Sinclair met
Massachusetts Institute of Technology professor
Leonard P. Guarente in 1993. Guarente had studied yeast as a model of aging, and after meeting him, Sinclair interviewed for a post-doc position in Guarente's lab. Sirtris was focused on developing Sinclair's research into
activators of sirtuins, work that began in the Guarente lab. The company went public in 2007 and was subsequently purchased by and made a subsidiary of
GlaxoSmithKline in 2008 for $720 million. Five years later, GSK shuttered the Sirtris program without successful drug development. In 2006, Sinclair co-founded of Genocea Biosciences, a company founded based on the work of Harvard scientist Darren E. Higgins around
antigens that stimulate
T cells and the use of these antigens to create
vaccines; The company delisted from the
NASDAQ and closed in 2022 due to lack of funding. In 2008, Sinclair was promoted to
tenured professor at Harvard Medical School. In 2008, he also joined the scientific advisory board of
Shaklee and helped them devise and introduce a product containing resveratrol called "Vivix". He later disputed the use of his name and words to promote the supplement, and resigned from the board. In 2011, Sinclair co-founded
OvaScience along with
Michelle Dipp, Aldrich, Westphal, and Jonathan Tilly. The company was based on scientific work done by Tilly concerning
mammalian oogonial stem cells and work on
mitochondria by Sinclair. The company merged with Millendo Therapeutics in 2018. In 2011, he also co-founded CohBar along with
Nir Barzilai and other colleagues. CohBar aimed to discover and develop novel
peptides derived from mitochondria. CohBar delisted from the
NASDAQ upon belief that it was a
public shell. In 2015, he co-founded Metro Biotech along with
Washington University in St. Louis professor Dr. Rajendra Apte. The pharmaceutical company focused on NAD+ precursors such as
NMN. He also co-founded Animal Bioscience in 2017 along with his brother Nick. The company focuses on small molecule-based therapy for the pet industry. In the same year he founded
Life Biosciences to develop gene therapies aimed at age-related disease. In 2022, Metro Biotech successfully urged the
FDA to take actions to take NMN off the market as a supplement because Metro Biotech had registered NMN in investigational new drug applications. The following year, he co-founded Tally Health, a supplement company with a stated goal to "change the way we age" at the cellular level. in Geneva In 2024, Sinclair resigned as the President of The Academy for Health and Lifespan Research, an organization made up of a group of scientists that Sinclair had co-founded. The resignation came after what
The Wall Street Journal described as a "cascade" of resignations from outraged members of The Academy after Sinclair and his brother announced that Animal Bioscience had proven that a supplement for dogs with undisclosed ingredients
reversed aging. The claim was also met with criticism and skepticism from other longevity researchers. ==Research==