The purpose of this study is to evaluate the safety and efficacy of Adipose-derived Mesenchymal Stem Cells (AD-MSCs) with moderate to severe psoriasis. Any adverse events related to AD-MSCs infusion will be monitored. Safety is assessed using incidence of Adverse Events(AEs) and Serious Adverse Events (SAEs). Efficacy is assessed via the proportion of the improvement of PASI (Psoriasis Area and Severity Index), relapse rate in treatment period, changes in PASI score and BSA, as well as DLQI.