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

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.

Spatiotemporal Dynamics of the Molecular Expression Pattern and Intercellular Interactions in the Glial Scar Response to Spinal Cord Injury

“…Here, we used the spatial mapping maps of known typical markers in different cell types to verify the spot division after applying the AddModule Score function from the Seurat R package. Fortunately, we found that each cluster was the most likely reasonable cell type shown in the previous studies [10,20,21].…”

Capacity of astrocytes to promote axon growth in the injured mammalian central nervous system

“…Interestingly, regional identity of astrocytes, as defined by gene expression signatures, is preserved even in a reactive state (Diaz-Castro et al, 2021). scRNA-seq confirmed that distinct astrocyte subtypes mount different transcriptional responses with temporal variation to the same CNS insult (Hasel et al, 2021;Li et al, 2022). Diseasespecific interaction of transcriptional regulators together with engagement of core reactivity-promoting transcription factors in reactive astrocytes collectively contributes to differential gene expressions that determine disease-specific astrocytic phenotype (Burda et al, 2022).…”

“…Evolution of astrocyte complexity was proposed to enable the integration and expansion of processing power of the human brain ( Oberheim et al, 2006 ). scRNA-seq revealed regional astrocyte diversity, defined transcriptomically, in the healthy brain and spinal cord of mice and humans ( Saunders et al, 2018 ; Hasel et al, 2021 ; Li et al, 2022 ; Sadick et al, 2022 ).…”

Inflammation: A Target for Treatment in Spinal Cord Injury

“…Furthermore, with transcriptional analysis of individual cells in the crush-injured spinal cord in adult mice, other authors demonstrated novel microglia and astrocyte subtypes and their dynamic conversions into additional stage-specific subtypes/states. Most of the dynamic changes occurred 3 days after injury; a recovery trend was observed between 3 and 14 days after injury, and after 14 days, reactivation of microglia and a further decrease in neuronal, astrocytic, and endothelial populations along with a continued increase in leukocyte population were evident [ 40 ].…”