The goal of this clinical trial is to learn about the safety of NouvNeu001 injection in Early-onset Parkinson's Disease (EOPD) patients. It will also learn about the effects of NouvNeu001 treatment. The main questions it aims to answer are:

What medical problems do participants have when transplanting NouvNeu001 into bilateral putamen using stereotactic neurosurgery? Does injection of NouvNeu001 improve the motor function and non-motor function in participants?

Participants will:

Be injectioned the NouvNeu001 into bilateral putamen using stereotactic neurosurgery.

Take immunosuppressants to prevent potential immune rejection for 24 to 36 weeks.

Inclusion Criteria:

• Age 18-70 years old, male or female
• Able to understand the rationale of the clinical trial and sign informed consent form (ICF)
• Diagnosis of Early-onset Parkinson's Disease in accordance with the MDS clinical diagnostic criteria for Parkinson's disease, and the age of onset was ≤50 years old
• Medically suitable for neurosurgery under anesthesia and able to participate in Computed Tomography (CT)/Magnetic Resonance Imaging (MRI) scan.
• Hoehn-Yahr staging for "off" episodes is 2 to 4
• The MDS-UPDRS-III score in the "off" state >30, and positive for the Acute Levodopa Challenge Test (ALCT)
• Acceptable laboratory test results during screening and prior to transplantation

Exclusion Criteria:

• Atypical Parkinsonism
• Patients who have had previous pallidotomy, striatal or extrapyramidal surgery or other brain surgery; as well as other surgical procedures that are judged by the investigator to affect patient's participation in this study; Patients with surgical contraindications or other neurosurgical contraindications
• Patients who have a previous head CT/MRI examination showing cerebral trauma, vascular malformation, hydrocephalus, brain tumor, etc., and patients who have brain imaging abnormalities in the striatum or other brain areas leading to a significantly increased risk for surgery
• Patients with a history of severe cardiovascular and cerebrovascular diseases
• Patients with a history of malignant tumors
• Patients who have received stem cell therapy for Parkinson's disease within 2 years before signing the ICF
• Patients with active disseminated intravascular coagulation and significant hemorrhagic tendency within 3 months prior to screening, or who cannot temporarily suspend anti-platelet agents or other anti-coagulant medications for at least 5 days before surgery
• Patients with long-term, heavy use of glucocorticoids or immunosuppressive drugs within 3 months prior to signing the ICF
• Patients with a history of mental illness who are deemed unfit to participate in the study by the investigator; or a history of suicidal ideation or suicide attempts within the past year or currently
• Patients who have used botulinum toxin within 6 months prior to signing the ICF
• Patients with active epilepsy or currently on anti-epileptic drugs
• Patients with a history of dementia or severe cognitive disorder, or the score of MDS-UPDRS 1.1 during screening is > 3; poor compliance, inability to accurately keep diary, and/or inability to sign ICF due to dementia
• Patients with severe depression or with severe anxiety
• Patients with the following abnormalities during screening, including: Abnormal coagulation; Abnormal immunological tests, and assessed by the investigator it is not suitable to participate in the trial; Hypertensive patients with poorly controlled blood pressure and patients with severe postural hypotension; Diabetic patients with poorly controlled blood glucose
• Patients with other combined severe systemic diseases, such as pulmonary heart disease, moderate to severe asthma, severe chronic obstructive pulmonary disease (COPD)
• Presence of one of the following: positive for human immunodeficiency virus (HIV) antibody, treponema pallidum antibody, hepatitis C virus (HCV) antibody and HCV RNA; Hepatitis B virus (HBV) surface antigen positive and HBV DNA copy number > detection of normal values; Tuberculosis is in the active stage; Other active infections that the investigator believes may affect Patients' participation in the study or affect study outcomes
• Patients with alcohol addiction or positive for drug of abuse testing
• Patients with a history of contraindication or allergy to the drugs used during the study or any of its components, or are allergic to the same drugs or other macrolides, or have allergies
• Female of childbearing potential who are not surgically sterilized/premenopausal/unwilling to use medically approved effective contraception with 2 years after administration of investigational drug and lactating women; men who are not surgically sterilized/unwilling to use medically approved effective contraception with 2 years after administration of investigational drug
• Patients who have received electric shock therapy within 30 days prior to surgery
• Patients who are participating in other clinical trials, or have been enrolled in other clinical studies and received intervention therapy within 3 months prior to the surgery
• Patients with poor compliance based on clinical evaluation of the investigator
• Patients who are being treated with drugs such as apomorphine, or levodopa/carbidopa infusion therapy
• Patients with severe dyskinesia in both on- and off-drug states