Scientists at the California biotechnology company, Stemagen, announced last week that they had successfully cloned the world's first human embryos, created from adult male skin cells. Although British scientists cloned human embryos two years ago, this is the first time that scientists have managed to grow such embryos to the 'blastocyst' stage - 5-day-old embryos consisting of 50 to 200 cells, according to the study published in the journal Stem Cells.
Stemagen CEO, Dr. Samuel Wood, views this achievement as 'a critical milestone in the development of patient-specific embryonic stem cell' (ES cells). Cloned stem cells are the holy grail of regenerative medicine because they could potentially allow the use of a patient's own cells to clone genetically-matched replacement cells, tissues and organs. Yet successful derivation of stem cell lines from cloned embryos remains problematic.
Stemagen's announcement inflamed opponents to embryo research and fanned fears of human 'reproductive' cloning. Fifty countries ban reproductive cloning, including the UK, but American law varies according to state. California was the first state to prohibit human cloning in 1997, whilst permitting therapeutic cloning. Today only fifteen states have cloning laws. The Vatican's bioethics spokesman and chief advisor denounced Stemagen's research as 'among the most morally illicit acts'. Opponents argue that medical research on embryos undermines human dignity and is unnecessary in light of last year's Japanese and US breakthroughs to re-programme adult stem cells to behave like ES cells, avoiding embryo destruction.
Supporters argue that research into therapeutic cloning is justified because it could revolutionise our understanding and treatment of degenerative diseases including diabetes and Alzheimer's and research upon excess fertility embryos to seek medical benefit for mankind does not disrespect human embryos that society accepts will be destroyed anyway as an unavoidable by-product of fertility treatments.
The study involved 25 eggs enucleated within two hours of extraction from three 20 to 24-year-old women who consented to donate their excess fertility eggs without financial remuneration. Five developed into blastocysts. Three were independently confirmed to be clones but only one was found likely to generate ES cells. Two suspected cloned embryos did not amplify enough DNA to test. Dr Wood attributed the high success rate to their unusual access to fresh, young eggs from previous fertile donors.
Many leading stem cell researchers were underwhelmed and felt the research evidenced existing knowledge rather than forged new frontiers. Dr George Daley of Harvard felt that cloned human embryos were a natural progression from the monkey embryos cloned last November. Many researchers expressed disappointment that Stemagen did not go further to create stem cell lines from cloned embryos.