(594b) Hierarchically Designed Agarose and Poly(ethylene glycol) Interpenetrating Network Hydrogels for Cartilage Tissue Engineering

A new method for encapsulating cells in interpenetrating network (IPN) hydrogels of superior mechanical integrity was developed. In this study, two biocompatible materials?agarose and poly(ethylene glycol) diacrylate (PEG-DA)?were combined to create a new IPN hydrogel with greatly enhanced mechanical performance. Unconfined compression of hydrogel samples revealed that the IPN displayed a 4-fold increase in shear modulus relative to a pure PEG-DA network (39.9 vs. 9.9 kPa) and a 4.9-fold increase relative to a pure agarose network (8.2 kPa). PEG and IPN compressive failure strains were found to be 71±17 and 74±17 percent, respectively, while pure agarose gels failed around 15 percent strain. Similar mechanical property improvements were seen in IPN gels with encapsulated chondrocytes. Live/Dead assays demonstrated that the majority of IPN-encapsulated chondrocytes remained viable one week post-encapsulation, and chondrocytes exhibited GAG synthesis comparable to that of agarose-encapsulated chondrocytes at three weeks post-encapsulation. The introduction of a new method for enhancing the mechanical performance of cell-containing hydrogels is a promising step toward cartilage defect repair. Biological performance can also be engineered using this technology through incorporation of functional groups like degradable crosslinks and adhesion sequences. Furthermore, this method may be applicable in other applications where mechanical integrity of cell-containing hydrogels is of great importance.

This work was supported by the NIH (1 R21 EB008783-01, 5 P20 RR 16475-08), and the NSF (IOS 0726425 and DMR 0805264).