Hello, Are there be any ethical issues involved in grafting non-human brain cells to human brains in such a way as to replace dopamine producing cells lost in PD, assuming that any possible animal to human virus transmission can be prevented? What if, as an improvement to this process, the tissue to be transplanted had human genes added to it so as to facilitate getting past the immune system without rejection? Phil Tompkins Hoboken NJ age 60/dx 1990