Hematopoietic stem/progenitor cell reservoirs

描述（由申请人提供）：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细胞群。维持这些细胞的正常功能，特别是长寿命的自我更新造血干细胞，对健康和生存至关重要。在HIV疾病中，存在涉及造血功能的严重缺陷，这不能简单地用HIV-1感染T细胞和巨噬细胞来解释。据推测，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感染所必需的受体，最近的研究表明HIV直接感染HSPC，这一假设得到了支持。也已经证明HIV可以在HSPC中建立潜伏感染，表明HSPC可以作为药物治疗个体中HIV-1的重要储存库。然而，这些研究的结论存在争议，因为它们主要基于HSPC的体外或离体HIV-1感染。我们建议解决的假设，HSPC可以被感染和功能废除，通过使用模型系统，BLT小鼠模型，它更接近模拟自然的HIV-1感染的骨髓（BM）。 对HSPC的HIV-1感染的研究进一步要求认识到HSPC不是一个统一的群体。几十年来，人们已经知道，大多数从骨髓中实验纯化的HSPC代表注定要分化为特定谱系的前体细胞。这些细胞中只有一小部分代表真正的造血干细胞，其具有无限自我更新以及产生定向祖细胞的能力。此外，我们最近在非人灵长类动物中对HSPC的研究表明，即使是长寿的干细胞，在其对造血输出的贡献以及其在淋巴与骨髓后代中的相对分布方面也具有不同的行为。因此，至关重要的是，HSPC的HIV-1感染研究应研究感染对个体HSPC而不是整个人群的影响。这可以通过称为克隆追踪的方法来实现，其中通过整合慢病毒载体对个体HSPC进行遗传标记，然后在移植和再增殖后进行追踪。通过将造血细胞亚群的克隆追踪与FACS分离相结合，我们可以研究HIV感染对HSPC克隆及其后代行为的影响。我们已经有效地使用这种方法来研究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.