Xenotransplantation: a new paradigm for human meiosis

描述（由申请人提供）：女性的生育能力是多种分子途径的产物，从胚胎发生开始，包括生殖细胞进入减数分裂，以及导致原始卵泡形成的卵巢结构重组。由于很难获得孕龄较晚的胎儿卵巢样本，因此对妇女的这些事件知之甚少。观察到减数分裂在女性中是高度容易出错的，70%的妊娠损失是由于母体减数分裂I型错误，这就强调了理解这些事件的重要性。虽然对减数分裂早期I前期的人类胎儿卵母细胞进行了一些有限的分析，但很难检查I前期后期和进入支配性停止的阶段，这发生在出生前后，并引发卵巢发育中的重要结构变化。为了克服这些困难，本R21应用程序寻求建立一种新的异种移植系统来分析人类减数分裂和卵巢发育。在目标1中，我们将建立使用人类胎儿卵巢和不同免疫功能低下小鼠宿主的异种移植方法，以优化异种移植建立的条件。异种移植物将通过一系列免疫组织化学和细胞遗传学标准评估细胞活力和发育。在目标2中，我们将利用我们在哺乳动物减数分裂方面的重要专业知识来分析同源染色体相互作用、重组动力学和交叉形成，研究异种移植的人类卵母细胞在前期I的进展。在目标3中，我们将研究人类卵母细胞中指示性阻滞的发生，以确定基质重组和原始卵泡形成过程中的分子/细胞事件。该模型为研究卵巢发育提供了一个新的范式，这是一个鲜为人知的过程，但与其他哺乳动物相比，女性的非整倍体率高，卵巢早衰和其他影响女性的生育问题可能是由于卵巢发育缺陷造成的。

DESCRIPTION (provided by applicant): Fertility in women is a product of multiple molecular pathways that start during embryogenesis and involve the entry of germ cells into meiosis, together with the structural reorganization of the ovary that results in primordial follicle formation. These events are poorly understood in women because of the difficulty in obtaining fetal ovarian samples of later gestational ages. The importance of understanding these events is underscored by the observation that meiosis is highly error-prone in women, with 70% of pregnancy losses being due to maternal meiosis I errors. While some limited analysis has been performed on human fetal oocytes during early meiotic prophase I, it has been hard to examine later stages of prophase I and the entry into dictyate arrest which occurs at around the time of birth and which triggers the important structural changes within the developing ovary. To overcome these difficulties, this R21 application seeks to establish a novel xenotransplantation system for analyzing human meiosis and ovarian development. In aim 1, we will establish the xenografting methodology using human fetal ovaries and different immunocompromised mouse hosts, to optimize the conditions for xenograft establishment. Xenografts will be assessed for cell viability and development by an array of immunohistochemical and cytogenetic criteria. In aim 2, we will examine the progression of xenotransplanted human oocytes through prophase I, taking advantage of our significant expertise in mammalian meiosis to analyze homologous chromosome interactions, recombination dynamics and crossover formation. In aim 3, we will examine the onset of dictyate arrest in human oocytes to define the molecular/cellular events during stromal reorganization and primordial follicle formation. This model provides a new paradigm for studying ovarian development, a poorly understood process, but defects in which may contribute to the high aneuploidy rates observed in women compared to other mammals, premature ovarian failure and other fertility issues affecting women.