Mesenchymal Stem Cells in the Treatment of Refractory Primary Immune Thrombocytopenia

Inclusion Criteria: 1. The subjects voluntarily signed the informed consent form; 2. The age is from 4 to 75 years old (including the critical value), male or female; 3. Patients clinically diagnosed as ITP (meeting the diagnostic criteria of the Chinese guidelines for the diagnosis and treatment of Primary immune Thrombocytopenia in Adults (2020 Edition)) had persistent thrombocytopenia for more than 3 months, but were ineffective to first-line drugs, second-line drugs for platelet production and rituximab, or ineffective to splenectomy / recurrence after operation. 4. Patients who received other maintenance regimens (including but not limited to corticosteroids, azathioprine, danazol or mycophenolate mofetil), but the stable dose had been maintained for at least 4 weeks, and the dose should remain unchanged during the trial period; 5. During screening, the liver and kidney function of the subjects met the following criteria: alanine aminotransferase (ALT) and / or aspartate aminotransferase (AST) ≤ 3 times of the upper limit of the normal value; total bilirubin ≤ 1.5 times of the upper limit of the normal value; creatinine ≤ 1.5 times of the upper limit of the normal value or creatinine clearance rate \& gt; 75ml / min; 6. Women of childbearing age must have negative blood or urine pregnancy tests and are not breast-feeding, and agree to use medically approved contraceptive measures (such as intrauterine devices, condoms or contraceptive) during the study period. 7. Fertile male patients must agree to use barrier contraception or physical abstinence during the study; 8. The subjects were able to understand the nature and purpose of the trial, including possible risks and side effects, and to understand the researchers' oral and written medical orders and comply with the requirements of the trial. Exclusion Criteria: 1. Have a history of severe allergic diseases or are allergic to research drugs; 2. There may be a history of angina pectoris, myocardial infarction, heart failure, severe arrhythmia, etc. 3. Combined use of anticoagulants or antiplatelet drugs; 4. In the first study, he was treated with gamma globulin within 2 weeks before medication. 5. The first study received rituximab within 24 weeks before treatment; 6. Other clinical trial drugs were used within 1 month before the use of drugs in the first study. 7. Uncontrolled hypertension (blood pressure is still higher than 160/100mmHg after active treatment); 8. Have a history of malignant tumor; 9. Those with a history of hepatitis B, or hepatitis C, or HIV, or immunodeficiency, or positive results of laboratory tests (hepatitis B surface antigen, or hepatitis C antibody, or HIV antibody) during screening; 10. Active / latent tuberculosis infection or other pathogen infection; 11. Live attenuated vaccine was vaccinated within 1 month before drug use in the first study, or there was a live attenuated vaccine program during the study period; 12. Hypogammaglobulinemia (IgG\<400mg/dl) or IgA deficiency (IgA\<10mg/dl); 13. History of important organ transplantation; 14. Patients with a history of severe mental illness; 15. The researchers believe that it is not appropriate for patients to participate in other conditions of this trial.