Résumé
Objective To explore the modification of bionic silk fibroin nerve conduits (SF-NCs) by silk sencin.Methods The innovative SS/SF blended-NCs was fabricated by a vertical sequential cooling thermal induced phase separation (TIPS) processing with SF solution added sericin in proportion,its morphology was observed by Scanning electron microscopy (SEM),X-ray diffraction (XRD) and infrared spectroscopy (FTIR) were used to detect its internal molecular structure.MTT assay was used to quantitatively analyzed the PC12 cells viability co-cultured with the innovative SS/SF-NCs,SEM was used to observe the adhesion and morphology of PC12 cells seeded into the innovative SS/SF,PC12 cells were used to assess the NGF bioactivity released from the SS/SF.Results The SEM results showed that the new fabricated SS/SF-NCs had linearly oriented lamellar-like multiple-channel which distributed evenly,got great changes on the channel microstructure and their mechanical properties had been greatly improved,compared to SF-NCs.The XRD and FTIR results showed that the SS/SF-NCs had the similar internal molecular structure with natural silk.The spaces between parallel lamellar-like channels,porosities and compressive strengths of the SS/SF-NCs decreased with decreasing Sequential freezing temperature.MTT assay results showed that the viability of PC12 cell was better than the control group (P ＜ 0.05).The SEM observation indicated that PC12 cells showed good adhesion and differentiation with neuritis outgrowth during the period of co-culture with the SS/SF-NCs.NGF release from the innovative SS/SF-NCs was prolonged over 4 weeks,and remained bioactive.Conclusion The new fabricated SS/SF-NCs modified though silk sericin,which was highly bionic the structure of peripheral nerve fasciculus,had excellent mechanical properties and could be used as another alternative of artificial nerve conduits.
Résumé
Sericin is a silk protein woven from silkworm cocoons (Bombyx mori). In animal model, sericin has been reported to have anti-tumoral action against colon cancer. The mechanisms underlying the activity of sericin against cancer cells are not fully understood. The present study investigated the effects of sericin on human colorectal cancer SW480 cells compared to normal colonic mucosal FHC cells. Since the size of the sericin protein may be important for its activity, two ranges of molecular weight were tested. Sericin was found to decrease SW480 and FHC cell viability. The small sericin had higher anti-proliferative effects than that of the large sericin in both cell types. Increased apoptosis of SW480 cells is associated with increased caspase-3 activity and decreased Bcl-2 expression. The anti-proliferative effect of sericin was accompanied by cell cycle arrest at the S phase. Thus, sericin reduced SW480 cell viability by inducing cell apoptosis via caspase-3 activation and down-regulation of Bcl-2 expression. The present study provides scientific data that support the protective effect of silk sericin against cancer cells of the colon and suggests that this protein may have significant health benefits and could potentially be developed as a dietary supplement for colon cancer prevention.