Segregation of Proteins and Sodium in Human Plasma upon Freezing

Abstract

The proteins and sodium in human source blood plasma are segregated and concentrated on freezing, particularly in plasma that is frozen slowly in a large container. The temperature and the concentration gradients at the freezing front induce a convection in the liquid phase and thus play the primary role in the segregation of proteins and sodium in the frozen mass. Unidirectional freezing, where the freezing front moves against gravity, minimizes segregation because the density gradient-induced convection is minimized at the solid-liquid interface. Microscopic observation of the freezing front of the plasma indicates that ice crystals are the primary solid formed. Their shape is generally irregular, and they become highly dendritic as the freezing rate increases. Apparently, the liquid phase at the freezing front is trapped between the ice crystals; it then undergoes a complex secondary freezing process at a lower temperature behind the primary freezing front of the ice crystals.

Storage of whole blood for up to 24 hours at ambient temperature before component preparation: implementation in the Netherlands

“…6 To meet self-sufficiency all blood centers in the Netherlands went to all lengths to harvest every milliliter of plasma, implementing the hard-spin centrifugation of whole blood and subsequent separation into plasma, buffy coat, and RBCs; 7 the use of additive solution (AS) for RBC storage; 8 the optimization of FVIII yield in recovered plasma 5,[9][10][11] and quick freezing of the plasma. 5,[12][13][14] Compared to ambient temperature lower yields of FVIII had been described following cold (approx. +4°C) storage of whole blood probably due to cryoprecipitate formation and subsequent loss of FVIII after high-spin centrifugation.…”