title: Negative pressure technology enhances bone regeneration in rabbit skull defects.
abstract: BACKGROUND
  Bone is a slowly regenerating tissue influenced by various physiological processes, including proliferation, differentiation, and angiogenesis, under the control of growth factors. Shortening this healing time is an important and popular clinical research focus in orthopedics. Negative pressure can stimulate angiogenesis, improve blood circulation, promote granulation tissue growth and accelerate tissue wound healing. We sought to determine whether negative pressure could reduce bone healing time in a rabbit cranial defect model.
  
  
  METHODS
  Four symmetrical holes (diameter, 3.5 mm) were drilled into the skulls of 42 New Zealand white rabbits, with two holes in each parietal bone. For each rabbit, the two sides were then randomly assigned into experimental and control groups. Using negative pressure suction tubes, experimental holes were treated with -50 kPa for 15 minutes, four times per day, whereas the control holes remained untreated. After 4 weeks, the negative pressure suction tubes were removed. At 2, 4, 6 and 8 weeks, three-dimensional (3D) reconstruction computed tomography (CT), X-ray radiopacity, and two-photon absorptiometry were used to evaluate new bone formation. Histological changes were determined by hematoxylin and eosin (H.E) staining. At weekly intervals until 6 weeks, the mRNA expression levels of vascular endothelial growth factor (VEGF) and bone morphogenetic protein (BMP)-2 were evaluated by RT-PCR. A paired student's t-test was employed to compare X-ray radiopacity and bone density measurements between the experimental and control groups.
  
  
  RESULTS
  3D-reconstruction CT showed that new bone regeneration in the experimental group was greater than that in the control group at 4 and 6 weeks. At these time points, the experimental group presented with higher X-ray radiopacity and increased bone density (P < 0.05) as compared with the control group. Cartilage islands and new bone were observed by H.E staining at 2 weeks in the experimental group. By 6 weeks, the new bone had matured into lamellar bone in the experimental group. RT-PCR results showed that VEGF and BMP-2 were highly expressed in the experimental group as compared with control.
  
  
  CONCLUSIONS
  Intermittent negative pressure can promote the regeneration of bone possibly by enhancing the expression of VEGF and BMP-2.
authors: Department of Orthopedics, First Affiliated Hospital of Medical College of Xi'an Jiaotong University, Xi'an 710061, China. zyingang@mail.xjtu.edu.cn
authors: Yin-gang
authors: YG
authors: Zhang
authors: Zhi
authors: Z
authors: Yang
authors: Hong
authors: H
authors: Zhang
authors: Miao
authors: M
authors: Liu
authors: Yushen
authors: Y
authors: Qiu
authors: Xiong
authors: X
authors: Guo
mesh_terms: D015502:Absorptiometry, Photon; D000818:Animals; D015519:Bone Density; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics / Q000378:metabolism; D001861:Bone Regeneration; D005260:Female; D021621:Imaging, Three-Dimensional; D008297:Male; D023421:Models, Animal; D054843:Negative-Pressure Wound Therapy; D010294:Parietal Bone / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology* / Q000601:surgery; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D011857:Radiographic Image Interpretation, Computer-Assisted; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013194:Staining and Labeling; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D014945:Wound Healing
chemical_list: C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D012333:RNA, Messenger; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A