Influence of gel properties on neocartilage formation by auricular chondrocytes photoencapsulated in hyaluronic acid networks

The objective of this study was to determine how changes in the network structure and properties of hyaluronic acid (HA) hydrogels, due to variations in the macromer molecular weight (50-1100 kDa) and macromer concentration (2-20 wt %), affect neocartilage formation by encapsulated auricular chondrocytes. To investigate tissue formation, swine auricular chondrocytes were photoencapsulated in the various networks, implanted subcutaneously in the dorsum of nude mice, and explanted after 6 and 12 weeks for biochemical and histological analysis. After 12 weeks, the various constructs were 81-93% water, contained between 0.1 x 10(6) and 0.6 x 10(6) chondrocytes per sample, and consisted of 0-0.049 mu g chondroitin sulfate/mu g wet weight (glycosaminoglycan (GAG) content) and 0.002-0.060 mu g collagen/mu g wet weight. Histological staining showed an even distribution of chondrocytes and GAGs in addition to minimal type I collagen staining and intense and uniform type 11 collagen staining in the constructs with greatest neocartilage production. Hydrogels fabricated from 2 wt % of the 50 kDa HA macromer most resembled the properties of native cartilage and show the greatest promise for continued development for cartilage regeneration. (c) 2006 Wiley Periodicals, Inc.