<qa>  What is the goal of the study?The investigators have already summarized the effectiveness of rabbit antithymocyte immunoglobulin ATG, cyclophosphamide Cy and cyclosporine, A CsA and the combination of the umbilical cord blood infusion for SAAVSAA patients without suitable donor, with short duration, without long-term immunosuppressive therapy history. The total effectiveness rates has improved to 88, with shorter immunosuppressive maintaining therapy , rapid hematopoietic reconstruction, fewer complications. The aim of this study is to further explore whether this solution can accelerate hematopoietic reconstruction of SAAVSAA patients and its clinical curative effect and security. This study scheme has been approved by the Jinan military region general hospital medical ethics committee. 