To rule out any risk of viral vectors integrating into the host genome and causing tumors, Okita et al. (p. 949, published online 9 October) used a plasmid transfection procedure to introduce transcription factor genes into mouse embryonic fibroblasts to make pluripotent cells. These cells show many features of embryonic stem cells, including the expression of pluripotency markers, as well as the capacity to develop teratomas and chimeras when transplanted into mice. Importantly, there was no evidence of plasmid integration and, although less efficient than other methods, this method looks like it will offer a safer way of inducing pluripotent stem cells.
Basically this is a safer way to go about delivering the transcription genes necessary to trigger a pluripotent state in embryonic muscle cells. It is safer because it does not use viral vectors that affect the target DNA by retro-fitting.
The resulting cells express protein markers that are signatures of pluri-potent cells.
I had to go and read up on Teratoma and Chimera. The first one is a cancerous growth that can be grotesque, like an eyeball, hair, teeth. Not good. Basically this means that the cells are not controllable by the environment and grow whatever. The second one says that many cells successfully implanted from other instances. Same specie, different instances (transplant). Are they saying that by allowing for the reprogramming of a cell it allows for more acceptance rate when you transplant?