How long can cord blood be stored?
Dr. Hal Broxmeyer, a well-recognized scientist and distinguished professor of microbiology and immunology, has studied and worked tremendously in the field of stem cell research and helped pioneer cord blood transplantation. Dr. Hal Broxmeyer and colleagues published studies with experimental results supporting that cord blood stem cells that were cryogenically frozen remained viable after 21 years of storage with efficient recovery of hematopoietic stem and progenitor cells, moreover, the cells were transplanted and engraftment was observed.1,2
Dr. Broxmeyer also recently demonstrated efficient recovery of stem and progenitor cells obtained from cord blood that were frozen and subsequently thawed after 23.5 years in a laboratory setting. In a few years time, Dr. Broxmeyer and his team will assess their oldest sample which will be 30 years old.3
So, what does it mean by “theoretically the cells can be stored lifelong in liquid nitrogen”?
Viability of cryopreserved human cord blood stem cells is mainly affected by temperature. The stability of the cells for centuries or millennia requires a temperature below -130°C and the temperature in the storage freezers is maintained well below this critical temperature by liquid nitrogen.
The other factor that affects the viability of mammalian cells is ionizing radiation. The dose of ionizing radiation that kills 63% of representative cultured mammalian cells at room temperature is 200-400 rads.4 Consequently, terrestrial background radiation, which is approximately 0.1 rad/yr, should require 2000-4000 years to kill that fraction of a population of typical mammalian cells at -196°C ( temperature of liquid nitrogen in liquid phase).
Therefore, in theory, the cryopreserved cord blood stem cells can be stored lifelong.
Read more here:
1. Broxmeyer HE, Srour EF, Hangoc G, et al. High-efficiency recovery of functional hematopoietic progenitor and stem cells from human cord blood cryopreserved for 15 years. Proc Natl Acad Sci USA. 2003;100(2):645–650.
2.Broxmeyer He, Lee M, Hangoc G, et al. Hematopoietic stem/progenitor cells, generation of induced pluripotent stem cells, and isolation of endothelial progenitors from 21- to 23.5-year cryopreserved cord blood. Blood. 2011; 117(18): 4773–4777.
3.Broxmeyer HE. How long can cord blood be stored? Parents’ guide to cord blood. 2014. http://parentsguidecordblood.org/newsletter_archive/newsletters_2014-09.php
4.Elkind M and G. Whitmore: The radiobiology of cultured mammalian cells. New York : Gordon and Breach, 1967.