Demyelination Plus Transplantation to Study CNS Repair

脱髓鞘是一种独特的成人中枢神经系统损伤，在许多情况下，它是由修复。能够再生髓鞘的脱髓鞘区域不以星形胶质瘢痕为特征。我们已经证明，由椎管内注射抗半乳糖脑苷抗体和补体蛋白产生的免疫性脱髓鞘区域能够由内源性少突胶质细胞重新脱髓鞘，并且星形胶质细胞肥大在免疫性脱髓鞘区域内和周围不存在。此外，我们的初步研究表明，免疫脱髓鞘区域内的星形胶质细胞在轴突损伤后不会变得肥大。因此，免疫脱髓鞘为我们提供了一种方法来操纵反应性细胞对轴突损伤的反应，并研究这种反应与大多数导致瘢痕形成的中枢神经系统损伤后的反应的不同之处。我们将使用集成光密度测量来确定星形胶质细胞和/或小胶质细胞/巨噬细胞对损伤的反应是否被免疫脱髓鞘消除、抑制或延迟。这些研究构成了本提案的最后两个目的，可能会导致操纵星形胶质细胞的新方法，从而防止星形胶质细胞激活或瘢痕形成。可能与星形胶质细胞肥大的缺失有关，免疫脱髓鞘区域促进移植细胞在整个免疫脱髓鞘区域的长距离均匀再分布。这提供了一个独特的机会，在中枢神经系统内创建一个类似pns的地形，而不是被星形胶质疤痕包围。这种实验模式使我们能够研究受伤的轴突从这种类似pns的地形再生到中枢神经系统环境的能力，而不会遇到硬化边界区。我们的再生分析将使用顺行尿道追踪进行。这些研究构成了本提案的第一个目标。有三个具体目标；1)验证再生的背柱轴突在界面无瘢痕的情况下从pns样地形延伸到纯粹CNS地形的假设；2)验证免疫脱髓鞘抑制轴突损伤后星形胶质细胞肥大的假设；3)验证免疫脱髓鞘改变轴突损伤后小胶质细胞/巨噬细胞活化的程度和持续时间的假设。

Demyelination represents a unique injury to the adult CNS in that it is followed in many instances by repair. Regions of demyelination that are capable of remyelinating are not characterized by an astroglial scar. We have demonstrated that regions of immunological demyelination, produced by the intraspinal injection of anti-galactocerebroside antibodies plus complement proteins, are capable of remyelination by endogenous oligodendrocytes, and that astroglial hypertrophy is absent within and around regions of immunological demyelination. Furthermore, our preliminary studies indicate that astrocytes within regions of immunological demyelination do not become hypertrophic following axonal injury. Thus, immunological demyelination provides us with a means to manipulate the response of reactive cells to axonal injury and investigate the ways in which that response differs from that following the majority of CNS injuries, which result in scarring. We will use integrated optical density measurements to determine whether the astrocyte and/or microglial/macrophage response to injury is eliminated, suppressed or delayed by immunological demyelination. These studies, which constitute the last two AIMS of this proposal, may lead to novel means of manipulating astrocytes such that astroglial activation or scarring is prevented. Likely associated with the absence of astroglial hypertrophy, regions of immunological demyelination promote long distance homogeneous redistribution of transplanted cells throughout the region of immunological demyelination. This provides a unique opportunity to create a PNS-like terrain within the CNS that is not bordered by an astroglial scar. This experimental paradigm allows us to study the ability to injured axons to regenerate from such a PNS-like terrain into the CNS environment without confronting a sclerotic border zone. Our regenerative analysis will be conducted using anterograde tract tracing. These studies constitute the first AIM of this proposal. There are three specific aims; 1) test the hypothesis that regenerating dorsal column axons will extend from a PNS-like terrain into a purely CNS terrain in the absence of scarring at the interface, 2) test the hypothesis that immunological demyelination suppresses astroglial hypertrophy following axonal injury, and 3) test the hypothesis that immunological demyelination alters the magnitude and duration of microglial/macrophage activation following axonal injury.