Editing Life extension (section)

=== Cloning and body part replacement ===
Some life extensionists suggest that [[therapeutic cloning]] and [[stem cell]] research could one day provide a way to generate cells, body parts, or even entire bodies (generally referred to as [[reproductive cloning]]) that would be genetically identical to a prospective patient. In 2008, the US Department of Defense announced a program to research the possibility of growing human body parts on mice.<ref>{{cite magazine |last1=Saletan |first1=William |title=Rearming America |url=https://slate.com/technology/2008/04/the-military-s-plan-to-regrow-body-parts.html |website=Slate |date=18 April 2008 |publisher=Slate |access-date=8 June 2024 |ref=WS2008}}</ref> Complex biological structures, such as mammalian joints and limbs, have not yet been replicated. Dog and primate brain transplantation experiments were conducted in the mid-20th century but failed due to [[transplant rejection|rejection]] and the inability to restore nerve connections. As of 2006, the implantation of bio-engineered bladders grown from patients' own cells has proven to be a viable treatment for bladder disease.<ref>{{cite magazine | vauthors = Khamsi R |date= April 4, 2006 |title=Bio-engineered bladders successful in patients |url=https://www.newscientist.com/article/dn8939-bioengineered-bladders-successful-in-patients.html |magazine=[[New Scientist]] |access-date=January 26, 2011}}</ref> Proponents of body part replacement and cloning contend that the required biotechnologies are likely to appear earlier than other life-extension technologies.

The use of human [[stem cells]], particularly [[embryonic stem cells]], is controversial. Opponents' objections generally are based on interpretations of religious teachings or ethical considerations.<ref>{{cite journal |last1=Lo |first1=Bernard |last2=Parham |first2=Lindsay |date=1 May 2009 |title=Ethical Issues in Stem Cell Research |journal=Endocrine Reviews |volume=30 |issue=3 |pages=204–213 |doi=10.1210/er.2008-0031 |pmid=19366754 |pmc=2726839 }}</ref> Proponents of stem cell research point out that cells are routinely formed and destroyed in a variety of contexts. Use of stem cells taken from the umbilical cord or parts of the adult body may not provoke controversy.<ref>{{Cite news| vauthors = White C |date=19 August 2005 |title=Umbilical stem cell breakthrough |url=http://www.stemcellnews.com/articles/stem-cells-umbilical-breakthrough.htm |work=[[The Australian]] |access-date=17 July 2009 |url-status=dead |archive-url=https://web.archive.org/web/20090720054316/http://www.stemcellnews.com/articles/stem-cells-umbilical-breakthrough.htm |archive-date=20 July 2009 }}</ref>

The controversies over cloning are similar, except general public opinion in most countries stands in opposition to [[reproductive cloning]]. Some proponents of therapeutic cloning predict the production of whole bodies, lacking consciousness, for eventual brain transplantation.