Stem-cell therapy: hope and hype.

In the fifth year since human cloning to generate stem cells was legalised in the UK, what progress has been made towards taking stem-cell therapy from laboratory to clinical practice? In 2000, articulating robust UK Government support, then Health Minister Yvette Cooper proclaimed that stem cells from cloned human embryos “could prove the Holy Grail in finding treatments for cancer, Parkinson’s disease, diabetes, osteoporosis, spinal cord injuries, Alzheimer’s disease, leukaemia and multiple sclerosis . . . transform[ing] the lives of hundreds of thousands of people”. But 4 years later, the technical difficulties and biological hazards inherent in cloning human embryos and developing treatments from their stem cells led Richard Gardner, Chairman of the Royal Society Working Group on Stem Cells and Therapeutic Cloning, to doubt whether this would ever be “a procedure that becomes widely available . . . There are concerns about the efficiency and elaborateness of the procedure, and it’s going to be very time-consuming and very expensive”. So, to paraphrase May 25th’s Saving Faces event in London, UK, are stem-cell therapies hype, or hope, or substance? Only two UK groups currently seek to clone human embryos, both with immediate aims not of developing therapies but of improving understanding of embryonic development or specific diseases. Techniques for culturing human embryonic stem cells have advanced—eg, allowing them (like adult stem cells) to be grown—but an increasing appreciation of the hazards of embryonic stem cells has rightly prevented the emergence or immediate prospect of any clinical therapies based on such cells. The natural propensity of embryonic stem cells to form teratomas, their exhibition of chromosomal abnormalities, and abnormalities in cloned mammals all present difficulties. The prospect of having to clone (to obtain embryonic stem-cells) every patient requiring therapy is surely unrealistic (the Korean report of cloning human embryos for stem cells used almost 250 human eggs in generating a single stem-cell line). If cloning is unrealistic and/or too hazardous, the autologous advantage of (cloned) embryonic stem cells vanishes: and immune rejection of embryonic stem cells generated from “foreign” in-vitro fertilisation or abortion presents further problems. These biological problems only add to the ethical objections. The Lancet declared in 2001 that: “the creation of embryos solely for the purpose of producing human stem cells is not only unnecessary but also a step too far”. Semantic questions about embryology and personhood are interesting, if unprovable, but what is unarguable is that the human embryo is alive and is human, and intentionally ending the life of one human being for the potential benefit of others (ie, for research) is not territory to which mainstream clinical researchers have hitherto sought claim—or which ethically conscious objectors could ever concede. So is stem-cell research a damp squib, another overhyped funding gambit? Far from it, for the embryonic stem-cell story forms only one aspect. Excitement about the potential of adult stem cells was tempered by reports in 2002 that in some circumstances such cells can fuse. Fusion might give a false appearance of metadifferentiation, the argument ran, therefore adult stem cells are not really multipotent, and are a nonstarter as an alternative to embryonic stem cells. Fortunately, for the now highly expectant patient, reports of the death of adult stem cells were greatly exaggerated. Much research (some indeed antedating the fusion excitement) clearly shows that although fusion can and does occur in certain tissues, adult (say) Published online May 20, 2005 DOI:10.1016/S0140-6736(05) 66554-3