 ml of Toluidin Blue in citrate-phosphate-dextrose (CPD). After 500 ml of glycerol solution had been pumped into the blood bag, the bag was emptied in fractions and the absorbance at 640 nm of each fraction (expressed as percentage of mixture absorbance) was plotted against the fraction number.

RESULTS

At a flow rate of 30 ml/min, the curves were very sigmoid, with high initial values that decreased during collection of the fractions. The absorbance values of the fractions collected later (after approximately 250-300 ml) were 10-50% (i.e. percentage of absorbance for complete mixing) for the different mixers, indicating that the CPD solution was incompletely mixed with the incoming solution, resulting in a lower-than-expected 'anticoagulant' content for the fractions collected later. At a flow rate of 50 ml/min the mixing was improved, but only at 75 ml/min did all mixers show relatively good mixing. Manual mixing, by kneading the bag three times/min, gave at all rates an almost ideal mixing curve, 105% initially to 90% in the final fractions.

CONCLUSION

At relatively high bleeding rates, all mixers performed well, although complete mixing was only obtained with manual kneading. However, most blood-mixing devices still fail to mix efficiently at normal and low bleeding rates. Although the minimal degree of necessary mixing is unknown, further optimization of mixing devices seems warranted.

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.

Clinical and laboratory experience with erythrocyte and platelet preparations from a 0.5CPD Erythro-Sol opti system

BACKGROUND

Red blood cells stored as concentrates or suspensions in additive solutions change rapidly their oxygen affinity mainly due to the loss of 2,3-diphosphoglycerate (2,3-DPG). When collected in CPD with half of the normal concentration of citrate and citric acid (0.5CPD) and stored in a new additive solution (Erythro-Sol), 2,3-DPG is better maintained. No studies of the oxygen affinity of red cells stored under these conditions have been published. In Erythro-Sol, red cells have a satisfactory in vivo recovery for 49 days but the conditions after 28 days, within which time most red cell units are transfused, have not been investigated. Of importance is also to be able to make platelet concentrates (PCs) from 0.5CPD blood. Little data are available concerning the clinical usefulness of platelets prepared from 0.5CPD buffy coats (BCs).

METHODS

Blood was collected in 0.5CPD, held at 20 degrees C for 3-4 h, then separated with the bottom-and-top technique into red cells, plasma and BC. In a storage experiment with 6 U the 2,3-DPG and P50 values were determined weekly and a number of in vitro parameters were tested on day 28. In 6 donors the in vivo recovery and survival of red cells were determined using a single-chromium technique. Transfusions of 212 0.5CPD-Erythro-Sol red cell units were given to hematological patients under supervision. PCs derived from pools of 0.5CPD BCs suspended in PAS2 (T-Sol) were transfused to 20 thrombocytopenic patients and compared with CPD-BC-PCs suspended in PASI. Corrected count increments (CCI) were determined.

RESULTS

The erythrocyte 2,3-DPG and P50 values were normal or slightly subnormal initially but increased to supernormal levels during the 1 week, and remained at these levels for a further 1-3 weeks; the 2,3-DPG was two thirds of normal after 28 days, the P50 was 3.72 +/- 0.28 kPa after 14 days and 2.84 +/- 0.41 after 28 days (mean +/- SD). The P50 values corresponded closely (r2 = 0.903) to 2,3-DPG. The in vivo recovery of 4-week-stored red cells was 89.6 +/- 5.5% and the T50 was 32.2 +/- 2.0 days. No adverse effects were observed in the transfusions. The CCI values did not differ between test and control groups; in both, 3- to 5-day-stored PCs gave lower CCI than fresh (0-2 days) PCs. Patients with acute myeloid leukemia AML (n = 11) had significantly lower CCI values than patients with myelodysplastic syndrome, myeloma and lymphoma (n = 9; CCI 1 h: p = 0.001; CCI 24 h: p = 0.006).

CONCLUSIONS

Red cells stored in Erythro-Sol sustain a normal or slightly lowered oxygen affinity for 2-4 weeks, their viability is excellent, and they are well tolerated in clinical transfusions. Platelets prepared from 0.5CPD-BCs cause CCI, of the same magnitude as CPD-BCs.

Storage of buffy coat preparations at 22 degrees C in plastic containers with different gas permeability

BACKGROUND

Buffy coats (BCs) are used as an alternative to platelet-rich plasma in the preparation of platelet concentrates (PCs). For this purpose the BCs have to be stored for same time at 20-24 degrees C which implies cellular metabolic activity. However, little information is available concerning the effects of a number of factors which may influence the suitability of the preparation as the source of PC.

