MMP13 and teratoma: Twelve weeks after transplantation, intense safranin O staining and aggrecan immunostaining were observed. Histological evaluation of ICRS scores demonstrated a significant superiority for cartilage histology after transplantation compared with untreated controls. A decrease in the expression of markers of inflammation and catabolism IL-1β, TNF- α, and MMP13 was also observed. No tumors or teratomas were found.