Haematopoietic Stem Cell Transplantation Flashcards
What is the difference between autologous stem cell transplantation and allogeneic stem cell transplantation?
Autologous uses the patient’s own stem cells which are collected prior to treatment and returned after a conditioning regimen.
Allogeneic uses stem cells from a matched donor (famly member or non-related person who is a close HLA match).
What types of allogeneic stem cell transplants are there?
Full myeoablative transplantation involves high intensity chemotherapy (usually with radiotherapy) before the patient receives the stem cells with the aim of wiping out / eradicating all disease.
Reduced intensity conditioning (RIC) stem cell transplantation involves a lower dose of chemotherapy which may be more suitable for patients who are unable to undergo high intensity chemo.
Double cord transplantation uses blood taken from two umbilical cords (two is required as one is likely to be insufficient), a good option for patients without a suitable donor.
Syngeneic transplantation is less common and is when an identical twin is the donor (therefore HLA identical)_.
What are the main advantages and disadvantages of autologous SCT?
Advantages: No risk of graft vs host disease (GVHD), don’t have to wait for a matched donor to be found, no donor so do not need to be monitored by chimerism post-transplant.
Disadvantages: No benefit from graft vs disease/leukaemia (GVL/GVD)
What is GVHD?
Graft vs host disease is a potentially serious complication of allogeneic SCT which occurs when the donor’s T cells (the graft) treat the patient’s healthy cells (the host) as foreign and attack/damage them. This can be mild, moderate or severe and is divided into acute (within 100 days of SCT) or chronic (after 100 days SCT)
What is GVL?
The graft vs leukaemia (or graft vs disease/tumour) effect occurs in allogeneic SCT when the donor immune cells react against the host leukaemic cells, resulting in the elimination of residual malignant cells. It has been shown to reduce the risk of relapse.
What is chimerism analysis and why is it important?
Chimerism analysis is performed to determine the ratio of donor to recipient DNA present in the blood of a recipient post-transplant (in sex-matched cases). These results are used to determine the success or failure of the graft and usually starts from 8-10 weeks post transplant. The most common method is by STR analysis using PCR. Sex-mismatched transplant patients can be monitored by FISH using probes specific to the sex chromosomes.
