Editing Life extension (section)

==Genetic editing==
{{Main|Genetics of aging|Genome editing}}
[[Genome editing]], in which [[nucleic acid]] polymers are delivered as a [[Biologic medical product|drug]] and are either [[gene expression|expressed]] as proteins, interfere with the expression of proteins, or correct genetic mutations, has been proposed as a future strategy to prevent aging.<ref>{{cite journal | vauthors = Goya RG, Bolognani F, Hereñú CB, Rimoldi OJ | title = Neuroendocrinology of aging: the potential of gene therapy as an interventive strategy | journal = Gerontology | volume = 47 | issue = 3 | pages = 168–173 | date = 2001-01-08 | pmid = 11340324 | doi = 10.1159/000052792 | s2cid = 10069927 }}</ref><ref>{{cite journal | vauthors = Rattan SI, Singh R | title = Progress & prospects: gene therapy in aging | journal = Gene Therapy | volume = 16 | issue = 1 | pages = 3–9 | date = January 2009 | pmid = 19005494 | doi = 10.1038/gt.2008.166 | doi-access =  }}</ref>

===CRISPR/Cas9===
{{Main|CRISPR}}
CRISPR/Cas9 edits genes by precisely cutting DNA and then harnessing natural DNA repair processes to modify the gene in the desired manner. The system has two components: the Cas9 enzyme and a guide RNA.<ref>{{cite web | url=https://crisprtx.com/gene-editing | title=Gene Editing }}</ref>  A large array of genetic modifications have been found to increase lifespan in model organisms such as yeast, nematode worms, fruit flies, and mice. As of 2013, the longest extension of life caused by a single gene manipulation was roughly 50% in mice and 10-fold in [[nematode]] worms.<ref>{{cite journal | vauthors = Tacutu R, Craig T, Budovsky A, Wuttke D, Lehmann G, Taranukha D, Costa J, Fraifeld VE, de Magalhães JP | display-authors = 6 | title = Human Ageing Genomic Resources: integrated databases and tools for the biology and genetics of ageing | journal = Nucleic Acids Research | volume = 41 | issue = Database issue | pages = D1027–D1033 | date = January 2013 | pmid = 23193293 | pmc = 3531213 | doi = 10.1093/nar/gks1155 }}</ref>

[[File:Healthspan, parental lifespan, and longevity are highly genetically correlated.webp|thumb|right|200px|"Healthspan, parental lifespan, and longevity are highly genetically correlated."<ref name="Multivariate"/>]]
In July [[2020 in science|2020]] scientists, using public [[List of biological databases|biological data]] on 1.75 m people with known lifespans overall, identify 10 [[Locus (genetics)|genomic loci]] which appear to intrinsically influence [[healthspan]], lifespan, and longevity – of which half have not been reported previously at [[Genome-wide association study|genome-wide significance]] and most being associated with [[cardiovascular disease]] – and identify [[Human iron metabolism|haem metabolism]] as a promising candidate for further research within the field. Their study suggests that high levels of iron in the blood likely reduce, and genes involved in metabolising iron likely increase healthy years of life in humans.<ref>{{cite news |title=Blood iron levels could be key to slowing ageing, gene study shows |url=https://phys.org/news/2020-07-blood-iron-key-ageing-gene.html |access-date=18 August 2020 |language=en |work=Phys.org |date=July 16, 2020 |author=University of Edinburgh}}</ref><ref name="Multivariate">{{cite journal |vauthors=Timmers PR, Wilson JF, Joshi PK, Deelen J |date=July 2020 |title=Multivariate genomic scan implicates novel loci and haem metabolism in human ageing |journal=Nature Communications |volume=11 |issue=1 |pages=3570 |bibcode=2020NatCo..11.3570T |doi=10.1038/s41467-020-17312-3 |pmc=7366647 |pmid=32678081}} [[File:CC-BY_icon.svg|50x50px|class=noviewer]] Text and images are available under a [[creativecommons:by/4.0/|Creative Commons Attribution 4.0 International License]].</ref> The same month other scientists report that yeast cells of the same genetic material and within the same environment age in two distinct ways, describe a biomolecular mechanism that can determine which process dominates during aging and [[genetically engineer]] a novel aging route with substantially extended lifespan.<ref>{{cite news |title=Researchers discover 2 paths of aging and new insights on promoting healthspan |url=https://phys.org/news/2020-07-paths-aging-insights-healthspan.html |access-date=17 August 2020 |work=Phys.org |language=en |date=July 16, 2020 |author=University of California}}</ref><ref>{{cite journal | vauthors = Li Y, Jiang Y, Paxman J, O'Laughlin R, Klepin S, Zhu Y, Pillus L, Tsimring LS, Hasty J, Hao N | display-authors = 6 | title = A programmable fate decision landscape underlies single-cell aging in yeast | journal = Science | volume = 369 | issue = 6501 | pages = 325–329 | date = July 2020 | pmid = 32675375 | pmc = 7437498 | doi = 10.1126/science.aax9552 | bibcode = 2020Sci...369..325L }}</ref>

===Fooling genes===
In ''[[The Selfish Gene]]'', [[Richard Dawkins]] describes an approach to life-extension that involves "fooling genes" into thinking the body is young.<ref>{{Cite book | vauthors = Dawkins R |author-link=Richard Dawkins |title=The Selfish Gene |publisher=[[Oxford University Press]] |orig-year=1976|year=2006 |location=[[New York City|New York]] |isbn= 978-0-19-929115-1 | pages = 41–42|title-link=The Selfish Gene }}</ref> Dawkins attributes inspiration for this idea to [[Peter Medawar]]. The basic idea is that our bodies are composed of genes that activate throughout our lifetimes, some when we are young and others when we are older. Presumably, these genes are activated by environmental factors, and the changes caused by these genes activating can be lethal. It is a statistical certainty that we possess more lethal genes that activate in later life than in early life. Therefore, to extend life, we should be able to prevent these genes from switching on, and we should be able to do so by "identifying changes in the internal chemical environment of a body that take place during aging... and by simulating the superficial chemical properties of a young body".<ref>{{Cite book | vauthors = Dawkins R |author-link=Richard Dawkins |title=The Selfish Gene |publisher=[[Oxford University Press]] |orig-year=1976|year=2006 |location=[[New York City|New York]] |isbn= 978-0-19-929115-1 | page = 42|title-link=The Selfish Gene }}</ref>

=== 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.