Jiang Jinlin, Kao Chen-Yuan, Papoutsakis Eleftherios T
Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, United States; Delaware Biotechnology Institute, University of Delaware, Newark, DE, United States.
Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, United States; Delaware Biotechnology Institute, University of Delaware, Newark, DE, United States; Department of Biological Sciences, University of Delaware, Newark, DE, United States.
J Control Release. 2017 Feb 10;247:1-18. doi: 10.1016/j.jconrel.2016.12.021. Epub 2016 Dec 24.
Megakaryocytic microparticles (MkMPs), the most abundant MPs in circulation, can induce the differentiation of hematopoietic stem and progenitor cells (HSPCs) into functional megakaryocytes. This MkMP capability could be explored for applications in transfusion medicine but also for delivery of nucleic acids and other molecules to HSPCs for targeted molecular therapy. Understanding how MkMPs target, deliver cargo and alter the fate of HSPCs is important for exploring such applications. We show that MkMPs, which are distinct from Mk exosomes (MkExos), target HSPCs with high specificity since they have no effect on other ontologically or physiologically related cells, namely mesenchymal stem cells, endothelial cells or granulocytes. The outcome is also specific: only cells of the megakaryocytic lineage are generated. Observation of intact fluorescently-tagged MkMPs inside HSPCs demonstrates endocytosis as one mechanism of cargo delivery. Fluorescent labeling and scanning electron microscopy (SEM) imaging show that direct fusion of MkMPs into HSPCs is also engaged in cargo delivery. SEM imaging detailed the membrane-fusion process in four stages leading to full adsorption of MkMPs into HSPCs. Furthermore, macropinocytosis and lipid raft-mediated were shown here as mechanisms of MkMP uptake by HSPC. In contrast, the ontologically related platelet-derived MPs (PMPs) cannot be taken up by HSPCs although they bind to and induce HSPC aggregation. We show that platelet-like thrombin activation is apparently responsible for the different biological effects of MkMPs versus PMPs on HSPCs. We show that HSPC uropods are the preferential site for MkMP binding, and that CD54 (ICAM-1), CD11b, CD18 and CD43, localized on HSPC uropods, are involved in MkMP binding to HSPCs. Finally, we show that MkMP RNA is largely responsible for HSPC programming into Mk differentiation.
巨核细胞微粒（MkMPs）是循环中最丰富的微粒，可诱导造血干细胞和祖细胞（HSPCs）分化为功能性巨核细胞。这种MkMPs的能力可用于输血医学，也可用于将核酸和其他分子递送至HSPCs以进行靶向分子治疗。了解MkMPs如何靶向、递送货物并改变HSPCs的命运对于探索此类应用至关重要。我们发现，与巨核细胞外泌体（MkExos）不同，MkMPs对HSPCs具有高度特异性靶向作用，因为它们对其他本体或生理相关细胞，即间充质干细胞、内皮细胞或粒细胞没有影响。结果也是特异性的：仅产生巨核细胞系的细胞。观察HSPCs内完整的荧光标记MkMPs表明内吞作用是货物递送的一种机制。荧光标记和扫描电子显微镜（SEM）成像显示，MkMPs与HSPCs的直接融合也参与了货物递送。SEM成像详细描述了膜融合过程的四个阶段，导致MkMPs完全吸附到HSPCs中。此外，巨胞饮作用和脂筏介导作用在此被证明是HSPC摄取MkMPs的机制。相比之下，本体相关的血小板衍生微粒（PMPs）虽然能与HSPCs结合并诱导其聚集，但不能被HSPCs摄取。我们发现，血小板样凝血酶激活显然是MkMPs与PMPs对HSPCs产生不同生物学效应的原因。我们发现HSPC的尾足是MkMPs结合的优先位点，并且位于HSPC尾足上的CD54（细胞间黏附分子-1）、CD11b、CD18和CD43参与了MkMPs与HSPCs的结合。最后，我们发现MkMP RNA在很大程度上负责将HSPC编程为巨核细胞分化。
