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Study shows stem cells can preserve visionPublic release date: 18-Nov-2004Contact: Patti spjacobs12@...617-872-0364Schepens Eye Research InstituteHolds hope for sufferers of macular degenerationBoston, MA – For the first time researchers have shown that transplantedstem cells can preserve and improve vision in eyes damaged by retinaldisease. In the cover article in the November 2004 InvestigativeOphthalmology and Visual Science, scientists from Harvard's Schepens EyeResearch Institute describe results of a mouse study in whichtransplanted stem cells develop into retinal cells, prevent the death of"at risk" retina cells in the recipient mice and improve the vision oftreated mice."These findings hold great promise for potential treatments for peoplesuffering from macular degeneration, diabetic retinopathy and otherretinal diseases," says Young, PhD, an assistant scientist atSchepens Eye Research Institute and the lead author of the study.The retina is a tissue-thin membrane at the back of the eye responsiblefor sending light and images from the outside world through the opticnerve to the brain, which interprets them. The retina contains lightsensitive cells, known as rods, which make it possible for us to see inblack and white and in low light, and cones, which are responsible forcolor and high-acuity vision. In diseases such as macular degeneration,it is these cells that are being destroyed.Believing that stem cells – cells that have the capacity to change intoother kinds of cells – could potentially save vision, Young and his teamdecided to test their theory in mice. They transplanted retinal stemcells from young "green" mice into the eyes of normal-colored mice thathad retinal disease. Green mice are genetically raised so that all theirtissues are fluorescent green. The green color makes it possible todetect where the transplanted cells are and how they are growing andchanging.After several weeks the team evaluated the eyes of the treated mice andfound that the green cells had migrated to where they were needed in thedamaged retina and had changed into what looked like normal retinalcells. The scientists also found that many of the cone cells that wereon the verge of dying before the transplant appeared to regain or retaintheir function. The researchers speculated that the transplanted cellswere secreting a factor or substance that saved these fragile cells.(There is growing evidence that rod cells keep cone cells alive bysecreting a special factor)To test whether the mice with transplanted stem cells could see better,the team then placed them and the control mice (without the transplantsor with non-stem cell transplants) in dark cages and flashed a series ofincreasingly lower level lights at both groups over a period of time.Mice are photophobic and stop their normal activity when they detectlight. The researchers took advantage of this natural response and foundthat the mice with the transplanted tissue continued to respond to thelight as it reached the lowest levels. The control mice did not."These are the first steps toward the use of stem cells for savingexisting vision and then -- down the road-- restoring vision that hasalready been lost," says Young, who believes that stems cells will havemany roles to play in the fight against blinding diseases. Young and histeam are now investigating the same phenomenon in pigs, whose eyes arelarger and more like human eyes.###Members of the research team include: Henry J. Klassen‡, Tat Fong Ng*,Yasuo Kurimoto*, Ivan Kirov‡, Marie Shatos*, Coffey†, and J. Young**Schepens Eye Research Institute, Department of Ophthalmology, HarvardMedical School, Boston, MA 02114†Visual Transplantation Research Group, Department of Psychology,University of Sheffield, Sheffield S10 2TP UK‡CHOC Research, Children's Hospital of Orange County, Orange, CA 92868The full article "Multipotent Retinal Progenitors Express DevelopmentalMarkers, Differentiate into Retinal Neurons, and Preserve Light-MediatedBehavior" can be obtained at http://www.iovs.org/current.shtml bysubscription or by emailingpjacobs12@... .Schepens Eye Research Institute is an affiliate of Harvard MedicalSchool and the largest independent Eye ResearchInstitute in the world.