4D Printed Hydrogel Expanders for Personalized and Accelerated Soft Tissue Regeneration.

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Tissue Engineering

Background:

• Controllable tissue expansion is vital for treating skin and mucosal defects.
• Current tissue expanders struggle with anatomical customization.
• Isotropic water-based expansion methods have limitations.

Purpose of the Study:

• To develop a 4D printed biocompatible hydrogel expander with customizable designs.
• To achieve anisotropic and programmable shape morphing for tissue expansion.
• To offer a thinner, minimally invasive alternative to existing expanders.

Main Methods:

• Synthesized water-swellable polymer sheets with non-swellable elastomer frameworks using digital photocuring.
• Utilized buckling of sheets upon tissue fluid adsorption for shape change.
• Implanted the 1.0 mm thin expander in rat scalps for evaluation.

Main Results:

• Achieved programmable 3D structure formation with time as the fourth dimension.
• Demonstrated significant skin area (2-fold) and weight (3-fold) increase within 5 days post-implantation without damage.
• Identified potential involvement of the PI3K-AKT pathway in buckling-induced regeneration via RNA sequencing.

Conclusions:

• The buckling-based 4D printed hydrogel expander enables safer and accelerated tissue expansion.
• This technology offers a thinner, customizable, and minimally invasive solution for regenerative medicine.
• The findings suggest a new strategy for personalized regenerative medicine by leveraging programmable material behavior.