Inclusion Criteria:

1. Individual of any sex ≥45 to ≤75 years of age at informed consent
2. Diagnosis of clinically established PD
3. ≥4 and \<12 years from time of PD diagnosis at informed consent
4. Must demonstrate responsiveness to levodopa therapy
5. Receiving medical therapy for the treatment of PD symptoms
6. ≥2.5 hours of daily OFF-time

Exclusion Criteria:

1. PD presenting with recurrent falls
2. Diagnosis of primary mitochondrial disorder, epilepsy, stroke, multiple sclerosis, or clinical features suggestive of a neurodegenerative disease other than PD, including multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration, or Lewy body dementia
3. Any current or relevant previous history of serious, severe, or unstable physical, neurological, or psychiatric illness that may interfere with study participation, participant's safety, or assessment of endpoints per investigator's judgment
4. History of gene therapy or cell therapy
5. Prior surgical or radiation therapy to the brain, including deep brain stimulation (DBS) and lesion therapy, or prior history of intradural spinal cord surgery
6. Contraindication to surgery, general anesthesia, cell therapy, immunosuppression, or other required drugs
7. Current or previously active malignant disease within the past 5 years
8. Chronic immunosuppressive therapy
9. Receipt of another investigational therapy
10. Pregnancy or breastfeeding