Bone marrow: why is it needed and what happens when its functions are impaired

What is bone marrow

People far from medicine know about bone marrow mainly from stories about its transplantation to patients with dangerous diseases. But usually they have little idea what kind of organ it is, where it is located and what it is responsible for.

Bone marrow should not be confused with the spinal marrow or brain. It has no neurons and is not part of the central nervous system. This substance is divided into two types: yellow bone marrow, consisting of adipose tissue, and red, containing hematopoietic stem cells (HSCs). Last answers for hematopoiesis in the body. In adults it located in flat bones and end sections of tubular bones.

Hematopoietic stem cells are a kind of universal blanks for blood cells. As they mature, they can divide repeatedly and become red blood cells, platelets and white blood cells.

Blood formation process called hematopoiesis. It is continuous: more than 500 billion cells develop daily; normally, a balance is maintained between their different types.

In addition to hematopoiesis, red bone marrow has another very important function. Organ participates in the process of immunopoiesis - the creation of lymphocytes, components of the immune system. They are produced in the bone marrow from the same stem cells.

Why does the bone marrow malfunction?

This happens if a person are developing diseases of the blood system, in particular of an oncohematological nature. These include malignant diseases such as lymphomas and leukemia. In addition, bone marrow function may be impaired in aplastic anemia.

Among possible reasons Such diseases are hereditary predisposition, exposure to radiation or toxic substances, weakened immunity and bad habits. Under the influence of these factors, a “breakdown” occurs in the body: instead of normal cells, pathological ones appear, which begin to rapidly divide. If lymphocytes are affected, are developing lymphoma, with damage to leukocytes arises leukemia, and when are dying stem cells - aplastic anemia.

How is a bone marrow transplant performed?

To achieve remission, patients with diseases of the blood system may be given a transplant of someone else's bone marrow or HSC (hematopoietic stem cells). This process called allogeneic transplantation. “Twins” by HLA genotype There is Most people have them, but they are difficult to find.

The chance that a suitable donor will be found among relatives is does not exceed 25%.

To make it possible to quickly find the perfect match, donor registries are created - unique catalogs of volunteers willing to share bone marrow.

After inclusion in the register Maybe It will take several years before a candidate is invited to donate. The more participants in such a directory, the higher the likelihood of a “match”.

The process of harvesting donor stem cells or bone marrow is carried out in one of two ways. In 90–95% of cases applies apheresis method. The donor is pre-injected with drugs that stimulate hematopoiesis and the release of stem cells into the bloodstream, then the blood from a vein in one arm is passed through a separator that separates the HSCs and returned through a catheter in the other hand. The procedure takes 4–5 hours, anesthesia is used for it not required. The donor's blood counts return to normal in about a week.

Also use exfusion method. Under general anesthesia, the donor's pelvic bone is pierced with a special sterile needle and bone marrow cells are removed. This manipulation takes from 30 to 60 minutes. The donor's hemoglobin level may decrease slightly, but it is restored within 2–4 weeks.

The recipient faces a much more serious intervention. When a suitable donor is found, they begin to prepare him for surgery. To prevent the body from rejecting the transplanted tissue, the patient carry out intensive chemotherapy, during which the hematopoietic and immune systems are destroyed. If the transplant fails at this stage, the person may face death. Therefore, it is important to approach the decision to join the donor register consciously.