Bone marrow, the cradle of blood cells

Bone marrow ensures the renewal of blood cells, such as red blood cells, white blood cells and platelets. Bone marrow donation is a lifesaving transplant for many leukemic patients or chemotherapy whose marrow no longer works.

What is bone marrow?

The marrow transplant is the only solution for certain blood diseases such as leukaemias, lymphomas, or spinal aplasia. This marrow transplantation obviously requires the existence of a donor, who can be of the same family if he is compatible, but who can also be an anonymous donor. According to the Agency for Biomedicine, there are today just over 263,000 volunteers registered in the French register of donors; they can be called at any time for a sample.

The bone marrow is distinct from the spinal cord. The spinal cord belongs to the nervous system, it is the relay between the brain and the nerves. It lodges in the canal formed by the stacking of the vertebrae of the column. The bone marrow, for its part, is located in the whole skeleton, and more particularly in the flat bones, such as the sternum, the ribs or the bones of the pelvis which are very rich in bone marrow.

The bone marrow is composed of two parts: the yellow marrow rich in fat and the red marrow found in the cancellous bone. Red marrow produces hematopoietic stem cells, in other words, future blood cells: red blood cells that carry oxygen, white blood cells that fight infections, platelets that stop bleeding. The bone marrow also manufactures the different types of lymphocytes, these are specialized cells in immunity, responsible for recognizing and destroying any foreign element introduced into the body.

The red bone marrow produces 350 billion blood cells each day: 200 billion red blood cells, 100 billion platelets and 50 billion white blood cells. They replace the blood cells that have been destroyed in the body. The bone marrow therefore has a vital role. When it can no longer play its role, the marrow transplant becomes indispensable for the patient’s survival.

What is bone marrow donation?

Bone marrow donation is a lifesaving transplant for many leukemic patients or chemotherapy whose marrow no longer works. Every year, more than 200,000 people need a bone marrow transplant (source: Federation of Associations for Organ Donation and Human Tissue).

The main problem is rejection, with each individual having his own characteristics and his tissues being defined genetically. All of these features are called “HLA system”.

The immune system is programmed to recognize the HLA system and eliminate all elements that are not part of it. When transplanting an organ that meets the HLA criteria, it is said to be compatible: the body of the recipient accepts it and the immune defenses do not destroy it. He is recognized as belonging to the organization.

When a transplant is performed, the donor is unknown or part of the family. The ideal is of course a brother or a sister, who are more likely to have a compatible marrow with the patient, but it is often impossible.

For 70% of patients, the only hope is the list of donors. Unrelated, the chance of being fully compatible is 1 in 1 million, hence the importance of this list being long.

How to donate bone marrow?

The donation is anonymous, voluntary and free. A triggering event is often at the origin of this beautiful step.

The donor’s marrow increases its activity immediately after the operation, which compensates for the removal: the quantity of blood cells produced is therefore not diminished.

In practical terms, all costs are covered by Social Security. Hospitalization lasts two days and an eight-day work stoppage is recommended afterwards. Once a compatible donor is found, the operation can be scheduled.

To become a donor, you must first be in good health and be 18 to 50 years old. Once registered, you stay there until you are 55 years old.

For the donor file to continue, 10,000 new volunteers are needed every year. Currently, in France, there is a lack of male donors under 40 years old. The inscription on this register gives chances of cure and a lot of hopes to the patients waiting for a transplant.

What is bone marrow transplant?

Bone marrow transplantation is a lifesaving treatment for people with life-threatening diseases, such as cancer, but like all transplants, suffers from a lack of donors.

Thus, in 2004, more than 11,000 patients would have needed an organ transplant. Only a little over a third benefited.

The role of the marrow is to produce all the figured elements of the blood: red blood cells, white blood cells and platelets. Normally, these cells are constantly renewed thanks to a reserve of stem cells that contains the marrow, “virgin” cells able to evolve in all types of cells.

This marrow is contained in the center of the long bones, like the humerus in the arm, and flat bones, like the iliac bone in the pelvis. It is very different from the spinal cord which is a part of the nervous system located in the canal that forms the stack of vertebrae.

A marrow transplant involves taking marrow from a donor’s bone and relocating it to a patient.

Several diseases can be treated by this act. This is the case of leukemias and lymphomas, because in these diseases, the cancer cells invade the marrow and then prevent it from functioning properly. This is also the case of aplasia, a disease in which the bone marrow no longer works and no longer produces white blood cells or red blood cells.

Finally, one can also do a transplant when a harmful treatment has destroyed the marrow and thus its cells. When there are no more red blood cells, the risk is anemia. The absence of white blood cells causes infections. When the disappearance of platelets, it is causing haemorrhages.

Two types of transplant

The allograft involves a donor, whether unknown or part of the family. Of course, the chances of finding a stranger to the compatible marrow, so accepted by the patient, are much rarer than if it is a brother or a sister.

Grafts are indeed much more effective when the donor is related to the recipient. The problem is that in one sibling, only one in four children has the same HLA system as their sick brother.

Autologous bone marrow transplant uses the patient’s own marrow. This is removed, frozen during aggressive treatment of the patient and then reimplanted.

In France, this donation is free. All expenses are covered by Social Security. The hospital stay lasts two days and an eight-day work stoppage is preferable.

Registration on the marrow transplant donor file provides hope and hope for future recipients.