The Effect of BMP7 on Ectopic Calcification with and without Nanosilver Particles in Gluteofemoral Muscle of Rat

Discovery, purification and synthesis of Bone Morphogenetic Proteins (BMP) were an important turning point in understanding of bone physiology for repair of bone defects. The present study aimed at eliminating the limitations caused by the application of bone auto-grafts and finding a proper substitute for bone grafts. This study was the first to evaluate the effect of BMP7 and nanosilver particles on the permeability of muscle cells for ectopic bone formation in Rat gluteofemoral muscle. This experimental double blind study was conducted on 42 rats divided into 6 groups of 7 each. The first 3 groups received an injection of 200 ng BMP7 with 0.1 mg nanosilver particles and the remaining 3 groups received 200 ng BMP7 in 0.4 mg normal saline. Rats were euthanized 7, 14 and 21 days post-operation and evaluated in terms of presence of tissue changes like necrosis, inflammation, and formation of fibrous or calcified tissue under a light microscope with X40, X100, and X400 magnification. The obtained results were analyzed with Hosmer-Lemeshow, chi square and Wilcoxon tests. Results of the 2 groups were analyzed and compared using Mann Whitney U and Kruskal-Wallis tests. No statistically significant differences were detected between the subgroups of our 2 main understudy groups in terms of bone formation, distribution of inflammation (P=0.439), the amount of inflammation (P=0.743) and presence or absence of foreign body (P=0.381) over time. However, the two groups of BMP7 + nanosilver and BMP7 alone showed significant differences over time. Rats do not have sufficient number of efficient receptors for BMP7 in muscle tissue. Even by using nanosilver particles for increasing the permeability of cells, BMP7 was not able to induce muscle cell differentiation to initiate calcification process.