Table 3.

Selection of currently available experimental platforms that are used to delineate the role of passive and active cues in the context of optimizing key scaffold properties.

Key Scaffold Properties	Mechanostimulation	Technique to Study	Variables	Current Limitations
	Passive
fibre diameter, fibre topography		• microgrooves	• groove width (nm–$\mathsf{\mu }$m) • shape	groove-depth as confounding parameter
	• dimension/topography
		• micropatterning	• pattern size ($\mathsf{\mu }$m) • shape • protein gradients	range of pattern-size
fibre stiffness, macroscopic stiffness, scaffold density	• substrate stiffness	• polyacrylamide gels (2D) [119]	• 1 Pa–100 kPa	unable to capture fibrous 3D morphology
		• hydrogels (3D) [120,121]	• <1 Pa–few kPa • stiffness gradients (2D) • non-linearity	low stiffness magnitude
	Active
anisotropy, geometry	• shear stress	• parallel plates [122]	• shear stress (<1 Pa–few Pa)	pressure as confounding parameter
		• orbital shaker [122]	• shear stress (<1 Pa–few Pa)	temporal and spatial variations in shear stress
anisotropy, geometry, macroscopic stiffness	• strain	• motor/pressure driven distensible membrane [122]	• strain (1–20%)	spatial variations in strain
anisotropy, geometry, macroscopic stiffness	• shear stress & strain	• mock artery [122]	• shear stress (<1 Pa) • strain (1–10%)	no independent control of variables
		• microfluidic device [123,124,125]	• shear stress (<1 Pa–few Pa) • strain (1–10%)	lack of 3D environment
	Passive and active
fibre diameter, anisotropy, pore size	• scaffold + shear stress	• parallel plates in mesofluidic device [126]	• shear stress (<1 Pa–few Pa) • scaffold properties	pressure as confounding parameter
anisotropy, pore size, connectivity, macroscopicstiffness, degradation rate	• scaffold + strain	• motor/pressure driven distensible membrane [99,127]	• strain (1–20%) • scaffold properties	spatial variations in strain
fibre diameter, anisotropy, pore size, connectivity, macroscopic stiffness, degradation rate	• scaffold + shear stress & strain	• perfusion bioreactor [128]	• shear stress (<1 Pa–few Pa) • strain (1–5%) • scaffold properties	no independent control of active variables