Time from cord blood collection to processing and temperature influence the quality of mononuclear cell products isolated using a density-gradient protocol

Background: For clinical cord blood (CB) transplantation, CB is processed using a standard hydroxyethyl starch protocol generally within 48 h of collection at room temperature. However, for tissue stem cell research, mononuclear cells (MNCs) were isolated from CB using a Ficoll-Paque density-gradient method. Here we report the effect of storage temperature and time from CB collection to processing on the cord blood mononuclear cells (CB-MNCs) isolated using a density-gradient method. Methods: We processed CB using a Ficoll-Paque density-gradient method to collect the cells in the MNC layer. Cells were analyzed using an automatic blood cell counter, and CD34+ cells were counted according to the ISHAGE method. Results: The recovery rate of viable MNCs in the CB-MNC layer was inversely related to the time from collection to processing of CB samples. However, recoveries of total nucleated cell and CD34+ were not affected by the time from collection to processing. The percentage of neutrophil contamination in the MNC layer increased significantly with increasing time from CB collection to processing (n=100, p