Table 1.

Key scaffolding properties of hydrogels used in cartilage tissue engineering.

Property	Features and Performance	References
Porosity	-higher porosity induces chondrocyte migration and proliferation -high porosity enhances cell spreading and type II collagen production -larger pore sizes improve gene expression and ECM secretion -300 μm pore size is ideal for chondrogenic gene expression	[48,49,50]
Mechanical Strength	-higher mechanical strength enhances cartilage regeneration -scaffolds with strong mechanical properties (i.e., elastic modulus) accelerate cell migration and spreading and cell differentiation	[51]
Stiffness	-lower stiffness gives higher mRNA levels of chondrogenic markers (Col2α1, Sox9, and Agc) -higher stiffness yields a higher percentage of cells with chondrocytic morphology -higher elastic modulus promotes hypertrophic differentiation of chondrogenic cells	[40,52,53]
Adhesion	-higher adhesion stimulates chondrogenic cell spreading, proliferation, and differentiation -adhesive ligands trigger chondrogenic gene expression	[41,54]
Degradation	-lower degradation of hydrogel scaffold is good for chondrogenesis of stem cells -differentiation of mesenchymal stem cells (MSCs) is regulated by degradation-mediated cellular traction -hydrolytically stable hydrogels show a higher level of chondrogenic marker gene expression and lower level of hypertrophic genes	[55,56,57]