This trial aims to evaluate the use of a proprietary product made from umbilical cord blood derived (Cartistem™) in treating cartilage damage. The trial is sponsored by a biotechnology company MediPost Co Ltd and is being conducted at two centres in the US - the Rush University Medical Centre in Chicago and the Brigham & Women's Hospital in Massachusetts. The trial proposes to recruit 15 patients from November 2012 and January 2015. Participants will receive a single injection of Cartistem™ directly into the knee. Cartistem™ has been prepared from donated umbilical cord where the mesenchymal stem cells have been expanded in the laboratory. blood derived stem cell in combination with hyaluronic acid preparation (in treating full thickness, focal cartilage defects of the knee resulting from trauma, ageing or degenerative diseases. Participants will be monitored for complications and changes in clinical condition over the next 24 months, including the degree of cartilage regeneration and morphological constitution of the repaired cartilage as assessed using MRI.