Hello Sir Stem cell research and therapy are very new modalities.  Yes it's one of the thing currently picking up but results are variable that means there is no guarantee of 100 percent cure. A lot of research is happening with regards to CP but what we need to understand is that there is not one problem but many things involved in it from intelligence to motor strength to other physical disabilities.  In you particular case you have not mentioned other things but Please remember that even if you go for it all the problems might not get cured or show equal improvements.  Results are indeed variable and also the cost of therapy is high. I wish you and your child well