STUDY DESIGN AND METHODS

We studied the effects on BCs of a high and low gas permeability of the wall of the plastic containers, PL2209 and PL146, respectively, mixing versus non-mixing during storage for 48 h at 22 degrees C, and two types of anticoagulant solutions, CPD and half strength citrate CPD (0.5CPD). The buffy coats were prepared by the bottom and top technique. The median values of volume and haematrocrit were 58-64 ml and 39-45%, respectively. A total of 48 BCs were tested. Blood gases, pH, bicarbonate concentration and haemolysis were determined in the blood mixtures and beta-thromboglobulin (beta-TG), lactate dehydrogenase (LDH), complement factor 3a, and elastase in the extracellular fluid.

RESULTS

The pH decreased in all units but to a lesser extent in PL2209 containers than in PL146 units. In the former the pCO2 decreased slowly in contrast to the latter where it increased by about 50%. Mixing during storage increased the pH and decreased the pCO2 in 0.5CPD-PL146 and CPD-PL2209 units, as compared to resting, while no effects of mixing were observed in the other groups. The pO2 decreased to low levels in PL146 units. The haemolysis and LDH release were higher in mixed than in unmixed units. The initial beta-TG levels were lowest in 0.5CPD-PL146 units which also had the lowest 24-hour levels. The release of beta-TG during storage was smallest in CPD resting units. The elastase release was significantly higher in 0.5CPD than in CPD units already from the beginning of storage and increased during storage at about the same rate irrespective of mixing. The C3a levels were higher in 0.5CPD-PL2209 units than in the other units at 2 h. Storage for 24 h caused an increase by 2-3 times of the original level without any clear relation to storage conditions.

CONCLUSIONS

In BC units accumulation of CO2 occurs in containers with low gas permeability. These also show the most rapid pH decrease during storage. Prolonged holding of BCs puts extra emphasis on the need of satisfactory gas permeability of the container for platelet storage in BC-derived PCs. Continuous mixing causes red cell damage and does not seem to have any clear benefit. The release of granulocyte elastase was higher in 0.5CPD than in CPD units but there was no indication of an associated increase in platelet activation.

SUMMARY

Study of buffy coats stored in various media and containers at 22 degrees C suggests that it is better to restrict storage to 24 h or less to avoid activation or other deleterious effects on the platelets.

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.

Buffy-coat-derived platelet concentrates prepared from half-strength citrate CPD and CPD whole-blood units. Comparison between three additive solutions: in vitro studies

The in vitro effects of storage of platelets prepared from 4 or 6 pooled buffy coat (BC) units and stored in a platelet storage medium consisting of 30-40% of CPD plasma or alternatively half-strength citrate CPD (0.5 CPD) plasma and 60-70% of different alternative platelet additive solutions (PASs) were evaluated. Measurements of mean platelet volume, pH, pO2, pCO2, bicarbonate, glucose, lactate, ATP, total adenine nucleotide content, extracellular lactate dehydrogenase or adenylate kinase activity, as markers for disintegration of platelets, and extracellular beta-thromboglobulin, as a marker for activation of platelets, were included in the in vitro studies. Previous studies indicated that a reduction of the citrate concentration from the standard 21 to 8 mmol/l is associated with a significant reduction of the consumption of glucose and production of lactate. Alternatively, similar effects can be obtained by the addition of acetate. In a preliminary paired study, the effects of different concentrations of acetate were tested. In an additional paired study, the effects of CPD plasma in combination with either saline or a PAS containing NaCl (115.5 mmol/l), citrate (10 mmol/l), and acetate (30 mmol/l), pH 7.2 (PAS-2) were evaluated. 0.5CPD plasma in combination with either PAS-2 or a nonacetate PAS (PAS-1) were also tested. The storage of platelets in 0.5CPD plasma was used as a reference. The conclusions are: (1) A minimum acetate concentration of 30 mmol/l is needed to counteract the effects of citrate on the production of lactate. (2) pH and the bicarbonate buffering capacity are significantly better maintained in PAS-2 than in PAS-1.(ABSTRACT TRUNCATED AT 250 WORDS)

The quality of red blood cells

The evolving practice of medicine has required a number of changes in red cell product manufacture to ensure that the final product is more specifically tailored to the needs of the individual patient. As a result of the increasing concern over the risks of transfusion pharmaceutical standards of manufacture are now applied to blood component preparation. Studies have been undertaken to define the optimum method of blood processing, and newer technologies are emerging to allow acquisition of a more consistent dose of red cells in a fashion which may minimize the lesion of collection. Use of high efficiency 3+ generation filter technologies reduces leukokine build up during storage and improves the quality and purity of the stored blood product. The combination of new plasticizers for packaging and improved red cell additive solutions should allow the blood center to supply a more functional red cell with longer storage shelf life. Overall these developments should result in the provision of a more consistent dose of fully functional red cells to the recipient who will be less exposed to the undesirable sequelae of transfusion than previously.

