EXPRESSION AND ACTIVATION OF THE BMP-SIGNALING COMPONENTS IN HUMAN FRACTURE NONUNIONS

Abstract

The immunohistochemical localization of all seven BMP-signaling components was demonstrated in seventeen (81%) of the twenty-one patients. The remaining four patients lacked one or more of the components. Areas of newly formed bone had the highest percentage of positively staining cells, with the staining generally decreasing in areas remote from bone formation. However, even in areas of dense fibrous tissue and in specimens that lacked newly formed bone, immunostaining was still present. The staining patterns showed co-localization of the BMP-2, BMP-4, and BMP-7 proteins with the BMP receptors. The presence of pSmad1 signified the activated state of the BMP receptors, which implies that the BMP signal is transduced inside the cell.