Study on the Mechanism of Qigu Capsule in Upregulating NF-κB/HIF-1α Pathway to Improve the Quality of Bone Callus in Mice at Different Stages of Osteoporotic Fracture Healing

Objective The present study intends to investigate the effects and underlying molecular mechanism of Qigu Capsule (QG) on fracture healing in mice with osteoporosis.Methods Ten-week-old female C57BL/6 mice were ovariectomized and three weeks later were evaluated for successful modeling. Then, all mice were prepared into models of transverse fracture in the right middle femoral shaft. Mice were treated daily using a gavage with normal saline (the NS group), Qigu Capsule (the QG group), or alendronate (the ALN group) postoperatively. Fracture callus tissues were collected and analyzed by X-ray, micro-CT, western blot (WB), and transmission electron microscope (TEM) on postoperation Day 14 (POD14), POD28, and POD42.Results (1) X-ray results showed that on POD14, the QG group had the fracture healing score significantly higher than the NS and ALN groups, and on POD28, it had the fracture healing score higher than the NS group, suggesting that QG could promote fracture healing. (2) Micro-CT results showed that on POD14, the QG group had tissue bone density (TMD) significantly higher than the NS and ALN groups, and on POD28 and POD42, it had bone volume fraction, trabecular number, and TMD significantly higher than the NS group. (3) WB results showed that, compared with the NS group, the QG group had significantly increased expression of nuclear factor kappa-B (NF- κ B), hypoxia-inducible factor-1 α (HIF-1 α ), bone alkaline phosphatase (BALP), runt-related transcription factor 2 (Runx2), bone Gla protein (BGP) and collagen I α 1 (COLI α 1) on POD14, significantly increased expression of NF- κ B, HIF-1 α , BALP and COLI α 1 on POD28, and significantly increased expression of NF- κ B, HIF-1 α , and Runx2 on POD42. (4) TEM scanning results showed that, compared with the NS and ALN groups, the QG group had significantly increased numbers of autophagic vacuoles (AVs) in osteocytes on POD14, POD28, and POD42.Conclusion QG could accelerate osteoporotic fracture healing by promoting bone formation and osteocyte autophagy, possibly through upregulating the NF- κ B/HIF-1 α signaling pathway.