NPCs derived from rat embryonic VM at E12 were expanded in vitro, harvested, and mixed with Ctx-NPCs (control), Ctx-Ast, VM-Ast, or N+F-VM-Ast before cell injection. The mixed cells were intrastriatally transplanted into 6-OHDA–lesioned PD model rats. Behavioral (A–C) and histological (D–L) analyses were carried out every month for the 6 months after transplantation (A) or at 6 months after transplantation (B–L). (A) Amphetamine-induced rotation scores were determined every month for the 6 months after transplantation. Data are given as percentage changes in rotation scores for each animal compared with the pretransplantation value. Mean + SEM of the rotation scores is depicted. n = 6 for each group. Significant decreases in rotation scores were seen in animals that received astrocyte cografts compared with those that received control NPCs alone. *P < 0.05; ^#P < 0.05, Ctx-Ast; ^†P < 0.05, VM-Ast at each posttransplantation time point, 1-way ANOVA. Behaviors of the transplanted animals were further assessed by step adjustment (B) and cylinder (C) tests at 6 months after transplantation. Statistical significances (P < 0.01) among groups are expressed using schematics in the graphs. One-way ANOVA followed by Bonferroni’s post hoc analysis. (D–L) Histologic analyses 6 months after transplantation. (D) Overview of the TH⁺ cell grafts. (E) Graft volume. (F) Total number of TH⁺ cells. (G) TH⁺ cell density in the graft. *P < 0.05; ^#P < 0.05, 1-way ANOVA. (H–J) Morphologic maturation of DA neurons in the grafts estimated by TH⁺ fiber length. Shown are immunohistochemical (H) and Neurolucida reconstruction of representative TH⁺ neuronal images (I). (K and L) Synaptic maturation of TH⁺ DA neurons estimated by synapsin⁺ puncta density. *P < 0.05; ^#P < 0.05, 1-way ANOVA. Scale bars, 100 μm (D); 50 μm (H); 25 μm (K).