Long-term safety of umbilical cord mesenchymal stem cells transplantation for systemic lupus erythematosus: a 6-year follow-up study

The aim of this study is to assess the long-term safety of allogeneic umbilical cord mesenchymal stem cells (UC MSCs) transplantation for patients with refractory systemic lupus erythematosus (SLE). Nine SLE patients, who were refractory to steroid and immunosuppressive drugs treatment and underwent MSCs transplantation in 2009, were enrolled. One million allogeneic UC MSCs per kilogram of body weight were infused intravenously at days 0 and 7. The possible adverse events, including immediately after MSCs infusions, as well as the long-term safety profiles were observed. Blood and urine routine test, liver function, electrocardiogram, chest radiography and serum levels of tumor markers, including alpha fetal protein (AFP), cancer embryo antigen (CEA), carbohydrate antigen 155 (CA155) and CA199, were assayed before and 1, 2, 4 and 6 years after MSCs transplantation. All the patients completed two times of MSCs infusions. One patient had mild dizzy and warm sensation 5 min after MSCs infusion, and the symptoms disappeared quickly. No other adverse event, including fluster, headache, nausea or vomit, was observed. There was no change in peripheral white blood cell count, red blood cell count and platelet number in these patients after followed up for 6 years. Liver functional analysis showed that serum alanine aminotransferase, glutamic-oxalacetic transaminase, total bilirubin and direct bilirubin remained in normal range after MSCs infusions. No newly onset abnormality was detected on electrocardiogram and chest radiography. Moreover, we found no rise of serum tumor markers, including AFP, CEA, CA125 and CA199, before and 6 years after MSCs infusions. Our long-term observational study demonstrated a good safety profile of allogeneic UC MSCs in SLE patients.