Dr. Johanna Weisbach (Erlangen/ DE), Prof. Dr. Jürgen Zingsem (Erlangen/ DE), Prof. Dr. Holger Hackstein (Erlangen/ DE), Prof. Dr. Volker Weisbach (Erlangen/ DE), PD Dr. Julian Strobel (Erlangen/ DE)
Background
Umbilical cord blood (UCB) is a valuable source of hematopoietic stem cells. So far, no end of shelf life has been defined for such stem cell products stored cryopreserved in the vapour phase over liquid nitrogen. We present cell content and viability measurements of UCB derived stem cell concentrates and attached sampe tubes thawed after 15 years of storage.
Methods
A total of 13 cord blood derived stem cell concentrates and 25 pilot tubes were thawed for further measurements and investigations. For each individual sample, the relative content of CD34+ cells, CD45+ cells, mononuclear cells (MNC) and viability of CD34+ cells and CD45+ cells were determined by flow cytometry. In addition, CFU tests were performed with each sample. Based on these values the absolute cell counts and recovery rates (CD34+, CD45+, MNC, CFU) were calculated.
Results
The recovery rate of CD34+ cells of the UCB concentrates was 78.6 +/- 20.1 % (mean +/- standard deviation). Viability of CD34+ cells was 88.4 +/- 5.3 %. The CFU recovery rate of UCB concentrates was 78.6 +/- 39.6 %. Cell viability, relative and absolute cell content, and the recovery rates of the different cell types and CFU were significantly lower in the corresponding pilot tubes compared to the UCB concentrate bags. However, there were significant correlations of the absolute number of different cell types in the PRB concentrates compared to the corresponding pilot tubes.
Conclusion
The quality of UCB stem cell concentrates after 15 years of storage is good. A high recovery rate of CD34+ cells and good viability were found. CFU testing showed very good clonogenic potential of the UCB products. These results are in line with published research. Cord blood can be used for transplantation after 15 years of storage. Pilot tubes are representative for the respective cord blood unit. However, quality of the pilot tubes after long-term storage is worse than the PRB concentrates.
Offenlegung Interessenkonflikt:
No conflicts of interest to declare