Umbilical Cord Mesenchymal Stem Cell-Derived Exosomes in the Treatment of Androgenic Alopecia

Inclusion Criteria: * Male, aged 18 to 60 years (inclusive), in good general health. * Clinical diagnosis of androgenetic alopecia (AGA) according to the 2023 Chinese Clinical Practice Guideline: Diagnosis and Treatment of Androgenetic Alopecia, with a disease duration of less than 5 years and a Hamilton-Norwood scale classification of stage II to IV at the screening visit. * Able to fully understand the study's content, procedures, potential benefits, and risks, and willing to provide written informed consent prior to any study-specific procedures. * Agrees to comply with the study protocol and refrain from using any other treatments for alopecia for the duration of the study. Exclusion Criteria: * Unwilling or unable to provide written informed consent. * History of any malignancy within the past 5 years (except for adequately treated non-scalp basal cell carcinoma or squamous cell carcinoma in situ). * Hypotension (blood pressure \< 90/60 mmHg) documented within 1 month prior to screening, or uncontrolled hypertension within 3 months prior to screening (defined as failure to achieve a target of \< 140/90 mmHg while on a stable regimen of at least two antihypertensive medications). * Known history of any systemic disease that may affect hair growth or confound study assessments (e.g., HIV infection, connective tissue disease, inflammatory bowel disease, hypothyroidism, iron deficiency anemia, malnutrition, syphilis). * Known history of other forms of non-androgenetic alopecia (e.g., diffuse alopecia, alopecia areata, cicatricial alopecia). * History of major organ dysfunction, significant autoimmune disease, or immunodeficiency. * Known coagulation disorders, current use of anticoagulant or antiplatelet therapy (except low-dose aspirin), thrombophilia, or inherited bleeding disorders. * Treatment with chemotherapy, cytotoxic drugs, scalp radiation, or laser/surgical hair restoration within 12 months prior to screening. * History of hair transplantation, or need for long-term use of wigs, hairpieces, or hair bonding agents during the trial. * History of severe or multiple drug allergies, atopy, known allergy to local anesthetics, or planned desensitization therapy during the study period. * Presence of any active dermatological condition in the target scalp area that could interfere with evaluation (e.g., infection, seborrheic dermatitis, psoriasis, eczema, folliculitis, open wounds, scars, or atrophy). * Participation in another interventional clinical trial within 4 weeks prior to screening (except for non-interventional studies or participants who only signed the informed consent form without receiving any investigational product). * Any other medical or psychiatric condition that, in the judgment of the investigator, would compromise the subject's safety, compliance, or suitability for study participation.