Cryopreservation

Find out all about the Cryopreservation process, its importance and the differences between Family Banks and Public Banks

01

What is stem cell cryopreservation and what is it used for?

Cryopreservation allows stem cells to be available at any time being easily thawed at any time to be used if it becomes necessary to treat a range of diseases.
Umbilical cord blood cells are already used to treat over 80 diseases. Umbilical cord tissue cells hold enormous potential for therapeutic use and have already been used to combat graft versus host disease.

Cryopreservation consists of storing cells at low temperatures (-196°C) for long periods of time, without losing their viability. Stem cells from umbilical cord blood and tissue are stored for 25 years, as this is the period during which cell viability is guaranteed, according to published studies.

Did you know…?

The first stem cells from umbilical cord blood were cryopreserved at the end of the 80s. It is with these stem cells that viability studies are performed to demonstrate viability of cells cryopreserved for long periods of time. As with other cells and tissues that have been kept under the same conditions for decades, it is likely that umbilical cord blood cells will remain viable for much longer. Cells and tissue kept in containers with liquid nitrogen, at -196°C, remain viable for long periods of time (in theory, forever).

03

Advantages and limitations

Cryopreserving stem cells from cord blood enables access to a treatment option that has a range of advantages when compared to alternative sources – bone marrow and peripheral blood.

It has the following main advantages:

  • Greater acceptability in the level of HLA compatibility between donor and patient.

  • Lower risk of graft versus-host disease (GVHD), a serious complication that can occur after a hematopoietic transplant.

  • Immediate availability of cells for transplantation.

  • Umbilical cord blood can be collected easily after birth. The process is painless and does not represent any risk to the mother or the baby.

Stem cells from cord blood also have some limitations:

  • The collected number of stem cells can be lower than the amount needed for a treatment.

    The number of stem cells depends on the volume of blood within the umbilical cord blood which is limited. Depending on the disease, the patient’s weight and the degree of compatibility, the sample may not contain sufficient stem cells for a particular transplant. However, several research groups are developing techniques that will allow the number of cells to be increased, to overcome this limitation.

  • Longer hematologic recovery time after the transplant, when compared with bone marrow or peripheral blood.

    This disadvantage is due to the smaller number of stem cells available in cord blood.

Umbilical cord blood Bone marrow
Availability
  • Stem cells from umbilical cord blood are cryopreserved and are ready to be used.
  • Waiting time to find a compatible donor may be longer and the risk of no donor to be found cannot be excluded.
Number of cells available for an effective transplant
  • 5 to 10 times fewer when compared to bone marrow. Use can be limited, depending on the weight of the patient and the disease.
  • More cells when compared to umbilical cord blood samples, and possibility of multiple collections.
Compatibility
  • Greater tolerance, possibility of using samples even when there is not a full match between donor and patient.
  • Lower tolerance making it more difficult to find a full match donor.
Risk of side effects (graft versus host disease – gvhd)
  • Lower, compared with bone marrow.1
  • Higher, compared with umbilical cord blood.
Hematopoietic reestablishment time
  • Around 1-2 weeks slower than with bone marrow.22
  • Faster than with cord blood.
Collection risk and discomfort
  • Collection is painless and poses no risk to the mother or baby.
  • Collection involves a simple yet invasive surgical procedure, with anaesthetic, which always carries some risk.

(1) The explanation is that with umbilical cord blood transplants, as the newborn is “immunologically immature”, there is a lower risk of inducing GVHD (graft-versus-host disease). This is a complication that sometimes occurs in allogeneic transplants (when the donor and patient are different people), where the donor’s transplanted white blood cells recognize the cells of the patient (host) as foreign and develop an immune response against them. This disease can be fatal.

(2) When compared to bone marrow transplants, this delay in recovery is likely to be related to the number of transplanted cells.

05

When is cryopreservation performed?

Umbilical Cord Stem Cells

The only time that umbilical cord stem cells can be cryopreserved is the 72 hours period following their collection at the time of birth. The collection is simple, safe and painless. After the umbilical cord has been clamped, blood is collected in a bag and tissue in a container. The samples are packaged appropriately to ensure that they are transported safely to the laboratory. It is vital that a decision about cryopreservation, either for storage in a family bank or public bank, is made a few weeks or months before birth, to ensure that the documentation can be prepared properly. If you choose not to store umbilical cord stem cells, the cord will be discarded by the hospital.

07

Family bank vs. Public bank

It is possible to choose a family bank or a public bank for cryopreservation.
The coexistence of these two options is fundamental to ensure that patients have access to the best possible treatment option.

Family bank Public bank
Sample
  • The greatest advantage of this is having stem cells available for the donor of the cells or compatible family members. The likelihood of a complete match between siblings is 25%, whereas this value is less than 0.01% between unrelated people.1.
  • Samples are donated for the purpose of setting up a register of donors that could benefit patients who need stem cells from third parties. The samples are public property, so the stem cell donor has no rights over the sample that he is giving .
  • A limited number of samples are stored due to criteria of representativeness and efficiency (stored samples should represent the characteristics of the population in general).
Clinical use
  • Samples are set aside for autologous transplants (for the donor of the cells) or allogeneic transplants (for compatible family members).
  • In this context, it should be mentioned that for diseases that can be treated with your own cells the probability of success is greater, when compared to transplants using cells from another donor. Allogeneic transplants with samples from family members have a higher success rate than allogeneic transplants from an unrelated donor
  • Samples are stored for allogeneic transplants, i.e. transplants between different people. Doctors identify possible donors using international donor registries.
Costs
  • Payment is made for the service after successful cryopreservation.
  • It is a donation for public purposes.

References:

1One Chance in a Million: Altruism and the Bone Marrow Registry, Ted C. Bergstrom, Rod Garratt, Damien Sheehan-Connor, April 23, 2008

Did you know…?

Public and family banks coexist all over the world

Public and family banks exist for the storage of stem cells from umbilical cord blood collected at the time of birth. Family banks store umbilical cord blood samples for autologous use (for yourself), or for use by compatible family members (related allogeneic use). Public banks store samples from voluntary donors to be used for allogeneic transplants (where the cell donor is somebody other than the recipient). In terms of current applications in the field of hematology-oncology, there are diseases (such as genetic diseases) for which the use of cells from a compatible donor is recommended. The existence of public banks is important for patients who do not have any compatible donors in their families. However, there are other applications for which autologous approaches are preferable. Even with allogeneic applications, the use of a sample from a compatible family member (preferably from a sibling) is better than a sample from an unrelated donor. Public and private banks are perfectly compatible and even complementary, as demonstrated in several countries where they both coexist, even at the same facilities.