A research team at Cornell University in New York has created what is believed to be the first genetically engineered human embryo. A gene that acts as a 'tracer' was inserted into the embryo, to determine whether its activity could be followed over time. The researchers from the Center for Reproductive Medicine and Infertility at Cornell Medical Center were successful in tracing the gene, and said that the purpose of their work was to study how diseases such as cystic fibrosis, hemophilia and cancer develop. The procedure has been technically feasible for many years, however this is believed to be the first instance where a foreign gene has been introduced into a human embryo. The embryo was destroyed after five days.
The research was originally presented in the autumn of 2007 at the annual meeting of the American Society of Reproductive Medicine. The UK Human Fertilisation and Embryology Authority (HFEA) included the study in a review of stem cell technology, and warned that such research would raise 'large ethical and public interest issues'. The study did not receive widespread media attention until recently, when it was reported in the Sunday Times newspaper last week.
The research did not violate any federal restrictions on human embryo research, and was approved by a review board at Cornell University. The National Institutes of Health (NIH) did not regard the research as gene therapy because the embryo is not considered a person under federal regulations. The embryo used in the study was non-viable because it contained extra chromosomes, and it could never have become an infant.
The inserted gene was one that makes green fluorescent protein (GFP), which is a common tool in life sciences research. It is typically used to understand the underlying biology of diseases by following the developmental trajectory or fate of cells labelled with the GFP gene in disease models. Cells that have successfully incorporated the gene into their DNA appear fluorescent green. The scientists used a modified virus, commonly used in gene therapy treatments, to deliver the GFP gene to the embryo.
Gene therapy involves introducing foreign genes into humans to treat diseases in a particular organ or tissue. Genetic alterations from such 'somatic gene therapy' are not passed onto future generations because they are not present in the gametes - the sperm or egg. In this study, because all the cells of the embryo were fluorescent, the gametes that would develop from the embryo would also be fluorescent, and in theory would be passed on in the germ line. The researchers stressed that the embryo was destroyed after five days and was non-viable.
However, critics have argued that this research represents the first step towards 'designer babies', demonstrating that the technology exists to genetically manipulate human embryos and insert genes with desired traits such as intelligence or fitness, or to correct genes which cause disease. Dr Zev Rosenwaks, who conducted the research, stated 'none of us wants to make designer babies', and said that the purpose of the work was stem cell research. Marcy Darnovsky, associate director at the Center for Genetics and Society, cautioned that the researchers crossed an 'important ethical boundary' without any public consultation or discussion, a concern that was also raised by the HFEA. Under the new UK Human Fertilisation and Embryology Bill, such genetic modification of embryos for stem cell research would be legalised, but implantation into the womb would remain banned.