Factors affecting banking quality of umbilical cord blood for transplantation

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.

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.

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).

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