BACKGROUND:Fracture healing mechanism is complex and affected by many factors, and delayed fracture healing or nonunion often occurs. How to promote fracture healing has become a serious problem.
OBJECTIVE:To observe the effect of local application of nerve growth factor on early fracture healing after peripheral nerve injury.
METHODS:Thirty-six healthy male Wistar rats were selected to establish tibial fracture models, which were randomly divided into four groups, with 18 limbs in each group. Group A: tibial fracture+normal saline injectionvia bilateral gastrocnemius muscles; group B: tibial fracture+nerve injury+normal saline injection; group C: tibial fracture+local injection of nerve growth factor; group D: tibial fracture+nerve injury+local injection of nerve growth factor. Calus metrology results were compared among different groups.
RESULTS AND CONCLUSION:The calus volume was the most in the group B at 4 weeks of intervention, but there were no different among the other three groups (P > 0.05). At 2 weeks of intervention, the bone resorption area was significantly larger in the group B than the group D (P < 0.05), and the osteoclast index was significantly higher in the group A than the group C (P < 0.05); while at 4 weeks of intervention, the mineralized bone trabecular width was significantly lower in the group A than the group C (P < 0.05) as wel as lower in the group C than the group D (P < 0.05). These findings indicate that after peripheral nerve injury, local application of nerve growth factor can enhance the osteogenic ability, effectively inhibit osteoclast activity, and promote the early healing of fracture.

Objective To investigate the effects of pterostilbene on human colon cancer LoVo cells and study the regulatory mechanism of nuclear factor E2-related factor 2(Nrf2)in the process of pterostilbene acting on LoVo cells.Methods LoVo cells were treated with different concentrations(5,10,20,40,60,80,100 panol/L)of pterostilbene.Cell viability,migration,invasion,and apoptosis were examined by CCK-8,scratch,Tran-swell,and TUNEL assays,respectively.The mitochondrial membrane potential was measured by the mitochon-drial membrane potential assay kit with JC-1.The reactive oxygen species level was measured by 2',7'-dichlo-rofluorescein diacetate.The protein levels of Nrf2,phosphorylated Nrf2,heme oxygenase 1,and apoptotic pro-teins(Bcl2 and Bax)were determined by Western blotting.In addition,cell viability,Nrf2 expression,and ap-optosis rate were determined after co-application of the Nrf2-specific agonist sulforaphane.Results Compared with the control group,40,60,80,100 μmol/L pterostilbene reduced the viability of LoVo cells(P=0.014,P＜0.001,P＜0.001,P＜0.001).Pterostilbene at 5,10,20 μmol/L did not show effects on cell viability but inhibited cell migration(P=0.008,P＜0.001,P＜0.001)and invasion(all P＜0.001).Pterostilbene at 40,60,80 μmol/L increased apoptosis(P=0.014,P＜0.001,P＜0.001),promoted mitochondrial membrane potential depolarization(P=0.026,P＜0.001,P＜0.001)and reactive oxygen species accumula-tion(all P＜0.001),and down-regulated the expression of phosphorylated Nrf2(P=0.030,P＜0.001,P＜0.001),heme oxygenase 1(P=0.015,P＜0.001,P＜0.001),and Bc12(P=0.039,P＜0.001,P＜0.001)in LoVo cells.Pterostilbene at 60,80 μmol/L down-regulated Nrf2 expression(P=0.001,P＜0.001)and up-regulated Bax expression(both P＜0.001).The application of sulforaphane reversed the effects of pterostilbene on cell viability(P＜0.001),apoptosis(P＜0.001),and Nrf2 expression(P=0.022).Conclusion Pterostilbene is a compound that can effectively inhibit colon cancer cells by inhibiting the Nrf2 pathway.