ACT’s Got Vision
Gary Rabin presented ongoing work from Advanced Cell Technology relating to the company’s embryonic stem cell product for macular degeneration. According to Rabin, chairman and CEO, standard methods for harvesting embryonic stem cells involve removal of the inner cell mass of a blastocyst, which is destructive to the embryo.
ACT developed a method that takes a single cell from the embryo at the morula stage. A morula has just four to eight cells total. This is the type of procedure used in preimplantation genetic diagnostics and is considered not to be destructive of the embryo.
But ACT’s cells may have scientific advantages in addition to being embryo-friendly.
“We tested our embryonic stem cell lines versus NIH approved lines,” Rabin says. “Our stem cell line was five times more efficient at creating the next germ layers.” The reason for this is that, when cells are extracted at the blastocyst stage, they are already committed to a cellular fat, such as blood cells, bone cells, etc. The earlier-stage morula cells don’t express those cell fate commitment factors, and are more malleable in their ability to create other kinds of cells in the body.
ACT has developed a line of embryonic stem cell-derived retinal pigment epithelial (RPE) cells. The RPE cells reside at the back of the macula. When they decline, there’s a corresponding decline in photoreceptor cells that results in loss of vision.
ACT is testing its RPE cells in three ongoing clinical trials in dry age-related macular degeneration, Stargardt macular dystrophy, and heart disease. It also has a preclinical program in disorders of the circulatory and vascular system, and expects to file an investigational new drug application to begin clinical trials in 2012.
The company published Phase II clinical data in The Lancet describing the use of its RPE cells in two patients with dry AMD. In addition to showing a favorable safety profile, both patients experienced improvements in their vision that lasted for over four months, with no hyperproliferation, tumorigenicity, ectopic tissue formation, or rejection. (Those are all adverse events associated with embryonic stem cells therapy.) The cells appeared to engraft properly and resume normal RPE morphology.