"First Evidence" of Long-Term Safety and Tolerability of Human Embryonic Stem Cell Treatment

By Amy Orciari Herman

Edited by David G. Fairchild, MD, MPH, and Lorenzo Di Francesco, MD, FACP, FHM

Two studies reported in the Lancet offer the "first evidence of the medium-term to long-term" safety and tolerability of using human embryonic stem cells to treat human disease, according to the researchers.

In the two phase 1/2 studies, nine U.S. adults with Stargardt macular dystrophy and nine with age-related macular degeneration underwent transplantation with retinal pigment epithelium derived from human embryonic stem cells. During a median 22 months' follow-up, the transplanted tissue was well tolerated, with no evidence of hyperproliferation or rejection. Over half of patients had improvements in visual acuity. In addition, vision-related quality of life improved for both overall and peripheral vision, and for near and distant activities.

A Lancet commentator calls the work a "major accomplishment," noting that while "much work remains to be done" before such therapies can be used outside of trials, "the path is now set in motion."