"Sima", a 47 months-old female rat, is being treated with E5, a treatment intended to recreate the circulatory environment of a young mammal; the maximum recorded lifespan  for this species is 45.5 months.

MOUNTAIN VIEW, Calif., Feb. 9, 2023 /PRNewswire/ -- An experiment led by Dr. Harold Katcher, one of the discoverers of the  first breast cancer gene, is giving humanity hope of fulfilling the dream of undoing aging. While working at Yuvan Research Inc., he discovered which part of the blood of young animals controls the age of the organism, and tested it in eight Sprague Dawley female rats. "Sima" is the last survivor, but the age she has reached allows us to see a path for human rejuvenation. "Cellular aging is a cell non-autonomous process — it doesn't depend on the cell's history, but on its environment", states Dr. Katcher, Chief Scientific Officer of Yuvan, a startup based in California working on rejuvenation treatments.

This experiment is a follow-up to another  experiment  showing that Yuvan's therapy caused a 54% rejuvenation in male rats according to an epigenetic clock analysis performed by then UCLA professor Dr. Steve Horvath. Afterward, a Belgian non-profit, HEALES, decided to fund two lifespan studies,  one  using Yuvan's treatment, called "E5", and  another one,  led by Dr. Rodolfo Goya, professor at La Plata University (Argentina), using young rat plasma.  Dr. Goya's  experiment  achieved moderate life extension. Yuvan's experiment is still ongoing as Sima is alive at 47 months of age.

Also, Sima and the other treated rats showed a grip strength 2.8 times higher than the controls. According to Dr. Goya, "muscular strength indicates prolonged healthspan." Sima is a  Rattus norvegicus, a species with a maximum recorded lifespan of  45.5 months. Their average lifespan is 24-36 months.  Yuvan's treatment started when the rats were already 24 months old and even so pushed the maximum lifespan of the species with a treated group comprising only 8 rats.  

The E5 production process is patent-pending, and the story of its discovery is captured in Dr. Katcher's book  The Illusion of Knowledge. Yuvan is planning trials in other species before testing it in humans — in human terms, Sima is already 126 years old, considering 122.5 years as the human maximum lifespan. "Sima" means "limit/boundary/frontier" in Sanskrit, and by surpassing the lifespan limit of its species, it reminds us that human history is a history of surpassing limits.

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