It does this by providing different instructions to different cells for which genes to turn on, and which to keep silent.The rebooting came in the form of a gene therapy involving three genes that instruct cells to reprogram themselves—in the case of the mice, the instructions guided the cells to restart the epigenetic changes that defined their identity as, for example, kidney and skin cells, two cell types that are prone to the effects of aging.We haven’t found a cell type yet that we can’t age forward and backward.” Rejuvenating cells in mice is one thing, but will the process work in humans?The researchers are attaching a biological switch that would allow them to turn the clock on and off by tying the activation of the reprogramming genes to an antibiotic, doxycycline.It’s a new way to think about medicine.” That could mean that a host of diseases—including chronic conditions such as heart disease and even neurodegenerative disorders like Alzheimer’s—could be treated in large part by reversing the aging process that leads to them."