TLDR Applying certain inhibitors to the skin can promote hair growth without harming cells.
The study by Miranda, Christofk, Jones, and Lowry demonstrated that topical application of electron transport chain (ETC) inhibitors (Phenformin, Rotenone, and Antimycin A) on mice can stimulate hair cycle activation, as evidenced by visible pigmentation and hair growth, without causing significant cell toxicity. Histological analysis confirmed a normal transition from the resting phase (telogen) to the growth phase (anagen) in hair follicles, and increased lactate production was observed, which is known to promote hair cycle activation. The treatment was also effective in aged mice, suggesting its potential for treating hair loss. The study involved 13 vehicle-treated and 9 Phenformin-treated male mice, and statistical significance was determined using a student's t-test with P < 0.05.
202 citations,
August 2017 in “Nature cell biology” Lactate production is important for activating hair growth stem cells.
56 citations,
March 2015 in “Journal of Investigative Dermatology” Healthy mitochondria in skin cells are essential for proper hair growth and skin cell interaction in mice.
277 citations,
February 2013 in “Science Signaling” Mitochondrial reactive oxygen species are essential for skin and hair development.
21 citations,
May 2022 in “Frontiers in Cell and Developmental Biology” Hair growth and health are influenced by factors like age, environment, and nutrition, and are controlled by various molecular pathways. Red light can promote hair growth, and understanding these processes can help treat hair-related diseases.
3 citations,
June 2017 in “International Journal of Radiation Biology” Gamma rays did not change hair follicle density but increased white and hypopigmented hairs in mice.
25 citations,
April 2015 in “Journal of Investigative Dermatology” GasderminA3 is important for normal hair cycle transitions by controlling Wnt signaling.
10 citations,
February 2013 in “PLoS ONE” 
12 citations,
December 2009 in “Amino Acids” Putting α-methylspermidine on mouse skin can start hair growth.
161 citations,
June 1994 in “The journal of investigative dermatology/Journal of investigative dermatology” Hair stops producing melanin as it transitions from the growth phase to the resting phase.
