Detection of bone and cartilage-related proteins in plasma of patients with a bone fracture using liquid chromatography-mass spectrometry

Following bone fracture, a large number of growth factors, cytokines, and their cognate receptors involved in the repair process are active at the fracture site. To determine whether they appear in patients' blood as candidate biomarkers for following the outcome of healing, we analysed the plasma of 25 patients with an acute bone fracture following affinity plasma purification, SDS gel electrophoresis and liquid chromatography - tandem mass spectrometry (LC-MS/MS). Two hundred and thirteen nonredundant proteins were identified in the in-gel analysis of pooled plasma proteins. Gene ontology (GO) analysis indicated that a majority of detected proteins were of extracellular origin, whereas only a small number were of intracellular (cytosol and nucleus) origin. A significant proportion of detected proteins was involved in the cell growth and proliferation, transport and coagulation. Twelve proteins were potentially related to bone and cartilage metabolism, and several have not been previously identified in the plasma, including: TGF-beta induced protein IG-H-3, cartilage acidic protein 1, procollagen C proteinase enhancer protein and TGF-beta receptor III.