Stem cells are used in medicine to treat a range of diseases. Describe what stem cells are and evaluate the use of stem cell therapy as a medical treatment.

Stem cells are unspecialised cells that retain the ability to differentiate into many different types of cell.

Stem cell therapy has several benefits:
1. Because the cells are derived from the patient or are not matched to a donor, they are not rejected by the immune system.
2. They can be used to treat a wide range of diseases and to repair damaged tissues.

However, there are also risks and ethical concerns:
3. The therapy is new, so long‑term risks are unknown and there is no guarantee that it will work.
4. Possible side effects include rashes, infections or bleeding.
5. Embryonic stem cells must be harvested from embryos, which are destroyed in the process, raising ethical issues.