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

Abstract

Cytoskeleton is composed of more than 100 proteins and represents a dynamic network of the cellular cytoplasm. Cytoskeletal functions include spatial organization of cellular components, structural connection of the cell with external environment, and biomechanical force generation. Cytoskeleton takes part, at different levels, in all phases of platelet biogenesis: megakaryocyte (MK) differentiation, MK maturation, and platelet formation. In addition, it also plays a major role in each stage of platelet function. Inherited platelet disorders (IPDs) are a group of rare diseases featured by low platelet count and/or impaired platelet function. Over the past decade, the investigation of platelet biomechanics has become a major and highly relevant theme of research due to its implications at every stage of development of human life. The initial use of diverse biophysical techniques (e.g., micropipette aspiration, atomic force and scanning ion conductance microscopy, real-time deformability cytometry) started unraveling biomechanical features of platelets that are expected to provide new explanations for physiological and pathological mechanisms. Although the impact of cytoskeletal alterations has been largely elucidated in various IPDs' pathogenesis, the understanding of their impact on biomechanical properties of platelets represents an unmet need. Regarding IPDs, improving biomechanical studies seems promising for diagnostic and prognostic implications. Potentially, these characteristics of platelets may also be used for the prediction of bleeding risk. This review addresses the current available methods for biophysical investigations of platelets and the possible implementations in the field of IPDs.

Platelet Shape Changes during Thrombus Formation: Role of Actin-Based Protrusions

“…It is envisioned that a comprehensive analysis of platelet cytoskeleton-dependent biomechanical properties using cutting-edge biophysical tools will have diagnostic and prognostic applications: potentially, biophysical characteristics of platelets may be used for the prediction of bleeding risk, risk stratification depending on type of cytoskeletal defect, and thus may also be helpful in determination of clinical need for prophylactic or therapeutic drug intervention and platelet transfusions. 26 Platelets can extend two different types of cellular protrusions, namely filopodia and lamellipodia, in a static spreading assay. It has been generally believed that platelet filopodial structures are important for sensing the extracellular environment, whereas lamellipodial structures are rather important for sealing the wound and propagating thrombus formation.…”

“…have been applied in platelet biology, the reader is referred to Ciciliano et al, 24 Feghhi et al, 25 and to the recent reviews from Zaninetti et al 26 and Sachs et al 27…”

Clot Retraction: Cellular Mechanisms and Inhibitors, Measuring Methods, and Clinical Implications

“…Subsequent to the activation of platelets, the contractile apparatus of the platelet changes the shape of the cell from a discoid to a spheroid shape and is responsible for the so-called spreading, the formation of filopodia and lamellipodia as well as clot retraction and migration [9]. Important constituents of the contractile apparatus are the microtubules and actin filaments.…”

Diagnosing Inherited Platelet Disorders: Modalities and Consequences

“…87 FC assessment of phosphatidylserine expression by annexin V binding can be of aid in diagnosing IPDs with enhanced or impaired procoagulant activity of platelets as reported in Stormorken and Scott syndrome, respectively. [87][88][89] Methodologies combining FC with microscopy (i.e., imaging FC), fluorescence labeling (i.e., multiplexed FC), or microfluidic techniques (i.e., real-time deformation cytometry, RT-DC) represent new generation tests, which seem promising for studying IPDs with high throughput and novel approaches, [90][91][92][93] but they are not well established for patient diagnosis, yet.…”

“…Methodologies combining FC with microscopy (i.e., imaging FC), fluorescence labeling (i.e., multiplexed FC), or microfluidic techniques (i.e., real-time deformation cytometry, RT-DC) represent new generation tests, which seem promising for studying IPDs with high throughput and novel approaches, 90 91 92 93 but they are not well established for patient diagnosis, yet.…”