Development of an EPIC-μCT imaging method for analyzing proteoglycan content in neocartilage constructs for the use in osteoarthritis therapeutics
Parchinski, Kaley Elizabeth
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Osteoarthritis (OA), characterized by debilitating joint pain, is a degenerative disease caused by the breakdown of cartilage in joints and adjacent bone. It is the most common type of arthritis, affecting 10-12% of the US adult population, and currently has no cure (Lawrence, et al.). Cartilage contains specialized molecules called proteoglycans (PGs). PGs are vital suppliers of swelling pressure that enable cartilage to withstand compressional forces applied by adjacent bones. A decrease in cartilage PG content can signal the subsequent onset of osteoarthritis. Current methods of OA therapy evaluation are destructive, however due to the degenerative nature of OA the longitudinal evaluation of therapies is crucial. EPIC- μCT (equilibrium partitioning of ionic contrasting agent – microcomputed tomography), is a volumetric, non-destructive imaging method. This method utilizes a contrast agent (Hexabrix 320 30%) that yields an equilibrium distribution that is inversely proportional to the density of PGs (Palmer, et al.) allowing for the quantification of PGs in neocartilage constructs. An EPIC- μCT method for analyzing proteoglycan content in neocartilage constructs would allow for the longitudinal evaluation of novel osteoarthritis therapies. To develop this model, neocartilage constructs were created from bovine chondrocytes and cultured to 17 days in serum-free media. PG content was then assessed at 6, 12, and 17 days using the EPIC-uCT method. Results have shown that constructs were not affected by longitudinal scanning and reached equilibration in Hexabrix after 30 minutes of incubation. A negative correlation was also found to exist between neocartilage PG content and x-ray attenuation. Current research is being conducted to quantify the longitudinal degradation of PG content.