Results from the world’s first human trial using human embryonic stem cell (hESC)-derived retinal pigment epithelium (RPE) cells for the treatment of Stargardt’s macular dystrophy (SMD) and dry age-related macular degeneration (dry AMD) have demonstrated the procedure’s safety.
The results of the study being undertaken by Advanced Cell Technology in the United States were reported for two patients, the first in each of the Phase 1/2 clinical trials. In addition to showing no adverse safety issues, structural evidence confirmed that the hESC-derived cells survived and continued to persist during the study period reported.
The evidence included increasing pigmentation at the level of RPE, within the area of the transplant, beginning one week after transplantation and throughout the follow-up period. Transplanted stem
cell derived RPE appeared to engraft in the proper location and assume normal RPE morphology.
Engraftment and increasing pigmentation were not detected in the dry AMD patient. However, both patients showed some visual improvement at the four-month follow-up period.
It has been over a decade since the discovery of human embryonic stem cells
Measuring visual improvement in patients with very low vision is difficult, and no regulatory consensus exists regarding how best to measure visual changes in these patients.
As reported in The Lancet, the visual acuity of the Stargardt’s patient improved from hand motions only to 20/800 vision. Before treatment, the patient was unable to read any letter on the ETDRS visual acuity chart. However, by two weeks post-transplantation, she was able to start reading letters, which improved to five letters at one to three months in the treated eye.
“It has been over a decade since the discovery of human embryonic stem cells,” said Robert Lanza, M.D., chief scientific officer of ACT, and co-senior author of the paper. “This is the first report of hESC-derived cells transplanted into patients, and the safety and engraftment data to date look very encouraging.
Although several new drugs are available for the treatment of the wet type of AMD, no proven treatments currently exist for either dry AMD or Stargardt’s disease. Despite the progressive nature of these conditions, the vision of both patients appears to have improved after transplantation of the cells, even at the lowest dosage. This is particularly important, since the ultimate goal of this therapy will be to treat patients earlier in the course of the disease where more significant results might potentially be expected.”