Ray Peat said:Early in the century, Alexis Carrell showed the importance of environmental factors in the aging process, by keeping
chicken cells alive and functioning for many years beyond the chicken's normal life-span.
From Youth, Energy, and Regeneration, Generative Energy: Restoring the Wholeness of Life
Wikipedia said:Carrel started an experiment on January 17, 1912 where he placed tissue cultured from an embryonic chicken heart in a stoppered Pyrex flask of his own design. He maintained the living culture for over 20 years with regular supplies of nutrient. This was longer than a chicken's normal lifespan. The experiment, which was conducted at the Rockefeller Institute for Medical Research, attracted considerable popular and scientific attention.
Carrel's experiment was never successfully replicated, and in the 1960s Leonard Hayflick and Paul Moorhead proposed that differentiated cells can only undergo a limited number of divisions before dying. This is known as the Hayflick limit, and is now a pillar of biology.