Association of Bone Morphogenetic Protein (BMP)/Smad Signaling Pathway with Fracture Healing and Osteogenic Ability in Senile Osteoporotic Fracture in Humans and Rats.

BACKGROUND To investigate the effect of the BMP/Smad signaling pathway on fracture healing and osteogenic ability in senile osteoporotic fracture on humans and rats. MATERIAL AND METHODS Sixty-two patients and well-matched normal controls were enrolled for clinical observation. A rat model of senile osteoporotic fracture was established. Serum BMP2 and Smad4 levels, as well as alkaline phosphatase (ALP) activity, were detected by ELISA. Fracture healing was observed by X-ray radiography and bone formation was analyzed by micro-CT. RESULTS Serum BMP2 and Smad4 levels in patients with senile osteoporotic fracture were significantly lower than those in normal controls (all P<0.01). BMP2 was highly positively correlated with Smad4 in patients with senile osteoporotic fracture (r=0.738). Compared with patients with low serum BMP2 and Smad4 levels, visual analog scale scores decreased, bone mineral density (BMD) increased, and duration of fracture healing was shortened in patients with high levels (all P<0.05). Compared with the Model group, serum BMP2 and Smad4 levels increased, fracture healing was improved, BMD, trabecular bone volume (TBV), tissue volume (TV), bone volume fraction (BV/TV), mean trabecular thickness (Tb. Th), and mean number of trabecular bone (Tb. N) were increased, and ALP activity increased in the BMP2 overexpression group (all P<0.05), while each index in the NC group showed no statistical difference relative to rats in the Model group (all P>0.05). CONCLUSIONS BMP2 overexpression can promote fracture healing and osteogenic ability in senile osteoporotic fractures through activating the BMP/Smad signaling pathway.