The purpose of this study is to evaluate the safety and efficacy of mesenchymal stem cells (MSCs) derived from human umbilical cord/placenta at a dose of 1.0E+6 MSC/kg in subject for the therapy of severe aplastic anemia (SAA).

Severe aplastic anemia (SAA) is a condition that involves a low level of red blood cells, white blood cells, and platelets without evidence of another bone marrow disease. Patients with severe aplastic anemia produce too few blood cells, causing fatigue, easy bruising and bleeding, and susceptibility to infections. In many cases, the very low blood counts result from an autoimmune process. The patient's own immune system damages their stem cells in bone marrow.

Although immune-suppressing drugs, such as corticosteroids, CsA and ATG, have been used in the treatment of SAA, however, many studies have indicated that the overall response rate to these drugs is less than 60%. Addition, the severe side effects of these immune-suppressing drugs have also been observed. The management of SAA patients therefore remains unsatisfactory and targeted therapies are needed. Human MSCs isolated from human umbilical cord/placenta have been shown to have immunosuppressive, stimulating hematopoiesis and tissue repairing properties. This study will evaluate the safety and effectiveness of MSC transplantation in the SAA patients.

This study will last 2 to 3 years. Participants will be randomly assigned to receive either MSC transplant and CsA therapy (experimental group) or CsA therapy alone (control group). Patients will undergo MSC transplant at the start of the study on Day 0. After 3 months, patients will receive the second MSC transplantation. After six and twelve months from the first transplantation, patients will be evaluated.

Inclusion Criteria:

1. Patient age 18~80 years old with plan to infuse MSCs.
2. Standard of diagnosis of aplastic anemia is according to Chinese domestic classification of AA for 1987.
3. Patients must have an ECOG 0~2.
4. No moderate or sever organ dysfunction: Ejection fraction>45%; Creatinine <176 umol/L.
5. No active severe viral or fungus infection.
6. Each patient must sign written informed consent.

Exclusion Criteria:

1. Psychiatric condition that would limit informed consent.
2. HIV positive
3. Positive Pregnancy Test
4. Patient has enrolled another clinical trial study within last 4 weeks.