Our Cord Blood Field Educators get asked this question all the time. It’s towards the top of our list of Frequently Asked Questions. How long can cord blood stem cells be stored? This month, an article in Nature magazine, endorses and provides evidence that the length of cryopreservation of cord blood units does not diminish from the viability of the cells for use in transplant.[i]
As the world’s first cord blood bank, Cryo-Cell International has been storing cord blood stem cells for more than two decades. Recent studies have shown that the number of umbilical cord blood transplantations (CBT) has been steadily increasing, and the outcomes of CBT are getting closer to those obtained from bone marrow transplantation. As the history of the cord blood banking system becomes longer, the number of cord blood units that are cryopreserved for years has increased.
Although long-term preservation of cord blood was shown to have no negative influence in trials in mice, it had been less clear whether or not there is an expiration date for cord blood transplants in humans. Until today.
The aim of the study was to evaluate the effect of long-term cryopreservation of cord blood units on the quality
of cord blood units (CBUs) and the hematologic recovery
after cord blood transplantation. The study retrospectively analyzed the quality
of 95 cord blood units AND the recovery
of 127 adult patients with blood-related malignancies following single-unit cord blood transplantation from April 2007 to September 2014.
- The 95 cord blood units were divided into two groups: 50 ‘younger’ units which were cryopreserved for less than five years, and 45 ‘older’ units which were cryopreserved for more than five years.
- Of the 127 cord blood units used for transplants, 42 units were cryopreserved for long periods (5-11.8 years).
The study measured the Total Nucleated Cell count (or TNC) after thawing and CD34+ cells (a protein found on the surface of stem cells) in each unit by a standardized method. The recovery rate of TNCs and CD34+ cells after thawing and engraftment serve as indicators of cord blood quality.
- What does the study reveal about the quality of cord blood units that have been cryopreserved for a long time?
Answer: the length of cryopreservation did not have statistically significant impact on recovery of TNCs or CD34+ cells. The length of cryopreservation CBUs did not change/alter the number of TNCs and CD34+ cells pre-freezing to post-thawing.
- What does the study reveal about the hematologic recovery after cord blood transplantation using cord blood units that have been cryopreserved for a long time?
Answer: length of cryopreservation did not have a significant impact on neutrophil engraftment after cord blood transplantation. The pre-freezing number of TNCs per recipient body weight did not influence neutrophil recovery for engraftment. (However, the pre-freezing CD 34+ cell dose significantly promoted/influenced neutrophil recovery)
In fact, the only factor that had an impact on hematological recovery after CBT in adults was the number of pre-freezing CD34+ cells provided by the cord blood bank. The pre-freezing CD34+ cell dose significantly promoted neutrophil recovery. (i.e. the larger the dose, the faster the median day of engraftment). Cryo-Cell’s premium processing method using PrepaCyte® CB collects a superior number of CD34+ stem cells compared to alternative methods used by other cord blood banks.[ii]
In addition, our methods also demonstrated significantly higher post-thaw viability of cell Colony Forming Units (CFU). Post thaw CFU is another important criteria doctors will use to assess the potency of stem cells before the transplantation.[iii]
While some private cord blood banks optimize their collection methods for high throughput and a lower cost, at Cryo-Cell we focus of providing the best quality for our families.
What’s new about this study is that, previously, it had been reported that long term cryopreservation did not influence hematological recovery after cord blood transplantation using units of at most
5 years old and by analysis of child
This study provides confirmative information that the length of cryo-preservation for up to 11.8 years had little impact on the engraftment ability in adult
recipients. It marks an important contribution to the body of studies corroborating that cryopreserved umbilical cord blood is a critical, dependable source of stem cells for life-saving and life-altering transplants. Today, Cryo-Cell’s parents and expectant parents have another resounding answer to the question of how long cord blood can be stored.
[i] Impact of length of cryopreservation and origin of cord blood units on hematologic recovery following cord blood transplantation
. Bone Marrow Transplantation (2015), 1-4. Appeared in www.nature.com/bmt
Henderson, Christianna, Jonathan Wofford, Kathy Fortune, and Donna Regan. Evaluation of Processing Technologies for Umbilical Cord Blood (UCB) (n.d.): n. pag. Regan Saint Louis Cord Blood Bank, SSM Cardinal Glennon Children’s Medical Center. Web.
Page, KM, L. Zhang, A. Mendizabal, S. Wease, S. Carter, T. Gentry, AE Balber, and J. Kurtzberg. "Result Filters." National Center for Biotechnology Information. U.S. National Library of Medicine, 20 Jan. 2011. Web. 17 Apr. 2015.