Tissue response and biodegradation of hydroxyapatite/gelatin/Thai silk fibroin scaffolds

Abstract

To investigate tissue response, in vitro and in vivo biodegradation of four types of Thai silk fibroin based-scaffolds. Four types of scaffolds including Thai silk fibroin (SF), conjugated gelatin/Thai silk fibroin (CGSF), hydroxyapatite/Thai silk fibroin (SF4) and hydroxyapatite/conjugated gelatin/Thai silk fibroin scaffold (CGSF4) were fabricated by salt-leaching, EDC/NHS crosslinking and alternate soaking techniques. The results on in vitro biodegradation tests showed that the remaining weight of scaffolds after 28 days of incubation in collagenase solution was in the order of CGSF>SF>SF4~CGSF4. The CGSF scaffold was found to have the slowest biodegradability due to the crosslinking by dehydrothermal and EDC/NHS treatment. From in vivo biodegradation tests, all scaffolds could still be observed after 12 weeks of implantation in subcutaneous tissue of Wistar rat. Comparing in vitro and in vivo biodegradation, the CGSF scaffold showed the slowest in vitro degradation while in vivo the slowest degradation was observed in the case of CGSF4 scaffold. The tissue response was evaluated using subcutaneous implantation model following ISO10993-6: Biological evaluations of medical devices. At 2 and 4 weeks of implantation, it was shown that four types of scaffolds were classified as "non-irritant" to "slight irritant", compared to Gelfoam® (control sample). The results indicated the high potential of Thai silk fibroin-based scaffolds for tissue engineering applications.