Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, Broad Stem Cell Research Center, University of California Los Angeles (UCLA), Los Angeles, California, USA.
Mol Ther. 2011 Apr;19(4):768-81. doi: 10.1038/mt.2010.281. Epub 2010 Dec 21.
The generation of hematopoietic cells from human embryonic stem cells (hESC) has raised the possibility of using hESC as an alternative donor source for transplantation. However, functional defects identified in hESC-derived cells limit their use for full lymphohematopoietic reconstitution. The purpose of the present study was to define and quantitate key functional and molecular differences between CD34(+) hematopoietic progenitor subsets derived from hESC and CD34(+) subsets from umbilical cord blood (UCB) representing definitive hematopoiesis. Two distinct sub-populations were generated following mesodermal differentiation from hESC, a CD34(bright) (hematoendothelial) and CD34(dim) (hematopoietic-restricted) subset. Limiting dilution analysis revealed profound defects in clonal proliferation relative to UCB particularly in B lymphoid conditions. Transcription factors normally expressed at specific commitment stages during B lymphoid development from UCB-CD34(+) cells were aberrantly expressed in hESC-derived CD34(+) cells. Moreover, strong negative regulators of lymphopoiesis such as the adaptor protein LNK and CCAAT/enhancer-binding protein-α (CEBPα), were exclusively expressed in hESC-CD34(+) subsets. Knockdown of LNK lead to an increase in hematopoietic progenitors generated from hESCs. The aberrant molecular profile seen in hESC-CD34(+) cells represents persistence of transcripts first expressed in undifferentiated hESC and/or CD326-CD56(+) mesoderm progenitors, and may contribute to the block in definitive hematopoiesis from hESC.
从人类胚胎干细胞 (hESC) 中生成造血细胞，使人们有可能将 hESC 用作移植的替代供体来源。然而，在 hESC 衍生细胞中鉴定出的功能缺陷限制了它们在完全淋巴造血重建中的应用。本研究的目的是定义和量化源自 hESC 的 CD34(+)造血祖细胞亚群与代表确定性造血的脐带血 (UCB) CD34(+)亚群之间的关键功能和分子差异。通过 hESC 中的中胚层分化产生了两个不同的亚群，CD34(bright)（血内皮）和 CD34(dim)（造血受限）亚群。有限稀释分析显示，与 UCB 相比，克隆增殖存在严重缺陷，特别是在 B 淋巴样条件下。在 UCB-CD34(+)细胞中 B 淋巴样发育的特定承诺阶段正常表达的转录因子在 hESC 衍生的 CD34(+)细胞中异常表达。此外，淋巴样发生的强负调节剂，如衔接蛋白 LNK 和 CCAAT/增强子结合蛋白-α (CEBPα)，仅在 hESC-CD34(+)亚群中表达。LNK 的敲低导致 hESCs 生成的造血祖细胞增加。在 hESC-CD34(+)细胞中观察到的异常分子谱代表了首先在未分化的 hESC 中表达的转录本的持续存在，和/或 CD326-CD56(+)中胚层祖细胞，并且可能导致 hESC 中确定性造血的阻断。
