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How Long Can Cord Blood Be Stored?

Source: Hal E. Broxmeyer, PhD, Indiana University School of Medicine

Cord blood transplantation is a clinically effective form of treatment for many patients with cancer and blood diseases who need a stem cell transplant (1-3). To date over 30,000 patients have been treated with cord blood transplants (3).

The precious ingredients in cord blood are the blood-forming (hematopoietic) stem cells and progenitor cells that can replicate and diversify to replace a patient’s entire immune system. These cells are rare, comprising less than one percent of the cells in cord blood, but nonetheless a typical cord blood collection contains millions of blood-forming stem and progenitor cells.

Cord blood transplants can come from either public banks or from private/family banks in which the cord blood stem cells are stored in a cryopreserved frozen state. The key to cord blood banking is to properly cryopreserve the stem cells so that when they are thawed for therapy they are still alive and maintain the functional capacity of the cells to repopulate the blood cells in a patient’s body.

A question that often comes up about stored cord blood, is how long can the stem and progenitor cells be maintained in frozen form and still be viable when they are thawed?

In theory, if the cord blood stem and progenitor cells were properly cryopreserved, it should be possible to keep them in a frozen state for many decades, if not longer, with subsequent retrieval of viable stem and progenitor cells.

Practically, this depends on the quality of the cryopreservation procedure. It depends on whether the storage facility assured that the cryogenic nitrogen tanks were maintained at a constant very low temperature. Finally it depends on the competence of the laboratory staff who thaw the cells to revive them.

There have been a number of studies on retrieval and viability testing of cord blood after many years of storage in liquid nitrogen-containing tanks. Our own studies, first reported in the late 1980’s when we suggested that cord blood stem cells could serve as a substitute for bone marrow transplants, noted highly efficient cell recovery after a few months of storage in cryopreserved form (4).

This led us to establish the first proof-of-principle cord blood bank in my laboratory (1-3). We supplied the frozen cells for the first five cord blood transplants ever performed, which were all between HLA-identical siblings. We also banked cells for two of the next five cord blood transplants performed.

Over the decades since, we have demonstrated efficient cell recovery at 5 years (5), 10 years (6), 15 years (7), and most recently 23.5 years (8) after the cells were frozen in cryopreserved form. The accuracy of these tests rests on the fact that we have had continuous custody of these cells, and we have performed their post-thaw analysis with the same tests as their pre-freeze measurements.

Coming up in another 2-3 years we will perform a 30 year assessment of our oldest cord blood specimens. Until then, the longest time that cord blood has been frozen and subsequently thawed with efficient recovery of stem and progenitor cells is 23.5 years in a laboratory setting. The longest storage interval of frozen cells that were given to a patient as a cord blood transplant is at least 14 years (pers. comm., Dr. P. Rubinstein).

Based on the studies in our laboratory, it is likely that cord blood can be stored frozen for decades and still be a potent source of cells for transplantation.

It may take some time before clinical studies demonstrate the viability of stem cells from long-term storage that we have established in the laboratory. Clinical proof would require treating patients with cord blood units that had been in storage for decades. But public cord blood banks tend not to use older stored cord blood collections if they have newer ones. Hence clinical proof of long-term storage success may have to come from private/family cord blood banks, when their clients eventually use the cord blood as therapy for the baby it came from or for a related family member.

Dr. Broxmeyer is a Distinguished Professor, Mary Margaret Walther Professor Emeritus, and Professor of Microbiology and Immunology at the Indiana University School of Medicine (IUSM), Indianapolis, Indiana, and is Co-Leader of the National Cancer Institute Designated Indiana University Simon Cancer Center on Hematopoiesis, Malignant Hematology and Immunology. He is the Founder of the CORD:USE Family Cord Blood Bank and is on the Medical Scientific Advisory Board of the CORD:USE Public Cord Blood Bank. He is a member of the National Marrow Donor Program (NMDP) Cord Blood Advisory Group.

