RATIONALE: It has been shown that about 30% of patients do not respond to immunosuppressive therapy or experience recurrence, and graft rejection and graft-versus-host-disease (GVHD) decrease event-free survival to 30% to 50% in the alternative donor (matched unrelated, partially matched family member) transplantation. Although an overall and disease free survival of 85% to 100%, can be obtained in allogeneic blood or bone marrow stem cell transplantation using an human leukocyte antigen (HLA) matched sibling donor, only about 25% of patients have such a donor.

PURPOSE: In an attempt to avoid GVHD, reduce earlier infection rate and decrease regimen-related toxicity while maintaining better engraftment, this study is to evaluate the effectiveness and safety of patient's own adipose-derived mesenchymal stem cell (AD-MSC) or AD-MSC transdifferentiated HSC (AD-HSC) transplant after an immunosuppressive regimen in treating patients who have severe aplastic anemia.

The patient will be in the study for one year for observation and active monitoring. After treatment and active monitoring are over, the patient's medical condition will be followed indefinitely. The principle measures of safety and efficacy will be :

1. Patient survival probability at 3 months, 6 months and 1 year.
2. Engraftment at 3 months, 6 months and 1 year
3. Incidence of graft versus host disease (GVHD), incidence of acute and chronic GVHD and Incidence of earlier infection rate as well as other complications within 6 months and 1 years.

Severe aplastic anemia is characterized by severe deficiencies in peripheral-blood platelets, white cells, and red cells. These defects in mature cells occur because aplastic bone marrow contains severely reduced numbers of hematopoietic stem cells. To date, Hematopoietic stem cell (HSC) transplants are routinely used to treat patients with many different diseases, including various cancers and blood disorders, such as aplastic anemia. The main sources of HSCs are bone marrow, cord blood and peripheral blood. However, challenges include obtaining enough functional HSCs to ensure optimal engraftment, and avoiding immune rejection and other complications associated with allogeneic transplantations. Novel abundant sources of clinical-grade HSCs are therefore being sought.

Our novel studies have demonstrated that adipose-derived mesenchymal stem cells (AD-MSCs) can be converted rapidly (in 4 days) into AD-HSCs on a large scale (2X108-9 cluster of differentiation 34（CD34）positive cells) by transfection of small RNAs to the the early region 1A (E1A)-like inhibitor of differentiation 1 (EID1) in the presence of specific cytokines. In vitro, AD-HSCs expanded efficiently and resembled cord-blood HSCs in phenotype, genotype, and colony-forming ability. In a mouse model, primary and secondary transplantation analysis and repopulating assays showed that AD-HSCs homed to the bone marrow, differentiated into functional blood cells, and showed a long-term ability to self-renew. we show that adipose-derived mesenchymal stem cells (AD-MSCs) can be converted into AD-HSCs by transfection of small RNAs to the E1A-like inhibitor of differentiation 1 (EID1) in the presence of specific cytokines. In vitro, AD-HSCs expanded efficiently and resembled cord-blood HSCs in phenotype, genotype, and colony-forming ability. In a mouse model, primary and secondary transplantation analysis and repopulating assays showed that AD-HSCs homed to the bone marrow, differentiated into functional blood cells, and showed a long-term ability to self-renew. In the safety aspect, we saw no evidence of leukemia, teratoma and other cancers in the blood, testes and subcutaneous tissues of transplanted mice. More importantly, our preliminary data have shown that AD-HSCs can reconstitute hematopoietic function in five patients with severe aplastic anemia. Based on these premilitary studies,, we have determined to conduct a further clinical investigation in multiple medical centers. In this study we plan to enroll up to 90 patients, to make a comprehensive assessment for this new treatment regimen and to show it is equal or superior to the current immunosuppressive regimen. Patients will be in the study for one years for treatment and active monitoring. All patients will be followed until death.

Inclusion Criteria:

Male or female recipients must have histopathologically confirmed diagnosis of SAA-I without or with more than 6 months after less than one treatment with ATG. Diagnostic Criteria for Server Aplastic Anemia will be based on the definitions set forth by the international Aplastic Anemia Study Group.

At least two of the following:

Absolute neutrophil count ≤ 0.5 X 109/l, Platelet count ≤ 20 X 109 /l, Anemia with corrected reticulocyte count ≤ 1%, and Bone marrow cellularity ≤ 25%, or bone marrow cellularity ≤ 50% with fewer than 30% hematopoietic cell, Hepatic: alanine aminotransferase (ALT)/ aspartate aminotransferase (AST) no greater than 4 times normal, Bilirubin: no greater than 2 mg/dl, Renal: Creatinine clearance at least 50 ml/min, Cardiovascular: Shortening fraction or ejection fraction at least 40% of normal for age by echocardiogram or radionuclide scan.

No clinically significant comorbid illnesses (e.g., myocardial infarction or cerebrovascular accident).

Exclusion Criteria:

Active and uncontrolled infection, Active bleeding, Severe allergic history of ATG, HIV-1 infection, Pregnancy or breastfeeding, Carbon monoxide lung diffusion capacity (DLCO) <40% predicted, SAA-II, Patients with severe psychological disorders, Recipients of other clinical trials.