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Human Neural Progenitor Cells Reverse Symptoms and Extend Longevity in a Rat Model of Ataxia
The spastic Han Wistar (sHW) rat serves as a model for human ataxia presenting symptoms of motor deterioration, decreased weight and a shortened lifespan. Correspondingly, sHW rats show progressive loss of cerebellar Purkinje cells starting at 30 days. Past experiments in our lab revealed that human neural progenitor cells (NPCs) have been effective in this ataxic rat model, including significant improvements in behavioral assays and human cell survival 20 days post-transplantation. Here, we examined the longer-term effectiveness and fate of human NPCs in this ataxic rat. For this experiment, rats were placed into four treatment groups (equal mix of male and female rats): an untreated normal control group (n=10), an untreated mutant rat control (n=10), a mutant group that received an injection of dead NPCs (n=9), and a mutant group that received live NPCs (n=10). Bilateral cerebellar injections of 500,000 of either live or dead NPCs were performed on mutant sHW rats at 40 days of age, and motor activity (via open field and rotarod assays) was tested twice per week henceforth. All mutant rats started to decline in open field testing around day 35. However, at day 45, the live NPC-treated mutants began to exhibit improved motor activity while dead NPC-treated and untreated mutants continued to display decreased motor abilities. Starting at day 60 (20 days post-transplantation), live NPC-treated mutant's motor behavior was statistically similar to normal rats, and this trend continued until the end of the experiment. Cerebellar decline was tested via the rotarod test. Live NPC mutants were statistically similar to normal rats; yet, dead NPC and untreated mutants showed significant decreases in rotarod performance. All rats were perfused with 4% paraformaldehyde, their brains removed and sliced for histological staining. While immunohistochemistry revealed few surviving human NPCs in the cerebellums of 100 day old NPC-treated mutants, cresyl violet staining revealed that live NPC-treated mutants had significantly more surviving Purkinje neurons compared to mutants that were untreated or received dead NPCs. Long-term implantation of NPCs alleviated the symptoms of ataxia, acting as a neuroprotectant for the remaining Purkinje neurons since paradoxically these human cells did not survive 60 days post-transplantation.