Growth factors in bone.
Bone contains several growth factors, including bone morphogenetic proteins (BMPs), transforming growth factor beta (TGF-beta), insulin-like growth factors I and II (IGF-I and IGF-II), platelet derived growth factor (PDGF) and basic and acidic fibroblast growth factor (bFGF and aFGF). Spatial and temporal variations in the expression and secretion of the various growth factors have been demonstrated in osteoblastic cultures and in various experimental and clinical in vivo models, including fracture healing in humans. Local application of various growth factors influences proliferation, differentiation and protein synthesis in osteoblastic cultures and bone formation in different animal models, including experimental fractures and skeletal defects. The BMPs are the only growth factors known to provoke bone formation heterotopically by making undifferentiated mesenchymal cells differentiate into osteoblasts (osteoinduction). BMPs and other growth factors, soon to become commercially available for clinical use, need a delivery system for their sustained release, as the factors are otherwise rapidly absorbed. Some existing systems inhibit bone formation by inducing chronic inflammation or physically by unresorbed carrier obstructing bone formation. New delivery systems are being investigated.
Solheim
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Section of Orthopaedics, Deaconess University Hospital, Haraldsplass, Bergen, Norway.
D001846:Bone Development / Q000187:drug effects* / Q000502:physiology*; D019485:Bone Morphogenetic Proteins / Q000502:physiology / Q000627:therapeutic use; D002478:Cells, Cultured; D004353:Drug Evaluation, Preclinical; D005346:Fibroblast Growth Factors / Q000502:physiology; D017102:Fracture Healing / Q000187:drug effects* / Q000502:physiology*; D006133:Growth Substances / Q000502:physiology* / Q000627:therapeutic use*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000502:physiology / Q000627:therapeutic use; D007335:Insulin-Like Growth Factor II / Q000502:physiology / Q000627:therapeutic use; D010982:Platelet-Derived Growth Factor / Q000502:physiology / Q000627:therapeutic use; D016212:Transforming Growth Factor beta / Q000502:physiology / Q000627:therapeutic use
D019485:Bone Morphogenetic Proteins; D006133:Growth Substances; D010982:Platelet-Derived Growth Factor; D016212:Transforming Growth Factor beta; D005346:Fibroblast Growth Factors; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II