This study will explore safety and efficacy of allogeneic mesenchymal stem cells transplantation (MSCT) to treat patients with diagnosis of systemic sclerosis(SSc) who have been resistant to multiple standard treatments. The underlying hypothesis is that the SSc condition is caused by an abnormal immune homeostasis that can be restored by MSCT.

• To test a new approach using allogeneic derived mesenchymal stem cell based therapy (MSCT) to treat refractory SSc
• To determine the disease-free survival in SSc patients treated with MSCT
• To assess adverse events of allogeneic MSC transplantation
• To assess the association of remission for organ function, clinical score and SSc serology levels at baseline with disease-free survival

Inclusion Criteria:

• All patients fulfilled the American College of Rheumatology (former American Rheumatism Association - ARA) for SSc
• Rapidly progressive disease <2 years duration with a modified Rodnan skin score(mRSS) above 20, plus ESR >25 mm/first h and/or Hb <11 g/dL, not explained by other causes than active SSc
• lung involvement: with a vital capacity (VC) or DLCO below 70% predicted, or a mean pulmonary artery pressure (PAP) above 40 mmHg (measured by echocardiography)
• digestive tract involvement: with serum albumin ,25 g/L or weight loss exceeding 10% body weight in the preceding year
• kidney involvement: with 24-h urinary protein above 0.5 g or serum creatinine above 120 mmol/L

Exclusion Criteria:

• Uncontrolled arrhythmia, echocardiographic left ventricular ejection fraction (LVEF) <50% or mean PAP >50 mmHg, DLCO<45% of predicted
• Creatinine clearance <20 ml/min
• Platelets<80 000/mm3, haemorrhagic cystitis
• (4) HIV or HTLV1 seropositivity, malignancy, pregnancy, a cardiac or vascular prosthesis, and no vascular access