Stem Cell Program, Division of Pediatric Hematology and Oncology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Harvard Stem Cell Institute, Cambridge, MA 02138, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA.
Stem Cell Program, Division of Pediatric Hematology and Oncology, Boston Children's Hospital, Boston, MA 02115, USA; Harvard Stem Cell Institute, Cambridge, MA 02138, USA.
Dev Cell. 2020 Feb 24;52(4):446-460.e5. doi: 10.1016/j.devcel.2020.01.006. Epub 2020 Feb 6.
Hematopoietic stem and progenitor cells (HSPCs), first specified from hemogenic endothelium (HE) in the ventral dorsal aorta (VDA), support lifelong hematopoiesis. Their de novo production promises significant therapeutic value; however, current in vitro approaches cannot efficiently generate multipotent long-lived HSPCs. Presuming this reflects a lack of extrinsic cues normally impacting the VDA, we devised a human dorsal aorta-on-a-chip platform that identified Yes-activated protein (YAP) as a cyclic stretch-induced regulator of HSPC formation. In the zebrafish VDA, inducible Yap overexpression significantly increased runx1 expression in vivo and the number of CD41 HSPCs downstream of HE specification. Endogenous Yap activation by lats1/2 knockdown or Rho-GTPase stimulation mimicked Yap overexpression and induced HSPCs in embryos lacking blood flow. Notably, in static human induced pluripotent stem cell (iPSC)-derived HE culture, compound-mediated YAP activation enhanced RUNX1 levels and hematopoietic colony-forming potential. Together, our findings reveal a potent impact of hemodynamic Rho-YAP mechanotransduction on HE fate, relevant to de novo human HSPC production.
造血干细胞和祖细胞（HSPCs）最初从腹主动脉背侧的造血内皮（HE）中特化而来，支持终生造血。它们的从头产生具有重要的治疗价值；然而，目前的体外方法不能有效地产生多能、长寿的 HSPCs。假设这反映了缺乏正常影响背主动脉的外在线索，我们设计了一个人类背主动脉芯片平台，该平台将 Yes 激活蛋白（YAP）鉴定为 HSPC 形成的循环拉伸诱导调节剂。在斑马鱼背主动脉中，诱导型 yap 过表达显著增加了体内 runx1 的表达和 HE 特化后 CD41 HSPCs 的数量。通过 lats1/2 敲低或 Rho-GTPase 刺激诱导内源性 yap 激活，模拟 yap 过表达，并在缺乏血流的胚胎中诱导 HSPCs。值得注意的是，在静态人诱导多能干细胞（iPSC）衍生的 HE 培养物中，化合物介导的 YAP 激活增强了 RUNX1 水平和造血集落形成潜力。总之，我们的研究结果揭示了血流动力学 Rho-YAP 机械转导对 HE 命运的强大影响，与从头开始产生人类 HSPCs 相关。
