Protease-Sensitive Hydrogel Biomaterials with Tunable Modulus and Adhesion Ligand Gradients for 3D Vascular Sprouting

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Cell Biology

Background:

• Designing biomaterial scaffolds with physiologically relevant gradients is crucial for understanding 3D vascular cell responses to dynamic matrix properties.
• Poly(ethylene) glycol (PEG) hydrogels offer tunable properties for creating such advanced biomaterials.

Purpose of the Study:

• To develop and characterize proteolytically degradable PEG hydrogel scaffolds with continuous gradients of elastic modulus and/or immobilized RGD peptide concentration.
• To investigate the impact of these gradients on vascular sprouting using a coculture model.

Main Methods:

• Utilized ascending photofrontal free-radical polymerization to fabricate hydrogel scaffolds.
• Generated gradients in elastic modulus (80 Pa/mm) with uniform RGD (2.06 ± 0.12 mM) and gradients in RGD concentration (58.8 μM/mm) with uniform elastic modulus (597 ± 22 Pa).
• Employed a coculture model of vascular sprouting to assess cell responses.

Main Results:

• Scaffolds with elastic modulus gradients induced an increase in the number of vascular sprouts in the direction opposite to the gradient.
• Scaffolds with RGD gradients promoted increased vascular sprout length towards the gradient direction.
• Vascular sprout length was significantly enhanced in regions with higher immobilized RGD concentrations.

Conclusions:

• Continuous gradients in biomaterial properties can differentially regulate vascular sprouting behavior.
• Elastic modulus gradients influence vascular sprout proliferation, while RGD gradients promote directed elongation.
• These findings highlight the potential of gradient biomaterials for controlling vascular network formation in tissue engineering applications.