Effect of Taohong Siwu Decoction() early intervention on mesenchymal stem cells homing in fracture healing in rats

Abstract

To observe the effects of Taohong Siwu Decoction(, THSWD) on the mesenchymal stem cells(MSCs) migration, homing number and cytokine expression in callus during the early process of fracture healing, and to explore the mechanism of THSWD on accelerationg fracture healing by regulating the homing of MSCs in rats. A rat model of right femoral shaft open fracture was established. Thirty-two 5-week-old male Sprague-Dawley rats, weighting 110 to 130 g, were divided into control group, low-dose group, medium-dose group and high-dose group by using random number table. Distilled water was given to the control group, and the other groups were given Taohong Siwu Decoction. The rats were gavaged twice a day for 5 consecutive days after surgery. Bone volume/tissue volume(BV/TV) and bone mineral density(BMD) were observed using micro-computed tomography (micro-CT) at 21 days after surgery. At 5 days post-fracture, peripheral blood MSCs from THSWD treated and untreated rats were cultured in vitro. Subsequently, the migration ability of MSCs was observed by cell migration assay. The number of MSCs homing to the callus at the early stage of fracture (5 d) was detected by Immunohistochemistry (IHC). Protein chip was used to detect the expression of cytokines in callus. Micro-CT results showed that BV/TV was higher in the high-dose group than in the medium-dose group (P=0.032), and higher in the medium-dose group than in the low-dose group(P=0.041), with no difference between the control and low-dose group (P=0.651). In addition, there was no difference in BMD between low-dose group and the model group (P=0.671), and lower in the low-dose group than in the medium-dose group(P=0.018), and the medium-dose group was lower than the high-dose group(P=0.008). Cell migration assay showed that THSWD promotes enhanced the migration ability of peripheral blood MSCs. IHC assay revealed that CD45-, CD90+, CD29+ MSCs significantly increased in bone callus after THSWD intervention compared with the control group. Protein chip showed that THSWD promoted the upregulation of CINC-1(×2.91), CINC-3(×1.59), LIX(×1.5), Thymus Chemokine (×2.55), VEGF (×1.22) and the down-regulation of TIMP-1 (×2.98). THSWD, a representative formula of "promoting blood circulation and removing blood stasis", can significantly accelerate fracture healing, and its mechanism may be related to enhancing the migration ability of peripheral blood MSCs and up-regulating CINC-1, CINC-3, LIX, Thymus Chemokine, VEGF and down-regulating TIMP-1 in bone callus, which promotes the peripheral blood MSCs homing in the early stage of fracture.