title: Microvascular protective role of pericytes in melatonin-treated spinal cord injury in the C57BL/6 mice.
abstract: BACKGROUND
  Pericytes, located on microvessels, help to maintain vascular stability and blood-brain barrier integrity. The influence of pericytes on microvessels after spinal cord injury (SCI) is less clear. Therefore, the aim of this study was to investigate whether pericytes took a protective effect on microvessels in melatonin-treated SCI.
  
  
  METHODS
  C57BL/6 mice were randomly divided into three groups: sham group, SCI group, and melatonin group (n = 27 per group). Functional recovery was evaluated using the Basso Mouse Scale. Motor neurons were observed using hematoxylin and eosin staining. Pericyte coverage was analyzed using immunofluorescence. Permeability of blood-spinal cord barrier (BSCB) was assessed by administration of Evan's Blue. Protein levels of occludin, aquaporin-4 (AQP4), angiopoietin-1 (Ang1), intercellular cell adhesion molecule-1 (ICAM-1), Bcl-2, and Bax were determined using Western blotting. Mimicking the pathological conditions of SCI, melatonin-treated primary pericytes were subjected to oxygen-glucose deprivation/reperfusion (OGD/R). Secretion of Ang1 was analyzed using an enzyme-linked immunosorbent assay, and the expression of ICAM-1 was detected by immunofluorescence.
  
  
  RESULTS
  Melatonin treatment improved locomotor functional outcome and rescued motor neurons. Pericyte coverage was significantly reduced after SCI; melatonin treatment alleviated the loss of pericyte coverage and rescued perfused microvessels 7 days after injury. The permeability of BSCB and loss of occludin were attenuated, and edema formation and upregulation of AQP4 were inhibited, after melatonin treatment. The expression of Ang1 and Bcl-2 was improved, while the expression of ICAM-1 and Bax was inhibited, in melatonin-treated SCI mice. Furthermore, the secretion of Ang1 was increased and the expression of ICAM-1 was inhibited in melatonin-treated pericytes after OGD/R.
  
  
  CONCLUSIONS
  Melatonin ameliorated the loss of blood vessels and disruption of BSCB to exert a protective effect on SCI, which might be mediated by increased pericyte coverage. The upregulation of Ang1 in pericytes could inhibit inflammation and apoptosis to protect the microvessels.
authors.affiliation: Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100005, China.
authors.forename: Yingli
authors.initials: Y
authors.lastname: Jing
authors.affiliation: Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100005, China.
authors.forename: Qingbin
authors.initials: Q
authors.lastname: Wu
authors.affiliation: Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100005, China.
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Yuan
authors.affiliation: Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100005, China.
authors.forename: Bingwei
authors.initials: B
authors.lastname: Li
authors.affiliation: Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100005, China.
authors.forename: Mingming
authors.initials: M
authors.lastname: Liu
authors.affiliation: Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100005, China.
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100005, China.
authors.forename: Shuying
authors.initials: S
authors.lastname: Liu
authors.affiliation: Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100005, China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Li
authors.affiliation: Institute of Microcirculation, Key Laboratory of Microcirculation, Ministry of Health, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100005, China. Email: xiurj@aliyun.com; xiurj@imc.pumc.edu.cn.
authors.forename: Ruijuan
authors.initials: R
authors.lastname: Xiu
mesh_terms: D042683:Angiopoietin-1 / Q000378:metabolism; D000818:Animals; D004797:Enzyme-Linked Immunosorbent Assay; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008297:Male; D008550:Melatonin / Q000494:pharmacology* / Q000627:therapeutic use*; D051379:Mice; D008810:Mice, Inbred C57BL; D055806:Microvessels / Q000166:cytology*; D062793:Occludin / Q000378:metabolism; D020286:Pericytes / Q000187:drug effects* / Q000378:metabolism*; D011897:Random Allocation; D013119:Spinal Cord Injuries / Q000188:drug therapy* / Q000378:metabolism*
chemical_list: D042683:Angiopoietin-1; D062793:Occludin; D018799:Intercellular Adhesion Molecule-1; D008550:Melatonin