Hematopoietic stem/progenitor cell reservoirs

描述(申请人提供)：造血干细胞和祖细胞(HSPC)代表负责维持和再生造血系统的不同群体的细胞。维持这些细胞的正常功能，特别是长寿的自我更新的造血干细胞，对健康和生存至关重要。在HIV疾病中，存在严重的造血功能缺陷，这不能简单地用HIV-1感染T细胞和巨噬细胞来解释。已有研究假设HIV-1可直接感染HSPC，导致造血功能障碍。研究表明HSPC表达HIV-1感染所需的受体，最近的研究表明HSPC直接感染HIV-1，这一假设得到了支持。研究还表明，HIV可以在HSPC中建立潜伏感染，这表明HSPC可能是吸毒者中HIV-1的重要储存库。然而，这些研究的结论是有争议的，因为它们主要是基于HSPC在体外或体外感染HIV-1。我们建议使用一种模型系统--BLT小鼠模型来解决HSPC可以被感染和功能被消灭的假设，该模型系统更接近于骨髓(BM)中自然的HIV-1感染。进一步了解HSPC的HIV-1感染情况需要认识到HSPC不是一个统一的人群。几十年来，人们已经知道，通过实验从骨髓中纯化的大多数HSPC代表着注定要分化为特定血统的前体细胞。这些细胞中只有一小部分代表真正的造血干细胞，这些干细胞具有无限自我更新的能力，并产生承诺的祖细胞。此外，我们最近对非人类灵长类动物HSPC的研究表明，即使是长寿的干细胞，在它们对造血输出的贡献以及它们在淋巴系和髓系后代中的相对分布方面也有不同的行为。因此，对HSPC的HIV-1感染的研究应该调查感染对HSPC个人而不是整个人群的后果，这是至关重要的。这可以通过一种称为克隆跟踪的方法来实现，即通过整合慢病毒载体对单个HSPC进行基因标记，然后在移植和重新繁殖后进行跟踪。通过克隆跟踪和FACS分离造血细胞亚群，我们可以研究HIV感染对HSPC克隆及其后代行为的影响。我们已经使用这种方法有效地研究了HSPC克隆在非人灵长类动物中的行为，并建议将这种方法扩展到HIV-1感染对HSPC的影响。

DESCRIPTION (provided by applicant): The hematopoietic stem and progenitor cell (HSPC) represents a diverse population of cells responsible for maintaining and regenerating the hematopoietic system. Maintaining the proper function of these cells, and particularly the long-lived self-renewing hematopoietic stem cell, is essential for health and survival. In HIV disease there are serious deficits involving hematopoietic function that cannot simply be explained by HIV-1 infection of T-cells and macrophages. It has been hypothesized that HIV-1 can directly infect HSPC leading to hematopoietic dysfunction. This hypothesis is supported by studies showing that HSPC express the receptors necessary for HIV-1 infection and recent studies demonstrating direct infection of HSPC by HIV. It has also been demonstrated that HIV can establish a latent infection in HSPC, suggesting that HSPC could serve as an important reservoir for HIV-1 in drug treated individuals. However, the conclusions of these studies are disputed since they are based principally upon in vitro or ex vivo HIV-1 infection of HSPC. We propose to address the hypothesis that HSPC can be infected and function abrogated by using a model system, the BLT mouse model, which more closely mimics natural HIV-1 infection in the bone marrow (BM). Investigation of HIV-1 infection of HSPC further requires the recognition that HSPC are not a uniform population. It has been known for decades that the majority of HSPC purified experimentally from bone marrow represent precursor cells that are destined to differentiate to specific lineages. Only a small fraction of these cells represent true hematopoietic stem cells which have the ability to self-renew indefinitely as well as give rise to the committed progenitor cells. In addition, our recent studies of HSPC in non-human primates demonstrate that even long-lived stem cells have different behaviors in regards to their contribution to hematopoietic output and their relative distribution to lymphoid versus myeloid progeny. Thus, it is critical that studies of HIV-1 infection of HSPC should investigate the consequences of infection upon individual HSPC rather than the entire population. This can be accomplished by a method known as clonal tracking, whereby individual HSPC are genetically marked by integrating lentiviral vectors and then tracked after transplant and repopulation. By combining clonal tracking with FACS separation of hematopoietic cell sub-populations, we can investigate the consequences of HIV infection on the behavior of HSPC clones and their progeny. We have used this methodology effectively to study the behavior of HSPC clones in non-human primates and propose to extend this methodology to the impact of HIV-1 infection upon HSPC.