You may be interested to know that scientists working on cell cultures do not and often do not need ethical approval for their work.
This is perhaps a shame as sometimes there is a load of old tosh coming out of some labs that solely focus on cell culture.
Once an animal is dead is is not protected by the laws that protect living animals that are used in research.
Each year you hear how many animals are used in research. However, this is a fudge and a massive under-representation because many animals that are killed for tissues do not need to be reported.
In neuroscience, this often may mean foetal or neonatal (freshly-born) animals are used e.g. to study myelination because they can be used to grow nerves and myelinating cells more easily as development in ongoing in these animals. e.g. Mice have little myelin on their nerves when they are born.
However, with the ability to grow human cells into brain tissue then becomes a very strong ethical argument against using animals for research in cell cultures. Why use a model when you can use the real thing? With iPS cells you could grow the brain tissue from MSers.
Yes it will be expensive to grow the human cells, but the cost-saving exercise has not been a valid reason to do living animal experiments when there is an alternative from the ethical standpoint. It is perhaps time that everybody using animal tissue, live or dead go through a full ethical review.
Maybe in your country they do already