Hubertus Vanessa, Meyer Lea, Waldmann Lilly, Roolfs Laurens, Taheri Nima, Kersting Katharina, von Bronewski Emily, Nieminen-Kelhä Melina, Kremenetskaia Irina, Uhl Christian, Fiedler Kim C, Ode Jan-Erik, Rex Andre, Prüß Harald, Rakhymzhan Asylkhan, Hauser Anja E, Niesner Raluca, Heppner Frank L, Fehlings Michael G, Vajkoczy Peter
Department of Neurosurgery, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
Scientific Workshops, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
J Neurotrauma. 2025 Feb;42(3-4):212-228. doi: 10.1089/neu.2024.0233. Epub 2024 Nov 26.
Traumatic spinal cord injury (SCI) is a devastating condition for which effective neuroregenerative and neuroreparative strategies are lacking. The post-traumatic disruption of the blood-spinal cord barrier (BSCB) as part of the neurovascular unit (NVU) is one major factor in the complex pathophysiology of SCI, which is associated with edema, inflammation, and cell death in the penumbra regions of the spinal cord adjacent to the lesion epicenter. Thus, the preservation of an intact NVU and vascular integrity to facilitate the regenerative capacity following SCI is a desirable therapeutic target. This study aims to identify a therapeutic window of opportunity for NVU repair after SCI by characterizing the timeframe of its post-traumatic disintegration and reintegration with implications for functional spinal cord recovery. Following thoracic clip-compression SCI or sham injury, adult C57BL/6J mice were followed up from one to 28 days. At one, three, seven, 14, and 28 days after SCI/sham, seven-Tesla magnetic resonance imaging (MRI), neurobehavioral analysis (Basso mouse scale, Tally subscore, CatWalk® gait analysis), and following sacrifice immunohistochemistry were performed, assessing vessel permeability via Evans blue (EVB) extravasation, (functional) vessel density, and NVU integrity. Thy1-yellow fluorescent protein+ mice were additionally implanted with a customized spinal window chamber and received longitudinal two-photon excitation imaging (2PM) with the injection of rhodamine-B-isothiocyanate-dextran for the combined imaging of axons and vasculature up to 14 days after SCI/sham injury. Post-traumatic edema formation as assessed by MRI volumetry peaked at one to three days after injury, while EVB permeability quantification revealed a thoroughly injured BSCB up to 14 days after SCI. Partial regeneration of functional vasculature via endogenous revascularization was detected after one to four weeks, however, with only 50-54% of existing vessels regaining functional perfusion. Longitudinal 2PM visualized the progressive degeneration of initially preserved spinal cord axons in the peri-traumatic zone after SCI while displaying a rarefication of functionally perfused vessels up to two weeks after injury. Neurobehavioral recovery started after one week but remained impaired over the whole observation period of four weeks after SCI. With this study, a therapeutic window to address the impaired NVU starting from the first days to two weeks after SCI is identified. A number of lines of evidence including 2PM, assessment of NVU integrity, and neurobehavioral assessments point to the critical nature of targeting the NVU to enhance axonal preservation and regeneration after SCI. Continuous multifactorial therapy applications targeting the integrity of the NVU over the identified therapeutic window of opportunity appears promising to ameliorate functional vessel perseverance and the spinal cord's regenerative capacity.
创伤性脊髓损伤（SCI）是一种严重的疾病，目前缺乏有效的神经再生和神经修复策略。作为神经血管单元（NVU）一部分的血脊髓屏障（BSCB）在创伤后遭到破坏，这是SCI复杂病理生理学中的一个主要因素，与脊髓损伤中心周围半暗带区域的水肿、炎症和细胞死亡有关。因此，保留完整的NVU和血管完整性以促进SCI后的再生能力是一个理想的治疗靶点。本研究旨在通过描述创伤后NVU解体和重新整合的时间框架及其对脊髓功能恢复的影响，确定SCI后NVU修复的治疗时机。对成年C57BL/6J小鼠进行胸段夹压性SCI或假手术损伤后，随访1至28天。在SCI/假手术后1、3、7、14和28天，进行7特斯拉磁共振成像（MRI）、神经行为分析（Basso小鼠评分、Tally子评分、CatWalk®步态分析），并处死小鼠后进行免疫组织化学分析，通过伊文思蓝（EVB）外渗评估血管通透性、（功能性）血管密度和NVU完整性。此外，对Thy1-黄色荧光蛋白+小鼠植入定制的脊髓视窗室，并在SCI/假手术损伤后长达14天内，注射异硫氰酸罗丹明-B-葡聚糖后进行纵向双光子激发成像（2PM），以联合成像轴突和脉管系统。通过MRI容积测量评估的创伤后水肿形成在损伤后1至3天达到峰值，而EVB通透性定量显示SCI后14天内BSCB受到严重损伤。在1至4周后，通过内源性血管再生检测到功能性脉管系统的部分再生，然而，只有50-54%的现有血管恢复了功能性灌注。纵向2PM显示，SCI后创伤周围区域最初保留的脊髓轴突逐渐退化，同时在损伤后两周内显示功能性灌注血管稀疏。神经行为恢复在1周后开始，但在SCI后的整个4周观察期内仍受损。通过本研究，确定了一个从SCI后第一天到两周开始解决受损NVU的治疗窗口。包括2PM、NVU完整性评估和神经行为评估在内的多项证据表明，针对NVU对于增强SCI后轴突保留和再生至关重要。在确定的治疗窗口期内，针对NVU完整性进行持续的多因素治疗应用，似乎有望改善功能性血管的持久性和脊髓的再生能力。
