Mechanical Tuning of the Cell Microenvironment Using a Biomimetic Hydrogel System for Articular Cartilage Tissue...

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Regenerative Medicine

Background:

• Articular cartilage tissue engineering requires a functional pericellular matrix (PCM) for optimal outcomes.
• Harvesting chondrocytes with their PCM (chondrons) yields low cell numbers and heterogeneous mixtures.
• Microscale hydrogels offer a method to mechanically tune the chondrocyte microenvironment, potentially enabling stiffer constructs.

Purpose of the Study:

• To investigate the impact of microenvironmental stiffness on articular chondrocyte (AC) regenerative performance, specifically ECM and PCM synthesis.
• To evaluate articular cartilage-derived progenitor cells (ACPCs) as an alternative cell source within this system.
• To explore differential tuning of encapsulating and bulk hydrogel properties for cartilage repair.

Main Methods:

• ACs were cultured in soft or stiff bulk hydrogels (GelMA) or encapsulated in soft microgels within stiff GelMA.
• Constructs were implanted in an ex vivo porcine chondral defect model and cultured for 28 days with dynamic mechanical stimulation.
• PCM and ECM quality were assessed via cell content, immunofluorescence, histology, and biochemical assays (GAG, collagen).

Main Results:

• Cell encapsulation significantly influenced ECM synthesis and PCM quantity and completeness.
• Encapsulated groups exhibited more uniform matrix deposition compared to non-encapsulated groups, despite weaker overall alcian blue staining.
• Articular cartilage-derived progenitor cells (ACPCs) demonstrated performance comparable to ACs.

Conclusions:

• Differential tuning of encapsulating and bulk hydrogel properties is a promising strategy for articular cartilage tissue engineering.
• Microscale hydrogel encapsulation can improve matrix deposition uniformity.
• ACPCs represent a viable alternative cell source for cartilage regeneration applications.