Two-photon microscopy as a tool to investigate the therapeutic time window of methylprednisolone in a mouse spinal cord injury model

Article type: Research Article

Authors: Zhang, Yiling^{a; b} | Zhang, Lihai^a | Ji, Xinran^a | Pang, Mao^d | Ju, Furong^e | Zhang, Jinhui^{a; b} | Li, Wei^b | Zhang, Shengxiang^e | He, Zhigang^f | Gan, Wen-Biao^{b; c; *} | Tang, Peifu^{a; *}

Affiliations: [a] Department of Orthopedics, the General Hospital of Chinese People’s Liberation Army, Beijing, China | [b] Drug Discovery Center, Key Laboratory of Chemical Genomics, Shenzhen Graduate School, Peking University, Shenzhen, China | [c] Skirball Institute, Department of Neuroscience and Physiology, New York University School of Medicine, New York, USA | [d] Department of Spine Surgery, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China | [e] School of Life Sciences, Lanzhou University, Lanzhou, China | [f] F.M. Kirby Program in Neuroscience, Children’s Hospital Boston, Harvard Medical School, Boston, Massachusetts, USA

Correspondence: [*] Correspondence to: Dr. Peifu Tang, MD, Department of Orthopedics, the General Hospital of Chinese People’s Liberation Army, Fuxing Road 28th, Beijing, 100853, PR China. Tel./Fax: +86 10 66938101; [email protected]

Correspondence: [*] Correspondence to: Pro. Wen-Biao Gan, PhD, Skirball Institute, Department ofNeuroscience and Physiology, New York University School of Medicine, New York, 10016, USA. [email protected]

Abstract: Purpose: 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.

Keywords: Axon, in vivo imaging, microglia, spinal cord injury, two-photon microscopy

DOI: 10.3233/RNN-140463

Journal: Restorative Neurology and Neuroscience, vol. 33, no. 3, pp. 291-300, 2015