Allogeneic Mesenchymal Stem Cells Transplantation for Primary Sjögren's Syndrome (pSS)

Inclusion Criteria: * All patients fulfilled the international classification criteria (2002) for primary Sjögren's Syndrome, man or woman aged from 15 to 70 years old, Sjögren's Syndrome Disease Activity Index (SSDAI)≥8. * Stimulated whole saliva flow rate less than 1\~6ml/6min. * Patients must be informed of the investigational nature of this study and give written informed consent in accordance with the institutional and hospital guidelines. * Women of reproductive potential may not participate unless they have agreed to use an effective contraceptive method while on this trial and for 12 months following treatment. Women of child-bearing potential must have a pregnancy test performed within 72 hours prior to initiation of treatment. Exclusion Criteria: * End-stage renal failure. * Severe cardiopulmonary compromise, or other system failure. * Active, uncontrolled infections. * Pregnant or nursing women may not participate due to the possibility of fetal harm or harm to nursing infants from this treatment regimen.