Table 2.

Tissue Mechanical Variations During Pathophysiological Processes

	Growth/maturation	Adulthood	Aging	Fibrosis
E (elastic modulus/behavior)	↑	∼	↑	↑
μ (viscosity)	↑	∼	↓	↑
η (viscous coefficient/behavior)	↓	∼	Depends on the relative variation of E and μ	↓
Main factors involved	Enzymatic controlled cross-linking Collagen physiological remodeling with loads ECM deposition	ECM reorganization Balance between ECM deposition and turnover	Glycation Collagen depletion Elastin damage accumulation	LOX upregulation Collagen hyperproduction
Time scales	From days to years	From days to years	Years	Years
References	2,33–36,89,90	2,3	2,37–39,56,91–94	2,94,95

As tissues mature, age, or remodel over time, the mechanical properties also evolve.

∼, almost constant; ECM, extracellular matrix; LOX, lysyl oxidase.