Preparation of Cryoprecipitated Factor VIII Concentrates

Abstract

Factors affecting the yield of factor VIII [human] in cryoprecipitate were investigated in the context of a blood component program. Both in vitro and in vivo measurements were used to assess the effects of critical variables on the yield of factor VIII activity. Variables such as anticoagulant, plastic bag, mixing during collection and platelet contamination had no significant effect on yield of factor VIII activity in cryoprecipitate. Among the most critical factors affecting yield were storage time of whole blood and procedures for freezing, thawing and reconstitution. The following procedures assured a 60% recovery of factor VIII in cryoprecipitate: processing of whole blood within 6 h of collection; use of a technique to freeze plasma within 30 min either in a 70.degree. C ethanol bath or -85.degree. C freezer; rapid thawing (1 1/2 h or less) in a 4.degree. C circulating water bath; centrifugation at 4500 .times. g for 10 min at 4.degree. C followed by draining of the supernatant in a 4.degree. C cold room; storage of the precipitate at -20.degree. C until ready for use; thawing in a 37.degree. C water bath for at least 15 min followed by addition of 20 ml of 0.15 M NaCl for a 20 min period at room temperature and gentle mixing before pooling units for transfusion. The recovery of factor VIII in cryoprecipitate appears to be limited to a about 65% by its solubility in plasma at 4.degree. C. Further effort to increase the amount available for treatment should involve improving the supply of plasma for its preparation and decreasing the cost of processing.