Elucidating the role of megakaryocytes as immune cells using iPSC-derived megakaryocyte progenitor models

最近的证据表明，人类巨核细胞 (MK) 代表了一个异质群体，其中包括一个经过基因编程的免疫子集。然而，人类 MK 中这种异质性的个体发育尚不清楚。在这项研究中，我们试图利用永生化 MK 细胞系 (imMKCLs) 来研究免疫偏向 MK 的调节，该细胞系源自人类诱导多能干细胞 (iPSC)，并作为临床试验中使用的 iPSC 衍生血小板 (iPSC-PLT) 的来源。2022 年，我们进行了一系列研究，旨在表征 imMKCL 的免疫特性并阐明所涉及的关键调节因子在免疫倾斜的 imMKCL 中。具体来说，我们研究了几种免疫相关表面标志物的表达，发现 ICAM-1 和 CD11b 在 imMKCL 上表达。为了确定 imMKCL 开发过程中参与免疫偏向转录特征谱系测定的潜在因素，我们使用 imMKCL 进行了单细胞 RNA 序列分析。通过功能获得和慢病毒介导的强制表达研究，我们确定了let-7a-5p及其下游靶基因X是参与免疫偏态imMKCL发育的潜在关键调节因子。出乎意料的是，我们发现 imMKCL 的免疫特性失调/亚群与增殖缺陷以及随后的 PLT 产生受损密切相关。

Recent evidence indicates that human megakaryocytes (MKs) represent a heterogeneous population, which includes an immune subset that is genetically programmed. However, the ontogeny of this heterogeneity in human MKs is not well understood. In this study, we sought to investigate the regulation of immune-biased MKs utilizing an immortalized MK cell line (imMKCLs), which is derived from human-induced pluripotent stem cells (iPSCs) and serves as a source of iPSC-derived platelets (iPSC-PLTs) used in clinical trials.In 2022, we conducted a series of studies aimed at characterizing the immune properties of imMKCLs and elucidating the key regulators involved in immune-skewed imMKCLs. Specifically, we investigated the expression of several immune-related surface markers and found ICAM-1 and CD11b were expressed on imMKCLs. To identify potential factors involved in the lineage determination of immune-biased transcriptional signatures during imMKCL development, we conducted single-cell RNA-seq analysis using imMKCLs. Through gain-of-function and lentiviral-mediated forced expression studies, we identified let-7a-5p and its downstream target gene X as potential key regulators involved in immune-skewed imMKCL development. Unexpectedly, we discovered that the dysregulated immune properties/subsets of imMKCLs were closely linked with deficient proliferation and subsequently impaired PLT production.