Attempts to expand ex vivo the numbers of human hematopoietic stem cells (HSCs) without compromising their marrow repopulating capacity and their ability to establish multilineage hematopoiesis has been the subject of intense investigation. Although most such efforts have focused on cord blood HSCs, few have been applied to adult HSCs, a more clinically relevant HSC source for gene modification. To date, the strategies that have been used to expand adult HSCs have resulted in modest effects or HSCs with lineage bias and a limited ability to generate T cells in vivo. We previously reported that culturing umbilical cord blood CD34+ cells in serum‐free media supplemented with valproic acid (VPA), a histone deacetylase inhibitor, and a combination of cytokines led to the expansion of the numbers of fully functional HSCs. In the present study, we used this same approach to expand the numbers of adult human CD34+ cells isolated from mobilized peripheral blood and bone marrow. This approach resulted in a significant increase in the numbers of phenotypically defined HSCs (CD34+CD45RA‐CD90+D49f+). Cells incubated with VPA also exhibited increased aldehyde dehydrogenase activity and decreased mitochondrial membrane potential, each functional markers of HSCs. Grafts harvested from VPA‐treated cultures were able to engraft in immune‐deficient mice and, importantly, to generate cellular progeny belonging to each hematopoietic lineage in similar proportion to that observed with unmanipulated CD34+ cells. These data support the utility of VPA‐mediated ex vivo HSC expansion for gene modification of adult HSCs.

中文翻译：

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用组蛋白脱乙酰基酶抑制剂离体培养的成人造血干细胞的功能活性的扩展和保存。

试图在不损害骨髓造血能力和建立多谱系造血能力的前提下扩大人类造血干细胞（HSC）的数量一直是研究的主题。尽管大多数此类努力都集中在脐带血HSC上，但很少将其应用于成年HSC，这是一种临床上更相关的HSC基因修饰来源。迄今为止，已用于扩大成年HSC的策略已导致适度的作用或具有谱系偏向且体内产生T细胞的能力有限的HSC。我们以前曾报道过，在补充有丙戊酸（VPA），组蛋白脱乙酰基酶抑制剂和细胞因子组合的无血清培养基中培养脐血CD34 +细胞会导致功能全面的HSC数量增加。在目前的研究中，我们使用相同的方法来扩大从动员的外周血和骨髓中分离的成年人类CD34 +细胞的数量。这种方法导致表型定义的HSC（CD34 + CD45RA-CD90 + D49f +）的数量显着增加。VPA孵育的细胞还表现出增加的醛脱氢酶活性和降低的线粒体膜电位，这是HSC的每个功能标记。从VPA处理过的培养物中收集的移植物能够植入免疫缺陷的小鼠中，并且重要的是，可以产生属于每个造血谱系的细胞后代，其比例与未操纵的CD34 +细胞观察到的比例相似。这些数据支持VPA介导的离体HSC扩增对成人HSC的基因修饰的实用性。