[Platelet collection by apheresis with reduced use of citrate: quantitative and qualitative evaluation of three protocols]

Three protocols of platelet collection by apheresis on Cobe Spectra with different citrate concentrations were compared. First we determined until what level we could diminish the ratio anticoagulant/whole blood flow to enhance the efficiency without clotting in the cell separator by platelet aggregates. We found that protocol 2 had a better platelet collection efficiency than the standard protocol 1: respectively 59% versus 52%. Protocol 3 had even a better efficiency but, due to the risk of clotting (5% of the procedures) we rejected it for routine use. We compared in vitro platelet functions of protocols 1 and 2 by aggregometry in vitro. The results with the different aggregating agents indicated that the less citrated environment kept the platelets more functional in vitro. A disadvantage of protocol 2 compared to the standard protocol is the more important number of platelet concentrates that contain more than 10(6) leucocytes.

Quality of plasma for fractionation--does it matter?

Many plasmapheresis techniques cause greater activation of platelets, complement and coagulation than does simple whole blood collection. Activation of the coagulation cascade has been particularly evident in tests for potential thrombogenicity in prothrombin complex concentrates made from apheresed plasma. Attempts to improve the factor VIII content and fractionation yield of source plasma have centred on rapid freezing, increased concentration of anticoagulants and the exploitation of anticoagulants optimal for the preservation of coagulant, rather than cellular, activities. The cumulative advantage is of the order of 10% over recovered plasma. There are potential pitfalls in applying low-citrate anticoagulation strategies to plasmapheresis. Recalcification of citrated plasma, under cover of an optimal concentration of heparin, might be explored more vigorously.

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.

Half-strength citrate CPD combined with a new additive solution for improved storage of red blood cells suitable for clinical use

Currently used systems for red blood cell (RBC) collection and storage for transfusion have the disadvantage that the RBC 2,3-bisphosphoglycerate (BPG) concentration is depleted within two weeks of storage, resulting in a left-shift of the oxygen dissociation curve and a temporarily impaired capacity to deliver oxygen. We have studied the effects on red cell metabolism, morphology and in vivo recovery of 49-day storage of RBC, with collection in half-strength citrate CPD (0.5CPD) and storage in an additive solution containing citrate, adenine, mannitol, phosphate and glucose (RAS2). Traditional CPD-SAGM was used for comparison. Component preparation was performed after an initial holding period of the whole blood at ambient temperature for 8 h. The BPG concentration in 0.5CPD-RAS2 RBC was 0.633 +/- 0.120 mol (mol Hb)-1 as compared to 0.454 +/- 0.138 mol (mol Hb)-1 in CPD-SAGM RBC which implied a decrease to 67 and 48% of normal concentration, respectively. The mean RBC BPG concentration was maintained at the initial level for 28 days in the new system but decreased to very low levels within 14 days in the controls. The total adenine nucleotides were well maintained in both systems, adenosine triphosphate slightly better in the new system. Hemolysis after 49 days was 0.35 +/- 0.21% in the new system and 0.72 +/- 0.25% in the controls (p < 0.001). The morphology was better maintained in the new system (p < 0.001). The 24-hour posttransfusion survival of 49-day stored RBC was 78.9 +/- 7.1%. The membrane leakage of sodium and potassium was not significantly different in the two systems.(ABSTRACT TRUNCATED AT 250 WORDS)

Half-strength citrate CPD and new additive solutions for improved blood preservation. I. Studies of six experimental solutions

Poor stability of plasma factor VIII in whole blood and loss of erythrocyte 2,3-bis-phosphoglycerate (BPG) during red cell storage are limitations with systems for blood component preparation in current use. This study presents attempts to improve post-collection storage conditions in both these respects using half-strength citrate CPD solution (0.5CPD) for blood collection, which has been shown by others to improve the stability of factor VIII, and some compositions of hypotonic additive solutions for red cell storage containing citrate, adenine, mannitol, and phosphate. Guanosine was also included in some of the media. The erythrocyte BPG concentration was maintained at a normal level for 3-4 weeks with the best of the tested compositions. Total adenine nucleotide concentration was maintained at the original level for 49 days and adenosine triphosphate for 28 days. Spontaneous storage haemolysis was low, 0.31% (mean) +/- 0.08-0.10% (SD) after 49 days in the two best compositions. The intracellular pH was 0.2-0.3 pH units higher than the extracellular pH at the beginning of storage, but this difference gradually diminished and disappeared after 4-5 weeks. We suggest two likely explanations of the effects: the maintenance of intracellular pH at a level sufficiently high not to impair BPG synthesis until after several weeks of storage, and a sufficient supply of phosphate needed in the synthesis of organic phosphate compounds. The content of citrate was selected such that the total amount supplied to a patient in a massive transfusion, when using a combination of 0.5CPD plasma and red cell suspension, would be smaller than that provided by a transfusion of CPD whole blood.

