Millimeter-Scale Dual-Opposing RNA-Gradient Hydrogel for Interfacial Gene Silencing.

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Microfluidics

Background:

• Tissue interface restoration is challenging due to complex cellular and biochemical gradients.
• Existing methods create gradients outside relevant biological length scales.
• Mimicking native tissue heterogeneity requires precise control over molecular distribution.

Purpose of the Study:

• To develop a microfluidic system for generating millimeter-scale hydrogels with dual-opposing gradients.
• To incorporate RNA interference (RNAi) molecules into these hydrogels for spatial gene regulation.
• To engineer functional tissue interfaces for regenerative medicine.

Main Methods:

• A branched microfluidic chip was used to generate dual-opposing gradients of RNAi-nanocomplexes.
• RNAi molecules were complexed with thiolated polyethyleneimine and incorporated into poly(ethylene glycol)-diacrylate (PEG-DA) hydrogels.
• The hydrogels were photocrosslinked, creating stable, linear 3-mm gradients.

Main Results:

• The microfluidic system successfully generated stable, linear, millimeter-scale dual-opposing RNA gradients.
• Encapsulated cells within the hydrogels showed precise spatial regulation of gene expression.
• The platform demonstrated the ability to influence both encapsulated and endogenous cell gene expression.

Conclusions:

• The developed microfluidic platform enables the creation of complex, gradient hydrogels at biologically relevant length scales.
• This technology facilitates targeted delivery of RNAi molecules for precise gene regulation in tissue engineering.
• The approach shows significant potential for regenerating critical tissue interfaces like tendon-to-bone and cartilage-to-bone.