Table 1.

Examples of acoustic modification of ECM scaffold structure and function. Abbreviations: CW, continuous wave; USWF, ultrasound standing wave field; I_SPPA, spatial peak, pulse average intensity; I_SPTA, spatial peak, temporal average intensity; PFC, perfluorocarbon; rtPA, recombinant tissue plasminogen activator.

ECM/US Interaction	Acoustic Conditions	Acoustic Mechanism	Scaffold Composition	Biological Response	Reference
Direct effect on ECM proteins	8 MHz, CW ISPPA ≤ 10 W/cm2	Thermal and non-thermal	Collagen and fibronectin	Fiber alignment, fibronectin fibril formation; Fibroblast self-assembly	[93]
Direct effect on ECM proteins	1 MHz, CW 1 – 8 W/cm2	Cavitation	Fibrin and rtPA	Decreased fiber density, enhanced proteolysis	[94, 95]
Direct effect on ECM proteins	Benchtop sonicator	Cavitation	Decellularized tendon	Decreased fiber density and increased pore size; Enhanced cellular infiltration	[96]
Acoustically responsive scaffold	20kHz, pulsed	Cavitation	Ca2+-spiked liposomes in transglutaminase-fibrinogen solution	Transglutaminase-triggered fibrinogen polymerization	[97]
Acoustically responsive scaffold	3.5 MHz, pulsed MPa +(−) = 12.9 [6.0]	Cavitation	PFC-growth factor emulsions embedded in fibrin	Increased pore size, increased stiffness; Growth factor release	[98, 99]
Acoustically responsive scaffold	2.5 MHz, CW ISPTA = 658–750 W/cm2	Thermal	Cell-embedded fibrin (+/− hydroxyapatite)	Growth factor expression	[100, 101]
Cellular ECM Remodeling	2–2.2 MHz, USWF 0.12 MPa	USWF	Collagen	Collagen contraction; Myoblast alignment along tensional axis	[80]
Cellular ECM Remodeling	1 MHz, USWF 0.2MPa	USWF	Cell-embedded collagen	Enhanced gel contraction; Fiber alignment along vascular sprouts	[74, 75]
Direct effect on ECM proteins; Cellular ECM Remodeling	8 MHz, CW ISPPA ≤ 10 W/cm2	Non-thermal	Collagen	Altered pore density and radial fiber alignment; Fibroblast migration and ECM contraction	[102–104]