Stem cells: The use of stem cells has potential risks such as transfer of viral infection, and some people have ethical or religious objections.

The idea

Stem cells can divide to form many cell types, so they are useful in medicine, but their use is not risk-free. Because stem cells are living cells, any virus present in donor tissue could be passed to the patient, especially if the patient's immune system is suppressed. There are also ethical and religious concerns: some people believe an embryo should not be used or destroyed for research, because they regard it as a potential human life. Others accept adult stem cells, which can be donated with consent, but object to embryonic sources. Scientists therefore weigh possible treatments against these risks and beliefs, and follow consent and safety rules.

What earns the marks

• State that stem cells are unspecialised cells that can divide and differentiate into other cell types.
• Explain that donated stem cells may carry viruses, so infection could be transferred to the patient.
• Describe ethical objections, such as the view that an embryo is a potential human life and should not be destroyed.
• Describe religious objections, such as beliefs that life begins at conception, so embryo research is wrong.
• Recognise that some people accept adult stem cell use but object to embryonic stem cell use.
• Explain that risk and benefit must be balanced when deciding whether to use stem cell treatment.

Common mistakes and how to put them right

• Saying stem cells always cause viral infection.

  Put it right: The risk is that a virus could be transferred, not that infection is certain.

• Treating all objections as scientific evidence.

  Put it right: Ethical and religious objections are moral views, not experimental data.

• Claiming all stem cell research is banned.

  Put it right: It is regulated and allowed in some forms, with consent and ethical review.

Exam tips

• Use the phrase 'potential risk' to show that infection transfer is possible but not guaranteed.
• Separate scientific risks from ethical or religious objections in your answer.
• Link each objection to a reason, such as 'because the embryo is a potential human life'.