Table 1 Multifaceted roles of platelets in supporting tissue repair
Functional event | Key factors involved | References |
|---|---|---|
Hemostasis/clot formation | Platelets, through their interaction with coagulation factors, are an essential component of a cascade of biochemical reactions leading to the formation of fibrin clots, which help prevent excessive bleeding from injured blood vessels. This platelet–fibrin clot with a tri-dimensional structure acts not only as a temporary hemostatic barrier, but also as a functional scaffold for tissue repair and tissue remodeling | |
Growth factor release | Platelets store in their alpha-granules a diverse range of growth factors, such as platelet-derived growth factor (PDGF), transforming growth factor-beta (TGF-β), vascular endothelium growth factor (VEGF), and insulin-like growth factor (IGF), which can be selectively released upon platelet activation in a free form or packaged into extracellular vesicles. These growth factors promote cell proliferation, angiogenesis, and tissue regeneration | |
Stimulation of angiogenesis | Platelet-released factors, including VEGF, PDGF, hepatic growth factor (HFG), and basic fibroblast growth factor (bFGF), support the formation of new blood vessels. Angiogenesis helps deliver oxygen, nutrients, and other biological entities, to sites of injury, facilitating tissue repair | |
Remodeling of the extracellular matrix (ECM) | Platelets release enzymes and molecules involved in ECM degradation and remodeling, such as matrix metalloproteinase (MMP)-2 and MMP-9. MMP-2 and MMP-9 break down proteins like collagen and facilitate tissue remodeling during wound healing. Platelets also release fibronectin and vitronectin that are instrumental glycoproteins involved in cell adhesion, migration, and wound healing. Fibronectin binds to the ECM and promotes the attachment and migration of cells during tissue repair | |
Modulation of immune responses | Platelets interact with immune cells and release immune-modulating molecules, including chemokines and cytokines, which contribute to regulating inflammation and recruiting immune cells to sites of injury | |
Recruitment and differentiation of cells | Platelet-derived trophic factors can attract and stimulate the differentiation of various cells involved in tissue repair, such as mesenchymal stem cells and fibroblasts, promoting their migration to and proliferation at sites of injury | |
Antibacterial defense | Platelets possess antimicrobial peptides and enzymes that aid in combating bacteria multiplication at sites of tissue damage, reducing the risk of secondary infections |