Red cell and platelet concentrates from blood collected into half-strength citrate anticoagulant: improved maintenance of red cell 2,3-diphosphoglycerate in half-citrate red cells

This study confirms previous work suggesting equivalent in vitro properties in blood components prepared from donations collected into half-citrate preservative (HCPD) compared to components derived from donations collected into standard citrate-phosphate-dextrose (CPD) preservatives. In addition, red cell products harvested from HCPD donations showed significantly improved maintenance of pH over storage, and this was reflected in improved maintenance of intracellular 2,3-diphosphoglycerate (2,3-DPG). This effect was observed in whole blood and in red cells suspended in a phosphate-containing additive solution (Tuta AAS). Collection into HCPD also improved 2,3-DPG maintenance in red cell concentrates processed following an 18-hour hold at 22 degrees C. These improvements were less pronounced in red cells suspended in a non-phosphate-containing medium (Fenwal Adsol) in which a higher pH was maintained even in units collected in CPD. Platelets harvested from HCPD blood and suspended in plasma showed equivalent quality to platelets from standard donations. Some deterioration of platelet properties was observed when HCPD platelets were stored in a non-citrate synthetic medium. Together with data indicating improved coagulation factor stability, these results suggest that collection into HCPD improves stored blood quality and may also allow logistical benefits in blood component preparation.

[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 clinical trial of red-cell concentrate prepared from blood collected in half-strength citrate anticoagulant

Earlier studies have indicated that plasma from blood donations drawn into half-strength citrate anticoagulant (0.5 CPD-A2) may give improved yields of factor VIII:C after fractionation. It has also been shown previously that cellular components from blood donations drawn into 0.5 CPD-A2 have satisfactory in-vitro and in-vivo properties. The present study examines the clinical use of red cell concentrate (RCC) from 0.5 CPD-A2 blood donations. Forty-nine patients who were undergoing elective orthopaedic surgery and who required blood transfusion received 0.5 CPD-A2 RCC. A transfused control group of 107 patients received standard CPD-A1 RCC for their transfusion requirements. Patients in the two transfused groups had similar haemoglobin responses to transfusion. All patients experienced a moderate pyrexia following the operation. Both study groups showed similar responses to serum lactate dehydrogenase levels in the 2 weeks following surgery, and in postoperative peripheral blood platelet counts. Serious postoperative complications arose in both groups. In the 0.5 CPD-A2 group two patients had pulmonary emboli (one fatal) and one patient had a non-fatal myocardial infarction. Three patients had pulmonary emboli in the CPD-A1 transfused group. These incidences of major adverse events were within the expected range of these complications in patients who were undergoing major joint replacement surgery and did not differ significantly between the study groups. This study indicates that red cell concentrate prepared in half-strength citrate anticoagulant is comparable to that prepared in CPD-A1 for patients undergoing orthopaedic surgery.

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.

Studies on the procurement of blood coagulation factor VIII. In vitro studies on blood components prepared in half-strength citrate anticoagulant 18 hours after phlebotomy

Our previous studies have shown that the use of half-strength citrate anticoagulant improves plasma factor VIII stability while maintaining the viability of red cells and platelets. This study extends these observations to show that the stability of factor VIII is maintained in blood stored at room temperature or 4 degrees C overnight and that in vitro tests indicate comparable quality of red cells and platelets prepared from half-strength citrate donations processed immediately or after overnight storage at room temperature. The exception to this was a more rapid loss of red cell 2,3-diphosphoglycerate, as has previously been observed for full-strength citrate donations.

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

To determine the viability of blood cells collected in half-strength (0.5 CPD.A2) and full-strength citrate anticoagulants, paired crossover autologous survival studies were performed in normal volunteers using 51Cr-labelled red cells after 35 days storage and 111In-labelled platelets after 5 days storage. For both studies, viability was better maintained in 0.5 CPD.A2 anticoagulant. This was significant for red cells (24-hour survival: 80 +/- 6 vs. 52 +/- 21%) but not for platelets by either linear or multiple-hit models (recovery 51 +/- 13 vs. 38 +/- 14%, survival 5.1 +/- 1.4 vs. 3.7 +/- 1.5 days). The poor viability of red cells after storage in full-strength anticoagulant was associated with low cellular adenosine triphosphate levels and was confirmed in follow-up studies.