Reeve-Irvine Research Center University of California Irvine School of Medicine, USA; Department of Anatomy & Neurobiology, University of California Irvine School of Medicine, USA.
Reeve-Irvine Research Center University of California Irvine School of Medicine, USA; Department of Anatomy & Neurobiology, University of California Irvine School of Medicine, USA; Department of Neurobiology & Behavior, University of California Irvine, USA; Department of Neurosurgery, University of California Irvine School of Medicine, USA.
Exp Neurol. 2023 Dec;370:114551. doi: 10.1016/j.expneurol.2023.114551. Epub 2023 Sep 29.
Spinal cord injuries (SCI) cause permanent functional impairments due to interruption of motor and sensory pathways. Regeneration of axons does not occur due to lack of intrinsic growth capacity of adult neurons and extrinsic inhibitory factors, especially at the injury site. However, some regeneration can be achieved via deletion of the phosphatase and tensin homolog (PTEN) in cells of origin of spinal pathways. Here, we deployed an AAV variant that is retrogradely transported (AAV-rg) to deliver gene modifying cargos to the cells of origin of multiple pathways interrupted by SCI, testing whether this promoted recovery of motor function. PTEN;Rosa mice and control Rosa mice received injections of different doses (number of genome copies, GCs) of AAV-rg/Cre into the cervical spinal cord at the time of a C5 dorsal hemisection injury. Forelimb grip strength was tested over time using a grip strength meter. PTEN;Rosa mice with AAV-rg/Cre (PTEN-deleted) exhibited substantial improvements in forelimb gripping ability in comparison to controls. Of note, there were major sex differences in the extent of recovery, with male mice exhibiting greater recovery than females. However, at around 5-7 weeks post-injury/injection, many mice with SCI and AAV-rg-mediated PTEN deletion began to exhibit pathophysiologies involving excessive scratching of the ears and back of the neck and rigid forward extension of the hindlimbs. These pathophysiologies increased in incidence and severity over time. Our results reveal that although intra-spinal injections of AAV-rg/Cre in PTEN;Rosa mice can enhance forelimb motor recovery after SCI, late-developing functional abnormalities occur with the experimental conditions used here. Mechanisms underlying late-developing pathophysiologies remain to be defined.
脊髓损伤 (SCI) 会因运动和感觉通路的中断而导致永久性功能障碍。由于成年神经元内在的生长能力不足和外在的抑制因子，轴突再生不会发生，尤其是在损伤部位。然而，通过删除脊髓通路起源细胞中的磷酸酶和张力蛋白同系物 (PTEN)，可以实现一些再生。在这里，我们使用一种逆行运输的 AAV 变体 (AAV-rg) 将基因修饰载体递送到 SCI 中断的多个通路的起源细胞中，测试这种方法是否能促进运动功能的恢复。PTEN;Rosa 小鼠和对照 Rosa 小鼠在 C5 背侧半切损伤时接受不同剂量（基因组拷贝数，GC）的 AAV-rg/Cre 颈脊髓注射。使用握力计随时间测试前肢握力。与对照相比，PTEN;Rosa 小鼠接受 AAV-rg/Cre（PTEN 缺失）注射后，前肢抓握能力有了显著提高。值得注意的是，在恢复程度上存在明显的性别差异，雄性小鼠的恢复程度大于雌性。然而，在损伤/注射后约 5-7 周，许多接受 SCI 和 AAV-rg 介导的 PTEN 缺失的小鼠开始表现出涉及过度抓挠耳朵和颈部后面以及后肢僵硬向前伸展的病理生理。这些病理生理变化随着时间的推移而增加。我们的结果表明，尽管在 PTEN;Rosa 小鼠的脊髓内注射 AAV-rg/Cre 可以增强 SCI 后前肢运动的恢复，但在使用这里的实验条件下，会出现迟发性功能异常。迟发性病理生理的发生机制仍有待确定。
