Syngeneic Stem Cell Transplant

What is syngeneic stem cell transplant?

A syngeneic stem cell transplant is a special type of allogeneic transplant in which the donor is an identical twin (or triplet) to the recipient. This means that the donor and the recipient both have identical tissue types.

This type of stem cell transplant is rare as identical twins or triplets are not very common. If you have an identical twin or triplet, their stem cells can be used to treat your leukemia or other blood disorders you may have.

How it works

A syngeneic stem cell transplant uses the stem cells from your identical twin to replace your abnormal bone marrow.

Before the stem cells transplant, you will receive high doses of radiotherapy or chemotherapy, or both, to destroy all of your cancer cells as well as the normal blood cells in your bone marrow.

You will then receive the new healthy stem cells, which are free of cancerous cells and will produce their own immune cells. These immune cells will fight any cancer cells remaining after treatment.

If more stem cells are needed, your identical twin will have to be recalled.

Why do you need a syngeneic stem cell transplant?

Syngeneic stem cell transplants are used to treat conditions such as:

  • Hodgkin lymphoma
  • Leukemia
  • Multiple myeloma
  • Myelodysplastic syndrome
  • Non-Hodgkin lymphoma
  • Severe aplastic anaemia
  • Testicular cancer

The advantages of syngeneic stem cell transplants include:

  • Your body readily accepts the cells. Graft-versus-host disease (GVHD) will not be an issue because your immune system recognises your identical sibling’s stem cells as your own (donor’s tissue type matches 100% with recipient).
  • You get cancer-free donor cells. Donors are required to undergo rigorous medical screenings, so their stem cells are verified to be free of cancer.

The disadvantages of syngeneic stem cell transplants include:

  • Your body may not fight the cancer cells. This type of transplant will not destroy the cancer cells as the newly-infused stem cells are identical to your own cells. Like your old immune system, your new immune system may not recognise and fight cancer cells, possibly leading to a relapse.

What are the risks and complications of a syngeneic stem cell transplant?

The side effects of a stem cell transplant may vary from person to person. Some individuals experience multiple side effects, while others may have fewer. Some side effects are short-term (acute), while others are long-term (chronic).

Many of the side effects result from the chemotherapy or radiation therapy given before the transplant. Others are related to the stem cell transplant.

Initial side effects can include:

  • Mouth and throat pain
  • Nausea and vomiting
  • Bacterial, viral or fungal infections
  • Bleeding and anaemia (low red blood cell count)
  • Lung problems such as pneumonitis, an inflammation of lung tissue
  • Veno-occlusive disease (VOD), when small blood vessels that lead to the liver become blocked

Longer-term side effects can include:

  • Eye problems such as cataracts
  • Organ damage
  • Return of the cancer
  • Secondary cancers
  • Lymph tissue problems
  • Infertility
  • Thyroid problems caused by hormone changes

After your stem cell transplant, your doctor will monitor you closely. They will take measures to prevent side effects and to quickly deal with any that develop.

This page has been reviewed by our medical content reviewers.

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