Bone marrow transplantation: A medical procedure which involves transplanting blood stem cells, travelling to the bone marrow where they produce new blood cells and promote growth of new marrow Bone marrow transplantation is to replace damaged or destroyed bone marrow with healthy bone marrow stem cells.
Blood cells are produced in bone marrow and it is a tissue that is found in the centre of bones, such as the hips (the iliac crests), thigh bone and the breastbone (the sternum). These areas are very rich in bone marrow and needs to continually produce blood cells to maintain normal health because like all cells, blood cells have a limited life span.
Bone marrow is responsible for producing:
- Red blood cells, carry oxygen and nutrients through the body
- White blood cells, fights infection
- Platelets, help in blood clotting.
Bone marrow transplantation (BMT) was an experimental procedure in 1970’s which has now become the treatment for a wide range of haematological, non-haematological disorders and cancers with major modifications.
Two categories of transplant have been identified such as, Autograft – the patient’s own bone marrow or stem cells are used and Allograft – the bone marrow or stem cells from a donor are used for transplant. A donor can be Sibling – a brother or sister, MUD (VUD) – a matched unrelated donor or a volunteer unrelated donor, Alternative family donor – a parent, cousin or child or Syngeneic – an identical twin
Most bone marrow transplants today are allogeneic. For donor harvests, the type of procedure used depends on what is most suitable for the patient and donor.
All donors need to go for a physical check-up to make sure that they are fit and healthy. This consists of a physical examination by a doctor and some blood tests (a blood count, blood chemistry and virology – including Hepatitis and HIV screening), a heart trace (ECG) and a chest X ray.
Transplant procedure:
Healthy marrow and blood cells are needed to live. Disease can affect the marrow’s ability to function. When this happens a bone marrow or cord blood transplant could be the best treatment option. The cells for transplant are obtained from the bone marrow or the blood known as stem cells and The process is called as harvesting. In two different ways the cells can be harvested known as Bone marrow harvest and Peripheral blood stem cell harvest. The type of procedure that is selected will be based upon certain criteria, such as your disease, previous chemotherapy and treatment.
Sources of blood forming cells: There are three sources of blood-forming cells used in transplants:
- Bone marrow
- Peripheral (circulating) blood (also called peripheral blood stem cell or PBSC)
- Umbilical cord blood collected after a baby is born
Chemotherapy with or without radiation is given before a transplant. . This is known as the preparative or conditioning regimen. This treatment is given in the days just prior to the infusion of blood-forming cells. The transplant day counted as Day 0, the replacement cells are infused into your blood stream. These cells know where they belong in the body. They move through the bloodstream and settle in the bone marrow. Waiting for engraftment is the term till the transplanted cells starts growing which takes 10 – 21 days. In this period there will low red blood count, low white blood count and low platelets.
When the cells start growing it is known as engraftment where the counts of healthy cells increases and makes the immune system stronger. Engraftment and early recovery lasts from around day 30 to day 100. The entire process, from the start of the preparative regimen until hospital discharge, can last weeks to months, followed by many months of recovery at home.
Bone marrow transplants can be used to treat patients with:
- Life-threatening blood cancers like leukemia
- Diseases which result in bone marrow failure like aplastic anemia
- Other immune system or genetic diseases.
Research on transplant has led to improved survival rates over time. For many diseases, bone marrow transplant is the only cure at this time.