['Bone grafting is used to repair large bone defects and autograft is recognised as producing the best clinical outcome, which is partly due to its cellular component. When autograft is unavailable, allograft and bone graft substitutes can be used; however, they rely on the host bed to provide cellular osteogenic activity.', 'Bone graft substitutes have the potential to benefit from the addition of stem cells aimed at enhancing the rate and quality of defect repair. Mesenchymal stem cells (MSCs) can be isolated from bone marrow or periosteum and culture expanded. Other sources of primary cells include muscle, adipose tissue, human umbilical cord and the pluripotent embryonic stem cells (ESCs).'] Does stem cells combined with bone graft substitute in skeletal tissue engineering?