Cellular therapy for the inner ear

描述（由申请人提供）：耳蜗神经元和毛细胞的丧失是感音神经性听力损失的主要原因。一种潜在的治疗方法是移植外源性祖细胞。我们的策略为发展细胞为基础的治疗内耳疾病是研究神经支配的一个去传入器官的Corti。我们采取这种方法是因为1）只有一种细胞类型，螺旋神经节细胞，必须被替换才能看到功能恢复; 2）通过细胞置换使受损组织部分再生已在其他神经变性疾病的动物模型中获得成功，例如帕金森病，这表明，如果引入适当的祖细胞，则可以重建成人神经系统中的神经元回路，以及3）理解成年人耳中毛细胞神经连接重建的潜在机制对于感音神经性听力损失的任何治疗方法都是重要的。具体目标包括四个相互关联的实验，以探索可能影响移植神经祖细胞的毛细胞神经再支配成功的关键变量。在目的1中，将通过免疫组织化学研究几个神经元引导分子家族的螺旋神经节神经元的发育表达。在目的2中，我们使用去传入耳蜗外植体来研究移植祖细胞对毛细胞的神经再支配，在体外，通过改变供体细胞的特征（例如沉默所选引导分子的表达或控制分化程度）或宿主环境（例如外植体的发育年龄或初始去传入的病因）。在目标3中，我们建立在体外结果的基础上，选择供体细胞在体内移植到化学去传入沙鼠耳，其中感觉细胞是完整的，但螺旋神经节细胞被破坏。在该模型系统中，神经再支配的成功可以在功能上和组织学上进行测定。在目标4中，我们使用报告基因测定来确定通过在定时序列中添加特异性生长因子以及通过在通向感觉神经元的通路中过表达转录因子来将干细胞偏向分化为对应于感觉神经元的谱系所需的条件。在此目标下分离的克隆细胞系将作为目标3和4中研究的额外供体细胞类型。

DESCRIPTION (provided by applicant): Loss of cochlear neurons and hair cells is a major cause of sensorineural hearing loss. One approach to potential treatments is the transplantation of exogenous progenitor cells. Our strategy for developing cell based therapies for inner ear disorders is to study the reinnervation of a de-afferented organ of Corti. We take this approach because 1) only a single cell type, the spiral ganglion cell, must be replaced to see functional recovery; 2) partial regeneration of damaged tissue by cell replacement has been successful in animal models of other neurodegenerative diseases, such as Parkinson's, suggesting that neuronal circuits in the adult nervous system can be reconstituted if appropriate progenitor cells are introduced and 3) understanding the mechanisms underlying re-formation of neural connections to hair cells in the adult ear is important to any therapeutic approach to sensorineural hearing loss. The Specific Aims comprise four inter-related experiments to probe key variables likely to influence the success of hair cell reinnervation by transplanted neural progenitor cells. In Aim 1 the developmental expression by spiral ganglion neurons of several families of neuronal guidance molecules will be studied by immunohistochemistry. In Aim 2 we use de-afferented cochlear explants to study the reinnervation of hair cells by grafted progenitors, in vitro, by modifying characteristics of the donor cells (e.g. silencing expression of selected guidance molecules or controlling degree of differentiation) or the host environment (e.g. developmental age of the explant or etiology of the initial de-afferentation). In Aim 3 we build on the in vitro results to choose donor cells for in vivo transplantation into a chemically de-afferented gerbil ear, in which the sensory cells are intact but spiral ganglion cells are destroyed. In this model system, success of reinnervation can be assayed both functionally and histologically. In Aim 4 we use a reporter assay to determine conditions needed to bias differentiation of stem cells to a lineage corresponding to sensory neurons by adding specific growth factors in a timed sequence, and by over expressing transcription factors in the pathway to sensory neurons. Clonal cell lines isolated under this Aim will serve as additional donor cell types to be studied in Aims 3 and 4.