CYTOLOGICAL STUDIES OF DEVELOPING AND MATURE NEURONS

描述（改编自申请人的摘要）当移植到 在中枢神经系统，雪旺细胞（Scs）促进轴突再生 和脱髓鞘轴突的髓鞘再生。 自体移植 因此，通过从小神经活检组织中体外生长产生的人类SC可能 具有重要的临床价值。 培养成年人干细胞的方法 并通过移植到免疫缺陷的啮齿动物体内来测试它们的功能 开发了 通过添加一种 生长因子、调蛋白和腺苷酸激活剂的组合 环化酶，毛喉素，但人SC似乎生长停滞后12-14 群体倍增和他们的能力，髓鞘轴突减少后， 有丝分裂原生长。 这些观察结果表明， 人SC的功能特性通过可溶性 体外促分裂原。 提出实验来检验这一假设， 表征人类SC特性的变化。 第一，组织培养 对heregulin受体表达和受体介导信号的影响 将评估转导。 第二，毛喉素的机制 增强调蛋白的促有丝分裂作用， 将检查组合的有丝分裂原改变SC对毛喉素的反应。 第三，实验将测试人类SC生长的停滞是否反映了 进入复制性衰老的状态 这些研究将 关注heregulin/forskolin激活衰老相关的 蛋白质，p53和p21。 对生长调节蛋白磷酸化的影响 蛋白质，pRb，将被确定。 端粒缩短的作用 通过引入催化剂来评估和预防生长停滞 将测试端粒酶亚基进入早期传代人SC的能力。 第四、 通过体外生长，人SC与轴突相互作用能力的变化 将评估对体内髓鞘形成能力的影响将被检查 以及为研究最早的SC-轴突而开发的体外模型 互动：供应链的初始接触、识别和关联 与轴突表面接触。 实验包括粘附力的评估 分子，N-钙粘蛋白和L1，并对SC的能力，以组装一个 细胞外基质 这些研究探索了人类使用 SC在临床应用中，同时扩大我们对 雪旺细胞的生物学和分子学特性。

DESCRIPTION (Adapted from applicant's abstract) When transplanted into the central nervous system, Schwann cells (Scs) promote regeneration of axons and remyelination of demyelinated axons. Autologous transplantation of human SCs generated by growth in vitro from small nerve biopsies might thus be of significant clinical value. A procedure for growing adult human SCs and testing their function by transplantation into immune-deficient rodents was developed. SCs are stimulated to divide rapidly by the addition of a combination of the growth factor, heregulin, and an activator of adenylyl cyclase, forskolin, but human SCs appear to growth arrest after 12-14 population doublings and their ability to myelinate axons decreases after growth with mitogens. These observations suggest that the molecular and functional properties of human SCs are changed by growth with soluble mitogens in vitro. Experiments are proposed to test this hypothesis and to characterize changes in the properties of human SCs. First, tissue culture effects on expression of heregulin receptors and receptor-mediated signal transduction will be evaluated. Second, the mechanism by which forskolin potentiates the mitogenic effect of heregulin and whether prolonged exposure to combined mitogens alters the SCs response to forskolin will be examined. Third, experiments will test whether arrest of human SC growth reflects their entry into a state of replicative senescence. These studies will focus on the ability of heregulin/forskolin to activate senescence-related proteins, p53 and p21. Effect on phosphorylation of the growth-regulating protein, pRb, will be determined. The role of telomere shortening will be assessed and prevention of growth arrest by introduction of the catalytic subunit of telomerase into early passage human SCs will be tested. Fourth, changes in the human SC's ability to interact with axons by growth in vitro will be evaluated Effects on myelination capability in vivo will be examined and an in vitro model developed for study of the earliest SC-axon interactions: the initial contact, recognition, and association of the SC with the axonal surface. Experiments include an assessment of adhesion molecules, N-cadherin and L1, and on the ability of the SC to assemble an extracellular matrix. These studies explore the potential for use of human SCs in clinical applications, while expanding our knowledge of the biological and molecular properties of Schwann cells.