1. Gluckman, E., Broxmeyer, H.E., Auerbach, A.D., Friedman, H., Douglas, G.W., Devergie, A., Esperou, H., Thierry, D., Socie, G., Lehn, P., Cooper, S., English, D., Kurtzberg, J., Bard, J. and Boyse, E.A. 1989. Hematopoietic reconstitution in a patient with Fanconi anemia by means of umbilical-cord blood from an HLA-identical sibling. New Engl. J. Medicine 321:1174-1178. PubMed: PMID2571931
 2. Broxmeyer, H.E. and Smith, F.O. 2009. Cord Blood Hematopoietic Cell Transplantation. In: Thomas' Hematopoietic Cell Transplantation 4th Edition. Eds: Appelbaum, F.R., Forman, S.J., Negrin, R.S., and Blume, K.G. Wiley-Blackwell, West Sussex, United Kingdom, Section 4, Chapter 39, pp. 559-576.
 3. Ballen, K.K., Gluckman, E., and Broxmeyer, H.E. 2013. Umbilical Cord Blood Transplantation - the first 25 years and beyond. Blood. 122:491-498. PubMed: PMC3952633
 4. Broxmeyer, H.E., Douglas, G.W., Hangoc, G., Cooper, S., Bard, J., English, D., Arny, M., Thomas, L., and Boyse, E.A. 1989. Human umbilical cord blood as a potential source of transplantable hematopoietic stem/progenitor cells. Proc. Natl. Acad. Sci. USA. 86:3828-3832. PubMed: PMC287234
 5. Broxmeyer, H.E., Hangoc, G., Cooper, S., Ribeiro, R.C., Graves, V., Yoder, M., Wagner, J., Vadhan-Raj, S., Benninger, L., Rubinstein, P. and Broun, E.R. 1992. Growth characteristics and expansion of human umbilical cord blood and estimation of its potential for transplantation of adults. Proc. Natl. Acad. Sci. USA 89:4109-4113. PubMed: PMC525642
 6. Broxmeyer, H.E. and Cooper, S. 1997. High efficiency recovery of immature hematopoietic progenitor cells with extensive proliferative capacity from human cord blood cryopreserved for ten years. Clin. and Exp. Immunol. 107:45-53. PubMed: PMID9020936
 7. Broxmeyer, H.E., Srour, E.F., Hangoc, G., Cooper, S., Anderson, J.A., and Bodine, D. 2003. High efficiency recovery of hematopoietic progenitor cells with extensive proliferative and ex-vivo expansion activity and of hematopoietic stem cells with NOD/SCID mouse repopulation ability from human cord blood stored frozen for 15 years. Proc Natl Acad Sci USA. 100:645-650. PubMed: PMC141050
 8. Broxmeyer, H.E., Lee, M-R, Hangoc, G., Cooper, S., Prasain, N., Kim, Y-J, Mallett, C., Ye, Z., Witting, S., Cornetta, K., Cheng, L., and Yoder, M.C. 2011. 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. 117:4773-4777. PubMed: PMC3100689
I have a concern regarding Zika Virus, what do I do next?

You can check out the Public Health Guidelines on Zika Virus here: Public Health Guidelines

Advice for mothers wishing to store cord blood at risk of Zika Virus:

Obligatory must not donate if:
a) A mother has been diagnosed with chikungunya, dengue or Zika Virus infection whilst in an endemic area or following her return to the UK during this pregnancy. OR PARTICULAR PARTNER COUNTRY
b) A mother has either had a history of symptoms suggestive of chikungunya dengue or Zika Virus infection whilst in an endemic area or following her return to the UK during this pregnancy. OR PARTICULAR PARTNER COUNTRY
c) In other cases it is less than four weeks from a mother’s return from a Tropical Virus Risk endemic area.

Source: UK National Blood Service

We recommend that you speak to your GP if you have any concerns regarding Zika Virus. Smart Cells are not able to assist any further with this matter.

You can also find this information in our FAQ’s section.

Who collects the samples?

The collection must be performed by a trained and licensed healthcare professional. This could be a private obstetrician or midwife or an assigned phlebotomist.

The Human Tissue Authority (HTA) requires the person who performs the collection to be appropriately trained in the Smart Cells collection process and hold a valid Third Party Agreement to do so. Smart Cells can arrange for a fully trained and qualified medical professional to carry out the collection at your birth.

What is TNC and CD34+?

These are all ways of counting cell types, and they tell you whether or not your cord blood collection has lots of stem cells and if they are healthy.

