Bone regeneration and stem cells

• Introduction • Bone fracture healing and healing problems • Biomaterial scaffolds and tissue engineering in bone formation ‐ Bone tissue engineering ‐ Biomaterial scaffolds ‐ Synthetic scaffolds ‐ Micro‐ and nanostructural properties of scaffolds ‐ Conclusion • Mesenchymal stem cells and osteogenesis ‐ Bone tissue ‐ Origin of osteoblasts ‐ Isolation and characterization of bone marrow derived MSC ‐ In vitro differentiation of MSC into osteoblast lineage cells ‐ In vivo differentiation of MSC into bone ‐ Factors and pathways controlling osteoblast differentiation of hMSC ‐ Defining the relationship between osteoblast and adipocyte differentiation from MSC ‐ MSC and sex hormones ‐ Effect of aging on osteoblastogenesis ‐ Conclusion • Embryonic, foetal and adult stem cells in osteogenesis ‐ Cell‐based therapies for bone ‐ Specific features of bone cells needed to be advantageous for clinical use ‐ Development of therapeutic biological agents ‐ Clinical application concerns ‐ Conclusion • Platelet‐rich plasma (PRP), growth factors and osteogenesis ‐ PRP effects in vitro on the cells involved in bone repair ‐ PRP effects on osteoblasts ‐ PRP effects on osteoclasts ‐ PRP effects on endothelial cells ‐ PRP effects in vivo on experimental animals ‐ The clinical use of PRP for bone repair ‐ Non‐union ‐ Distraction osteogenesis ‐ Spinal fusion ‐ Foot and ankle surgery ‐ Total knee arthroplasty ‐ Odontostomatology and maxillofacial surgery ‐ Conclusion • Molecular control of osteogenesis ‐ TGF‐β signalling ‐ FGF signalling ‐ IGF signalling ‐ PDGF signalling ‐ MAPK signalling pathway ‐ Wnt signalling pathway ‐ Hedgehog signalling ‐ Notch signalling ‐ Ephrin signalling ‐ Transcription factors regulating osteoblast differentiation ‐ Conclusion • Summary This invited review covers research areas of central importance for orthopaedic and maxillofacial bone tissue repair, including normal fracture healing and healing problems, biomaterial scaffolds for tissue engineering, mesenchymal and foetal stem cells, effects of sex steroids on mesenchymal stem cells, use of platelet‐rich plasma for tissue repair, osteogenesis and its molecular markers. A variety of cells in addition to stem cells, as well as advances in materials science to meet specific requirements for bone and soft tissue regeneration by addition of bioactive molecules, are discussed.