Eyeworld

I GENE THERAPY N FOCUS 38 | EYEWORLD | SEPTEMBER 2020 "I think we are at the beginning of [stem cell therapy for the eye] because there is so much more that we can do. For example, I think the future is we might take the limbal biopsy, grow the cells, and genetically modify these cells … before we transplant them," Dr. Jurkunas said. In December 2019, NEI launched its first clinical trial for stem cell-derived therapy for advanced dry age-related macular degeneration. The historical basis for this research, Kapil Bharti, PhD, said, is a procedure where a piece of healthy retinal pigment epithelium (RPE) is cut and transplanted to the degenerated area of the macula. This procedure was complicated and often failed, but there were a small number of cases where vision was restored. "For me this was a founding principle, that if we were to make an autologous RPE patch from a macular degeneration patient and from their own stem cell and bring it to the right place, we have a chance at making a therapy," Dr. Bharti said. In animal models, a transplanted patch of RPE cells, derived from stem cells, was eval- uated with OCT, measurement of electrical Stem cells are cultivated from a healthy limbal biopsy, grown on an amniotic membrane scaffold, and transplanted to the limbal stem cell deficient eye. Source: Ula Jurkunas, MD patient's own tissue and thus won't elicit an immune response. Another treatment option is to take two larger biopsies from the other eye, if it's healthy, but this, Dr. Jurkunas said, puts the other eye at risk for stem cell deficiency. "With [cultivated stem cell therapy] we can take a small biopsy, 2 mm as opposed to two 4 mm biopsies; that makes it safer and helps a bigger population. A lot of times people have asymmetry, some stem cell deficiency in their 'good' eye, and they might not have the ability to take those big biopsies," she said. Simple limbal epithelial transplantation (SLET), which also involves taking a small bi- opsy and transplanting small pieces of this stem cell tissue onto the LSCD eye, doesn't always work, Dr. Jurkunas said. "I am a big believer that SLET works in milder cases, but in more severe cases it is a little hard for it to work," she said. Once FDA approved, Dr. Jurkunas envi- sioned that any cornea specialist would have the skills to take the limbal biopsy and transplant the sheet of expanded, cultivated stem cells back onto the cornea. continued from page 37

• Blank Page
• Blank Page (1)