Which factors potentiate mice blastocyst to expand into full organism (except extra embryonic tissues) whereas not human cells, upon injection of embryonic stem cells?
There is no reason to believe that human cells cannot do the same. These types of experiments are not done in humans due to ethical constraints. No one will transplant a human chimeric blastocyst into an adult pseudopregnant human female, at least not in any country with regulations.
I have not done embryonic microinjection for quite a while now, but when I did, the only way to get a 100% ES cell derived mouse directly from microinjection was to do so into a tetraploid blastocyst.
As already mentioned, this murine work is done for research only. Doing so on human embryos is considered unethical.
Aside from ethical considerations, another issue is that murine ES cells that can produce chimeras or even entire body are the type that are in the naive state, while human ES cells tend to be in the primed state. For that reason, they would need to be converted to naive prior to being used for what remains to be considered an unethical experiment.
This type of experiments can not be done under any circumstances due to ethical issues.