Srivastava Anand S, Shenouda Steve, Mishra Rangnath, Carrier Ewa
Moores University of California San Diego Cancer Center, Department of Medicine, 92093-0062, USA.
Stem Cells. 2006 Jul;24(7):1689-94. doi: 10.1634/stemcells.2005-0531. Epub 2006 Mar 30.
An understanding of feasibility of implanting embryonic stem cells (ESCs), their behavior of migration in response to lesions induced in brain tissues, and the mechanism of their in vivo differentiation into neighboring neural cells is essential for developing and refining ESC transplantation strategies for repairing damages in the nervous system, as well as for understanding the molecular mechanism underlying neurogenesis. We hypothesized that damaged neural tissues offer a niche to which injected ESCs can migrate and differentiate into the neural cells. We inflicted damage in the murine (C57BL/6) brain by injecting phosphate-buffered saline into the left frontal and right caudal regions and confirmed neural damage by histochemistry. Enhanced yellow fluorescent protein-expressing ESCs were injected into the nondamaged left caudal portion of the brain. Using immunohistochemistry and fluorescent microscopy, we observed migration of ESCs from the injection site (left caudal) to the damaged site (right caudal and left frontal). Survival of the injected ESCs was confirmed by the real-time polymerase chain reaction analysis of stemness genes such as Oct4, Sox2, and FGF4. The portions of the damaged neural tissues containing ESCs demonstrated a fourfold increase in expression of these genes after 1 week of injection in comparison with the noninjected ESC murine brain, suggesting proliferation. An increased level of platelet-derived growth factor receptor demonstrated that ESCs responded to damaged neural tissues, migrated to the damaged site of the brain, and proliferated. These results demonstrate that undifferentiated ESCs migrate to the damaged regions of brain tissue, engraft, and proliferate. Thus, damaged brain tissue provides a niche that attracts ESCs to migrate and proliferate.
了解植入胚胎干细胞（ESC）的可行性、它们对脑组织损伤的迁移行为以及它们在体内分化为邻近神经细胞的机制，对于开发和完善用于修复神经系统损伤的ESC移植策略以及理解神经发生的分子机制至关重要。我们假设受损的神经组织提供了一个微环境，注射的ESC可以迁移到该微环境并分化为神经细胞。我们通过向小鼠（C57BL/6）大脑的左额叶和右尾状区域注射磷酸盐缓冲盐水造成损伤，并通过组织化学确认神经损伤。将表达增强型黄色荧光蛋白的ESC注射到大脑未受损的左尾状部分。使用免疫组织化学和荧光显微镜，我们观察到ESC从注射部位（左尾状）迁移到受损部位（右尾状和左额叶）。通过对Oct4、Sox2和FGF4等干性基因的实时聚合酶链反应分析，确认了注射的ESC的存活。与未注射ESC的小鼠大脑相比，注射1周后，含有ESC的受损神经组织部分这些基因的表达增加了四倍，表明有增殖现象。血小板衍生生长因子受体水平的升高表明ESC对受损神经组织有反应，迁移到大脑的受损部位并增殖。这些结果表明，未分化的ESC迁移到脑组织的受损区域，植入并增殖。因此，受损的脑组织提供了一个吸引ESC迁移和增殖的微环境。
