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Stem Cells Grown From Patient's Arm Used To Replace Retina
BarbaraHudson writes: The Globe and Mail is reporting the success of a procedure to implant a replacement retina grown from cells from the patient's skin. Quoting: "Transplant doctors are stepping gingerly into a new world, one month after a Japanese woman received the first-ever tissue transplant using stem cells that came from her own skin, not an embryo. On Sept. 12, doctors in a Kobe hospital replaced the retina of a 70-year-old woman suffering from macular degeneration, the leading cause of blindness in the developed world. The otherwise routine surgery was radical because scientists had grown the replacement retina in a petri dish, using skin scraped from the patient's arm.
The Japanese woman is fine and her retinal implant remains in place. Researchers around the world are now hoping to test other stem-cell-derived tissues in therapy. Dr. Jeanne Loring from the Scripps Research Institute in La Jolla, Calif., expects to get approval within a few years to see whether neurons derived from stem cells can be used to treat Parkinson's disease."
The Japanese woman is fine and her retinal implant remains in place. Researchers around the world are now hoping to test other stem-cell-derived tissues in therapy. Dr. Jeanne Loring from the Scripps Research Institute in La Jolla, Calif., expects to get approval within a few years to see whether neurons derived from stem cells can be used to treat Parkinson's disease."
As outlined here, it is the retinal pigmented epithelial (RPE) cells and/or photo-receptors that are being grown and transplanted here. The RPE cells are the supply source for the photo-receptors and comprise the far rear layer of the retina (the neurons of the retina are supplied by blood vessels at the front which you're looking through right now). The photo-receptors, while technically sensory neurons, don't project very far, so replacing them could conceivably restore sensitivity without disrupting the neural connections of the retina. Growing them with the proper alignment to the optics of the eye might be a challenge, though.
Replacing the whole retina is not yet feasible. The ganglion cells project through the optic nerve all the way to the middle of the brain - you can't just swap these out. The other neurons (amacrine, bipolar, horizontal, etc.) of the retina form very specific types of connections during development, and simply replacing these with new cells won't restore such connections. The RPE cells and photo-receptors are about the only thing that might be replaced to restore some lost sensitivity, and are also the easiest to reach surgically, being near the back.
http://www.nature.com/news/jap...
"Age-related macular degeneration results from the breakdown of retinal epithelium, a layer of cells that support photoreceptors needed for vision. The procedure Kurimoto performed is unlikely to restore his patient's vision. However, researchers around the world will be watching closely to see whether the cells are able to check the further destruction of the retina while avoiding potential side effects, such as bringing about an immune reaction or inducing cancerous growth."
And this:
http://www.riken-ibri.jp/AMD/e...
"This is a very early-stage form of clinical research, and is intended to assess the safety of this intervention; it is not expected to yield significant improvements in visual acuity or other symptoms in the patients who participate in the study."
Generally the first stage testing a new clinical technique is to make sure that it does not cause harm. That's what they're doing with this test.