Neuronal and Tissue Regeneration Laboratory, Centro de Investigación Príncipe Felipe, 46012, Valencia, Spain.
Department of Biotechnology, Universitat Politècnica de València, Valencia, Spain.
Cell Mol Life Sci. 2022 Jul 29;79(8):455. doi: 10.1007/s00018-022-04494-w.
Neural progenitor cell (NPC) transplantation represents a promising treatment strategy for spinal cord injury (SCI); however, the underlying therapeutic mechanisms remain incompletely understood. We demonstrate that severe spinal contusion in adult rats causes transcriptional dysregulation, which persists from early subacute to chronic stages of SCI and affects nearly 20,000 genes in total tissue extracts. Functional analysis of this dysregulated transcriptome reveals the significant downregulation of cAMP signalling components immediately after SCI, involving genes such as EPAC2 (exchange protein directly activated by cAMP), PKA, BDNF, and CAMKK2. The ectopic transplantation of spinal cord-derived NPCs at acute or subacute stages of SCI induces a significant transcriptional impact in spinal tissue, as evidenced by the normalized expression of a large proportion of SCI-affected genes. The transcriptional modulation pattern driven by NPC transplantation includes the rescued expression of cAMP signalling genes, including EPAC2. We also explore how the sustained in vivo inhibition of EPAC2 downstream signalling via the intrathecal administration of ESI-05 for 1 week impacts therapeutic mechanisms involved in the NPC-mediated treatment of SCI. NPC transplantation in SCI rats in the presence and absence of ESI-05 administration prompts increased rostral cAMP levels; however, NPC and ESI-05 treated animals exhibit a significant reduction in EPAC2 mRNA levels compared to animals receiving only NPCs treatment. Compared with transplanted animals, NPCs + ESI-05 treatment increases the scar area (as shown by GFAP staining), polarizes microglia into an inflammatory phenotype, and increases the magnitude of the gap between NeuN + cells across the lesion. Overall, our results indicate that the NPC-associated therapeutic mechanisms in the context of SCI involve the cAMP pathway, which reduces inflammation and provides a more neuropermissive environment through an EPAC2-dependent mechanism.
神经祖细胞 (NPC) 移植代表了一种有前途的脊髓损伤 (SCI) 治疗策略；然而，其潜在的治疗机制仍不完全清楚。我们证明，成年大鼠严重的脊髓挫伤会导致转录失调，这种失调会持续存在于 SCI 的早期亚急性期和慢性期，并影响到总组织提取物中的近 20000 个基因。对这个失调转录组的功能分析显示，cAMP 信号成分在 SCI 后立即显著下调，涉及 EPAC2（cAMP 直接激活的交换蛋白）、PKA、BDNF 和 CAMKK2 等基因。脊髓源性 NPC 在 SCI 的急性或亚急性期的异位移植会导致脊髓组织中产生显著的转录影响，这可以从很大一部分受 SCI 影响的基因的表达正常化中得到证明。NPC 移植驱动的转录调节模式包括 cAMP 信号基因的恢复表达，包括 EPAC2。我们还探讨了通过鞘内注射 ESI-05 持续抑制 EPAC2 下游信号在 NPC 介导的 SCI 治疗中涉及的治疗机制中的作用。在存在和不存在 ESI-05 给药的情况下，将 NPC 移植到 SCI 大鼠中会促使 rostral cAMP 水平升高；然而，与仅接受 NPC 治疗的动物相比，NPC 和 ESI-05 治疗的动物的 EPAC2 mRNA 水平显著降低。与移植动物相比，NPCs+ESI-05 治疗会增加疤痕面积（如 GFAP 染色所示），将小胶质细胞极化成炎症表型，并增加损伤处 NeuN+细胞之间的间隙幅度。总体而言，我们的结果表明，NPC 相关的治疗机制涉及 SCI 中的 cAMP 途径，该途径通过 EPAC2 依赖的机制减少炎症并提供更有利于神经发生的环境。
