Temporal and spatial cellular and molecular pathological alterations with single-cell resolution in the adult spinal cord after injury

Chen Li,Jingliang Shao,Xiaohang Yang ,Dandan Luo,Kunshan Zhang,Wei Xu,Yi Sun ,Jing Yu,Jiping Liu,Xiao Hu,Changhong Zheng,Libing Zhou ,Weihong Ge,Rongrong Zhu,Yilong Ren,Zhourui Wu,Xuding Zhu ,Wenmin Zhu,Runzhi Huang,Liming Cheng

doi:10.1038/s41392-022-00885-4

Abstract

Spinal cord injury (SCI) involves diverse injury responses in different cell types in a temporally and spatially specific manner. Here, using single-cell transcriptomic analyses combined with classic anatomical, behavioral, electrophysiological analyses, we report, with single-cell resolution, temporal molecular and cellular changes in crush-injured adult mouse spinal cord. Data revealed pathological changes of 12 different major cell types, three of which infiltrated into the spinal cord at distinct times post-injury. We discovered novel microglia and astrocyte subtypes in the uninjured spinal cord, and their dynamic conversions into additional stage-specific subtypes/states. Most dynamic changes occur at 3-days post-injury and by day-14 the second wave of microglial activation emerged, accompanied with changes in various cell types including neurons, indicative of the second round of attacks. By day-38, major cell types are still substantially deviated from uninjured states, demonstrating prolonged alterations. This study provides a comprehensive mapping of cellular/molecular pathological changes along the temporal axis after SCI, which may facilitate the development of novel therapeutic strategies, including those targeting microglia.

Highlights

Traumatic injuries to the central nervous system (CNS) including the spinal cord often result in permanent loss of sensory, motor, and autonomic functions, without effective treatment
Such an injury consistently led to motor behavioral deficits as measured by Basso Mouse Scale (BMS) scoring in a double-blinded manner
We examined the expression of signature genes of repopulated microglia in adult mouse spinal cord after spinal cord injury (SCI) and found that they were highly expressed in clusters 3 and 7 (Fig. 5e, and Fig. 6b), as well as in neonatal mouse spinal cord microglia after SCI, where regeneration was prominent (Fig. 6c, d, and Supplementary Fig. 6f)

Summary

Introduction

Traumatic injuries to the central nervous system (CNS) including the spinal cord often result in permanent loss of sensory, motor, and autonomic functions, without effective treatment. There have been multiple reports describing enhanced SCI repair, not just through long-distance axonal regeneration, but through building new local relay-neural circuits either by implementing exogenous neural stem/progenitor cells (NSCs) or engaging endogenous NSCs.[1–3]. This new repair strategy created a microenvironment that would facilitate axonal outgrowth, the new strategy is much more complicated, involving new neurogenesis, subsequent neuronal maturation, synaptogenesis, neural circuit formation, and neural plasticity. These are biological processes distinct from axonal regeneration per se, and with additional hurdles to overcome.[1–5]

Methods

Results

Conclusion