Defining the Earliest Stages of Lymphoid Commitment in Human Bone Marrow

描述（由申请人提供）：大量报告继续完善小鼠淋巴细胞生成的分化阶段。然而，对人类淋巴样分化的最早阶段知之甚少，存在的少数报告大多使用脐带血。本研究提案中的研究将通过鉴定和表征人类骨髓中能够产生T细胞的最原始淋巴祖细胞来解决我们对成人淋巴细胞生成知识的关键空白。这些研究的总体目标是鉴定成人骨髓中具有最大T细胞生产能力的淋巴祖细胞。我们已经在人骨髓中鉴定出一个祖细胞群体，该群体表达高水平的归巢分子L-选择素（CD 62 L），并在体外具有强大的淋巴潜能。我们假设这种CD 34 + CD 10-CD 62 L ++（“CD 10-”）淋巴限制性祖细胞群体标志着人造血干细胞向淋巴样分化途径定型的第一阶段。此外，我们提出，CD 10-群体是一种更原始的前体，具有上级先前描述的人骨髓中的CD 34 + CD 10+（“CD 10+”）LP群体的T淋巴潜能。目的1中的研究通过定义CD 10-和CD 10 + LP的分子特征，阐述了人淋巴定型的生物学。这些研究基于两个LP群体的基因表达谱，在全球范围内和特异性地使用已知对淋巴发育至关重要的基因，定义了两个LP群体之间的谱系关系。目的2中的研究通过测定CD 10-和CD 10 + LP归巢和重建胸腺的能力，并通过使用体外试验和使用异种移植模型在体内定量每个群体的T细胞的相对功能输出，解决了临床相关性。这方面的知识是必不可少的诊断和治疗进展的发展过程中的淋巴分化和胸腺重建。

DESCRIPTION (provided by applicant): A large number of reports continue to refine the differentiation stages of murine lymphopoiesis. However very little is known about the earliest stages of human lymphoid differentiation, those few reports that exist have mostly used umbilical cord blood. The studies in this research proposal will address a critical gap in our knowledge of adult human lymphopoiesis, through the identification and characterization of the most primitive lymphoid progenitors in the human bone marrow able to generate T cells. The overall goal of these studies is to identify the lymphoid progenitors in adult human bone marrow with maximum T cell production capacity. We have identified a progenitor population in human bone marrow that expresses high levels of the homing molecule L-selectin (CD62L) and possesses robust lymphoid potential in vitro. We hypothesize that this CD34+ CD10- CD62L++ ("CD10-") lymphoid-restricted progenitor population marks the first stage of commitment by human hematopoietic stem cells to the lymphoid differentiation pathway. Further, we propose that the CD10- population is a more primitive precursor with superior T lymphoid potential to the previously described CD34+ CD10+ ("CD10+") LP population in human bone marrow. The studies in Aim 1 address the biology of human lymphoid commitment by defining the molecular characteristics of the CD10- and CD10+ LPs. These studies define the lineage relationship between the two LP populations based on their gene expression profiles, both globally and specifically using genes that are known to be critical to lymphoid development. The studies in Aim 2 address clinical relevance by determining the ability of the CD10- and CD10+ LPs to home and reconstitute the thymus and by quantifying the relative functional output of T cells from each population using in vitro assays and in vivo using a xenogeneic transplant model. This knowledge is essential for the development of diagnostic and therapeutic advances toward the process of lymphoid differentiation and thymic reconstitution.