³í¹®) Intravenous Infusion of Umbilical Cord Blood- Derived Mesenchymal Stem Cells in Rheumatoid Arthritis: A Phase 1a Clinical Trial ¼¿ï´ëº´¿ø¿î¿µ ¼¿ïƯº°½Ãº¸¶ó¸Åº´¿ø(¿øÀå ±èº´°ü) ·ù¸¶Æ¼½º³»°ú ½Å±âö ±³¼ö(»çÁø) ¿¬±¸ÆÀ