Studies on the procurement of blood coagulation factor VIII: effects of plasma freezing rate and storage conditions on cryoprecipitate quality

Use of Cryoprecipitate in Newborn Infants

Cryoprecipitate is a transfusion blood product derived from fresh-frozen plasma (FFP), comprised mainly of the insoluble precipitate that gravitates to the bottom of the container when plasma is thawed and refrozen. It is highly enriched in coagulation factors I (fibrinogen), VIII, and XIII; von Willebrand factor (vWF); and fibronectin. In this article, we have reviewed currently available information on the preparation, properties, and clinical importance of cryoprecipitate in treating critically ill neonates. We have searched extensively in the databases PubMed, Embase, and Scopus after short-listing keywords to describe the current relevance of cryoprecipitate.

Biochemical and cellular markers differentiate recovered, in-line filtered plasma, and plasma obtained by apheresis methods

BACKGROUND AND OBJECTIVES

Assessment of plasma quality often focuses on the common safety tests for minimizing the risk of transmitting blood-borne pathogens. Little attention is paid to the possible quality attributes that ensure a consistent biochemical composition of plasma for fractionation. We therefore investigated the suitability of selected biochemical and haematological attributes that could be used as markers of plasma quality obtained by different separation and pre-treatment procedures.

MATERIAL AND METHODS

We characterized six plasma types, including source plasma, plasma recovered by classic means and in-line filtered plasma, by determining the analytical attributes protein content, coagulation factors and markers of coagulation, contact and complement activation. Residual cell content and cell-specific variables were also measured.

RESULTS

We found relevant differences between the plasma types in complement activation, as indicated by C3a measurements, while thrombin antithrombin complex values and, to a minor extent, activated factor XII concentrations indicated only moderate differences in activation levels of coagulation and contact systems. The most striking differences, however, were detected in residual cell content and concentrations of the platelet-associated proteins, platelet factor 4 and β-thromboglobulin. We showed that leucocyte reduction filters disrupt cells. This includes platelets, thereby releasing the platelet-associated proteins platelet factor 4 and β-thromboglobulin, and leucocytes as demonstrated by the release of elastase from polymorphonuclear leucocytes. Furthermore, the filtration processing of whole blood can lead to activation of the complement system.

CONCLUSION

Our results show that biochemical and cellular surrogate markers are valuable discriminators of plasma types.

Comparison of coagulation factor XIII content and concentration in cryoprecipitate and fresh-frozen plasma

BACKGROUND

For patients with plasma coagulation factor XIII (pFXIII) deficiency, recommended means of replacement include infusions of fresh-frozen plasma (FFP), cryoprecipitate, or (where available) factor (F)XIII concentrates. Quantitative differences in pFXIII concentration in FFP and cryoprecipitate are not well defined and were, therefore, the subject of this study.

STUDY DESIGN AND METHODS

FFP and cryoprecipitate (10 bags each from blood group O donors) were analyzed to quantify pFXIII activity and antigen. Coagulation FVIII, fibrinogen, and von Willebrand factor (VWF) were also quantitated.

RESULTS

Mean (+/-SD) pFXIII activity in cryoprecipitate and FFP bags was 60 +/- 30 and 288 +/- 77 U per bag, respectively, and pFXIII antigen and activity levels were concordant. Other comparisons (mean +/- SD) between cryoprecipitate and FFP, respectively, were as follows: coagulation FVIII activity, 133 +/- 37 and 265 +/- 83 U per bag; fibrinogen content (Clauss kinetic assay), 183 +/- 44 and 725 +/- 199 mg per bag; VWF antigen content, 181 +/- 53 and 218 +/- 70 U per bag; VWF ristocetin cofactor activity, 168 +/- 34 and 221 +/- 65 U per bag; VWF collagen-binding activity, 164 +/- 40 and 208 +/- 71 U per bag; and fluid (plasma) volumes per bag, 21.3 +/- 2.7 and 245 +/- 29 mL.

CONCLUSION

In contrast to other cryoprecipitable coagulation proteins, pFXIII is only mildly enriched in cryoprecipitate when compared with FFP (approx. two- to threefold). Although both products can provide effective pFXIII replacement, FFP may be preferred when infusion volume is not a major consideration and pFXIII concentrates are not available. VWF is substantially enriched in cryoprecipitate (approx. ninefold compared with its concentration in FFP), with VWF activity content exceeding that of FVIII by approximately 26 percent on average.

