Synergistic effect ofRhBMP-2 and bFGF on ectopic osteogenesis in mice

ABSTRACT

Objective:To investigate the synergistic effect and mechanism of the combined application of recombinant human bone morphogenetic protein-2(rhBMP-2) and basic fibroblast growth factor (bFGF).Methods:24KM male mice were randomly divided into6 groups with4 mice in each group, namely,GroupA(control group),GroupB(only treated with collagen),GroupC(treated with 2 ng bFGF+collagen),GroupD(treated with4 μg rhBMP-2+collagen),GroupE(treated with4 μg rhBMP-2+2 ng bFGF+collagen) andGroupF(treated with4 μg rhBMP-2+4 ng bFGF+collagen). The composites were implanted into the intermuscular septum of hind legs mice; whereas in control group, intermuscular septum of mice was separated and no implantation was performed. General observation, detection of concentration of calcium content, micro computed tomography (Micro-CT), three-dimensional reconstruction scan, measurement of bone mineral density(BMD), bone volume fraction(BVF) and trabecular thickness(Tb.Th), as well as histological observation withHE staining andALP andCD34 immumohistochemical staining were performed.Results:Ectopic osteogenesis was found inGroupsD,E andF mice.The difference in concentration of calcium contentswas statistically significant betweenGroupsD andE(P0.05).Micro-CT and three-dimensional reconstruction revealed continuous newborn bone substance in external surface of ectopic bone formation, and the center of bone formation did not show obvious substantial filling by bone substance.The differences in BMD,BVF andTb.Th were statistically significant betweenGroupsD andE orF(P<0.01 or <0.05). HE staining showed that inGroupsD,E andF, newborn bone substance was mainly located at the edge of ectopic bone formation, and the bone formation inGroupsE andF was better than that in GroupD.ALP andCD34 immumohistochemical staining revealed the positive expression mainly at the edge of ectopic bone formation, and area of positiveexpression inGroupsE andF was larger than that inGroupsD.Conclusions:rhBMP-2 possesses the capacity to induce ectopic osteogenesis independently, but bFGF does not have this ability; the combined application of rhBMP-2 and bFGF can enhance the synergetic effect on inducing ectopic osteogenesis.