What is Bone Marrow and what it does?
Bone Marrow is a spongy tissue found in the centre of bones such as the back of hips and breastbone (the sternum) which produces blood cells. Bone Marrow produces three different types of blood cells called red cells, white cells and platelets. Like all other Cells they have limited life span hence need for continuous production.
- Red cells- carry oxygen, if low one get tired easily (Anaemia)
- White cells- help us fight infections
- Platelets- help to prevent or stop bleeding or bruising
- Without normal blood cell production, you can become tired, susceptible to infections and bruise easily.
- Specific terms are used to describe low numbers in all three groups and you may hear these terms mentioned frequently.
- Neutropenia- when one type of white cells is low
- Thrombocytopenia- when platelet numbers are low
- Anaemia- low hemoglobin (many synonymously use as low blood)
What is bone marrow Transplantation? Is it same as stem cell transplantation?
Bone marrow transplant is a process of replacing diseased marrow with healthy marrow. Traditionally stem cells derived from donor’s bone marrow but recently many unrelated transplants are done with stem cells derived from peripheral blood.
The term stem cell transplant is used if source of marrow cells are obtained from donors blood rather than bone marrow.
Donor is given injections under the skin for 5-7days and stem cells mobilized from bone marrow to peripheral blood and are collected by aphaeresis machine which looks similar to blood donation. Many times these two words used synonymously.
Where do stem cells come from?
There are two categories of transplants. One is called Autograft where patients own stem cells are re infused after high dose chemotherapy. Second is called Allograft where bone marrow cells derived from donor- who could be sibling, unrelated, family donor and cord. If sibling is used we call it Sib Allo transplant. If unrelated donor is used we call it Matched unrelated donor transplant (MUD)
If Father, Mother, Son or Daughter are used who would be at least half match we call that transplant as Half match Transplant or Haplo Bone Marrow Transplant.
How the donor is selected?
Once we identify there is need for Bone marrow transplant, we will perform a Blood test called HLA testing on patient and look for similar HLA type or close match from the donor.
If there are siblings they are tested as 1 out of every four siblings will be a full match. If no siblings we check on the bone marrow donor registry database to identify suitable match. If no suitable donor available then we would recommend half match transplant from parent/children/half match sibling.
Who is the preferred donor?
Younger and healthier donor is an acceptable match. (20-30 yr age is preferred)
What is HLA (Human Leucocyte Antigen) Tissue typing?
HLA are proteins or markers found on most cells in your body. Your immune system uses these markers to recognize which cells belong in your body and which do not. HLA typing is the testing used to determine a person’s tissue type.
Can we find Acceptable match for every patient?
No. Sometimes we cannot get perfect match for patient from donor registry. The new research has enabled us to use father/Mother or sibling who would be biologically half match. So called half match transplants are giving more hope for patient without fully matched donor.
MBBS, MD, MRCP, FRCPath(Haem) UK,
Haemato oncologist and
Bone Marrow Transplant Consultant,