Beneficial Effects of Chondroitinase ABC Release From Lipid Microtubes Encapsulated in Chondrocyte-Seeded Hydrogel Constructs

Tissue-engineered cartilage using a hydrogel scaffold is capable of achieving native compressive properties and glycosaminglycan (GAG) content [1]; however, promoting collagen growth towards native values has been challenging. As the cells in the cartilage constructs deposit matrix over time in culture, transport of nutrients to the construct center becomes increasingly hindered [2]. Digestion of mature tissue engineered constructs with chondroitinase (chABC) temporarily suppresses the GAG content, allowing an increase in the collagen content and eventually improving the mechanical properties after GAG content recovers [1]. However, adding chABC into the feeding media limits its effectiveness to the construct’s periphery, reflecting enzyme diffusion gradients. Additionally, long-term use of chABC, without re-application, is limited since its enzymatic activity degrades within 5 days at 37°C [3]. Lee and co-workers have developed a method for delivering thermostabilized chABC using sugar trehalose and hydrogel-microtubes for applications desiring extended enzyme release [4]. Lipid microtubes loaded with thermostabilized chABC may be incorporated into an agarose hydrogel scaffold to provide long-term release of the enzyme uniformly throughout the construct [3]. The objective of this study was to test the hypothesis that chABC-filled microtubes will enhance in vitro development of engineered cartilage.