Biocompatibility and stability of disulfide-crosslinked hyaluronan films.

Hyaluronan (HA) can be chemically modified to engineer robust materials with pre-selected mechanical properties and resorption rates that can be dictated by the intended clinical use. Disulfide-crosslinked HA films were prepared by air oxidation of thiol-modified HA, followed by treatment with 0.3% hydrogen peroxide. The degradation of the disulfide-crosslinked films in vitro was very slow (<10% in 7 days) in buffer alone and shorter (t1/2=3-5 days) in the presence of hyaluronidase (HAse). The cytocompatibility of the disulfide-crosslinked HA films was determined using two separate conditions: (i) in vitro culture of mouse fibroblasts in indirect contract with the films, and (ii) in vitro culture of fibroblasts directly on films coated with poly d-lysine. Excellent cytocompatibility was observed in murine fibroblasts that were cultured in indirect contact with thiolated HA films. Although cells were unable to attach and spread on thiolated HA films, pre-coating the thiolated HA films with poly D-lysine resulted in attachment and spreading equivalent to that observed on polystyrene. Rates of resorption in vivo were obtained by subcutaneous implantation of disulfide-crosslinked HA films into the backs of Wistar rats. Biocompatibility in vivo was determined in both subcutaneous flank and peritoneal cavity implantation of the films in Wistar rats. The disulfide-crosslinked HA films were less than 30% resorbed after 42 days in vivo, and histochemical and cytochemical analysis indicated that the films were well-tolerated with mild inflammatory response at both sites of implantation.