Table 2.

Summary of research studies conducted on natural hydrogel-based materials used for immunomodulation of skin regeneration.

Hydrogel Type	Main Characteristic	Immunomodulatory Role in Skin Regeneration	Ref.
Decellularized ECM	Containing proteins, glycoproteins, and polysaccharides	Binding to the specific surface receptors of immune cells, the ECM composition can affect immunomodulation, promoting anti-inflammatory phenotype polarization in some cases	[230,243,244,245]
Collagen	Protein-based material and the most abundant ECM component	Binding to LAIR-1 receptors on immune cells, suppressing immune cell activity, and resolving post-wound inflammation	[246,247]
Fibrin	The main component of the haemostatic clot	Decreasing TNF-α cytokine secretion, decreasing macrophage motility, reduction of neutrophil recruitment, and extending pro-healing effects	[248,249,250,251,252]
Hyaluronic acid	Glycosaminoglycans material with various MWs	Modulation of leukocyte function, immunomodulatory effect dependent on MW, suppressing immune cell activity by high-MW HA, enhancing an inflammatory by low-MW HA, delaying inflammation by High-MW HA	[253,254]
Chitosan	A natural polysaccharide	Employing leukocytes and macrophages to the wound site, decreasing the inflammatory cells, and TNF-α and MMP-9 levels, and affecting macrophage polarization	[255,256,257,258]
Carrageenan	A natural marine polysaccharide from red seaweed	Stimulating IL-10 expression, prohibiting cytotoxic T cell responses, and delaying neutrophil activation	[259,260,261]
L-arginine	Amino acid-based material	Decreasing nitric oxide production, stimulating macrophages to express both TNF-α and NO in combination with chitosan	[262,263,264]