The role of the PCM in reducing oxidative stress induced by radical initiated photoencapsulation of chondrocytes in poly(ethylene glycol) hydrogels

• Published in: Osteoarthritis and cartilage Vol. 20; no. 11; pp. 1326 - 1335
• Main Authors: Farnsworth, N, Bensard, C, Bryant, S.J
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-11-2012
• Subjects: Aggrecans - biosynthesis; Aggrecans - genetics; Animals; Cattle; Cells, Cultured; Chondrocyte; Chondrocytes - cytology; Chondrocytes - metabolism; Chondrocytes - radiation effects; Collagen - genetics; Collagen - metabolism; Extracellular Matrix - metabolism; Extracellular Matrix - radiation effects; Free Radicals - chemistry; Free Radicals - radiation effects; Gene Expression - radiation effects; Hydrogels - chemistry; Hydrogels - radiation effects; Matrix Metalloproteinase 13 - genetics; Matrix Metalloproteinase 13 - metabolism; Oxidative stress; Oxidative Stress - physiology; Oxidative Stress - radiation effects; Pericellular matrix; Photochemical Processes - radiation effects; Photopolymerization; Poly(ethylene glycol); Polyethylene Glycols - chemistry; Polymerization - radiation effects; Reactive Oxygen Species - metabolism; Reactive Oxygen Species - radiation effects; Rheumatology; Tissue Engineering - methods; Ultraviolet Rays; Pericellular matrix; Oxidative stress; Chondrocyte; Photopolymerization; Poly(ethylene glycol)
• ISSN: 1063-4584; 1522-9653
• DOI: 10.1016/j.joca.2012.06.015

Summary Objective The objectives for this study were to determine whether radical initiated photopolymerizations typically employed for cell encapsulations lead to oxidative stress incurred by chondrocytes and whether the development of a pericellular matrix (PCM) decreases this oxidative stress and has longer-term benefits on chondrocyte function. Methods Freshly isolated bovine chondrocytes were encapsulated in poly(ethylene glycol) (PEG) hydrogels devoid of a PCM or with a PCM, confirmed by immunocytochemistry (IC), and cultured for up to 2 weeks. Reactive oxygen species (ROS) production and damage to cell membrane by lipid peroxidation were accomplished using carboxy-2,7-difluorodihydrofluorescein diacetate (carboxy-H2 DFFDA) and by malondialdehyde (MDA) content, respectively. Gene expression and proteoglycan synthesis were analyzed using reverse transcription (RT)-quantitative PCR (qPCR) and35 SO4 incorporation, respectively. Results The photopolymerization reaction, which alone generates radicals and extracellular ROS, led to oxidative stress in chondrocytes evidenced by increased intracellular ROS and lipid peroxidation. The presence of a PCM decreased intracellular ROS and abrogated membrane lipid peroxidation, improved aggrecan, collagen II and collagen VI expression, and enhanced proteoglycan synthesis. Conclusions The development of the PCM prior to photoencapsulation in PEG hydrogels reduces oxidative stress and improves chondrocyte anabolic activity. Our data suggest this reduction occurs by decreased ROS diffusion into the cell and decreased membrane damage. Our findings suggest that minimizing oxidative stress, such as through the presence of a PCM, may have long-term beneficial effects on tissue elaboration when employing photopolymerizations to encapsulate chondrocytes for cartilage tissue engineering applications.