Via ScienceDaily: researchers "have made early retina structures containing proliferating neuroretinal progenitor cells using induced pluripotent stem (iPS) cells derived from human blood. And in another advance, the retina structures showed the capacity to form layers of cells - as the retina does in normal human development - and these cells possessed the machinery that could allow them to communicate information. ... Put together, these findings suggest that it is possible to assemble human retinal cells into more complex retinal tissues, all starting from a routine patient blood sample. Many applications of laboratory-built human retinal tissues can be envisioned, including using them to test drugs and study degenerative diseases of the retina such as retinitis pigmentosa, a prominent cause of blindness in children and young adults. One day, it may also be possible replace multiple layers of the retina in order to help patients with more widespread retinal damage. ... We don't know how far this technology will take us, but the fact that we are able to grow a rudimentary retina structure from a patient's blood cells is encouraging, not only because it confirms our earlier work using human skin cells, but also because blood as a starting source is convenient to obtain."