This is an exploratory, randomized, single-blind, placebo-controlled, multiple-dose, dose-escalation clinical study. The study aims to evaluate the safety and preliminary efficacy of nebulized inhalation of Human Umbilical Cord Mesenchymal Stem Cell-Derived Extracellular Vesicles (hUCMSC-EVs) in patients with interstitial lung disease (ILD).

This study is designed to include three sequential dose cohorts-low, medium, and high-with dose escalation proceeding in an ascending order. Eligible subjects will be enrolled and randomized sequentially, with a planned enrollment of 8 subjects per cohort. Within each cohort, subjects will be randomly assigned in a 3:1 ratio to receive either hUCMSC-EVs or saline placebo.

Key Inclusion Criteria:

• Age 18 years and older, regardless of gender.
• Diagnosed with interstitial lung disease (ILD).
• High-resolution computed tomography (HRCT) findings within 3 months prior to randomization must be consistent with interstitial pulmonary imaging changes.
• Pulmonary function test within the protocol-defined acceptable range prior to randomization.
• Good compliance, able to understand and cooperate with the required examinations and procedures, and willing to attend follow-up visits as scheduled.
• Voluntary participation and signing of written informed consent form.

Key Exclusion Criteria:

• Inability to tolerate nebulized inhalation therapy.
• Requirement for oxygen supplementation > 15 hours per day during the screening period.
• Allergic diathesis or a history of life-threatening drug hypersensitivity.
• History of malignancy within 5 years.
• Active hepatitis B, hepatitis C, or HIV infection.
• Active systemic infection requiring antibiotic therapy.
• Clinically significant laboratory abnormalities at screening.
• Concomitant significant or severe respiratory disease.
• History of psychiatric illness, epilepsy, or other central nervous system disorders.
• Concomitant severe cardiovascular, hepatic, or renal systemic disease.
• Pregnancy, planned pregnancy in the near future, or breastfeeding.
• Unwillingness to use effective contraception during the study period.
• Any condition that, in the opinion of the investigator, may increase the risk to the participant or interfere with the study outcomes.