Structure of pericellular matrix around agarose-embedded chondrocytes

Area of Science:

• Biomaterials Science
• Cell Biology
• Tissue Engineering

Background:

• The chondrocyte pericellular matrix (PCM) is crucial for articular cartilage function.
• Understanding PCM structure in engineered tissues is vital for successful cartilage repair.

Purpose of the Study:

• To compare the structure of type VI collagen in the PCM of chondrocytes cultured in agarose hydrogels with that of native articular cartilage.
• To investigate the temporal and spatial deposition and gene expression of type VI collagen in cultured chondrocytes.

Main Methods:

• Confocal microscopy and quick-freeze deep-etch electron microscopy were used to analyze PCM structure.
• Real-time polymerase chain reaction (PCR) assessed type VI collagen gene expression (col6).
• Bovine chondrocytes cultured in agarose hydrogels were compared to chondrocytes from intact cartilage.

Main Results:

• Type VI collagen accumulated uniformly in agarose, with deposition slowing after two weeks.
• PCM fibrils in agarose were oriented perpendicular to cells, unlike the tangential arrangement in native cartilage.
• Initial col6 gene expression was significantly higher in cultured cells than in native cartilage, declining over the first week.

Conclusions:

• The structure and composition of the PCM in hydrogel scaffolds may differ from native cartilage.
• These differences have implications for mass transport and mechanotransduction in engineered tissues.
• Findings may influence the design of future cartilage tissue engineering strategies.