Department of General Pathology, Pomeranian Medical University, Al. Powstancow Wlkp. 72, 70-111 Szczecin, Poland.
Exp Eye Res. 2013 Jul;112:68-78. doi: 10.1016/j.exer.2013.04.004. Epub 2013 Apr 25.
The retinal pigment epithelium (RPE) has been reported to demonstrate feasible self-regenerative potential under specific conditions. However, the precise underlying mechanisms involved in this process are still elusive. Here, we performed a sequential morphological, molecular, and functional analysis of retinal injury and subsequent tissue regeneration after intravenous administration of a low dose of sodium iodate (15 mg/kg) in mice over long-term observation, up to 3 months post-injury. To assess the kinetics of the injury/recovery process, the electroretinography (ERG) responses were correlated with ongoing alterations in retinal structure and the global gene expression profile of injured retinas using genome-wide RNA microarray technology, western blotting and immunohistochemical analyses. We observed considerable improvement in the rod cell-mediated ERG response, which was accompanied by the regeneration of RPE within the injury site by the 3rd month post-injury. Our results confirm that the repairing mechanisms within injured retinas involve a significant glial cell reaction marked by glial cell proliferation, migration from their original location toward the injury site, followed by a significant overproduction of NTs such as BDNF, GDNF and NT-3. The global gene expression analysis revealed that initially up-regulated genes associated with cell death, apoptosis, acute response to stress pathways underwent considerable down-regulation in the late post-injury period. Accordingly, the genes implicated in nervous tissue remodeling and neuron development, the regulation of synaptic transmission and the establishment of localization were substantially induced by the 3rd month. Collectively, our observations support the view that Müller glial cells might well play an active role not only in retinal cell reorganization following injury but potentially also in RPE regeneration, which appears to be the key event in retinal reparative process. Furthermore, we provided novel compelling evidence of the crucial role of neurotrophins in the pathophysiology of retinal repair and identified the signaling pathways that are activated during this process.
视网膜色素上皮 (RPE) 在特定条件下已被证明具有可行的自我再生潜力。然而，这个过程中涉及的确切潜在机制仍难以捉摸。在这里，我们在长期观察中（最长可达 3 个月），在小鼠中静脉给予低剂量碘酸钠（15mg/kg）后，对视网膜损伤和随后的组织再生进行了连续的形态学、分子和功能分析。为了评估损伤/恢复过程的动力学，我们将视网膜结构的持续变化与视网膜损伤后的电视网膜图 (ERG) 反应相关联，使用全基因组 RNA 微阵列技术、western blot 和免疫组织化学分析来评估。我们观察到杆状细胞介导的 ERG 反应有了相当大的改善，这伴随着损伤部位的 RPE 再生，在损伤后第 3 个月。我们的结果证实，损伤视网膜内的修复机制涉及到明显的神经胶质细胞反应，其特征是神经胶质细胞增殖，从它们的原始位置迁移到损伤部位，随后神经营养因子（如 BDNF、GDNF 和 NT-3）的过度产生。全基因组基因表达分析显示，最初与细胞死亡、凋亡、急性应激途径相关的上调基因在损伤后期经历了相当大的下调。相应地，与神经组织重塑和神经元发育、突触传递调节和定位建立相关的基因在第 3 个月被大量诱导。总之，我们的观察结果支持这样一种观点，即 Müller 胶质细胞可能不仅在损伤后视网膜细胞重组中发挥积极作用，而且可能在 RPE 再生中发挥积极作用，这似乎是视网膜修复过程中的关键事件。此外，我们提供了新的令人信服的证据，证明神经营养因子在视网膜修复的病理生理学中起着关键作用，并确定了在这个过程中被激活的信号通路。
