Human cloning: ethical considerations
The debate surrounding therapeutic cloning has intensified since the granting of the first UK license for its study in August this year. Jez Fabes and Francesca Mazzola outline some of the main ethical questions
The 5 day old human embryo (blastocyst) is about 100 cells—roughly 30 inner cell mass (ICM) cells embedded in an outer layer. Removing these and culturing them leads to the production of pluripotent embryonic stem cells (ESCs) that can form any adult cell type. Current research involves removing ICM cells from blastocysts grown from the leftover fertilised eggs of in vitro fertilisation (IVF) treatment and their subsequent in vitro culture, with the donors' permission. Studying the development of ESCs into various adult tissues sheds light on early human development and may lead to novel therapeutic techniques.w1 Using ESCs from IVF, embryos diagnosed with a disease before implantation, such as Down's syndrome, permits the study of the progression of these diseases in culture and assessment of potential therapeutics.
Most countries permit generating ESCs for research, except the United States, which bans governmental grants for this research, other than for 72 established