To evaluate the efficacy and safety of umbilical cord blood mononuclear cells in the treatment of chronic atrophic gastritis.

Inclusion Criteria:

1. Subjects voluntarily participated in the study and signed an informed consent.
2. The age is 18-65 years old, regardless of gender.
3. Patients with chronic atrophic gastritis by gastroscopy and pathological examination.
4. Patients with a negative C13 breath test or have eradicated Helicobacter pylori infection.
5. Patients without contraindications to submucosal injection of umbilical cord blood derived mononuclear cells.

Exclusion Criteria:

1. Patients with gastric ulcer, erosive gastritis, active upper gastrointestinal bleeding, gastric varices, or other gastric tumors.
2. Patients who are taking or have taken proton pump inhibitors, antibiotics, glucocorticoids, nonsteroidal anti-inflammatory drugs and immunosuppressants in the last six months.
3. People who have had gastric surgery or required gastric surgery during the study.
4. Patients with severe systemic diseases (diseases of cardiovascular, liver, blood, kidneys, lungs or liver).
5. Pregnant or nursing females.
6. Patients who are reluctant to accept endoscopy and treatment.