by: Dr. Yitzchak Yaniv
In a collaborative project of the IDF and Ezer Mizion’s International Bone Marrow Registry, all new conscripts are offered the chance to join the Registry during their chain of induction. The response is growing all the time and the result is significant expansion of the Registry with ideal potential donors – young, healthy people with a variety of tissue types compatible with a wide range of populations
A bone marrow transplant is a medical procedure that leads to the recovery of many patients suffering from blood disease, cancer, hereditary diseases, and immune system deficiencies. In recent years, the number of bone marrow donations has risen dramatically around the world, including in Israel.
Bone marrow is the tissue within the bones from which stem cells develop – the body’s primary cells which regenerate on a regular basis and give rise to differentiated cells, among them blood system components such as red blood cells, white blood cells and platelets. The multipurpose/primary (hematopoietic) stem cells renew the blood system every day, in keeping with the body’s needs: The red blood cells are responsible for providing oxygen to the body tissues, the white blood cells are in charge of protecting the body from infection, and the platelets take care of blood clotting.
In the case of cancer, a transplant enables replacement of the patient’s bone marrow so as to renew his blood and immune systems. In the case of immune deficiency, it enables the body to replace the defective immune system.
The cells necessary for transplant to a sick person, the stem cells, which, as mentioned, are the factory for our body’s blood and immune systems, can be harvested from a healthy donor in a number of ways: under anesthesia, by a puncture, taking blood from the pelvic bone, or taking peripheral blood (which flows through the arteries and veins) by hooking up the patient intravenously to a device that separates out the necessary cells in a procedure that takes several hours and does not involve anesthesia or pain. None of these techniques generates any sort of deficiency in the body of the donor since bone marrow renews itself so quickly all the time.
After the bone marrow is harvested from the donor, it is processed in the laboratory and transferred to the patient by injection into his blood. The cells find their way to the patient’s bone marrow spaces and within a few weeks are absorbed there and begin producing the blood and immune system components.
In order for the donor’s bone marrow to be appropriate for the recipient, the tissue type has to be compatible. Tissue-typing is a characteristic that is transmitted hereditarily and determines our body’s immune system structure. This characteristic enables the immune system cells to identify any foreign element, such as a bacteria, virus, or cell from some other external source. From the genetic standpoint, every person is different from the next (except for identical twins). As a result of this difference, the immune system tends to reject tissue or an organ that is from any source other than the person himself. How does the immune system know how to distinguish between the person and someone else? On the surface of all body cells (with the exception of sperm cells), there are special structures called “receptors” that are connected to the tissue-typing system. Therefore, the chances of two unrelated people having similar tissue types are extremely slight. Ordinarily, one would need registries containing tens of millions of potential donors to find such a match. Everyone who joins the registry does a blood test for tissue typing, and the results are saved in a computerized information bank.
The optimal donor is generally a close family relative, such as a brother, because he has a 25% chance of carrying the same exact genetic charge, to create full compatibility. If there is no matching brother, we look for a donor from the same ethnic background as the patient, since tissue types in different ethnic groups are preserved through the generations. In Israel, the merging of the many ethnic groups has led to a situation in which today’s young potential donors are the best donors of all, since they represent the genetic melting pot that took place in the general population, which, of course, is also the source of the patients awaiting the transplant. Every donor who is found to be a match for a specific patient undergoes a full medical evaluation designed to eliminate medical conditions such as heart disease that the donor might have and which can endanger him if he gives a donation.
Ezer Mizion’s International Bone Marrow Registry is one of the largest registries in the world today, and is certainly the largest Jewish registry. In a collaborative project with the IDF, all new conscripts are offered the opportunity to join the Registry in the course of their induction. The response is growing all the time, and the result is an expansion of the Registry with a supply of ideal potential donors – young, healthy people with a variety of tissue types compatible with a wide range of populations. Today, the Registry numbers more than 713,000 potential donors and has already provided 1,504 donations of bone marrow for transplant to patients, half of them in Israel and half around the world.
In a British study presented at the last International Convention for Bone Marrow Transplants in Milano under the aegis of the European Bone Marrow Transplant (EBMT) Association at the beginning of April, findings showed that the time that elapses from the moment of locating a potential donor in the computer until the actual transplant ranges from 109 to 141 days. Some of the patients for whom this search process is done do not make it to a transplant in the end because of the progress of their disease or a decline in their health condition.
Finding a donor in Israel significantly shortens the search process, offers greater flexibility in setting a date for the transplant, improves the chances of obtaining an additional blood donation if necessary, and sharply cuts costs. It is important to remember that giving a bone marrow donation is a lofty act of the highest level, and every additional potential donor increases the chances of saving lives.
On May 1st, an event took place to mark the 500th soldier to donate bone marrow.
Professor Yitzchak Yaniv is the head of the Oncology Department at Schneider’s Children’s Hospital and Medical Director of Ezer Mizion’s International Bone Marrow Donor Registry.