This article is more than 5 years old. Information may no longer be current.
Subretinal surgery and RPE cell transplantation holds promise for AMD
Finding the best source for cells and preventing rejection are challenges for the future.
Click Here to Manage Email Alerts
BALTIMORE — Subfoveal surgery with retinal pigment epithelial cell transplant is a potential future treatment option for patients with choroidal neovascularization, according to a presentation given here.
“Since 90% of age-related macular degeneration patients have choroidal neovascular membrane (CNVM) at the subfoveal level, a potential future surgical option is CNVM excision combined with a retinal pigment epithelial (RPE) cell transplant,” said Lucian V. Del Priore, MD, PhD, in a presentation here at a seminar at the Glaser Murphy Retina Treatment Center.
Dr. Del Priore shared results of his RPE cell transplantation work over the past 5 years here at the seminar.
Surgical procedure
RPE transplant surgery begins with a pars plana vitrectomy on the recipient eye. RPE cells can be derived from one of a number of potential sources: stem cells, human adult donor eyes from an eye bank or the iris pigment epithelium.
The RPE cells are inserted into the subretinal space before the choriocapillaris undergoes atrophy. If the RPE cells migrate and proliferate, a successful RPE transplant has occurred.
Early work
Gholam Peyman, MD, of Tulane University Eye Clinic in New Orleans, published clinical results of his work with RPE transplantation in 1991. His article described preparing a large flap of temporal retina and removing the disciform scar. The RPE was taken from either the same patient (autologous) or from another enucleated eye (homologous).
Of his original five patients, Dr. Peyman is still following two.
“Within 3 to 6 months following the surgery, the homologous transplant gradually was rejected and replaced with a fluffy scar and no neovascularization,” Dr. Peyman said. The transplanted cells were completely lost.
“The important issue is to maintain proper orientation of the cells, which are transplanted like a sheet when taken from an adjacent area. The cells need to be very carefully separated to avoid clumping and becoming loose,” he explained.
Subsequent research has revealed some of the problems with the early work.
“Now we are finding that the situation is more complex than we originally thought. The choriocapillaris and sensory retina are two structures affected in addition to the RPE layer,” he said.
He drew an analogy to a car that needs all four wheels to be fully operational. He spoke of the “need to prevent the degeneration of the choriocapillaris or to restore it so that the three tissues can maintain their integrity.”
Dr. Del Priore noted that in Dr. Peyman’s 1991 publication of early RPE cell transplantation surgery, one patient with an autologous pedicle graft showed visual acuity improvement from finger counting to 20/400 at 14 months postoperatively. In another patient, however, after 10 months the homologous RPE and Bruch’s membrane became encapsulated, and visual acuity remained at finger counting at 2 feet.
Future directions
Dr. Del Priore presented three major challenges for achieving successful RPE cell transplantation in the future. First, the initial attachment and proliferation of the cells seeded onto Bruch’s membrane must be successful. Second, the ideal source for cells for transplantation must be identified. Dr. Del Priore said possible sources include human adult RPE, fetal RPE, stem cells, iris pigment epithelium or xenotransplantation from fetal porcine RPE. The third challenge is to prevent rejection.
Bert M. Glaser, MD, head of the Glaser Murphy Retina Treatment Center where the seminar was held, suggested that a viable cell source for RPE cell transplantation might be stem cells from another part of the damaged eye that could differentiate into RPE cells. Another possibility is xenotransplantation from pigs.
“The likelihood of using iris pigmented epithelial cells is low because they grow so slowly and are hard to stimulate, while harvesting cells from a donor eye is the least practical,” Dr. Glaser said.
For Your Information:Reference:
- Lucian V. Del Priore, MD, PhD, can be reached at Columbia University, Edward S. Harkness Eye Institute, 635 W. 165th St., New York, NY 10032; (212) 305-9535; fax: (973) 450-3044.
- Bert M. Glaser, MD, can be reached at 5530 Wisconsin Ave., Suite 835, Bethesda, MD 20815; (301) 986-8747; fax: (301) 986-8944.
- Gholam Peyman, MD, can be reached at Tulane University, 1430 Tulane Ave., SL-69, Room 5157, New Orleans, LA 70112; (504) 584-2460; fax: (504) 988-1390; e-mail: gpeyman@tulane.edu.
- Peyman GA, Blinder KJ, et al. A technique for retinal pigment epithelium transplantation for age-related macular degeneration secondary to extensive subfoveal scarring. Ophthalmic Surg. 1991;22:102-108.