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.