engleski

BMP-1 enhances bone fracture repair

Bone is the only organ which can be fully regenerated following injury. However, the fracture repair is often limited due to reduced bone regenerative potential. Normal extracellular matrix (ECM) deposition, needed for creating a scaffold for bone mineralization during fracture repair, requires BMP1 a key metalloproteinase involved in ECM formation. In this study we evaluated the role of BMP1 in vitro and on bone repair in a rat fracture model. An osteotomy of the femur was made in male Spraque-Dawley rats. The fragments were fixed by an intramedullary Kirschner pin. The rats were assigned to four groups: control group, group receiving 3ug of BMP1 3 times a week, group receiving 50ug BMP1-3 antibody once a week and the final group receiving 50ug BMP1-1 antibody once a week. The effect of treatment was monitored radiographically and femurs were scanned ex vivo by uCT. Bone biomechanical testing was done using a material testing system. In parallel, bone marrow cells harvested from femurs of 8-week-old WT mice were pooled and plated together with mouse osteoblast-like MC3T3-E1 cell line. Cultures were treated with BMP1 (150ng/mL) or BMP1-3 antibody (1ug/mL). THe von Kossa stain was used to determine the mineralized matrix formation. After treatment total RNA was extracted from MC3T3-E1 cell culture using TRIzol. Gene expression was analyzed by quantitative PCR. Systemically applied BMP1 enhanced bone repair in rat fracture model by increasing extracellular matrix processing and deposition at the fracture site. BMP1 neutralizing antibodies delayed the fracture repair by sequestering BMP1 protease activity. Biomechanical testing confirmed results obtained by the uCT analysis. The exogenous BMP1 enhanced the differentiation of bone marrow-derived MSC towards osteoblasts. Gene expression analysis of MC3T3E1 treated with BMP1 protein showed an increased expression of procollagen I, Bmp1-3 and osteocalcin., while it decreased the expression of Bmp6 and Bmp7. BMP1-3 antibody increased the expression of Bmp6 and Bmp7 in the MC3T3E1 cell culture, mirroring the effects of BMP1. Enhanced bone repair by BMP1 proved its essential role in fracture repair, while BMP1 inhibition resulted in delayed fracture repair, due to prolonged ECM processing. BMP1 supports the bone fracture repair via stimulating the processing of ECM proteins and via increased osteoblasts formation and differentiation.

BMP1; fracure repair

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