Sakurai Yumiko, Fitch-Tewfik Jennifer L, Qiu Yongzhi, Ahn Byungwook, Myers David R, Tran Reginald, Fay Meredith E, Ding Lingmei, Spearman Paul W, Michelson Alan D, Flaumenhaft Robert, Lam Wilbur A
Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA; Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Atlanta, GA; Department of Pediatrics, Emory University School of Medicine, Atlanta, GA; Parker H. Petit Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA; Winship Cancer Institute, Emory University, Atlanta, GA; Institute of Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, GA;
Division of Hemostasis and Thrombosis, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA; and.
Blood. 2015 Jul 23;126(4):531-8. doi: 10.1182/blood-2014-11-607614. Epub 2015 May 11.
Although the biology of platelet adhesion on subendothelial matrix after vascular injury is well characterized, how the matrix biophysical properties affect platelet physiology is unknown. Here we demonstrate that geometric orientation of the matrix itself regulates platelet α-granule secretion, a key component of platelet activation. Using protein microcontact printing, we show that platelets spread beyond the geometric constraints of fibrinogen or collagen micropatterns with <5-µm features. Interestingly, α-granule exocytosis and deposition of the α-granule contents such as fibrinogen and fibronectin were primarily observed in those areas of platelet extension beyond the matrix protein micropatterns. This enables platelets to "self-deposit" additional matrix, provide more cellular membrane to extend spreading, and reinforce platelet-platelet connections. Mechanistically, this phenomenon is mediated by actin polymerization, Rac1 activation, and αIIbβ3 integrin redistribution and activation, and is attenuated in gray platelet syndrome platelets, which lack α-granules, and Wiskott-Aldrich syndrome platelets, which have cytoskeletal defects. Overall, these studies demonstrate how platelets transduce geometric cues of the underlying matrix geometry into intracellular signals to extend spreading, which endows platelets spatial flexibility when spreading onto small sites of exposed subendothelium.
尽管血管损伤后血小板在内皮下基质上的黏附生物学特性已得到充分表征，但基质的生物物理特性如何影响血小板生理功能仍不清楚。在此，我们证明基质本身的几何取向调节血小板α颗粒分泌，这是血小板活化的关键组成部分。使用蛋白质微接触印刷技术，我们发现血小板能够扩散到具有<5-µm特征的纤维蛋白原或胶原蛋白微图案的几何限制之外。有趣的是，α颗粒胞吐作用以及纤维蛋白原和纤连蛋白等α颗粒内容物的沉积主要出现在血小板延伸超出基质蛋白微图案的那些区域。这使得血小板能够“自我沉积”额外的基质，提供更多细胞膜以扩展铺展，并加强血小板-血小板连接。从机制上讲，这种现象由肌动蛋白聚合、Rac1激活以及αIIbβ3整合素重新分布和激活介导，并且在缺乏α颗粒的灰色血小板综合征血小板和具有细胞骨架缺陷的威斯科特-奥尔德里奇综合征血小板中减弱。总体而言，这些研究证明了血小板如何将潜在基质几何形状的几何线索转化为细胞内信号以扩展铺展，这赋予血小板在铺展到暴露的小面积内皮下部位时的空间灵活性。
