Cellular and Molecular Therapeutics Branch, National Heart, Lung and Blood Institute (NHLBI), National Institutes of Health (NIH), 9000 Rockville Pike, Bethesda, MD 20892, USA.
Translational Stem Cell Biology Branch, NHLBI, NIH, Bethesda, MD 20892, USA.
Stem Cell Reports. 2021 Sep 14;16(9):2336-2350. doi: 10.1016/j.stemcr.2021.08.001. Epub 2021 Aug 26.
Activation of NOTCH signaling in human hematopoietic stem/progenitor cells (HSPCs) by treatment with an engineered Delta-like ligand (DELTA1 [DXI]) has enabled ex vivo expansion of short-term HSPCs, but the effect on long-term repopulating hematopoietic stem cells (LTR-HSCs) remains uncertain. Here, we demonstrate that ex vivo culture of human adult HSPCs with DXI under low oxygen tension limits ER stress in LTR-HSCs and lineage-committed progenitors compared with normoxic cultures. A distinct HSC gene signature was upregulated in cells cultured with DXI in hypoxia and, after 21 days of culture, the frequency of LTR-HSCs increased 4.9-fold relative to uncultured cells and 4.2-fold compared with the normoxia + DXI group. NOTCH and hypoxia pathways intersected to maintain undifferentiated phenotypes in cultured HSPCs. Our work underscores the importance of mitigating ER stress perturbations to preserve functional LTR-HSCs in extended cultures and offers a clinically feasible platform for the expansion of human HSPCs.
通过用工程化的 Delta 样配体（DELTA1 [DXI]）处理，NOTCH 信号在人造血干/祖细胞（HSPCs）中的激活已能够实现短期 HSPCs 的体外扩增，但对长期造血干细胞（LTR-HSCs）的影响仍不确定。在这里，我们证明与常氧培养相比，在低氧张力下用 DXI 对人成体 HSPCs 的体外培养可限制 LTR-HSCs 和谱系定向祖细胞中的 ER 应激。在低氧条件下用 DXI 培养的细胞中上调了一个独特的 HSC 基因特征，并且在 21 天的培养后，与未培养的细胞相比，LTR-HSCs 的频率增加了 4.9 倍，与常氧+DXI 组相比增加了 4.2 倍。NOTCH 和低氧途径相交以维持培养的 HSPCs 的未分化表型。我们的工作强调了减轻 ER 应激扰动以在扩展培养中保存功能性 LTR-HSCs 的重要性，并为人类 HSPCs 的扩增提供了一种临床可行的平台。
