title: Two-photon microscopy as a tool to investigate the therapeutic time window of methylprednisolone in a mouse spinal cord injury model.
abstract: OBJECTIVE
  The aim of the present study was to explore the use of two-photon microscopy for investigating the therapeutic time window of methylprednisolone (MP) treatment after spinal cord injury (SCI).
  
  
  METHODS
  Twenty-four YFP H-line mice were subjected to hemisection SCI and then divided into four groups. Group 1 received MP at 30 min post-injury; group 2 received MP at 8 h post-injury; group 3 received MP at 24 h post-injury; and group 4 received saline at 30 min post-injury. Post-injury axonal dieback was imaged in vivo using two-photon microscopy. After all imaging sessions, histological examination of the surviving neurons and microglial/macrophage accumulation was performed.
  
  
  RESULTS
  Two-photon imaging revealed the degree of progressive axon damage after SCI. Group 1 exhibited a shorter axonal dieback distance and slower axonal dieback speed than groups 2, 3, and 4 (p < 0.01). MAP-2 staining revealed greater neuronal survival in group 1 than in groups 2, 3, and 4 (p < 0.05). F4/80 staining revealed greater microglial/macrophage density in groups 2, 3, and 4 than in group 1 (p< 0.05).
  
  
  CONCLUSIONS
  MP therapy may help attenuate progressive axon damage, reduce neuronal death, and inhibit microglial/macrophage accumulation, especially when initiated shortly after SCI.
authors.affiliation: Department of Orthopedics, the General Hospital of Chinese People's Liberation Army, Beijing, China.|Drug Discovery Center, Key Laboratory of Chemical Genomics, Shenzhen Graduate School, Peking University, Shenzhen, China.
authors.forename: Yiling
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Orthopedics, the General Hospital of Chinese People's Liberation Army, Beijing, China.
authors.forename: Lihai
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Orthopedics, the General Hospital of Chinese People's Liberation Army, Beijing, China.
authors.forename: Xinran
authors.initials: X
authors.lastname: Ji
authors.affiliation: Department of Spine Surgery, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Mao
authors.initials: M
authors.lastname: Pang
authors.affiliation: School of Life Sciences, Lanzhou University, Lanzhou, China.
authors.forename: Furong
authors.initials: F
authors.lastname: Ju
authors.affiliation: Department of Orthopedics, the General Hospital of Chinese People's Liberation Army, Beijing, China.|Drug Discovery Center, Key Laboratory of Chemical Genomics, Shenzhen Graduate School, Peking University, Shenzhen, China.
authors.forename: Jinhui
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Drug Discovery Center, Key Laboratory of Chemical Genomics, Shenzhen Graduate School, Peking University, Shenzhen, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: School of Life Sciences, Lanzhou University, Lanzhou, China.
authors.forename: Shengxiang
authors.initials: S
authors.lastname: Zhang
authors.affiliation: F.M. Kirby Program in Neuroscience, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Zhigang
authors.initials: Z
authors.lastname: He
authors.affiliation: Drug Discovery Center, Key Laboratory of Chemical Genomics, Shenzhen Graduate School, Peking University, Shenzhen, China.|Skirball Institute, Department of Neuroscience and Physiology, New York University School of Medicine, New York, USA.
authors.forename: Wen-Biao
authors.initials: WB
authors.lastname: Gan
authors.affiliation: Department of Orthopedics, the General Hospital of Chinese People's Liberation Army, Beijing, China.
authors.forename: Peifu
authors.initials: P
authors.lastname: Tang
mesh_terms: D000818:Animals; D001369:Axons / Q000473:pathology; D008297:Male; D008775:Methylprednisolone / Q000627:therapeutic use*; D051379:Mice; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D023421:Models, Animal; D018696:Neuroprotective Agents / Q000627:therapeutic use*; D013119:Spinal Cord Injuries / Q000188:drug therapy* / Q000473:pathology
chemical_list: D018696:Neuroprotective Agents; D008775:Methylprednisolone
keywords: Axon; in vivo imaging; microglia; spinal cord injury; two-photon microscopy