Cationic hydrogels of PEG crosslinked by a hydrolyzable polyrotaxane for cartilage regeneration

Microporous hydrogels of poly(ethylene glycol) crosslinked by a hydrolyzable polyrotaxane, in which many primary amino group-introduced α-cyclodextrins (α-CDs) are threaded onto another PEG chain having ester linkages at the terminals, were prepared and evaluated in terms of chondrocyte attachment on the hydrogels and the following cellular growth. In addition to the modulated erosion of the hydrogels by inclusion and dissociation of α-CDs with the terminal ester linkages in highly water friendly condition [T. Ichi, J. Watanabe, T. Ooya, N. Yui, Biomacromolecules 2 (2001) 204], the introduction of primary amino group into α-CDs significantly enhanced the initial chondocyte attachment on the microporous hydrogels. Introducing the primary amino group did not cause the mutagenicity and cytotoxicity. The chondrocyte proliferation was affected by the erosion behavior of the hydrogels rather than the introduction of primary amino group. The introduction of primary amino group and the appropriate erosion time enhanced glycoaminoglycan production due to population of chondrocytes on the cationic hydrogels.