1917 Dunn successfully grafted rat neonatal cerebral cortex into the brains of adult rats (Dunn EH 1917). Dunn’s work helped link transplantation characteristics such as the immature development of the neural graft and blood vascularization of the implant site with increased graft survival.

1940 Embryos were first used as a source of transplantation (Le Gros Clark WE 1940).

1979 After nearly forty years of technique development and improvement of graft survival, neural transplantation was applied to the treatment of neurodegenerative diseases, most notably Parkinson’s disease. Bjorklund and Stenevi used allogenic fetal transplantation to successfully treat adult animal models of Parkinson's disease (Bjorklund.and Stenevi 1979).

1982 The first human brain transplantation clinical trials were performed. Autografts of the adrenal gland were unsuccessfully used to treat Parkinson’s disease. Clinical trials of this procedure were abandoned in the United States in 1990 (Kanelos and McDeavitt 1998).

1988 Due to the potent side effects of systemic immunosuppressants such as cyclosporin A, scientists began to develop alternative methods to prevent host immune rejection of non-autologous tissue, such as the utilization of polymer capsules to protect allogenic and xenogenic neural tissue (Aebischer P et al 1988). Encapsulated techniques will be clinically tested soon (Boyer and Bakay 1995).

1990 The use of fetal dopamine producing tissue to treat the depletion of dopaminergic neurons in Parkinson’s disease was found to be effective in clinical trials (Lindvall O et al 1990). Ethical issues and the limited supply of human fetal tissue have led some scientists to examine xenogenic sources of neural tissue.

1995 Porcine fetal neurons were shown to grow in the brains of rats with a model of Parkinson's disease (Isacson et al. 1995).

1997 Deacon documented the first successful transplantation of fetal pigdopaminergic tissue into a patient with Parkinson’s disease (Deacon et al 1997).