Table 1.

The effect of skin aging on the wound healing process.

Effect of Aging on Wound Healing	Cell/Tissue/Organ Involved	Action	References
Prolong inflammatory phase	↑Platelets	↑Pro-inflammatory cytokines (e.g., PDGF, TGF-β & TGF-α)	[57]
	↓Adhesion molecules	Impairs the monocyte infiltration	[46]
	↓Macrophage	↓Granulation tissue formation, angiogenesis, collagen and growth factor synthesis ↓M2, hence prolong inflammation and halt tissue repair	[46,56]
	↑Pro-inflammatory cytokines	Activates the COX pathway ↑PGE2 production	[35,56]
	↑PGE2	↓Fibroblast and collagen synthesis, hence impairs the proliferative phase	[35]
Oxidative stress	↑Reactive oxygen species (ROS)	↑Tissue damage, lipid peroxidation, promote protein breakdown and DNA damage, hence↑cell apoptosis and senescence	[23,64]
Inefficient microcirculation	Impaired blood vessels	↓Inflammatory cells and chemical mediators at injury site Relative hypoperfusion at injury site Hypoxia that causes cell death due to apoptosis and necrosis	[5,64]

↑ Increase. ↓ Decrease.