title: Platelet mechanosensing of substrate stiffness during clot formation mediates adhesion, spreading, and activation.
abstract: As platelets aggregate and activate at the site of vascular injury to stem bleeding, they are subjected to a myriad of biochemical and biophysical signals and cues. As clot formation ensues, platelets interact with polymerizing fibrin scaffolds, exposing platelets to a large range of mechanical microenvironments. Here, we show for the first time (to our knowledge) that platelets, which are anucleate cellular fragments, sense microenvironmental mechanical properties, such as substrate stiffness, and transduce those cues into differential biological signals. Specifically, as platelets mechanosense the stiffness of the underlying fibrin/fibrinogen substrate, increasing substrate stiffness leads to increased platelet adhesion and spreading. Importantly, adhesion on stiffer substrates also leads to higher levels of platelet activation, as measured by integrin αIIbβ3 activation, α-granule secretion, and procoagulant activity. Mechanistically, we determined that Rac1 and actomyosin activity mediate substrate stiffness-dependent platelet adhesion, spreading, and activation to different degrees. This capability of platelets to mechanosense microenvironmental cues in a growing thrombus or hemostatic plug and then mechanotransduce those cues into differential levels of platelet adhesion, spreading, and activation provides biophysical insight into the underlying mechanisms of platelet aggregation and platelet activation heterogeneity during thrombus formation.
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332; Department of Pediatrics, Division of Pediatric Hematology/Oncology, Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Emory University School of Medicine, Atlanta, GA 30322; Winship Cancer Institute of Emory University, Atlanta, GA 30322;
authors.forename: Yongzhi
authors.initials: Y
authors.lastname: Qiu
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332; School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332;
authors.forename: Ashley C
authors.initials: AC
authors.lastname: Brown
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332; Department of Pediatrics, Division of Pediatric Hematology/Oncology, Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Emory University School of Medicine, Atlanta, GA 30322; Winship Cancer Institute of Emory University, Atlanta, GA 30322;
authors.forename: David R
authors.initials: DR
authors.lastname: Myers
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332; Department of Pediatrics, Division of Pediatric Hematology/Oncology, Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Emory University School of Medicine, Atlanta, GA 30322; Winship Cancer Institute of Emory University, Atlanta, GA 30322;
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Sakurai
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332; Department of Pediatrics, Division of Pediatric Hematology/Oncology, Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Emory University School of Medicine, Atlanta, GA 30322; Winship Cancer Institute of Emory University, Atlanta, GA 30322;
authors.forename: Robert G
authors.initials: RG
authors.lastname: Mannino
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332; Department of Pediatrics, Division of Pediatric Hematology/Oncology, Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Emory University School of Medicine, Atlanta, GA 30322; Winship Cancer Institute of Emory University, Atlanta, GA 30322;
authors.forename: Reginald
authors.initials: R
authors.lastname: Tran
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332; Department of Pediatrics, Division of Pediatric Hematology/Oncology, Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Emory University School of Medicine, Atlanta, GA 30322; Winship Cancer Institute of Emory University, Atlanta, GA 30322;
authors.forename: Byungwook
authors.initials: B
authors.lastname: Ahn
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332; Department of Pediatrics, Division of Pediatric Hematology/Oncology, Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Emory University School of Medicine, Atlanta, GA 30322; Winship Cancer Institute of Emory University, Atlanta, GA 30322;
authors.forename: Elaissa T
authors.initials: ET
authors.lastname: Hardy
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332;
authors.forename: Matthew F
authors.initials: MF
authors.lastname: Kee
authors.affiliation: Department of Bioengineering, University of California, Berkeley, CA 94720; and.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332; Parker H. Petit Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332.
authors.forename: Gang
authors.initials: G
authors.lastname: Bao
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332; Parker H. Petit Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332.
authors.forename: Thomas H
authors.identifier: http://orcid.org/0000-0002-3218-8111
authors.initials: TH
authors.lastname: Barker
authors.affiliation: Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA 30332; Department of Pediatrics, Division of Pediatric Hematology/Oncology, Aflac Cancer Center and Blood Disorders Service of Children's Healthcare of Atlanta, Emory University School of Medicine, Atlanta, GA 30322; Winship Cancer Institute of Emory University, Atlanta, GA 30322; Parker H. Petit Institute of Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332 wilbur.lam@emory.edu.
authors.forename: Wilbur A
authors.initials: WA
authors.lastname: Lam
mesh_terms: D000180:Acrylic Resins / Q000378:metabolism; D001777:Blood Coagulation / Q000502:physiology*; D001792:Blood Platelets / Q000166:cytology* / Q000378:metabolism; D002465:Cell Movement / Q000502:physiology*; D060833:Cellular Microenvironment / Q000502:physiology; D005337:Fibrin / Q000378:metabolism; D005340:Fibrinogen / Q000378:metabolism; D006801:Humans; D055767:Immobilized Proteins / Q000378:metabolism; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D018613:Microscopy, Confocal; D019007:P-Selectin / Q000378:metabolism; D010718:Phosphatidylserines / Q000378:metabolism; D015539:Platelet Activation / Q000502:physiology*; D010973:Platelet Adhesiveness / Q000502:physiology*; D010974:Platelet Aggregation / Q000502:physiology; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism; D013314:Stress, Mechanical; D013927:Thrombosis / Q000503:physiopathology; D020830:rac1 GTP-Binding Protein / Q000378:metabolism; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D005337:Fibrin; D005340:Fibrinogen; D055767:Immobilized Proteins; D019007:P-Selectin; D010718:Phosphatidylserines; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D020830:rac1 GTP-Binding Protein; D000099166:Polyacrylamides
keywords: biomaterials; cell mechanics; mechanotransduction; platelet cytoskeleton