Factors influencing factor VIII activity in frozen plasma

BACKGROUNDS AND OBJECTIVES

Fresh frozen human plasma is an important raw material in the production of coagulation factor concentrates used in patients with haemorrhagic disorders. The aim of the study was to determine how the handling of plasma influences the recovery of coagulation factor VIII activity (FVIII:C), i.e. the influence of time between donation and freezing, of the freezing time and of the ice front velocity. We also studied a tentative eutectic point in human plasma.

MATERIALS AND METHODS

Aliquots of plasma from 12 different donors were kept at room temperature for 2, 4 and 6 h before start of freezing. We achieved fast freezing with a freezer that blows cooled air at a high velocity on the plasma containers. Freezing times were 0.5, 1, 4 and 24 h. Temperature was registered continuously during freezing. Plasma and NaCl solutions were frozen slowly to investigate the eutectic point.

RESULTS

Storage at room temperature for 6 h caused a small but statistically significant decrease in FVIII:C. Slow freezing with programmed freezing times of 4 and 24 h caused a more pronounced drop in FVIII:C as compared to that of 30 and 60 min. We found no eutectic point in plasma or in plasma with addition of 2 % (w/v) NaCl.

CONCLUSION

For an optimal yield of FVIII, freezing should start within 4 h after plasma donation. We propose the use of the term 'ice front velocity' instead of 'freezing speed', taking into consideration that the volume and shape of plasma containers may differ. We found only a marginal loss of FVIII:C when the ice front velocity was 26 mm/h or faster, but a significant loss when it was 9 mm/h or slower. We recommend freezing times of 60 min or shorter. We were not able to demonstrate any eutectic point in human plasma. We therefore recommend that the term eutectic point should not be used as a reference temperature in guidelines on plasma handling.

Cryoprecipitate prepared from plasma treated with methylene blue plus light: increasing the fibrinogen concentration

When cryoprecipitate is prepared from plasma which has been treated with methylene blue plus light (MB) for the purpose of virus inactivation, clottable fibrinogen content is 40% lower compared with units prepared from untreated plasma. Initial studies showed that when frozen MB plasma units were removed to +2 to +6 degrees C for 4 h and then returned to -40 degrees C prior to cryoprecipitation, fibrinogen recoveries increased from 24 to 42%. Although fibrinogen yield improved when plasma units were stored at +2 to +6 degrees C for varying lengths of time, FVIII levels decreased with increasing time. Conditioning for 8 h was studied in more detail. Groups of two plasma units were mixed together, divided into two equal units, frozen/thawed and treated with MB. One of each pair was stored continually at -40 degrees C, whereas the other was removed to +2 to +6 degrees C for 8 h. Samples were assayed for fibrinogen, FVIII, VWF:Ristocetin cofactor activity (RCo), VWF:Ag and VWF:Collagen binding (CB). The cryoprecipitate fibrinogen content increased to a mean of 207 mg unit(-1). VWF:Ag, VWF:RCo and VWF:CB recoveries also increased. FVIII recovery decreased from 50 to 45% (mean 124 iu unit(-1)). Conditioning has been validated for routine production of cryoprecipitate from imported plasma.

Modulation of fibrinogen content in cryoprecipitate by temperature manipulation during plasma processing

In routine blood bank production of single-donation cryoprecipitate, the introduction of a 16-hour hold at 4 degrees C, with the frozen plasma units packed into polystyrene containers, resulted in plasma prethaw temperatures of -4 degrees C to -8 degrees C. This in turn resulted in cryoprecipitate fibrinogen levels that were 214 percent of those obtained when units were thawed immediately after removal from -30 degrees C storage. In scale-model production of factor VIII concentrate, plasma warmed from -30 to -10 to -15 degrees C over 18 hours before pooling and thawing yielded cryoprecipitate fibrinogen levels that were 66 percent of those found in plasma warmed to -2 to -5 degrees C over the same period. Processing -30 degrees C plasma without a warming period led to cryoprecipitate fibrinogen levels that were 40 percent of those obtained from plasma warmed to -2 to -5 degrees C. These differences were accentuated after purification of the cryoprecipitates to an intermediate-purity factor VIII concentrate. These results suggest that simple modifications in production methods allow the fibrinogen content of cryoprecipitate to be tailored to specific uses.

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.