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 ISHAGEmethod. 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<0.0001). Furthermore, CB stored at low temperatures had significantly less neutrophil contamination in theMNC layer than those stored at room temperature for 30 h after CB collection. Discussion: Storage temperature and time from collection to processing influence the composition of CB-MNCs products processed using a Ficoll-Paque density-gradient method.