HUMAN HEMOPOIESIS IN NEW SCID MOUSE MODELS

由于缺乏合适的小动物模型，人类造血干细胞(HSC)的研究一直受到阻碍。我们最近通过利用转基因的SCID小鼠品系开发了一个人类造血的小动物模型来解决这一缺陷。这一模型现在将被用来确定小鼠宿主基因在人类HSC植入中的作用，以及不同人类干细胞群体在体内的竞争性再繁殖。为了实现这些目标，我们提出了一种综合方法，包括两个在哺乳动物遗传学和人类细胞移植小动物模型的开发和表征方面具有专业知识的实验室。具体目标1将利用经典哺乳动物遗传学与转基因和基因敲除技术相结合，开发用于人类造血干细胞移植的改进的免疫缺陷小鼠受体。我们已经证明，先天免疫缺陷的NOD-SCID小鼠的遗传背景允许人类脐带血细胞的植入是C.B-17-SCID小鼠的5-10倍。在初步研究中，我们发现NOD-SCID-beta2m0/0小鼠移植人类干细胞的水平高于NOD-SCID小鼠，而NOD-RAG-10/0小鼠移植人类外周血细胞的水平与NOD-SCID小鼠相当。我们将通过产生新的转基因和敲除免疫缺陷的NOD小鼠来改进这个模型系统。具体目标2将测试这些新的小鼠遗传库，以确定移植人类HSC的最佳宿主。一种新的竞争性再繁殖试验将被用来量化从不同个体同时获得的两个或更多人类干细胞群体在单个SCID小鼠中的竞争性植入。人类造血小动物模型的开发和验证也应该允许对基因治疗的进展进行快速评估和应用，并对设计造血疾病、艾滋病和其他疾病的治疗方案非常重要。

The investigation of human hemopoietic stem cells (HSC) has been hindered by the lack of suitable small animal models. We have recently addressed this deficiency by utilizing genetically altered strains of scid mice to develop a small animal model of human hemopoiesis. This model will now be used to determine the role of murine host genes on human HSC engraftment and the in vivo competitive repopulation of different human stem cell populations. To accomplish these goals, we propose an integrated approach involving 2 laboratories with expertise in mammalian genetics and in the development and characterization of small animal models of human cell engraftment. Specific Aim number 1 will utilize classical mammalian genetics in combination with transgenic and knockout technology to develop improved immunodeficient mouse recipients for human HSC engraftment. We have already shown that the genetic background of the NOD-scid mouse with defects in innate immunity allows a 5-10-fold increase in engraftment of human cord blood cells over that of C.B-17-scid mice. In Preliminary Studies we have documented that NOD-scid-beta2m0/0 mice engraft at higher levels with human stem cells than do NOD-scid mice, and that NOD-rag-10/0 mice engraft with human peripheral blood cells at levels comparable to that of NOD-scid mice. We will improve this model system by generating new transgenic and knockout immunodeficient NOD mice. Specific Aim number 2 will test these new genetic stocks of mice to identify the optimal host for human HSC engraftment. A novel competitive repopulation assay will be used to quantify the competitive engraftment of two or more human stem cell populations obtained from different individuals simultaneously in a single scid mouse. The development and validation of a small animal model of human hemopoiesis should also allow rapid evaluation and application of advances in gene therapy, and be important for designing treatment for hemopoietic disorders, AIDS, and other diseases.