Structure of pericellular matrix around agarose-embedded chondrocytes

Center for Biomedical Engineering and Biological Engineering Division, Massachusetts Institute of Technology, Cambridge, MA, USA.
Osteoarthritis and Cartilage (Impact Factor: 4.17). 11/2007; 15(10):1207-16. DOI: 10.1016/j.joca.2007.03.023
Source: PubMed


Determine whether the structure of the type VI collagen component of the chondrocyte pericellular matrix (PCM) generated by agarose-embedded chondrocytes in culture is similar to that found in native articular cartilage.
Confocal microscopy, quick-freeze deep-etch electron microscopy, and real-time polymerase chain reaction (PCR) were used to investigate temporal and spatial patterns of type VI collagen protein deposition and gene expression by bovine chondrocytes during 4 weeks of culture within a 2% agarose hydrogel. Similar analyses were performed on chondrocytes within samples of intact cartilage obtained from the same joint surfaces as those used for cell isolation for comparison.
Type VI collagen accumulated uniformly around cells embedded in agarose, with the rate of deposition slowing after the second week. After 1 week, PCM fibrils were observed to be oriented perpendicular to the cell surface, in contrast with the primarily tangential fibrillar arrangement observed in native articular cartilage. Expression of col6 in agarose-embedded cells was initially much higher ( approximately 400%) than that in chondrocytes within cartilage. Expression of col6 in the cultured chondrocytes declined by approximately 60% after 1 week, and remained stable thereafter.
PCM structure and composition around cells in a hydrogel scaffold may be different than that in native cartilage, with potential implications for mass transport, mechanotransduction, and ultimately, the success of tissue engineering approaches.

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    • "Such timedependent behaviors are important because tissue-engineered constructs implanted in vivo are expected to undergo cyclic and impact loading that includes frequency components as high as 1 kHz, just as native cartilage does (Shepherd 1997). Given the known hydrated and porous microstructure of the tissue-engineered cell-associated matrix (DiMicco 2007), rate-dependent poro-viscoelastic processes are expected (Kim 2008). The objectives of this study were (1) to establish the experimental and theoretical methodologies for quantifying the dynamic mechanical properties of newly developed tissue-engineered matrix associated with single cells, (2) to investigate the temporal evolution of these properties with increasing time in 3D alginate gel culture, and (3) to quantify the effect of specific growth factors (IGF-1 and OP-1) on the dynamic mechanical functionality of the newly developed matrix. "
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    • "doi:10.1016/j.ejps.2009.02.011 agarose/␤-TCP pieces loaded with vancomycin (Román et al., 2008), a hydrophilic antibiotic drug, commonly used for treating osteomyelitis and preventing osseous staphylococcal infections after surgery. Besides its traditional uses (Rinaudo, 2008) agarose has gained a new appreciation in tissue engineering applications such as cell–hydrogel hybrids (Prashant et al., 2006), nerve guidance scaffolds (Dodla and Bellamkonda, 2006), matrix material for dental and bone replacement (Tabata et al., 2003; DiMicco et al., 2007), beads and microcarriers for drug delivery or cell culture (Liu and Li, 2005; Meilander et al., 2003), micropatterned stamping arrays (Mayer et al., 2004) and molecularly imprinted membranes for protein recognition (Lin et al., 2008). ␤-Tricalcium phosphate (Ca 3 (PO 4 ) 2 , ␤-TCP) has been observed to resorb in vivo, with new bone growth replacing the original graft (Dorozhkin and Epple, 2002; Vallet-Regí and González-Calbet, 2004). "
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