Allogeneic Bone Marrow Transplantation, Types, Procedure & Risks

The allogeneic transplant involves infusing stem cells from a healthy donor who can be related or unrelated to the patient. It is most commonly used for treating conditions like leukemia, immune system disorders, and lymphoma.

What are the Different Types of Allogeneic Bone Marrow Transplants?

An allogeneic transplant can be of various types. These include:

1. Conventional or unmodified stem cell transplant: In this method, the stem cells are given without any modifications in the laboratory. This is usually given to people who can take medicines after the transplant to eliminate the risk of graft vs host disease(GVHD).

2. T cell-depleted transplants: Since T cells from the donor can cause GVHD, these are usually removed in this type of allogeneic transplant. After removing the T cells in the lab, the remaining stem cells are infused in the patient. These stem cells can then give rise to T cells in the patient’s body. However,  these will pose a lower risk of GVHD. Thus, people who have received this kind of transplant need not take medicines to prevent GVHD.

3. Cord Blood transplants: In this, stem cells are taken from the umbilical cord of a newborn. Here also the chances of GVHD are low. This can be a good option for people who cannot find a donor.

4. Donor lymphocyte infusions (DLI): In some patients, cancer can relapse after the transplant. So, to eliminate cancer cells, doctors can give T cells from the donor. The low levels of T cells can fight cancer cells without increasing the chance of graft vs host disease.

Procedure

If the donor stem cells are being harvested from the bone marrow, then the donor will have to be anesthetized. These are usually collected from the back of the hip(pelvic) bone. The procedure lasts for about 2 hours within which around 10% of the bone marrow is collected. The donor doesn’t have any complications. Instead of bone marrow harvest, stem cells can also be collected from blood.

The patient undergoes conditioning where he/ she is exposed to chemotherapy drugs to kill the cancer cells or suppress the immune system. This will be then followed by the transfusion of stem cells into the bloodstream. After this, the patient is observed in the hospital for engraftment. This is the process where the stem cells travel from the blood to the bone marrow. It can take up to 1 year after the procedure to recover.

Benefits VS Risks of Allogeneic Transplant

The most obvious drawback of an allogeneic transplant is the possibility of graft rejection. Here, the term graft refers to donor stem cells. These stem cells may begin to produce immune cells that can attack the body of the recipient. This can lead to graft vs host disease, a serious illness. However, most of these cases can be successfully managed with medicines.

When the donor stem cells turn out as a good match, they can produce immune cells which can efficiently fight off cancer cells. This is known as the graft versus cancer effect.

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Conclusion

You should be aware of all possible outcomes of an allogeneic transplant to ensure that the process is actually required for you. From asking questions to your doctor and researching the process in-depth, there are multiple things you can do to make an educated decision for your health.