Silk fibroin/sericin 3D sponges: The effect of sericin on structural and biological properties of fibroin

Among naturally occurring polymers, silk fibroin and sericin have attracted much attention in the field of tissue engineering; however, clinical application of silk fibroin/sericin scaffolds in a combined form has been questioned due to the possible pro-inflammatory reaction against native silk and fibroin/sericin 3D constructs. The objective of this study was to fabricate 3D spongy fibroin/sericin scaffolds and to explore the structural, biological and immunological properties of different ratios of fibroin and sericin. Structural characterization revealed a highly porous structure (>91%) with a large surface area and water uptake capacity for all different fibroin/sericin scaffolds. Notably, the scaffolds showed enhanced mechanical properties and a higher degradation rate with increasing sericin content. Excellent cell attachment and no significant cytotoxicity were observed in all scaffold types 7 days after seeding of osteoblast-like MG63 cells. Gene expression of pro-inflammatory markers TNF-α, CXCL10 and CD197 as well as TNF-α secretion by THP-1-derived macrophages revealed no significant immune response to all fibroin/sericin scaffold types when compared to sericin-free F1:S0 samples and a TCP (Mɸ) control group. These results demonstrate that spongy fibroin/sericin scaffolds are able to support the growth of osteoblast-like cells without eliciting a pro-inflammatory response, thus being a promising material for bone tissue engineering.