Cellular strategies in bone tissue engineering: a review

The objective of bone tissue engineering is to reconstruct bone stock using matrix structures, osteoinductor factors and osteogenic cells. Different types of natural or synthetic biomaterials are available or under development. The objective of recent work is to optimize matrix materials, particularly with better cell adhesion to the surface and better osteoconduction. For osteoinductors, most research is currently focused on bone morphogenetic protein (BMP) and angiogenic factors such as vascular endothelial growth factor (VEGF). Concerning the nature of the cells to be implanted, there is a clear dissociation between fundamental and clinical studies. Many clinical studies have demonstrated the strong osteogenic potential of fresh harvested total bone marrow. There has been nevertheless little fundamental work on the use of total bone marrow as a source of cells for bone tissue engineering. Most of the fundamental work has been focused on the use of mesenchymatous stromal cells selected from bone marrow and cultivated ex vivo. This approach which was first developed more than fifteen years ago has shown that the adjunction of these cells can improve the osteoformative capacity of bone substitutes. This strategy has, however, had almost no clinical impact to date since only two studies involving four patients have been reported. The purpose of this article is to review current research concerning bone tissue engineering using total bone marrow and mesenchymatous stromal cells.