Fracture healing represents a physiological process regulated by a variety of signalling molecules, growth factors and osteogenic progenitor cells. Bone healing following trauma is associated with increased serum concentrations of several pro-inflammatory and angiogenic growth factors1. Platelet-derived growth factor (PDGF) has been shown to stimulate mesenchymal stem cell (MSC) proliferation in vitro. However, the in vivo relationship between the levels of PDGF and the numbers of MSCs in humans has not yet been explored. The aim of this study was to investigate PDGF release in the peripheral circulation following trauma and to correlate it with the numbers of MSCs in iliac crest bone marrow (BM) aspirate and in peripheral blood. Trauma patients with lower extremity fractures (n=12, age 18-63 years) were recruited prospectively. Peripheral blood was obtained on admission, and at 1, 3, 5 and 7 days following admission. The serum was collected and PDGF was measured using the enzyme-linked immuno-sorbent assay (ELISA) technique. Iliac crest (BM) aspirate (20ml) and peripheral blood (PB) (20ml) was obtained on days 0-9 following admission. MSCs were enumerated using standard colony-forming unit fibroblasts (CFU-F) assay.Background and objectives
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