Safety and Preliminary Efficacy of hUCMSC-EVs in Interstitial Lung Disease

• Human Umbilical Cord Mesenchymal Stem Cell-Derived Extracellular Vesicles (hUCMSC-EVs) (Biological): hUCMSC-EVs , nebulized BID × 7d/cycle, 3 cycles
• Normal Saline Placebo (Biological): Nebulized inhalation BID × 7d per cycle, 3 cycles

Primary outcomes

• Incidence and Severity of Adverse Events [From first dose to Week 12]

Secondary outcomes

• Change from Baseline in Forced Vital Capacity (FVC) [From first dose to Week 24]: Forced Vital Capacity (FVC) will be assessed using standardized spirometry in accordance with American Thoracic Society (ATS)/European Respiratory Society (ERS) guidelines. Measurements will be performed at Baseline (prior to first dose) and at scheduled post-baseline visits. Spirometry will be conducted using a calibrated spirometer. Results will be summarized as absolute change from baseline and percent predicted normal values.
• Change from Baseline in Diffusing Capacity of the Lung for Carbon Monoxide (DLCO) [From first dose to Week 24]: Diffusing Capacity of the Lung for Carbon Monoxide (DLCO) will be assessed using the single-breath method in accordance with ATS/ERS guidelines. Hemoglobin-corrected DLCO values will be recorded if applicable. Measurements will be performed at Baseline and at scheduled post-baseline visits. Results will be summarized as absolute change from baseline and percent predicted normal values.
• Change from Baseline in 6-Minute Walk Test (6MWT) Distance [From first dose to Week 24]
• Change from Baseline in St. George's Respiratory Questionnaire (SGRQ) Total Score [From first dose to Week 24]: The St. George's Respiratory Questionnaire (SGRQ) is a disease-specific instrument designed to measure health-related quality of life in patients with chronic respiratory diseases. The Total Score is calculated as a weighted sum of the domain scores and ranges from 0 to 100, with higher scores indicating worse health-related quality of life. A change of 4 units is generally considered the minimal clinically important difference (MCID).

Sex: All, ages: 18 Years to any

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.