Stem cell therapy for macular degeneration

Stem cell therapy for macular degeneration is the use of stem cells to heal, replace dead or damaged cells of the macula in the retina. Stem cell based therapies using bone marrow stem cells as well as retinal pigment epithelial transplantation are being studied. A number of trials have occurred in humans with encouraging results.

Historical background
In 1959, the first fetal retinal transplant into the anterior chamber of the eyes of animals was reported. Cell culture experiments on RPE were carried out in 1980. Cultured human RPE cells were transplanted into the eyes of animals, first with open techniques and methods and later with closed cavity vitrectomy techniques.

In 1991, Gholam Peyman transplanted RPE (Retinal Pigment Epithelium) in humans but with limited success rate. Later, allogenic fetal RPE cell transplantation was tried in which immune rejection of the graft was a major problem. It has also been observed that the rejection rates were lower in dry AMD than that in wet AMD. Autologous RPE transplantation is conventionally done employing two techniques, namely, RPE suspension and autologous full-thickness RPE-choroid transplantation. Encouraging clinical outcomes has already been reported with the transplantation of the autologous RPE choroid from the periphery of the eye to a disease affected portion.

Since 2003, researchers have successfully transplanted corneal stem cells into damaged eyes to restore vision. "Sheets of retinal cells used by the team are harvested from aborted fetuses, which some people find objectionable." When these sheets are transplanted over the damaged cornea, the stem cells stimulate renewed repair, eventually restore vision. The such development was in June 2005, when researchers at the Queen Victoria Hospital of Sussex, England were able to restore the sight of forty people using the same technique. The group, led by Sheraz Daya, was able to successfully use adult stem cells obtained from the patient, a relative, or even a cadaver.

In September 2014, the team of surgeons from Riken Institute's Center for Developmental Biology in Kobe, (Japan), led by Masayo Takahashi succeeded in a world-first transplanting of cells made from induced pluripotent stem cells into a human body. The operation was conducted as a clinical study and involved creating a retinal sheet from iPS cells, which were developed by Shinya Yamanaka. iPS cells are created by removing mature cells from an individual and reprogramming these cells back to an embryonic state. The retinal sheet was transplanted into a female patient in her 70s with age related macular degeneration (AMD), an eye complication that blurs the central field of vision and can progress into blindness. The iPS cells were hoped to stop the progression of AMD. The team used iPS cells made from the patient's own skin cells. Then in March 2017 team carried out the world's first successful transplant of retinal cells created from donor iPS cells into the eye of a patient with advanced wet age-related macular degeneration. Time and cost used in the surgery has been significantly reduced by using super donor cells, cells derived from people with special white blood cell types that aren't rejected by the immune systems of receiving patients. During the surgery the patient received a transplant of approximately 250,000 retinal pigment epithelial cells into the eye generated from donor-derived iPSCs. Results of this landmark study were published in the New England Journal of Medicine.