Latexin in human hematopoietic stem cell expansion

项目总结 这项研究的目标是开发新的策略来扩大人类造血干细胞(HSC)，通过 将深低温保存的脐带血用于NHLBI生物库。造血干细胞移植目前正在进行 作为再生医学用于治疗儿童先天性缺陷和恶性疾病 血液和免疫系统。这种疗法成功的一个主要障碍是每个人的HSC数量有限 收获和鲜为人知的扩张和分化行为。这项提案旨在增加CB 通过靶向新发现的分子途径进行肝星状细胞体外扩增。自然遗传多样性提供了一种 破译HSCs和HSCs分子调控机制的重要但在很大程度上尚未开发的储存库 造血术。我们之前发现了第一个，也可能是迄今为止唯一的干细胞调控基因？？latexin。 (LXN)，采用遗传多样性方法。LXN是HSC数量和功能的负性调节因子。我们的 对LXN基因敲除小鼠的初步研究表明，LXN失活会增加HSC的数量，并且 扩张被控制在生理变异的范围内。扩展的HSC保持容量 自我更新和多谱系分化。考虑到LXN作为自然变异调节器的性质 HSCs，我们推测LXN在人类中可能具有类似的功能。我们的初步研究表明 HSC数量与LXN在人体标本中的表达呈负相关。因此，我们 假设LXN负性调节人HSC，其抑制导致HSC通过 在保持多谱系分化能力的同时，增加自我更新。具体目标是：1) 确定敲除LXN是否可以在保持人HSC自我更新的同时扩大其数量 多系分化能力，2)决定LXN-Thbs1的分子机制 信号通路调控人HSC的扩增和功能。这项研究将提供新的见解 LXN抑制促进HSC扩张的潜在效用，从而使需要HSC的患者受益 移植。

PROJECT SUMMARY The goal of this study is to develop new strategies to expand human hematopoietic stem cells (HSC) by utilizing cryopreserved umbilical cord blood (CB) in NHLBI Biorepository. HSC transplantation is currently being used as regenerative medicine for the treatment of congenital deficiencies and malignant diseases of the blood and immune systems. A major roadblock of success of this therapy is the limited number of HSC per harvest and the poorly understood expansion and differentiation behavior. This proposal aims to increase CB HSC ex vivo expansion by targeting a newly identified molecular pathway. Natural genetic diversity offers an important yet largely untapped reservoir for deciphering molecular regulatory mechanisms of HSCs and hematopoiesis. We previously identified the first and probably so far the only stem cell regulatory gene, latexin (Lxn), by employing genetic diversity approach. Lxn is a negative regulator of HSC number and function. Our preliminary work in Lxn knockout mice showed that Lxn inactivation increases HSC numbers, and the expansion is controlled within the physiological range of variation. The expanded HSCs maintain the capacity of self-renewal and multilineage differentiation. Considering the nature of Lxn as a natural variant regulator of HSCs, we speculate that Lxn may function similarly in human population. Our preliminary studies demonstrate the negative correlation between HSC numbers and Lxn expression in human samples. We therefore hypothesize that Lxn negatively regulates human HSCs, and its inhibition leads to HSC expansion by increasing self-renewal while maintaining multi-lineage differentiation capacity. Specific aims are to: 1) determine whether knockdown of Lxn can expand human HSCs while maintaining their self-renewal and multilineage differentiation capacity, and 2) Determine the molecular mechanisms by which Lxn-Thbs1 signaling pathway regulates human HSC expansion and function. This research will provide new insight into the potential utility of Lxn inhibition to promote HSC expansion, thereby benefiting patients needing HSC transplantation.