Influence on Time to Cryopreservation in Umbilical Cord Blood Units

It is accepted that the Umbilical Cord Blood (UCB) units can be cryopreserved to 48 h after their harvest and the delay in this procedure influences the final quality. The aim of this study was to determine the influence on time to cryopreservation in Umbilical Cord Blood Units. A selection of the 2134 samples arrived to the UCB Bank from 36 Andalusian linked hospitals was analyzed for a period of six months. The date and hour of collection, hospital of origin, time in the hospital, time of transport, time of arrival to the bank to cryopreservation, viability and CD34+ cells were determined. Our results showed that the median time from harvest to cryopreservation was 27.9 h. However, a great variability was found (range: 5.3 to 47.6 h), which was dependent on transport variables: time from collection to leave the hospital (median 12.6 h, range: 0.1 - 28.8), time of transport from hospital to UCB Bank (median 1.8 h, range: 0.1 - 20.6) and time kept in the bank before freezing. Viability of cells were reduced directly proportional in samples that took longer to be cryopreserved (93.9 vs 96.6%, p = 0.001), by contrast, CD34+ count did not differ significant at shorter or longer times of cryopreservation. In conclusion, the delay in transport time and in processing reduce the umbilical cord units quality, consequently, the time of transport and storage previous to cryopreservation must be reduced less than 36 h.