This study aimed to evaluate the safety and efficacy of unrelated umbilical cord blood microtransplantation in the treatment of above-mentioned MDS patients by observing the factors related to the efficacy and adverse reactions.

Inclusion Criteria:

1. Patients diagnosed with MDS with WHO criteria through bone marrow morphology, histochemistry, immunophenotyping, pathological testing, etc. Patients can be newly diagnosed, recurrent or unresponsive, with International prognostic scoring system (IPSS-R) score> 3.5

2. Patients aged 14-80, gender and race are not limited;

3. Karnofsky score ≥ 60%, Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2;

4. Expected survival time ≥ 3 months;

5. The examination results meet the following requirements:

   ALT and AST ≤ 3 × Upper limit of normal value (ULN); Total bilirubin ≤ 3 × ULN; Creatinine ≤ 2 × ULN or creatinine clearance rate ≥ 40mL/min; The left ventricular ejection fraction (LVEF) measured by echocardiography or multigated acquisition (MUGA) scanning is within the normal range (>50%);

6. The recipient and selected donor should be 0-3/10 HLA-matched with same blood type;

7. Patients who voluntarily participate in this clinical study and have signed an informed consent.

Exclusion Criteria:

1. Patients who have suffered from malignant tumors;
2. Patients have suffered from hematopoietic failure after chemotherapy, and have undergone ineffective blood transfusion with unknown cause;
3. Patients who have undergone Class II or above surgery within 4 weeks prior to enrollment;
4. Suffering from life-threatening diseases other than MDS;
5. Allergic to the drugs in the research;
6. Patient with severe cardiac insufficiency, including uncontrolled or symptomatic arrhythmia, congestive heart failure, myocardial infarction within 6 months, or any grade 3 (moderate) or grade 4 (severe) heart disease;
7. Patients with test positive for HIV, HCV or HBV;
8. Stroke or intracranial hemorrhage occurred within 6 months prior to enrollment;
9. Warfarin or vitamin K antagonists (such as phenprocoumarin) is necessary for anticoagulation;
10. Patients with mental illnesses or cognitive impairments;
11. Patients have participated within the month prior to enrollment or patients are currently participating in other clinical trials;
12. There are other conditions that the investigators consider inappropriate for inclusion.