Isopsoralen accelerates tibia fracture healing by promoting bone formation in mice / 陆军军医大学学报

ABSTRACT

Objective To determine the effect of isopsoralen(ISO)on the healing of tibia fracture in mice and explore its underlying mechanism.Methods Fifty male C57BL/6 mice(2 month old,20±2 g)were randomly divided into model group and ISO treatment group,with 25 animals in each group.From the 3rd day after modeling,the mice from the ISO group were given an intragastric gavage of 40 mg/kg ISO,once per day for 28 consecutive days,while those of the model group was given same volume of normal saline in same way.On the 7th,14th,21st,and 28th day after gavage,the tibia on the surgical side was taken,and the fracture area was quantified by bone volume/total volume(BV/TV)after micro-CT scanning.The healing and shaping of the fracture end were observed through HE staining.ELISA was used to detect the serum contents of bone alkaline phosphatase(BALP)and procollagen type I N-terminal peptide(PINP)on the 14th day of gavage.Western blotting was employed to determine the expression levels of Collagen Ⅰ,Runx2,BMP2,OSX,and VEGF in the tibial callus tissue in 7 and 14 d after gavage.Vascular perfusion was applied to observe the callus microvessels in 28 d to quantitatively analyze the vascular volume fraction and vessel diameter.Immunohistochemical staining was conducted to observe the expression of VEGF in the callus in 14 d after gavage.Results HE staining displayed that the ISO group had faster healing process than the model group.Micro-CT quantification results showed that the ISO group had higher BV/TV ratio in 7 d after gavage though no statistical difference,significantly higher ratio in 14 d(P＜0.05),but obviously lower ratio in 21 and 28 d after gavage(both P＜0.05)when compared with the model group.The serum contents of BALP and PINP were also remarkably higher in the ISO group than the model group(P＜0.05).Western blotting results indicated that the expression levels of Collagen Ⅰ,Runx2,BMP2,OSX and VEGF in the ISO group were higher than those in the model group(P＜0.05).The results of angiography revealed that the vascular volume fraction and vessel diameter were notably increased in the ISO group than the model group(both P＜0.05).Immunohistochemical assay showed that the expression of VEGF was higher in the ISO group than the model group(P＜0.05).Conclusion ISO can improve the activity of osteoblasts,increase the expression of osteogenesis-related proteins,and accelerate the angiogenesis to promote fracture healing.