A skin cell is like a ball rolling across terrain dotted with pits. When young, the ball easily hops between shallow pits, but with age one pit becomes deep and the ball gets stuck in it. That pit is the cell's old state, where genes run on an "old" program.
Scientists wanted to understand which genes keep the cell in that pit. They built a computer model in which each gene can be switched on or off, like a light bulb. The model showed that genes with the most conspicuous changes during aging do not help restore youth. But if you switch off an inconspicuous gene called BACH2, the deep pit disappears and the ball rolls toward youth.
Now scientists know which genes to target to try rejuvenating skin cells in the lab. If it works, the same method could be used for other tissues and, possibly, for fighting cancer.
Boolean networks for modeling gene regulation were proposed by Stuart Kauffman back in 1969, long before single-cell sequencing existed. His idea that cell types correspond to network attractors only gained experimental support decades later.
The idea of reprogramming a cell from an old state to a young one by intervening in its regulatory network echoes the plot of the film 'The Cloverfield Paradox', where a particle accelerator accidentally alters the fundamental parameters of reality. Here, though, the switch is not random but computed.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.