Rapamycin facilitates fracture healing through inducing cell autophagy and suppressing cell apoptosis in bone tissues
Authors: J Yu
J Yin
Z-Y Yin
L-X Sheng
Y-F Huo
Y-F Dong
Journal: European review for medical and pharmacological sciences (2017)
Discipline: PHARMACOLOGY & TOXICOLOGY
Keywords: Cell autophagy; Rapamycin; Fracture healing; Molecular mechanism; Sprague-Dawley rats
Affiliations: Department of Orthopedics, the Affiliated Lianyungang Hospital of Xuzhou Medical University, The First People's Hospital of Lianyungang, Lianyungang, China. .

Abstract:  Objective: To investigate the changes in cell autophagy and the molecular mechanism of rapamycin affecting the fracture healing. Material and methods: Sprague-Dawley (SD) rats were used to establish the right femoral shaft fracture models, and then underwent immunofluorescence assay to detect the autophagy level in bone tissues. After model establishment, SD rats were divided into two groups, the control group and the rapamycin group (1 mg/kg/d). Respectively, at the 2nd, 4th, and 6th week, rats were randomly selected from each group for X-ray and Micro-computed tomography (Micro-CT) examinations to determine callus growth, immunofluorescence assay to detect the protein expression of light chain 3 II (LC3 II), immunohistochemistry to evaluate the autophagy level through detecting the expression of Beclin1 in rats, Western blotting assay to detect cell apoptosis in tissues, hematoxylin and eosin staining (HE staining) to evaluate the osteoblastic activity through count of osteoblast in bone tissue at the end of fracture, and measure the expression of vascular endothelial growth factors (VEGF). Results: Significant increases were seen in protein expression of cells in bone tissues at the end of fracture. In rapamycin group, callus formation and calcification level in rats were all higher than those in control group; compared with control group, for rats in rapamycin group, cell autophagy was significantly elevated in bone tissues, while cell apoptosis at the end of fracture was reduced with a significant increase in osteoblastic activity. The expression of VEGF in rapamycin group was higher than that in control group. Conclusions: Rapamycin can facilitate fracture healing through inducing cell apoptosis and suppressing cell apoptosis in bone tissues. 

Retracted: No

PubPeer comments:
  Figure 1. Immunofluorescent assay of LC3 II in callus tissues during fracture healing. (A) Immunofluorescent assays of LC3 II in callus tissues in blank control group and respectively at 12 h, 24 h, 3 d and 7 d after fracture . ![file] You had just one job... , 
 *[left]* Fig 3A. The panels were previously published as *[right]* Fig 6 of  Elcatonin attenuates disuse osteoporosis after fracture fixation of tubular bone in rats ([Ji et al 2015] ). Here flipped through 180 deg for ease of comparison. I have left most of the panel matches as an exercise for the reader. ![] , 
 *[left]* Fig 4C. The panels were taken from *[right]* Fig 4a-f of  LC3, an autophagosome marker, is expressed on oligodendrocytes in Nasu-Hakola disease brains ([Satoh et al 2014] ), after flipping them through 180 deg. to make them original work. ![] , 
 #1 Fig 1 *[left]*, meet Fig 4A *[right]*. ![file] But I see that you re already acquainted. ,