Neuroprotection of grafted neurons with a GDNF/caspase inhibitor cocktail

Transplantation of fetal ventral mesencephalic (VM) tissue shows great prom ise as an experimental therapy for patients with Parkinson's disease. Howev er, cell survival in brain tissue grafts is poor, with survival rates of on ly 5-15%. We have utilized a combination of the caspase inhibitor bocaspart yl (OMe)-fluoromethylketone (BOC-ASP-CH2F) and glial cell line-derived neur otrophic factor (GDNF) to enhance survival of grafted dopamine neurons. The VM tissue was dissected from embryonic day 13-15 rat fetuses, incubated in different doses of BOC-ASP-CH2F and GDNF, and transplanted to the anterior chamber of the eye of adult rats. Growth of the tissue was assessed throug h the translucent cornea. Doses of 50 and 100 micromolar of the general cas pase inhibitor appeared to have detrimental effects on mesencephalic tissue , while 20 micromolar had beneficial effects on overall transplant growth. A combination of the caspase inhibitor and GDNF appeared to have more promi nent effects on cell survival as well as dopaminergic fiber density than ei ther agent by itself. The transplants doubled in size when they were treate d with a combination of BOC-ASP-CH2F and GDNF, and cell death markers were significantly reduced at both 48 h and 4-6 days postgrafting. This is, to o ur knowledge, the first combined approach using apoptotic blockers with tro phic factors, and demonstrates a viable strategy for protection of developi ng neurons, since several different aspects of graft function may be addres sed simultaneously. (C) 2001 Academic Press.