This study is to evaluate the safety and efficacy of Umbilical Cord Derived Mesenchymal Stem Cells transplantation in aplastic anemia.

Aplastic anemia (AA) is a disorder thought to be caused by an immune-mediated bone marrow failure. Not all people with AA are eligible for today's standard treatments. One new treatment approach uses umbilical cord derived mesenchymal stem cells-specialized cells capable of developing into other types of cells-to provide the basis for clinical application. The aim of the present study is to investigate the safety and efficacy of vein infusion of allogeneic mesenchymal stem cells in patients with AA .

Inclusion Criteria:

1. Diagnosis of AA according to established criteria in 2010
2. Age from 14 to 60 years
3. Suffering from AA within six months
4. No serious infection or acute hemorrhage.
5. Left ventricular ejection fraction (LVEF) ≥ 50%
6. No acute infectious diseases.
7. Understanding and willingness to sign a written informed consent document.
8. Eastern Cooperative Oncology Group(ECOG) score of 0-2pionts.

Exclusion Criteria:

- Patients with AA have to be disqualified from this study if any of the following is applicable.

1. Severe aplastic anemia(SAA) with severe infection.
2. Severe aplastic anemia(SAA) with active hemorrhage.
3. Severe heart attack, liver and kidney disease following serious complications
4. Patients with allergic constitution.
5. Pregnancy and lactation.
6. Accompanied by malignant tumors and other clonal disease.
7. Patients with active tuberculosis, acute sever hepatitis or infectious period of diseases.