Regeneration and cell replacement therapy for ischemic brain injury Approach from endogenous neural progenitors

近十年来，由于细胞生物学领域的研究取得了显著进展，再生或细胞替代疗法已成为细胞生物学领域的主要课题之一。特别是在成熟哺乳动物成年脑中发现了内源性神经干细胞或祖细胞的存在，这为通过诱导内源性祖细胞再生来重建各种损伤导致的神经元网络提供了新的途径。根据这一概念，我们提出了一个问题，即在大鼠缺血性神经元死亡后，海马CA1区（一个被认为是非神经源性的区域）是否可以诱导神经元再生。我们发现神经元祖细胞存在于CA1区附近的心室周围区域，对缺血有反应。缺血3天后，经脑室内给予EGF和FGF-2，可成功诱导该区域的神经祖细胞增殖、迁移和分化，使神经元群恢复40%以上。此外，这些神经元表现出成熟的表型和延长的树突和长轴突。通过Marris水迷宫测试，他们最终恢复了长期增强的电生理活动，并改善了认知功能。这些发现表明，脑损伤后“非神经源性区域”在某些因素的刺激下仍保持再生能力，为各种中枢神经系统疾病的治疗开辟了新的途径。我们还试图建立小鼠海马CA1一致缺血性神经元损伤的体内模型，以探索神经元再生的分子机制，因为在小鼠中有几种基因修饰的动物。在BL6菌株中，我们可以通过暂时阻断颈部的三根血管，使其缺血14分钟来制作该模型。该模型将为进一步研究原位祖细胞的分子调控提供重要依据。少

Regeneration or cell replacement therapy has become one of the main topics in the field of cell biology due to remarkable advance of research in this field over the past decade. In particular, existence of endogenous neural stem cell or progenitors has been found in mature mammalian adult brain, which led to new approach to reconstruct lost neuronal network incurred by various insults through induction of neuronal regeneration from endogenous progenitors. In line with this concept, we addressed question whether neuronal regeneration can be induced in the hippocampal CA1 sector, a region supposed to be non-neurogenic, following ischemic neuronal death in rats. We found that neuronal progenitors exist in the periventricular region adjacent to CA1 sector, which respond to ischemia. Following administration of EGF and FGF-2 intraventricularly for 3 days after ischemia, we could successfully induce proliferation, migration and differentiation of neural progenitors in this region, resulting … More in 40% recovery of neuronal population. In addition, these neurons displayed mature phenotype and extended dendrites and long axons. They finally re-established electrophysiological activity demonstrated by recovery of long-term potentiation, as well as improvement of cognitive function by assessing Marris Water Maze test. These findings imply that "non-neurogenic regions" still retain capacity for regeneration when stimulated by some factors after brain insults, and would open a new approach for various central nervous system disorders.We also tried to establish an in vivo model of consistent ischemic neuronal injury in hippocampal CA1 in mice to explore molecular mechanisms of neuronal regeneration, since several gene modified animals are available in mice. In BL6 strain, we could produce this model by subjecting them to 14 minute ischemia through temporary occlusion of three vessels in the neck. This model would contribute greatly to understating of molecular control of progenitors in situ in the future research. Less