Force generation in human blood platelets by filamentous actomyosin structures

Adsorption Force of Fibronectin Regulates Protein Reorganization, Desorption, and Endocytosis

Protein adsorption on biomaterials occurs before cell adhesion. To adapt the properties of biomaterials, adhered cells may utilize and modify adsorbed proteins for survival and function. In this process, the protein-material interfacial force (Fad) is supposed to play vital roles, which, however, has received little attention. Here, we found that rat mesenchymal stem cells (rMSCs) can utilize the adsorbed fibronectin (FN) via reorganization, desorption, or endocytosis, and these utilization processes are regulated by Fad through regulating cell adhesion and force balance between the cell traction force and Fad. Furthermore, protein utilization has an Fad-dependent temporal sequence. On low Fad surface, FN endocytosis might happen prior to FN desorption and aggregation. This work confirms the importance of Fad in protein utilization and provides new insight into the mechanism by which cells process their surrounding ECM proteins, which may help to guide the design of better biomaterials.

Platelet mechanosensing as key to understanding platelet function

PURPOSE OF REVIEW

This review highlights how the perception of platelet function is evolving based on recent insights into platelet mechanobiology.

RECENT FINDINGS

The mechanosensitive ion channel Piezo1 mediates activation of free-flowing platelets under conditions of flow acceleration through mechanisms independent of adhesion receptors and classical activation pathways. Interference with the initiation of platelet migration or with the phenotypic switch of migrating platelets to a procoagulant state aggravates inflammatory bleeding. Mechanosensing of biochemical and biophysical microenvironmental cues during thrombus formation feed into platelet contractile force generation. Measurements of single platelet contraction and bulk clot retraction show promise to identify individuals at risk for hemorrhage.

SUMMARY

New findings unravel novel mechanotransduction pathways and effector functions in platelets, establishing mechanobiology as a pivotal component of platelet function. These insights highlight limitations of existing treatments and offer new potential therapeutic approaches and diagnostic avenues based on mechanobiological principles. Further extensive research is required to distinguish between core hemostatic and pathological mechanisms influenced by platelet mechanosensing.

Platelet-Rich Plasma in Dermatology: New Insights on the Cellular Mechanism of Skin Repair and Regeneration

The skin's recognised functions may undergo physiological alterations due to ageing, manifesting as varying degrees of facial wrinkles, diminished tautness, density, and volume. Additionally, these functions can be disrupted (patho)physiologically through various physical and chemical injuries, including surgical trauma, accidents, or chronic conditions like ulcers associated with diabetes mellitus, venous insufficiency, or obesity. Advancements in therapeutic interventions that boost the skin's innate regenerative abilities could significantly enhance patient care protocols. The application of Platelet-Rich Plasma (PRP) is widely recognized for its aesthetic and functional benefits to the skin. Yet, the endorsement of PRP's advantages often borders on the dogmatic, with its efficacy commonly ascribed solely to the activation of fibroblasts by the factors contained within platelet granules. PRP therapy is a cornerstone of regenerative medicine which involves the autologous delivery of conditioned plasma enriched by platelets. This is achieved by centrifugation, removing erythrocytes while retaining platelets and their granules. Despite its widespread use, the precise sequences of cellular activation, the specific cellular players, and the molecular machinery that drive PRP-facilitated healing are still enigmatic. There is still a paucity of definitive and robust studies elucidating these mechanisms. In recent years, telocytes (TCs)-a unique dermal cell population-have shown promising potential for tissue regeneration in various organs, including the dermis. TCs' participation in neo-angiogenesis, akin to that attributed to PRP, and their role in tissue remodelling and repair processes within the interstitia of several organs (including the dermis), offer intriguing insights. Their potential to contribute to, or possibly orchestrate, the skin regeneration process following PRP treatment has elicited considerable interest. Therefore, pursuing a comprehensive understanding of the cellular and molecular mechanisms at work, particularly those involving TCs, their temporal involvement in structural recovery following injury, and the interconnected biological events in skin wound healing and regeneration represents a compelling field of study.