Ourednik Václav, Ourednik Jitka
Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
Ann N Y Acad Sci. 2005 May;1049:172-84. doi: 10.1196/annals.1334.016.
A new light was shed on the utility of neural grafts when it was recognized that donor tissues and cells offer more than a source of immature progenitors potentially capable of cell replacement: First, they have the inherent capacity to produce multiple trophic and tropic factors promoting cell survival and tissue plasticity often characteristic of the immature central nervous system (CNS). Second, by their interaction with the host microenvironment via cell/cell and cell/ECM interactions, these grafts are capable of re-establishing homeostasis, which can be, for example, reflected in rescue and protection of host elements from harmful influences. This second capacity of donor cells relies, in part, also on a "dormant" but still present regenerative capacity of mature or even aged CNS and on the possibility of its mobilization in the damaged nervous system by neural grafts. For this to occur efficiently after transplantation, a bi-directional dialogue between donor and host cells must gradually be established, in which both "partners" transmit signals (cell/cell contact, molecular messengers), "listen to" and "understand" each other and are able to react by modifying their own plasticity- and development-related programs. Thus, for the best possible recovery of functionality in the injured adult and aged nervous system, neurotransplantation must always try to find optimal conditions for all three of the mentioned qualities of neural grafts, especially for the protection and/or reactivation of neural circuitry embedded in non-neurogenic CNS areas. Once fully understood, this newly recognized aspect of neurotransplantation (and topic of this review) might, someday, even allow the recovery of systems that would otherwise be doomed, such as cognition- and experience-related circuitry.
当人们认识到供体组织和细胞所提供的远不止是潜在能够进行细胞替代的未成熟祖细胞来源时，神经移植的效用有了新的认识：首先，它们具有产生多种营养和促生长因子的内在能力，这些因子可促进细胞存活和组织可塑性，这通常是未成熟中枢神经系统（CNS）的特征。其次，通过细胞/细胞和细胞/细胞外基质相互作用与宿主微环境相互作用，这些移植能够重新建立体内平衡，例如，这可以体现在保护宿主成分免受有害影响。供体细胞的这种第二种能力部分还依赖于成熟甚至衰老的中枢神经系统的“休眠”但仍然存在的再生能力，以及神经移植在受损神经系统中动员这种能力的可能性。为了在移植后有效地发生这种情况，供体细胞和宿主细胞之间必须逐渐建立双向对话，其中两个“伙伴”都传递信号（细胞/细胞接触；分子信使），“倾听”并“理解”彼此，并能够通过修改自身与可塑性和发育相关的程序做出反应。因此，为了在受伤的成年和老年神经系统中尽可能最佳地恢复功能，神经移植必须始终努力为神经移植的上述所有三个特性找到最佳条件，特别是对于嵌入非神经源性中枢神经系统区域的神经回路的保护和/或重新激活。一旦被充分理解，神经移植的这个新认识的方面（以及本综述的主题）有朝一日甚至可能使原本注定要失败的系统恢复功能，例如与认知和经验相关的回路。
