Early transplantation of growth differentiation factor 11-silenced bone marrow stromal cells promotes osteogenesis in necrotic femoral head induced by steroid in rats / 中华创伤骨科杂志

ABSTRACT

Objective@#To study the effect of growth differentiation factor (GDF) 11-silenced bone marrow stromal cells (BMSCs) on bone regeneration in early steroid-induced osteonecrosis of the femoral head in rats.@*Methods@#After GDF11 expression in BMSCs was inhibited by siRNA, the knockdown efficiency and transfection cytotoxicity were detected. The further experiments both in vitro (n=3) and in vivo (n=8) were divided into 4 groups respectively: blank control group (without any intervention), model group (glucocorticoid treatment), experimental group (siRNA transfection and glucocorticoid treatment) and negative control group (negative control transfection and glucocorticoid treatment). The BMSCs were induced into osteogenic differentiation. Alkaline phosphatase (ALP) staining and alizarin red staining were applied to evaluate the osteogenic differentiation ability of the cells while reverse transcription polymerase chain reaction (qRT-PCR) was employed to detect the relative expression levels of osteogenic markers. The osteogenesis in the necrotic femoral head was evaluated by microCT, H&E staining, immunohistochemistry staining and biomechanical test.@*Results@#No transfection cytotoxicity was found (P>0.05). The ALP staining and alizarin red staining showed that the osteogenic differentiation of BMSCs in the experimental group was better than that in the model group. At the level of mRNA, the relative expression of ALP, runt-related transcription factor (Runx) 2, osteocalcin (OCN) and type Ⅰ collagen (α1) (COL1A1) in the blank control group (1.00±0.09, 1.02±0.23, 1.03±0.30 and 1.02±0.25, respectively) were significantly higher than those in the model group (0.46±0.11, 0.50±0.11, 0.35±0.01 and 0.57±0.02, respectively) but significantly lower than those in the experimental group (1.97±0.30, 0.94±0.19, 1.50±0.18 and 1.28±0.37) (all P<0.05). MicroCT images and quantitative analysis showed that the bone mass in the experimental group was significantly increased compared with the model group (P<0.05). Histological examination showed better bone regeneration and higher expression of Runx2 and COL1 in the necrotic femoral head in the experimental group than in the model group. Improved biomechanical properties were shown in the experimental group compared with the model group (P<0.05).@*Conclusions@#Silence of GDF11 expression may alleviate the inhibitory effect of glucocorticoid on osteogenic differentiation of BMSCs. Early transplantation of GDF11-silenced BMSCs may promote osteogenesis in the necrotic femoral head in rats.