Systemic Treatment with GM1 Ganglioside Improves Survival and Function of Cryopreserved Embryonic Midbrain Grafted to the 6-Hydroxydopamine-Lesioned Rat Striatum

Abstract

Cryopreservation may allow long-term storage of embryonic ventral mesencephalon (VM) for neural transplantation. We investigated whether the ganglioside GM1 or the lazaroid tirilazad mesylate (U-74006F) could improve survival of grafts derived from cryopreserved VM in a rat model of Parkinson's disease. VM was dissected from rat embryos (E14–E15), frozen and stored in liquid nitrogen under controlled conditions, thawed, dissociated, and then grafted into the 6-hydroxydopamine-lesioned rat striatum. In Experiment I, VM fragments were exposed in vitro either to GM1 (100 μM) or to lazaroid (0.3 μM) during all preparative steps. In Experiment II, rats receiving GM1-pretreated VM were, in addition, treated systematically with GM1 (30 mg/kg) daily for 3.5 weeks. Rats grafted with untreated cryopreserved or fresh VM were used as controls, respectively. Rats receiving fresh VM control grafts showed complete recovery from lesion-induced rotations after 6 weeks whereas rats grafted with cryopreserved VM (untreated or pretreated) did not recover. Cryografts contained significantly less (18%, control; 23%, GM1; and 12%, lazaroid) tyrosine hydroxylase-positive cells compared to fresh grafts (1415 ± 153; mean ± SEM). Graft volume was also significantly smaller after cryopreservation. In contrast, with additional systemic GM1 treatment cryografts contained almost the same number of tyrosine hydroxylase-positive cells (376 ± 85) as fresh grafts (404 ± 56), which was significantly more than that of untreated cryografts (147 ± 20), showed a significantly larger volume (0.15 mm3) compared to that of untreated grafts (0.08 mm3) (fresh controls, 0.19 mm3), and induced significant and complete functional recovery in the rotation test. In conclusion, systemic treatment of rats with GM1 improved the low survival and functional inefficacy of grafts derived from cryopreserved VM whereas tissue pretreatment alone with either GM1 or lazaroid was not effective.