Donation procedure, fibrinopeptide A, and factor VIII

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.

Evaluation of two new integrated adapters for blood drawing in closed blood bag systems: influence on different molecular coagulation markers

We compared a conventional blood donation bag system (A) with two newly developed ones (B, C) with integrated Y-shaped adapters. The new systems facilitate the withdrawal of blood samples in a closed system under aseptic conditions. The purpose of the study was to determine whether disturbances during blood donation in the different tubings influence the quality of the donated plasma due to activation processes of the coagulation system. In all bag samples from 34 probands for each system, we found higher levels of the global tests (aPTT, TT) compared to intraindividual controls. This was due to a greater amount of anticoagulant in the bag samples. An increase of procoagulant activity was demonstrated for bags A and C. Concerning the fibrinolytic system, values were reduced in all three systems compared to controls. In summary, the quality of the plasma in the three different bag devices was comparable to controls concerning factor activities measured as global tests. The activation of the coagulation system was only slightly higher in the new system B and C than in the conventional one (A). Therefore, the new closed systems are suitable for blood donation and reveal a high coagulation quality of the plasma.

Effect of donation time on platelet concentrates and fresh-frozen plasma. An in vitro study

To investigate the effect of donation time on the quality of blood components, we measured the platelet count and pH on platelet concentrates, and the factor V and VIII:C levels and fibrinopeptide A concentration on fresh-frozen plasma by duration of donation time. Platelet concentrates and fresh-frozen plasma were classified into three groups according to donation time: group 1, less than 10 min; group 2, 10-15 min, and group 3, longer than 15 min. Mean platelet counts of platelet concentrate were: group 1, 8.6 +/- 2.5 (in x 10(10], group 2, 8.1 +/- 2.6, and group 3, 6.5 +/- 3.2 (p less than 0.05). The same pH was maintained in all three groups. The fibrinopeptide A concentrations in groups 1 and 2 were 24 +/- 53 and 169 +/- 64 ng/ml, respectively, while in group 3 all were greater than 200 ng/ml, indicating correlation of a higher fibrinopeptide A level with longer donation time. Although a higher fibrinopeptide A level indicated a greater degree of thrombin generation, assays of factors V and VII:C did not show decreased activity in groups 2 and 3.

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 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.

Thrombin generation during collection of blood from donors taking oral contraceptives

Thrombin generation, as evidenced by plasma fibrinopeptide A (FPA) concentrations, was studied during blood collection from donors taking oral contraceptives (OC). 450 ml blood were drawn into Fenwal PVC bags from 26 OC users and 28 nonusers. Blood samples for determination of FPA, beta-thromboglobulin (BTG), thrombotest (TT), prekallikrein (PKK), antithrombin-III (AT-III) and factor VIII procoagulant activity (FVIII:C) were drawn from the bags immediately after ending blood donation and following storage for 24 h at 4 degrees C. The FPA concentrations following donation were significantly higher in the OC than in the control group (p less than 0.05). The levels of PKK were also higher in blood obtained from OC users (p less than 0.001), as was the FVIII:C level, the latter difference, however, was not significant (p = 0.06). No cold-promoted activation of factor VII, as evidenced from TT, was detected following storage at 4 degrees C, neither was any change observed in the FPA, PKK and AT-III levels. The BTG concentrations increased significantly during storage, most pronounced in the control group (p less than 0.05). The decay of FVIII:C was similar in the two groups, averaging 24.7%. No correlation was observed between the FPA levels and the other parameters determined. We conclude that thrombin generation is more pronounced during routine blood collection from donors taking OC.

Generation and degradation of fibrinopeptide A in stored platelet concentrate

The levels of fibrinopeptide A (FPA) were measured in samples from stored platelet concentrates (PC) by radioimmunoassay. In 27 standard, citrated PC, the mean FPA was 13.6 ng/ml, which is elevated 5-6X over background levels. This value did not change significantly over a 7-day storage period. Addition of PGE-1 and theophylline resulted in higher initial levels of FPA (18.0 ng/ml) and a pronounced rise during the storage period (to 43.4 ng/ml by day 10). In contrast, addition of a thrombin inhibitor, D-phenylalanyl-L-prolyl-L-arginine chloromethyl ketone-2 HCl (PPACK) or hirudin, resulted in lower initial levels of FPA relative to standard, citrated PC and a slow increase over time. Introduction of exogenous FPA into citrated PC resulted in a predicted elevation of FPA levels followed by a rapid loss of immunoreactivity (t1/2 = 18 h). Addition of PPACK did not affect this fall-off. However, PC prepared and stored in the presence of PGE-1 and theophylline showed a much slower fall-off of exogenous FPA (t1/2 = 38 h). These data indicate that FPA levels in samples from citrated PC represent a dynamic balance between generation and degradation processes and, thus, the data above underestimate the amount of thrombin activity present in stored, citrated PC.