[The Optimal Storage Condition and Storage Time of Umbilical Cord Blood from Collection to Preparation]

To explore the optimal storage condition and time of umbilical cord blood from collection to preparation.

Collect cord blood samples from 30 healthy newborns, with each new born's umbilical cord blood was divided into two parts on average. One part was stored in cold storage (4 ℃) and the other was stored at room temperature (20-24 ℃). Samples were taken at 24, 36, 48, 60 and 72 h, respectively, total nucleated cells (TNC) count and TNC viability was analyzed. Flow cytometry was used to detect the ratio of viable CD34⁺ cells to viable CD45⁺ cells and viability of CD34⁺ cells, and colony-forming unit-granulocyte-macrophage (CFU-GM) count was performed by hematopoietic progenitor cell colony culture. The change trend of each index over time was observed, and the differences in each index was compared between cold storage and room temperature storage under the same storage time.

The TNC count (r _{4 ℃}=-0.9588， r _{20-24 ℃}=-0.9790), TNC viability (r _{4 ℃}=-0.9941， r _{20-24 ℃}=-0.9970), CD34⁺ cells viability (r _{4 ℃}=-0.9932， r _{20-24 ℃}=-0.9828) of cord blood stored in cold storage (4 ℃) and room temperature storage (20-24 ℃) showed a consistent downward trend with the prolongation of storage time. The percentage of viable CD34⁺ cells (r _{4 ℃}=0.9169， r _{20-24 ℃}=0.7470) and CFU-GM count (r _{4 ℃}=-0.2537， r _{20-24 ℃}=-0.8098) did not show consistent trends. When the storage time was the same, the TNC count, TNC viability, CD34⁺ cells viability and CFU-GM count of cord blood stored in cold storage were higher than those stored at room temperature. Under the same storage time (24, 36, 48, 60 or 72 h), TNC viability in room temperature storage was significantly lower than that in cold storage (P <0.001), but TNC count, percentage of viable CD34⁺ cells and CFU-GM count were not significantly different between room temperature storage and cold storage. When stored at room temperature for 24 h and 36 h, the viability of CD34⁺ cells was significantly lower than that in cold storage (P <0.001, P <0.01), when the storage time for 48, 60 and 72 h, there was no significant difference in the CD34⁺ cells viability between room temperature storage and cold storage.

It is recommended that cord blood be stored in cold storage (4 ℃) from collection to preparation, and processed as soon as possible.