Comparison of the different strategies for cryopreserving and storage of the bone marrow CD34+ cells. Possibility of unprogrammed rate freezing and storage at -80 degrees C mechanical freezer

We have compared the efficiency of the different strategies allowing for a long term storage of a human CD34+ bone marrow cells. Accordingly, the aliquots of CD34+ cells isolated from bone marrow were frozen using: controlled rate freezing equipment, or freezer unprogrammed in a -80 degrees C mechanical freezer. After freezing, CD34+ cells were subsequently stored for one month in a liquid nitrogen tank at -196 degrees C or in mechanical freezer at -80 degrees C. We have found that both the viability and the recovery of clonogeneic progenitors of CD34+ cells samples stored at different temperature were similar. Therefore, regarding the costs and simplicity, we recommend the unprogrammed freezing and storage of human CD34+ cells at -80 degrees C in a mechanical freezer as a convenient, inexpensive, and reliable method for storing marrow for transplantation. This data also indirectly indicate that the aliquots of the CD34+ cells can be shipped frozen on dry ice (-80 degrees C), and that these cells will maintain viability under this conditions. Furthermore, in this study we have confirmed validity of our earlier observation that human CFU-Meg progenitors are more sensitive to cryopreservation.