Bone Marrow Transplant - bone marrow transplant procedure for donor
Conditioning
Chemotherapy or chemotherapy plus radiation destroys bone marrow so there is room for new destroys recipients immune system so it doesn’t destroy transplanted cells destroys diseased cells (leukemic or pre-leukemic) These treatments lead to an increased risk for infections during treatment also nausea, vomiting, hair loss, skin rash, mouth sores Long term these treatments lead to an increased risk for:sterility endocrinopathies cancer rarely - vessels in liver swell shut, juandice, liver damage rarely - lung damage or cardiomyopathy FA patients have impaired DNA repair, and thus these treatments are less well tolerated and more risky for them
Affected child in this case was treated with cyclophosphamide total body irradiation also needed due to MDS (preleukemia)
Introduction of new cells
Bone marrow or cord blood is put into the blood of the transplant recipient.
The bone marrow cells will travel to their proper locations in the recipient’s bones and establish themselves there.
Treatments to prevent infection during immunosuppression
Granulocyte colony stimulating factor to increase white cell production Anti-fungal (prevent candida and aspergillus) Cefazolin (prevent Streptococcal infection) Acyclovir (prevent herpes infection) Cotrimoxazole (prevent pneumocystis infection)
Additional Treatments
Cyclosporin A to prevent graft versus host (GVH) (the transplanted cells attack the recipient)
Long-term
Affected child in this case No acute or chronic GVH (she had a matched sibling donor) Mild adenovirus gastroenteritis resolved by 3 mos No other opportunistic infections developed Mild drug related toxicity developed in the liver All medications were discontinued by 24 months post transplant.
Molly Nash
Molly still needs treatment for some of her congenital defects (intestinal and spinal abnormalities) Her risk of developing cancer other than leukemia remains high since the other cells in her body still contain mutations in FANCC.
Bone Marrow Transplant
Engraftment
Usually donor bone marrow cells begin to function in the recipient within 30 days.
Affected child in this case Neutrophils were to target levels by day 17 Platelets were to target levels by day 30
Importance of a Matched Donor
2 year survival rates vary for FA patients who have received BMTs matched sibling donor - 66 - 85%
match from bank 22 - 40%
What does a matched donor mean?
Our cells have molecules on their surface called human leukocyte antigens (HLA).
Our immune system uses to these molecules to distinguish between our cells and invaders.
These molecules enable infected cells to signal and initiate an immune response.
In a matched donor, the molecules on the surface of the donor cells would be the same as those found on the surface of the recipient.
Bone Marrow Transplant
Why is it important for HLA type to match?
If the HLA antigens are the same between the donor and the recipient, neither with recognize the other as foreign.
If the HLA antigens are different…
Possibility 1
The donor bone marrow cells may recognize the recipient cells as foreign and attack the recipient.
This can range from mild to fatal.
It is known as Graft versus Host or GVH GVH is a major risk in all BMT.
Possibility 2
Any remaining bone marrow cells in the recipient may recognize the transplant as foreign and destroy it.
For transplant purposes
HLA-A, HLA-B and HLA-DR antigens are the most important.
Since you have two copies of the genes for each of these antigens (one from your mother, one from your father), there are 6 antigens that need to be matched.
They are all co-dominant, meaning they are all expressed on the surface of cells.
A bone marrow transplant will not usually be done unless 5 out of 6 of these antigens match, and 6 out of 6 is considered best.
Matching of additional HLA antigens (beyond HLA-A, HLA-B and HLADR is optimal and reduces chances of long-term complications.
For transplant purposes
HLA-A, HLA-B and HLA-DR antigens are the most important.
Since you have two copies of the genes for each of these antigens (one from your mother, one from your father), there are 6 antigens that need to be matched.
They are all co-dominant, meaning they are all expressed on the surface of cells.
A bone marrow transplant will not usually be done unless 5 out of 6 of these antigens match, and 6 out of 6 is considered best.
Matching of additional HLA antigens (beyond HLA-A, HLA-B and HLADR is optimal and reduces chances of long-term complications.
Chances of finding a matched donor
Bone Marrow Transplant
There are two type of HLA:
Major Histocompatilbility Classes I and II MHC Class I antigens. These antigens are found on the surface
of all nucleated cells in our body. In humans the MHC Class I antigens are called HLA-A, HLA-B and HLA-C.
Bone Marrow Transplant
MHC Class II Antigens
These antigens are found on B-cells and macrophages.
In humans these antigens are HLA-D, HLA-DR, HLA-DP and HLA-DQ
HLA variability HLA genes are highly variable in humans. This polymorphism represents a species response to maximize protection against diverse microorganisms.
This diversity in HLA antigens makes finding a transplant donor difficult.
Chances of creating an HLA-matched sibling
All HLA genes are located on chromosome 6 Recombination between the HLA loci is relatively rare So, chances of any given sibling being a matched donor are just under 25% In addition, the sibling will be matched
at other HLA loci as well.
To create a sibling who could serve as a donor
The case we are discussing goes beyond just HLA matching, we need to find an embryo that is FA-free and is HLA-matched.
HLA matching is on chromosome 6 FANCC is on chromosome 9 So, we are looking at 2 chromosomes rather than one.
The genotypes of the family members are shown below.
What are the chances of creating an HLA-matched, FA-free embryo?
Bone Marrow Transplant - bone marrow transplant procedure for donor
