Pediatric Bone Marrow Transplant

Overview

Hematopoietic / Blood stem cells obtained from different sources in the treatment of Pediatric Bone Marrow Transplantation are given to patients who need it for a variety of reasons, similar to a blood transfusion. Cells used for bone marrow transplantation in children can be obtained from three different sources. 

• Bone marrow

• Blood circulating in the veins (peripheral blood)

• Umbilical cord blood taken from newborns

Stem cells from the bone marrow are increasingly used and are replaced by peripheral stem cells. 

Allogeneic Stem Cell Transplantation:

In this type of stem cell transplant, stem cells are obtained from another source, not from the patient himself. The preferred HLA tissue group is to transplant from a compatible sibling or relative. Otherwise, transfer from alternative donors should come to the agenda. For this purpose, HLA compatible non-relative bone marrow donor screening is performed first. These people are called bone marrow / stem cell donors. If there is no non-relative donor, non-relative cord blood is investigated. When all of these resources are consumed, HLA incompatible or haploidentic stem cell transplants can be performed as an alternative stem cell source. Today, the scientific process should be this way.In allogeneic stem cell transplant, donor stem cells form their own immune cells in the patient's body. This helps to eliminate cancer cells that may remain in the body, especially despite chemotherapy. Another advantage is that this type of transplantation can be treated with more stem cells. In addition, because donors are healthy, the stem cells they donate do not contain cancer cells. However, there are some problems that may arise in allogenic transport. The first of these problems is the so-called graft failure. Transplanted cells can be eliminated by the recipient's body before they settle in the patient's bone marrow. Another problem is when the donor's immune cells attack the patient's body. This condition is called graft-versus-host disease. In addition, due to the drugs used for transplant and drugs that will prevent rejection of the given stem cell, the patient's immune system is suppressed, and some factors, especially in his body, can cause serious infections. 

Autologous Stem Cell Transplantation:

In this transplant type, unlike allogeneic stem cell transplant, the stem cell source is the patient itself. Firstly, the patient regression is evaluated after taking a certain number of chemotherapy cures depending on the type of the disease. The most important point in this evaluation is the absence of the disease in the patient's bone marrow. If the disease is not detected in the bone marrow, drugs with G-CSF active substance are applied under the skin in the morning and evening to increase the number of stem cells. The number of CD34 positive cells in 2-3 ml of blood is examined in the period when the blood count is observed every other day and the number of leukocytes starts to increase after the fall. If the CD34 number is above a certain value, stem cells are collected by apheresis method. 

When is stem cell transplant done?

The patient receives a certain number of chemotherapy depending on his illness, and then the disease state is evaluated. If the disease is in complete remission, that is, if all the visible disease has disappeared, then stem cell transplantation is performed. The basic logic in autologous stem cell transplantation is to eliminate the disease completely with high-dose chemotherapy, ie without a single malignant tumor cell. To achieve this, combined chemotherapy drugs called disease preparation regimen are used. Due to this high dose of chemotherapy, erythrocytes, leukocytes and platelets become unproductive in the bone marrow. In this process, intensive supportive treatments are applied to the patient.The preparatory regimen can be defined as the combined application of different chemotherapy drugs selected depending on the disease. Before the patient is given this chemotherapy, in other words, before the autologous stem cell transplant, the patient is evaluated in detail. In this evaluation, the patient's kidney and liver functions, heart and lung health are examined, and the endocrine system, immune system, eye and other systems are evaluated in detail and recorded. After plenty of fluid support, the patient is given intravenously on certain days in accordance with the rules of each chemotherapy drug. Subsequently, stem cell transplantation is performed and today it is considered as the 0th day of stem cell transplantation. Afterwards, intensive supportive treatments are applied. The first two weeks after stem cell transplantation are very critical and especially bone marrow engraftment, that is the involvement of the bone marrow, occurs within this period.In the process after the stem cell transplant, blood products are transfused according to the need. The patient is highly protected against infections. However, patients may still have fever and need to use antibiotics intravenously. Nutrition of the patient is closely monitored and supported. Some medications can be used for bone marrow engraftment. In this process, the patient is closely and dynamically monitored, and possible complications developed by daily examinations are tried to be identified early. In addition, the patient is provided with social and psychological support at every stage of these processes. After autologous stem cell transplantation, the patient is closely monitored. Occasional blood tests, imaging tests are performed to evaluate the disease status and all body systems are examined in detail. The problems identified are tried to be solved with a multidisciplinary approach with the support of the relevant departments.