Scientists have worked for years to develop various chemical stains which have a high affinity for stem cells. The best known marker for blood-forming stem cells is that they test positive for CD34, a protein found on the surface of stem cells. But, CD34+ counts are not an accurate measure of stem cells: CD34+ results vary between labs, they can vary within a single lab, and only 1-2% of the MNC that have CD34+ are actually stem cells.

The Total Nucleated Cell count or TNC is the test most often reported as a measure of the cell count after cord blood processing. The main advantage of measuring TNC is that the count is highly reproducible within and among labs, so it can be used accurately throughout the blood banking community. Even better, the TNC count can be automated with the use of a device called a flow cytometer.

Source: Parent’s Guide to Cord Blood

What is an HLA test and how is it used?

The term “HLA” is short for Human Leukocyte Antigens, and these are proteins in the immune system that determine whether a patient will react against a donor transplant. A very good basic tutorial about HLA types is on the Stanford Website, and the national Be The Match program (aka NMDP) has more info on the role of HLA type in transplants of stem cells from bone marrow or cord blood.

Briefly, there are 6 HLA types that are important for stem cell transplants: in a bone marrow transplant the patient and donor must match at all 6 (100% match), whereas a cord blood transplant is just as effective at curing patients with only a 4 out of 6 match (67% match) between donor and patient. This is the reason that donations to the national cord blood inventory managed by NMDP are so important to help patients who come from minority or mixed racial backgrounds.

The HLA type of cord blood is always measured by public banks, and then the type is listed on a registry that can be searched by patients seeking a transplant. Family banks typically do not measure the HLA type at the time of banking, because it is an expensive lab test and and can always be checked later from a testing segment of the stored cells.

Source: Parent’s Guide to Cord Blood

Does the cord blood sample need to be processed before storage?

The earliest cord blood transplants were performed with whole cord blood. Thus, it is not absolutely necessary to process cord blood in order to save patient lives. There has never been a prospective randomized trial to compare transplant patient outcomes with cord blood that had been stored whole versus processed.

Most cord blood banks, both public and private, now process cord blood to remove both the plasma and the red cells, and cryo-preserve the remaining buffy coat holding stem cells. Some banks also save the removed red cells and plasma in companion storage. Some banks save a sample of maternal blood.

The removal of plasma is also called volume reduction. The volume reduction enables more collection units to fit in a freezer and requires less cryogenic nitrogen per unit.

Also, the majority of banks remove red blood cells prior to freezing, primarily because these cells often burst during freezing and release iron from hemoglobin that can be toxic. The alternate to removing the red cells before freezing is to wash any broken cells out of the collection upon thaw. Removing the red cells also removes the donor’s blood type (the ABO and Rh types). When cord blood goes from a donor to a patient for a transplant, the donor and patient can be compatible on all the HLA types used for transplant matching and still have incompatible red blood types.

Source: Parent’s Guide to Cord Blood

If I have banked for one child, do I need to do it for additional children/siblings?

All the reasons that you banked for the first child are still valid for additional children.
1. If you want the baby to have the option of using his/her own cells, then you need to bank them.
2. If you are banking to cover siblings, then the ability to use cord blood from one child for another depends on whether they have matching HLA type. Two full siblings have a 25% chance of being a perfect match, a 50% chance of being a half match, and a 25% chance of not matching at all. For a cord blood transplant, donor and patient must match at 4 out of 6 (67%) HLA types. The more siblings with banked cord blood, the more chance that they cover each other for possible transplants or other therapies for which sibling stem cells are accepted.

References: Odds of sibling match are based on haplotype inheritence: that the child will receive 3 HLA types as a group from each parent.
Source: Parent’s Guide to Cord Blood

How much blood and stem cells does a typical umbilical cord contain?

The median size of cord blood collections in family banks is 60mL or 2 ounces. That small volume of liquid corresponds to 470 million Total Nucleated Cells (TNC) or 1.8 million cells that test positive for the stem cell marker CD34. Thus, most healthy full-term babies have over a million blood-forming stem cells in their umbilical cord blood. By comparison, most public cord blood banks will only keep collections that are much bigger than average, and throw out the donations that are below a threshold of a billion TNC, corresponding to a blood volume of about 90-100 mL or 3 ounces.

