Overnight refrigerator storage of autologous peripheral progenitor stem cells without cryopreservation.

We compared cryopreservation of peripheral blood progenitor cell (PBPC) products immediately and after overnight storage. There was no statistically significant difference in the groups regarding median CD(34)+ cell count of the product, storage duration at -80 degrees C, viability rates, neutrophil and platelet engraftment days. Overnight storage of products with leukocyte count >300x10(9)/l has longer leukocyte (P=0.03) and platelet (P=0.01) engraftment days compared to other groups. Overnight storage without adding any medium or plasma for the apheresis product with leukocyte count of less than 300x10(9)/l in a commercially available refrigerator can easily and safely be used in transplantation centers.