The field of partial reprogramming is transitioning from successful mouse studies to its first human clinical trials.
At the heart of this experiment is the discovery of Yamanaka factors, proteins that specialize in converting adult cells back into embryonic-like stem cells.
Discovery of Yamanaka factors
In 2006, stem-cell biologist Shinya Yamanaka and colleagues, in a major breakthrough, discovered four transcription factors with the ability to reset the adult cell to a pluripotent state.
This discovery proved important as it could pave the way for stem-cell based treatments.
In 2010, biologist Prime Singh and his colleague Fred Zaccotto proposed a paradigm shift in thinking about anti-aging processes. According to the scientists, instead of creating induced pluripotent stem cells, activation of Yamanaka factors could theoretically restore youthfulness while maintaining cellular identity.
Later, in 2016, Juan Carlos Izpisua Belmonte and his team demonstrated the effectiveness of Yamanaka factors in mice. Cyclic expression of these factors extended lifespan as mice with progeria lived longer.
In naturally aged mice, the treatment promoted regeneration of damaged muscle and pancreatic tissue. Later studies also indicated improved memory performance in elderly rats.
Partial cellular reprogramming trials in humans
Life Biosciences, a Boston-based biotech firm co-founded by Harvard’s David Sinclair, is set to lead the first human trials for partial cellular reprogramming in 2026.
The trial strategy will focus on the eye, targeting retinal nerve damage caused by NAION and glaucoma. The mechanism will revolve around delivering three of the four “Yamanaka factors” into the eye via a viral vector without c-Myc.
To ensure safety, the genes are controlled by a genetic switch that is activated only when the patient takes a specific antibiotic.
The initial phase will involve approximately 18 participants (12 with glaucoma, 6 with NAION), with a five-year follow-up period to monitor long-term side effects such as cancer.
“If it works, it would be a blast. It would be a huge step forward,” said Vittorio Sebastiano, a stem-cell and reproductive biologist at the University of California, Irvine.
potential risk
The tests also pose some serious risks. For example, if scientists push cells too far toward a stem-like state, it could trigger uncontrolled cell division, which could lead to cancer.
During experimentation, the cell’s identity may also be lost as there is a delicate balance between making the cell younger and losing its specific purpose in the body.
Some experts warn that some trained reprogrammed cells may also act in unpredictable and dangerous ways.
