Safety and quality must be assured before this treatment can really benefit patients

The use of human embryonic stem cells has been hailed as the next major step in the battle against serious degenerative disorders, such as diabetes and heart disease, and for some debilitating or lethal neurological diseases, such as Parkinson's and motor neurone disease. News reports and promotional material on websites often convey the impression that this therapy is safe and immediately or imminently available. Whether this is just hype, and how much hope patients should invest in this technology, are issues being discussed at a public debate in London this week.^w1

Although the number of human embryonic stem cell lines has increased considerably in the past two years, few of these have been well characterised, and large hurdles still need to be overcome to ensure safety and efficacy.1 These will require substantial further investment and research. Stem cells have not yet been grown in the conditions that would be expected for any pharmaceutical product destined for use in vivo.2 Even the embryos from which human embryonic stem cells could be derived are still cultured in vitro in …