Improved Method for the Cryopreservation of Human Red Cells in Liquid Nitrogen with Hydroxyethyl Starch.

摘要

Refinement of a method described previously made possible routine freezing of full units of packed erythrocytes after separation of platelet rich plasma, and buffy coats. The volume frozen was 405 ml which included packed red cells (190 - 220 ml), plasma (43 - 73 ml) and cryo-HES (Hydroxethyl starch) (142 ml, final concentration 14% w/v). The units could be frozen with or without shaking by direct immersion in liquid nitrogen. Thawing rate was the critical variable in producing the most stable thawed cells. Plasma expander HES was usable but the thawed units were more viscous and about 7% less stable. Red cells prewashed with 0.15 M NaCl and frozen without plasma showed no significant changes in cellular yield or stability. The optimum resuspension medium was 3% glucose. A morphologic study of cells fixed in 1% glutaraldehyde revealed that before freezing red cells were partially dehydrated in 14% HES. Cells fixed on thawing were extensively dehydrated. On dilution with 6% glucose (1:1) these swelled and reverted to biconcave discocytes except for approximately 5% echinocytes. Storage in liquid nitrogen measured in groups of 3 units of 15 units for 0, 3, 6, 9 and 12 weeks revealed normal postthawed oxygen delivery (P-50). The greatest measurable effect of freezing red cells in HES was a loss of cellular K(+) compensated by a corresponding increase in Na(+).