Induced pluripotent stem cells (iPS cells) offer a way round many of the ethical problems of embryonic stem cells. Shinya Yamanaka shared the 2012 Nobel Prize in Physiology or Medicine for discovering how to make them.Ethical advantages
• No embryo is created or destroyed.
• No donated eggs are needed, so there is no risk to egg donors.
• They are made from the patient's own cells, such as skin cells, so they are genetically identical to the patient, including their mitochondrial DNA, and should not be rejected.
• Cells can be collected with simple, consented procedures such as a skin biopsy.Remaining concerns
• Safety: early methods used viral vectors that insert the genes into the host chromosomes, and one gene (c-Myc) is an oncogene, so there is a cancer risk. Newer methods do not insert the genes into the host chromosomes, for example by adding the transcription factor proteins or RNA instead.
• Epigenetic memory: iPS cells may keep some epigenetic marks from their original cell type, which can affect how well they differentiate.
• New ethical questions: because iPS cells are pluripotent, it may be possible to make eggs and sperm from them, and so embryos, reviving some of the same debates.Comparison with embryonic stem cells
Research on embryonic stem cells continues because they are the natural pluripotent cells against which iPS cells are judged. Scientists need them to check that iPS cells behave normally, so the two areas of research support each other.
• No embryo is created or destroyed.
• No donated eggs are needed, so there is no risk to egg donors.
• They are made from the patient's own cells, such as skin cells, so they are genetically identical to the patient, including their mitochondrial DNA, and should not be rejected.
• Cells can be collected with simple, consented procedures such as a skin biopsy.Remaining concerns
• Safety: early methods used viral vectors that insert the genes into the host chromosomes, and one gene (c-Myc) is an oncogene, so there is a cancer risk. Newer methods do not insert the genes into the host chromosomes, for example by adding the transcription factor proteins or RNA instead.
• Epigenetic memory: iPS cells may keep some epigenetic marks from their original cell type, which can affect how well they differentiate.
• New ethical questions: because iPS cells are pluripotent, it may be possible to make eggs and sperm from them, and so embryos, reviving some of the same debates.Comparison with embryonic stem cells
Research on embryonic stem cells continues because they are the natural pluripotent cells against which iPS cells are judged. Scientists need them to check that iPS cells behave normally, so the two areas of research support each other.