Transplantation of expanded hematopoietic stem cells (HSCs) and gene therapy based on HSC engineering have emerged as promising approaches for the treatment of hematological diseases. Nevertheless, the immunophenotype of cultured HSCs remains poorly defined. Here, we identify Integrin-α3 (ITGA3) as a marker of cultured human HSCs. Exploiting the pyrimidoindole derivative UM171 to expand cord blood (CB) cells, we show that ITGA3 expression is sufficient to separate the primitive EPCR⁺CD90⁺CD133⁺CD34⁺CD45RA⁻ HSC population into two functionally distinct fractions presenting mostly short-term (ITGA3⁻) and both short-term and long-term (ITGA3⁺) repopulating potential. ITGA3⁺ cells exhibit robust multilineage differentiation potential, serial reconstitution ability in immunocompromised mice, and an HSC-specific transcriptomic signature. Moreover, ITGA3 expression is functionally required for the long-term engraftment of CB cells. Altogether, our results indicate that ITGA3 is a reliable marker of cultured human long-term repopulating HSCs (LT-HSCs) and represents an important tool to improve the accuracy of prospective HSC identification in culture.

扩展的造血干细胞（HSC）的移植和基于HSC工程的基因治疗已成为治疗血液疾病的有前途的方法。然而，培养的HSC的免疫表型仍然不清楚。在这里，我们确定整合素α3（ITGA3）作为培养的人类HSCs的标志物。利用该pyrimidoindole衍生物UM171扩大脐带血（CB）的细胞，我们表明，ITGA3表达足以原始EPCR分开⁺ CD90 ⁺ CD133 ⁺ CD34 ⁺ CD45RA ^- HSC群体分成两个功能上不同的部分呈现大多短期（ITGA3 ^-）以及短期和长期（ITGA3 ⁺）的潜力。ITGA3 ⁺细胞在免疫功能低下的小鼠中表现出强大的多系分化潜能，系列重建能力以及HSC特异性转录组特征。此外，ITB3表达在功能上是CB细胞长期移植的必需条件。总之，我们的结果表明ITGA3是培养的人类长期繁殖HSC（LT-HSC）的可靠标记，并且是提高前瞻性HSC鉴定在培养物中准确性的重要工具。