Study of Human Umbilical Cord-derived Mesenchymal Stem Cells for Treatment of Refractory Immune Thrombocytopenia

Inclusion Criteria: * Aged 18 to 60 years old, male or female; * Conform to the diagnostic criteria of immune Thrombocytopenia (ITP); * Three months after splenectomy; * The first-line treatment drugs such as human immunoglobulin, glucocorticoid, and the second-line treatment of thrombopoietin drugs and rituximab were invalid, or there was no response or recurrence after splenectomy; * Diagnosis of ITP\>6 months； * More than 3 months after rituximab treatment； * Platelet counts \<30 ×10\^9/L, and bleeding tendency; * People who are willing to sign the informed consent voluntarily and follow the research program. * Subject is practicing an acceptable method of contraception. Women of childbearing potential must have a negative serum pregnancy test in the whole study; Exclusion Criteria: * ECOG score standard \>2； * Secondary thrombocytopenic purpura; * Patients with poor compliance; * Positive serology for HIV, hepatitis B virus (HBV), hepatitis C virus (HCV), and/or hepatitis D virus (HDV), Syphilis; Positive for Epstein-Barr Virus DNA, Cytomegalovirus DNA; * Pregnancy or lactation period; * History of thrombosis; * The serum chemistry results exceed the upper laboratory normal range by more than 20%, such as ALT, AST, TBIL, BUN, Cre etc; * Pre-existing cardiac disease, including congestive heart failure of New York Heart Association \[NYHA\] Grade III/IV, arrhythmia requiring treatment or myocardial infarction within the last 6 months. No arrhythmia known to increase the …