Is this finally some good news for ESCs? Last week we hear that scientists have "successfully used mouse embryonic stem cells to replace diseased retinal cells and restore sight in a mouse model of retinitis pigmentosa." Then reality strikes:
However, complications of benign tumors and retinal detachments were seen in some of the mice, so Dr. Tsang and colleagues will optimize techniques to decrease the incidence of these complications in human embryonic stem cells before testing in human patients can begin.
Yeah, right… Optimise those techniques, decrease those teratomas… Touching optimism by Dr Tsang, the triumph of hope over experience.
Reality check: the very nature of ESCs is to proliferate into tumours, and here we see ESCs acting according to their nature.
The same thwarted hope is there in abstract in the journal Transplantation - excited by the improved electrical response in some mice retinas, but then running aground on the tumours (and retinal detachment):
Although more than half of the mice were complicated with retinal detachments or tumor development, one fourth of the mice showed increased electroretinogram responses in the transplanted eyes.
The no-brainer is that if you want cells to treat human eyes, use human 'adult stem cell' derivatives – as noted earlier on this Blog, at the University of Nebraska for instance – which will not give you tumours.