Editing Alexis Carrel (section)

=== Tissue culture and cellular senescence ===
Carrel developed methods to keep animal tissues alive in [[Tissue culture|culture]]. He was interested in the phenomenon of [[senescence]] or aging. He believed that all cells continued to grow indefinitely, which became a widely accepted view in the early 20th century.<ref name="Fossel2004">{{cite book | url = https://books.google.com/books?id=UYeUk9m9yeQC&pg=PA24 | title = Cells, Aging, and Human Disease | first = Michael B. | last = Fossel | publisher = Oxford University Press | isbn = 978-0-19-514035-4 | pages = 504 | date = 2004-06-02 }} page 24.</ref> In 1912, Carrel began an experiment at the [[Rockefeller Institute for Medical Research]], where he cultured tissue from an embryonic chicken heart in a stoppered [[Pyrex]] flask of his own design.<ref name="JEM-CARREL">{{cite journal|title=On the Permanent Life of Tissues Outside of the Organism|journal=Journal of Experimental Medicine|date=1912-05-01|first=Alexis|last=Carrel|volume=15|issue=5|pages=516–528 |doi=10.1084/jem.15.5.516|pmid=19867545|pmc=2124948 }}</ref> He supplied the culture with nutrients regularly and maintained it for over 20 years, longer than a chicken's normal lifespan. This experiment received significant popular and scientific attention,<ref>{{cite news|url=https://www.theguardian.com/science/2015/feb/18/haruko-obokata-stap-cells-controversy-scientists-lie|title=What pushes scientists to lie? The disturbing but familiar story of Haruko Obokata|last=Rasko|first=John|author2=Carl Power|date=18 February 2015|newspaper=[[The Guardian]]|access-date=19 February 2015|archive-date=18 February 2015|archive-url=https://web.archive.org/web/20150218215536/http://www.theguardian.com/science/2015/feb/18/haruko-obokata-stap-cells-controversy-scientists-lie|url-status=live}}</ref> but it was never successfully replicated.

In the 1960s, [[Leonard Hayflick]] and Paul Moorhead proposed the concept of the [[Hayflick limit]], which states that [[Cellular differentiation|differentiated cells]] undergo only a limited number of divisions before dying.<ref name="Fossel2004" /> Hayflick suggested that Carrel's daily feeding of nutrients continually introduced new living cells to the culture, resulting in anomalous results.<ref>{{cite journal | title = Mortality and Immortality at the Cellular Level. A Review | first = L. | last = Hayflick | journal = Biochemistry (Moscow) |date=November 1997 | volume = 62 | issue = 11 | pages = 1180–1190 | pmid = 9467840 }}</ref> J. A. Witkowski argued that the deliberate introduction of new cells into the culture, possibly without Carrel's knowledge,{{efn|1=Witkowski's explanation is actually based on the account of a visiting medical researcher, Ralph Buchbaum, who reports being told by a technician in Carrel's lab "Dr. Carrel would be so upset if we lost the strain, we just add a few embryo cells now and then". After the first six months, Carrel's colleague Albert Ebeling had actually taken charge of the cultures and published several papers about their development, until they were eventually discarded in 1946. Witkowski, in "Dr. Carrel's immortal cells", op. cit., quotes Buchbaum's account. At the end Buchbaum writes that "I told this story, of my visit to Carrel's laboratory, to various people. Dr. Bloom (''Buchbaum's director of research in Chicago'') refused to believe it. Others chuckled gleefully. Dr. Carrel was to blame only in that he did not keep on top of what was really going on in the laboratory (mostly, he wrote the papers). Dr. Parker and Dr. Ebeling probably suspected something, hence the "retirement". In the interest of truth and science, the incident should have been thoroughly investigated. If it had been, some heads might have rolled, sacrificed to devotion to a wrong hypothesis - immortality of cell strains.". Witkowski also reports Dr. Margaret Murray, an early tissue culturist, telling him that "one of Carrel's technicians of that time was passionately anti-fascist and detested Carrel's political and social ideas" and expressing her belief that "this technician would willingly have discredited Carrel scientifically if possible."}} could also explain the results.<ref>{{cite journal | title = Dr. Carrel's immortal cells | first = JA | last = Witkowski | year = 1980 | volume = 24 | issue = 2 | pages = 129–142 | journal = Medical History | pmid = 6990125 | pmc = 1082700 | doi=10.1017/S0025727300040126}}</ref>

Despite the doubts surrounding Carrel's experiment, it remains an important part of scientific history, and his work on tissue culture had a significant impact on the development of modern medicine.