Promoting Optimisation, Safety, Experience sharing and quality Implementation for Donation Organisation and Networking in Unrelated Haematopoietic Stem Cell Transplantation in Europe

Autoimmunity is the capacity of the immune system of an organism to recognize its own constituent parts as foreign material. This capacity is characterized by the production of antibodies (called auto-antibodies) directed against elements of “the self”. While everyone experiences a low level autoimmunity which is usually harmless, an excess of this can lead to various pathologies called autoimmune diseases.

Autologous* :

This term designates cells, tissues or organs which are implanted in the same individual from which they were collected.

Compatible donors :

Related

Related compatible donors come from the same family as the patient, generally siblings who have the highest histocompatibility rate among the other family members.

Unrelated

It is possible to find unrelated donors and recipients with a high histocompatibility rate and thus sharing a similar HLA type.

Cord blood* :

Haematopoietic stem cells harvested from placental vessels and umbilical cord vessels, which has a high concentration of haematopoietic stem cells, after the umbilical cord is clamped and/or severed.

Cord blood Bank* :

Is a facility in which haematopoietic stem cells harvested from the placental and umbilical cord blood vessels are processed, cryopreserved, and/or stored.

Cord blood unit collection* :

Refers to the collection of a unit of cord blood, for cryopreservation and transplantation.

Cryopreservation* :

Refers to a technique of stocking frozen cells using devices, supplies, and techniques validated to maintain their viability.

Donor/Donation * :

Every human source, whether living or deceased of human cells or tissues for human application.

Expending donor registries :

The size and the genetic composition of registries is different from one country to another. Inscription policies can be compared and studied to improve the quality and the efficiency of the registries.

Ethnic minorities :

Populations with specific HLA polymorphism and often under represented on the majority of donor registries.

Graft vs. Host Disease (GvHD) :

This disease is a common adverse event in HSCT. After an allogeneic transplant, the donor’s immune cells may react and attack the recipient’s organism. This disease is a expression of the immune system, and can be prevented by selecting very close HLA typings  for donation and immunosuppressive treatment.

HSC (Haematopoietic Stem Cells) * :

Include primitive pluripotent haematopoietic cells capable of self-renewal as well as maturation into any of the haematopoietic lineages (blood cells), including committed and lineage-restricted stem cells, unless otherwise specified, regardless of tissue source. Due to their pluripotency HSC are now regularly used in transplantations to treat several types of diseases.

Haematopoietic Stem Cells Apheresis (HPC – A) * :

Haematopoietic progenitor cells collected from the peripheral blood of a donor using an aphaeresis technique.

Haematopoietic Stem Cells Cord Blood (HPC - C) * :

Haematopoietic progenitor cells collected from placental and umbilical cord blood vessels after the umbilical cord is clamped and/or severed.

Haematopoietic Stem Cells Marrow (HPC – M)* :

Haematopoietic progenitor cells aspirated from the iliac crests, sternum or other bones of a human donor.

Hematopoietic Stem Cell Transplantation (HSCT) :

Medical procedure intended to transplant hematopoietic stem cells harvested from the bone marrow or the blood of a living donor, or from cord blood. Patients requiring a transplantation generally present life-threatening diseases such as leukaemia (cancer of the blood or bone marrow).

The stem cells are harvested directly from peripheral blood (after G-CSF stimulation) or from the bone marrow but also from umbilical cord blood at birth. The cells can then be cryocopreserved for various periods of time before being transfused to a patient. The transplant is said autologous if the donor is the same person as the recipient (HSC are harvested and stocked before being transfused) or allogeneic if the patient and the donor are two different persons. In this case the donor may be related or not to the patient but both must have a similar HLA typing for the graft to be successful.

Histocompatibility :

Designates the compatibility rate between a donor and a recipient for organs, tissues or cells. It is based on the human leukocyte antigen (HLA) system – a set of polymorphic genes – and is an essential factor in the success of a graft.

Human Leukocyte Antigen (HLA) :

Human Leukocyte Antigens are several proteins expressed on the surface of all cells which are used a “signposts” by the immune system to distinguish cells of the self from foreign cells. The HLA system, the set of genes coding for the proteins, is highly polymorphic thus providing a unique HLA type for each individual. A cell expresses several HLA on its surface and the likeliness of the combinations influences the compatibility rate (Histocompatibility) between two individuals.

Immune System :

The immune system is a defence mechanism within an organism designed to protect against pathologies and foreign bodies. The immune system can distinguish self material from non self (or foreign) material in order to successfully protect the organism. Graft rejection is a consequence of this mechanism.

Immunogenetic typing (HLA typing) :

Immunogenetic typing is a biological test used to determine an individual’s HLA type. In case of a transplant HLA types of the donor and the patient are compared to assess their histocompatibility rate which is essential for the success of the graft.

Polymorphism :

Polymorphism is a term used to describe genetic diversity such as the many forms that can be observed for the HLA system genes.

Registries :

Unrelated Stem Cell Donor Registries record important information on potential and volunteer donors such as their HLA types and their physical and medical ability to donate. When a patient needs an HSCT these registries are scanned for a compatible immunogenetic match. Once the match is found, the donor is informed and his stem cells are harvested, they can then be transplanted to the patient.

* : Definitions originally from the european project Eurocet