 The objective of this clinical trial is to generate efficacy and tolerability profiles of single injections of 2 dosages of autologous ASCs versus standard of care placebo, when administered locally into a knee joint affected by OA after in vitro cell expansion. The potential of ASC to lead to a disease-modifying therapeutic option for the treatment of this chronic and debilitating disease will be assessed by MRI after 1 and 2 years. 