(From EurekAlert). Researchers are consistently finding that tissues thought not to regenerate do, in fact, have some capacity for regrowth. Modern biotechnology can then be turned to make "some" into "a lot": "scientists conducting experiments with mice have found evidence that the body naturally replenishes small amounts of cells in the eye essential for healthy vision. The finding may shatter the belief that a cell layer vital for eyesight called the retinal pigment epithelium, or RPE, is a nonrenewable resource ... What this tells us is for problems such as age-related macular degeneration, we should be able to harvest stem cells to help repair the damage ... In people, retinal pigment epithelium can become damaged with age. ... The problem is without these cells, the rods and cones - our primary cells for vision - die. If we can regenerate the retinal pigment epithelium, it could make a big difference in our visual health."