Reference: Sun, JJ et al., Transfusion Sept. 2010; 50(9):1980-1987
Source: Parent’s Guide to Cord Blood

Do I need to store the cord blood and tissue stem cells in the country I intend to use it?

No. After cord blood is collected at birth, the samples are delivered, processed and stored in our labs. If you ever need the cord blood for therapy, it will be shipped in a special container that keeps it frozen. When cord blood is released for therapy can travel anywhere in the world with no loss of viability, because it travels frozen. It is only thawed at the clinic where it will be used. We have successfully shipped samples within the UK, Europe, USA, India and the Far East so far.

Can I donate my cord blood and tissue stem cells?

Smart Cells offer a fully private storage option for the long term storage of cord blood stem cells. This service is a paid service and the sample is solely stored for your own private use. If you wish to inquire more about cord blood and tissue donation then please visit the NHS Blood Bank.

How can the stem cells be used on the future?

A stem cell transplant is the infusion of healthy stem cells into your body. Stem cell transplants can help your body make enough healthy white blood cells, red blood cells or platelets, and reduce your risk of life-threatening infections, anaemia and bleeding. Stem cell transplants are used to treat people whose stem cells have been damaged by disease or the treatment of a disease. View more information on the rest of our website.

Does my hospital allow me to have stem cells collected?

We are pleased to inform you that the majority of maternity hospitals allow us to perform this service for you. If you would like to discuss your individual hospital with us then please contact us by phone or via our ‘contact us’ page.

Can I still have my stem cells collected if I have a home birth?

Yes, we have a fully trained team of phlebotomists* who are able to visit your home to collect the sample during a home birth. They will discuss all of your options with you and make sure that they have a safe and sterile area to collect your samples.

*Specific to the United Kingdom only.

Can I still delay the clamping of the cord?

Yes, you can still delay the clamping of the cord. It is recommended however that the cord blood is collected before pulsating stops. A prolonged delay will mean that the blood begins to clot which will affect the volume of blood available for the collection. If clamping is delayed, it should be between 1-3 minutes, as advised by the World Health Organisation. A timed delay will mean that your baby will benefit from the delayed clamping as well as having their cord blood stem cells stored for future use.

You can read more here: Delayed cord clamping & umbilical cord blood banking


Can I wait for the placenta to deliver naturally?

You may either wait for the placenta to delivery naturally or induce the delivery via an injection. Either method does not prevent us from collecting samples for you.

Does it matter if the birth is caesarean section or natural delivery?

No. If you have a Caesarean the collection can take place after the delivery of the placenta, as it would with a natural birth. Either birthing scenario is fine for the collection of cord blood and cord tissue stem cells.

Does cord blood and tissue collection hurt?

No. Cord blood and tissue collection is painless, convenient and safe for both mother and newborn. The cord blood and tissue is collected after your baby is born and the umbilical cord has been clamped and cut. The samples collected are normally discarded after birth as medical waste.

You may keep your original birthing plan, except to collect your baby’s cord blood and tissue. Cord blood and tissue collection can take place after a vaginal or C-section birth within a hospital or during a home birth and collection can still be performed after delayed clamping.

Why do we only store for up to 30 years?

Smart Cells offers a storage plan that enables you to pay up front to store your samples for up to 30 years.

There is currently no evidence to suggest that the health of your stem cells will deteriorate after 30 years and experts believe that your baby’s stem cells will be viable indefinitely.

At the end of your contract you will be given the option of extending your storage term or discarding the sample.

Do you have payment plans?

We offer all customers the opportunity to spread the final balance on a payment plan. We offer 3, 6 and 12 month options. To spread the cost over 3, 6 or 12 months there are no additional fees.

Do I have to pay to release or transport the sample if it is required for use in a transplant?

No additional costs will be incurred for the transportation of the sample at any time for therapeutic use.

What happens if we go out of business?

Establishments licensed by the HTA are legally required to ensure that in the event of activities ceasing, any tissues/cells and records are transferred to another HTA licensed establishment.

You should ensure that your chosen cord blood establishment has an agreement in place with another HTA licensed establishment for the safe storage of the sample in the event of them closing down. Smart Cells currently has this agreement in place with Source Bioscience.

How long have we been operating?

Smart Cells was founded in 2000 and we have been collecting samples ever since.

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