"First and foremost, it is a disingenuous (to be kind!) and misleading report. If I had been a reviewer, I would have rejected it for two reasons: 1) misrepresentation of the facts as reported; and 2) unacceptable experimental design.
Misrepresentation of the facts:
Although the title is a faithful representation, important statements in the abstract are not supported by the data in the report. To be exact, the combination of bone marrow stromal cells and mouse embryonic stem cells is no more effective for reversing the effects of the induced spinal cord injury than a compared buffered salt solution (PBS = phosphate buffered saline) that contained no cells of any type.
Unacceptable experimental design:
Here there is cause for two objections.
First, a crucial control comparison is omitted without mention. They did not evaluate the effect of the bone marrow stromal cells alone. Whether this was motivated by unethical politics or poor science, I cannot say. However, it is predicted by the studies of previous groups that the addition of bone marrow stromal cells on their own would be more effective than the buffered salt solution; and importantly, they may be more effective than the presented combination of mouse embryonic stem cells and bone marrow stromal cells.
Second, though they do report a dramatic reduction in the number of tumors produced when bone marrow stromal cells are added to mouse embryonic stem cells (versus the mouse embryonic stem cells on their own), they only waited 5 weeks and they only evaluated 15,000 cells per injection. Conventional assays to rule out tumor formation in mice use 1-10 million cells per injection and wait several months for certainty. Thus, the assay upon which their conclusion of tumor prevention rests is well below the established standards for such a determination ...
All in all though, on the more important notes of ethics and morality, even if this approach were scientifically sound, and were proven to work for human embryonic stem cells, and adult stem cells were not an alternative (as they are!), it would still be unacceptable, because it would still require the sacrifice of innocent human beings to make the embryonic stem cells."
James Sherley is a leading stem cell scientist and has travelled the world pointing out the inefficacy of embryonic stem cell research to his scientific colleagues.