What are the risks to patients of stem cell transplants?

Clinical Settings 1

Stem cell transplantation is a complex process. However, the transplant procedure itself is straightforward, similar in fact to a blood transfusion.

The donor stem cells are transfused through a central line (a catheter) which goes into a major vein in the chest.

The donor stem cells travel through the circulatory system and the stem cells can then start homing to the bone marrow and start dividing and replenishing the immune and blood system.

Chemotherapy and Infection

Once a stem cell transplant has taken place it can take several weeks or months for the donor cells to engraft. Engraftment means the stem cells have started to proliferate (reproduce themselves) within the recipient host.

Before stem cells can be transplanted a patient must undergo high dose chemotherapy. Following transfusion, the patient must be isolated for several weeks or months to avoid infection and to give the donated stem cells a chance to grow and proliferate.

While a patient is waiting for a stem cell transplant to engraft their immune system is severely compromised, because chemotherapy has essentially destroyed it. Therefore, infections before the donated stem cells successfully engraft can be serious and sometimes fatal - this is why patients are kept in isolation for several months, while their body and the donor stem cells grow a corrected, fully functional immune system.

Chemotherapy has significant side effects on the digestive system and sometimes on the body as a whole. Adults cannot withstand the levels of toxicity in chemotherapy that children invariably can and in elderly patients the risk is greater still.

Transplant Failure and GvHD

Failure to engraft, otherwise known as transplant rejection, is another risk. This means the donor recipient's body has decided the donor stem cells are a threat, rejecting them.

In some cases, transplanted cells and the recipient’s cells can clash in the opposite way, causing what is called “graft versus host disease” (GvHD). This is where the donor cells attack the person who has received the transplant.

GvHD can happen within days of transplants – and up to two years later.

GvHD can be a mild condition with symptoms including:

  • itchy rash
  • diarrhoea
  • nausea
  • dry skin
  • joint pain
  • jaundice
  • irritated eyes

But in its most serious form GVHD can be fatal.

Chronic Graft-versus-Host disease symptoms may include:

  • all or some of the symptoms for the lesser form (above)
  • shortness of breath
  • a fever
  • difficulty or pain when swallowing
  • increased need to urinate
  • burning or bleeding during urination
  • weakness and fatigue

When a perfectly matched donor can be found, the risk of developing GvHD is reduced. However, not every patient can find a perfect match.

The risk of GvHD increases if a recipient receives stem cells or bone marrow from a mismatched related donor or an unrelated matched donor.

Weighing Up the Risk

While there have been remarkable success stories for patients who have undergone stem cell transplants, each case must be weighed up carefully. There are a number of other specific risks relating to different diseases and the age and medical history of patients who might undergo a stem cell transplant.

The patient and their medical team must examine the potential risks and take a decision together as to whether the potential pay-off in terms of quality of life and life expectancy will be worth undertaking a stem cell transplant.

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