Survival and function of aggregate cultures of rat fetal dopamine neurons grafted in a rat model of Parkinson's disease.

The ability to maintain tissue in culture prior to grafting would greatly facilitate the widespread application of graft therapy to neurological diseases such as Parkinson's disease. However, neurons cultured on planar substrata can be easily damaged when they are removed from the substrata and redissociated for use in grafting procedures. To overcome this limitation we utilized aggregate tissue culture methods, which allowed dopamine (DA)-rich neuronal tissue to be grafted directly following culture, without an additional redissociation. Fetal rat dopamine-neuron-containing ventral mesencephalon was cultured for 9 days in rotating flasks. The cells formed many small spheres (280 microns mean diameter), each estimated to contain about 10,000 cells. Forty such aggregate spheres were injected via a 22G needle into the DA-denervated striata of host Parkinsonian rats. A significant reduction of amphetamine-induced rotation was seen onward from 6 weeks post-transplantation, with a complete reversal of rotational asymmetry by 15 weeks post-transplantation. Well placed, surviving grafts were found in all behaviorally compensated rats (N = 6). Grafts contained an average of 517 tyrosine hydroxylase (TH)-positive neurons, as well as TH-positive fibers seen extending into the host striatum. These results suggest that aggregate culture methods are a promising means to maintain and deliver tissue for transplant therapy.