What does a bone marrow transplant look like?

For some patients, bone marrow transplantation is the only option. It is used with people whose hematopoietic system has been damaged as a result of disease or treatment. The task of the donated cells is to restore bone marrow in the patient’s body. In this article, you will learn what a bone marrow transplant is and how to donate bone marrow.

What is a bone marrow transplant?

Bone marrow transplant, is a procedure involving the transplantation of hematopoietic stem cells to a patient. The purpose of this procedure is to rebuild the patient’s damaged hematopoietic system. It can become damaged, for example by leukemia, which is also the most common indication for bone marrow transplantation.

What is the function of the bone marrow?

The first question to be answered is: What is bone marrow? It is a soft and highly supplied tissue located in long bones, more precisely in the marrow cavities, as well as in small pits found in the essence of spongy bone. The bone marrow is made up of reticular tissue and capillaries, which together form a kind of net.

In addition, there are two types of bone marrow in the body:

• Red bone marrow, where the production and continuous renewal of blood cells takes place, i.e. red blood cells, leukocytes and platelets. This means that the bone marrow is hemopoietic.
• Yellow bone marrow, which consists mainly of fat cells and does not produce blood cells (it is hematopoietically inactive), but in the event of organism disorders, it can transform into red bone marrow.

One of the main functions of the bone marrow is the production of blood elements. The function of the bone marrow that is most important during transplantation is the restoration of blood cells and the production of B lymphocytes (cells of the immune system). Thanks to this, in the event of the appearance of a pathogen in the body, an appropriate defense reaction is possible. The bone marrow is also responsible for the disposal of old and damaged blood cells, and for the collection of iron derived from them.

What does a bone marrow transplant look like?

The bone marrow transplant procedure begins long before the surgery itself. The first stage is the initial qualification of the patient, i.e. the moment when the medical team determines on the basis of tests whether a person should be referred for transplantation. Then, after qualifying, the process of searching for a suitable donor begins. After finding the right person, both donor and the patient undergo very detailed tests. Then a hematopoietic stem cell transplant is planned. But what is the bone marrow transplant itself?

Types of transplants

There are two types of transplant:

• Autologous bone marrow transplant in which the patient is the donor of stem cells. After its collection, marrow is cleaned and then reintroduced into the patient’s body.
• Allogeneic bone marrow transplant in which the donor is a tissue compatible person. Ideally, it would be a family member, e.g. a brother or sister, but a transplant from an unrelated person is also possible.
  The first type of transplant is most often used with patients who have had treatment that has destroyed their bone marrow. Allogeneic transplant is used in lymphocytic leukemia and acute non-lymphocytic leukemia and severe immunodeficiency.

Donor preparation

Bone marrow transplantation requires proper preparation of the donor, who must undergo tests prior to the procedure. Thanks to them, the doctor can precisely determine whether a potential donor is eligible for bone marrow donation. For this purpose, it is necessary to perform detailed blood tests, electrocardiography (ECG), chest radiographs, and abdominal ultrasound. It is also necessary to exclude infection with hepatitis virus, cytomegalovirus, HIV, and also Epstein-Barr virus (EBV).

How is bone marrow collected?

The area from which the cells are collected is the donor pelvic bone, precisely the posterior upper iliac spine. The bone marrow is collected under general anesthesia in the operating room. During the procedure, about 15-20 ml / kg of the recipient's body weight are taken from the donor, i.e. usually about 1-1.15 liters. This amount contains the appropriate number of stem cells that are able to rebuild the recipient's marrow. Hematopoietic stem cells can be collected not only from bone marrow, but also from peripheral blood or umbilical cord blood. Currently, haematopoietic stem cells collected from the donor's blood are most often used for transplantation. The procedure of collecting stem cells is safe for the donor.

Bone marrow transplant

The entire bone marrow transplant process is divided into several stages:

• Stage I (conditioning regimen) - involves the introduction of the so-called conditioning regimen, i.e. intensive anti-cancer therapy. It aims to destroy both the recipient's cancer cells and lymphocytes, which could cause rejection of the transplant.
• Stage II (implantation) - this is the moment when stem cells from the donor are transplanted. Implantation is performed intravenously and the entire procedure takes place in the operating room. Usually it takes several minutes.
• Stage III (postoperative period) - a characteristic feature of this stage is the reduction in the number of all morphotic elements in the blood, i.e. pancytopenia. Immunity is also lowered, and therefore the risk of infections is still increased. During this period, the recipient remains in hospital for approximately 4 to 8 weeks.
• Stage IV (bone marrow regeneration) - this is the recovery period, which in the initial phase requires the patient to regularly and quite frequently visit the transplant center.

Complications after transplantation

One of the complications that can arise after transplantation is graft-versus-host disease (GVHD). It appears when the donor's lymphocytes begin to attack the recipient's body, considering it "foreign". Moreover, it can occur regardless of whether the donor and recipient are related. The disease takes two forms - acute, the symptoms of which appear up to 100 days after transplantation, and chronic, the symptoms of which usually appear more than 100 days after transplantation. GVHD is, along with infections, the most common cause of death in patients. Recipients may also develop bacterial and viral infections, as well as fungal infections. Another complication that patients may experience is severe pancytopenia, which is a reduction in the number of all blood components. For this reason, in some cases, a blood transfusion may be necessary. In the worst case scenario, complete rejection of the transplanted bone marrow may occur. It is observed in recipients of allogeneic transplantation.

How to donate a bone marrow?

To become a bone marrow donor, all you need to do is register with one of the national organisations. To register, it is necessary to answer all the questions and then order a free registration package. After receiving it, complete the form and take a swab from the inside of the cheek. In the next step, the potential donor should send set to the provided address. Then the sample will be tested for histocompatibility antigens - based on the results, donors are matched with patients. After all the data is entered into the system, you become an active donor.