Effect of vitrification state of protective solutions on recovery of red blood cells after lyophilization preservation / 中国实验血液学杂志

ABSTRACT

To study effect of vitrification state of protective solutions on recovery of red blood cells after lyophilization, four protective solutions composed of isotonic buffers containing 7% DMSO (v/v) and 20%, 30%, 40% or 50% polyvinylpyrrolidone (PVP) (w/v) were adopted. Vitrification state of protective solutions was examined first when white ice crystal appeared in any protective solution during freezing or thawing, if the used solution was not a vitrification solution. Red blood cells were lyophilized in MINILYO45 freeze-dryer after washing, mixing with protective solutions and prefreezing. After lyophilization, the samples were quickly rehydrated by 37 degrees C rehydration solution. The results showed that in vitrification and devitrification experiments, white ice crystal appeared in solution of 20% PVP + 7% DMSO and 30% PVP + 7% DMSO during freezing and thawing; vitrification appeared in solution of 40% PVP + 7% DMSO during freezing, but devitrification appeared during thawing; vitrification appeared in solution of 50% PVP + 7% DMSO during freezing and thawing. After rehydration, the recoveries of red blood cells and hemoglobin in 40% PVP + 7% DMSO group were (81.36 +/- 14.94)% and (77.54 +/- 12.86)%, which were significantly higher than that in 20% PVP + 7% DMSO, 30% PVP + 7% DMSO and 50% PVP + 7% DMSO groups (P < 0.01). The concentration of free hemoglobin in 40% PVP + 7% DMSO group was also significantly lower than that in other three groups (P < 0.01). With increase of PVP concentration in protective solutions, vitrification state and protective effect of these solutions also increased; when concentration of PVP in protective solution was 40% though it was not a vitrification solution, the effect of lyophilization was the best; but when concentration of PVP further increased to 50%, though it was a vitrification solution, the effect decreased. It is concluded that excessive vitrification state could not benefit lyophilization of red blood cells.