"Who can be used for a cord blood unit stored in a family bank?" is one of the frequent questions addressed by the future parents considering to collect and storeat birth of their child.
Before diving into a detailed presentation of this topic is very important to highlight the following 4 basic principles:
- The clinical usability of a stored cord blood unit by other persons, except the donor, is first of all conditioned by genetic aspects.
- Even if there is genetic compatibility between the donor and the patient, not always the therapeutic usage of stored cord blood unit is appropriate. For instance: in case that the donor have a genetic disease, even if there is compatibility between the donor and the patient, the cord blood unit may not be used for clinical application.
- Only the medical team or the patient’s physician in charge with the treatment can decide on the appropriateness of using the cord blood unit from a family bank, as the best solution for treating the patient, or not. In their decision there are taken into consideration more aspects than only the compatibility between donor and the patient. Such as type and form of disease, stage of disease’s evolution, response to standard treatments, availability of other stem cells source etc.
- A cord unit stored in a family bank can be available for therapeutic purpose only for the family members. Unlike the public registries, where the donated cord blood units are available to be used in stem cells transplants for any unrelated compatible patient according to the physician’s indication of treatment.
1. What types of transplants can be performed with an umbilical cord blood unit?
Umbilical cord blood unit can be used for autologous or allogeneic transplants(related or unrelated).
Autologous transplant imply that the donor and the recipient are one and same person.
This means the umbilical cord blood unit used for transplantation was harvested at the birth of the patient.
Related allogeneic transplant implies that the donor and the recipient are members of the same family, immunologically compatible.
This means that umbilical cord blood stem cell harvested at the birth of the donor if used by another family member.
Unrelated or non-related allogeneic transplant implies the use of a donated umbilical cord blood unit by an immunologically compatible patient without any family relation to the donor.
In this case the donated umbilical cord blood was processed and stored in a public registry. The release and distribution of the cord blood unit to the transplant center where the patient is treated are also responsibilities of the public registry.
Umbilical cord blood units from family banks may be released and distributed for autologous or for related allogeneic transplantations only with the consent of the child’s parents (contract holders up to the full age of the child) based on the medical indication established by the specialist physician and upon the request received from the transplant center.
For allogeneic transplantation the immunological compatibility between donor and recipient is a mandatory condition.
2. What does it means “immunological compatibility” between donor and recipient?
Donor is the child at who's birth the cord blood was collected.
Recipient is the patient who is transplanted with the donated cord blood unit, as source of stem cells.
In order to have a successful allogeneic transplant, first of all it has to be an "immunological similarity" between donor and recipient.
This means that some special proteins responsible for the regulation of the immune system in humans, has to be identical (this is so called "perfect match" compatibility) or at least a few of them has to be similar (this condition is so called "partial match" compatibility).
Each of us has on the surface of all nucleated cells of our bodies small molecules which gives us our immunological identity.
These molecules/proteins belong to the major histocompatibility complex (MHC) and are responsible for the regulation of the immune system. Each molecule from the MHC are encoded and are synthesized by genes from chromosomes 6, which are part of the so called HLA (human leukocytes antigens) system or complex.
We are inheriting 1 set of genes from HLA (human leukocytes antigens) system) from both our parents.
This is a very important aspect to be remembered in order to understand the immunological compatibility between the family members.
HLA system has major importance for cells, tissue or organ transplants from donors, if these are accepted or rejected by the patient’s body.
HLA system contains a large number of genes, but from the transplant perspective the most important are the genes encoding the 6 major antigen-presenting proteins. (A, B and C antigens from MHC class I and DP, DR, DQ, DO and DM antigens included in MHC class 2). These proteins have been proven to have a great impact on the transplant outcome.
There is a wide diversity of HLA system genes has in population, especially between different races and ethnicities.
In the following post you can learn about:
3. What kind of tests are performed in order to check the immunological compatibility between 2 the donor and the recipient.
4. The odds of the immunological compatibility between the members of a family.