Controlling collagen fiber microstructure in three-dimensional hydrogels using ultrasound

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Biophysics

Background:

• Type I collagen is crucial for extracellular matrix structure and function.
• Collagen fiber architecture significantly impacts tissue properties.
• Controlling collagen microstructure is key for advanced tissue engineering.

Purpose of the Study:

• To investigate ultrasound's ability to control collagen microstructure during hydrogel fabrication.
• To explore site-specific patterning of collagen fibers using ultrasound.
• To assess the impact of ultrasound-patterned collagen on fibroblast behavior.

Main Methods:

• Utilized ultrasound exposure during type I collagen polymerization.
• Employed scanning electron microscopy and second-harmonic generation microscopy for structural analysis.
• Investigated mechanistic aspects, including thermal effects.
• Applied a high-frequency (8.3-MHz) ultrasound beam for site-specific patterning.

Main Results:

• Ultrasound exposure decreased collagen fiber diameters.
• Site-specific ultrasound patterning created distinct collagen microstructures within gels.
• Fibroblasts seeded on patterned gels migrated and aggregated within the ultrasound-exposed area.
• Clustered fibroblasts remodeled ultrasound-patterned collagen into dense sheets.

Conclusions:

• Ultrasound can noninvasively pattern collagen microstructures in engineered tissues.
• This technique allows for enhanced control over extracellular matrix microenvironments.
• Ultrasound-induced collagen patterning influences cellular functions within 3D engineered tissues.