Platelets exploit fibrillar adhesions to assemble fibronectin matrix revealing new force-regulated thrombus remodeling mechanisms

Abstract

Upon vascular injury, platelets are crucial for thrombus formation and contraction, but do they directly initiate early tissue repair processes? Using 3D super-resolution microscopy, micropost traction force microscopy, and specific integrin or myosin IIa inhibitors, we discovered here that platelets form fibrillar adhesions. They assemble fibronectin nanofibrils using αIIbβ3 (CD41/CD61, GPIIb-IIIa) rather than α5β1 integrins, in contrast to fibroblasts.Highly contractile platelets in contact with thrombus proteins (fibronectin, fibrin) pull fibronectin fibrils along their apical membrane, whereas platelets on basement membrane proteins (collagen IV, laminin) are less contractile generating less stretched planar meshworks beneath themselves. As probed by vinculin-decorated talin unfolding, platelets on fibronectin generate similar traction forces in apical fibrillar adhesions as fibroblasts do. These are novel mechanobiology mechanisms by which platelets spearhead the fibrillogenesis of the first de novo ECM, including its 2D versus 3D network architectures depending on their ECM environment, and thereby pave the way for cell infiltration.

Role of Platelet Cytoskeleton in Platelet Biomechanics: Current and Emerging Methodologies and Their Potential Relevance for the Investigation of Inherited Platelet Disorders

“…44,45 A wide variety of biophysical techniques are currently used to assess cytoskeleton-dependent contractile force generation at piconewton (pN) and biomechanical properties of platelets at nanometer (nm) regimes. [46][47][48][49] In this review we are focusing on micropipette aspiration, atomic force microscopy (AFM), scanning ion conductance microscopy (SICM), and real-time deformability cytometry (RT-DC) that offer varying degree of sensitivities and throughputs to investigate platelet biomechanics up to single platelets (►Table 1).…”

Ex vivoanticoagulants affect human blood platelet biomechanics with implications for high-throughput functional mechanophenotyping

“…Currently, a wide array of biophysical methods is available for the investigation of platelet biomechanics. They include micropipette aspiration [15][16][17] , atomic force microscopy [18][19][20] , scanning ion conductance microscopy 21,22 , traction force microscopy 23,24 , including flexible micropost arrays [25][26][27] . Although these methods have proven valuable in advancing our insights into platelet biomechanics, these are technically demanding, labor-intensive, and mostly limited to analysis of adherent platelets 28 .…”