Taking stem cells from humans, still perpetatues the notion that animals are resources, which is the problem that enables all exploitation of animals in the world. Some more moral problems: 
long as animals are viewed as resources/property, they will be victims
of unnecessary harm and death, including the unnecessary harm and death
that they are inflicted in the production of animal foods, that people
pay for when they are consuming meat, milk, eggs and other animal foods.
I recommend this article discussing this: http://blog.nj.com/njv_guest_blog/2013/08/are_we_the_animal-lovers_we_th.html