Factors affecting banking quality of umbilical cord blood for transplantation.

BACKGROUND: The most important objective for cord blood banks is to store cord blood units of high quality, which is determined by total nucleated cells (TNCs) and CD34+ cells. Determining the factors affecting the stored life-saving cells would be beneficial to the field.

STUDY DESIGN AND METHODS: A total of 4930 cord blood units were collected between January 2007 and October 2009 and processed using a double extraction technique to sediment red blood cells with variable centrifugation time determined by the formula CT = KL - M, where CT is centrifuge time, K is 7.7227, M is 29.742, and L is ln (volume of cord blood with anticoagulant). The recovery rate of TNCs and other relevant factors affecting banking quality were analyzed.

RESULTS: The mean recovery rate of TNCs was 97.7 ± 2.5% with 0.04% (2/4930) units below 80% and 10.8% (532/4930) units below 95%. The TNCs per unit was affected by gestation duration (p < 0.01), sex of infant (p < 0.01), mode of delivery (p < 0.01), collection method (p < 0.01), and ethnicity (p < 0.001). The number of postprocessing CD34+ cells was affected only by sex of the infant (p < 0.05). The viability of nucleated cells after processing was 94.8 ± 4.8% and was affected by the number of hours between collection and processing (p < 0.01). In contrast, the viability of CD34+ cells was 99.5 ± 1.0% (n = 30) when samples with low viability of TNCs were assessed. The results did not reveal a significant correlation (r = 0.07, p = 0.38).

CONCLUSION: The double extraction technique provides a high and consistent recovery of TNCs, which ensures that more life-saving cells will be banked for transplants.