Growth of human cells on a non-woven silk fibroin net: a potential for use in tissue engineering.

We have examined a novel biomaterial consisting of a non-woven fibroin net produced from silk (Bombyx mori) cocoons for its ability to support the growth of human cells. Various human cells of different tissue and cell types (endothelial, epithelial, fibroblast, glial, keratinocyte, osteoblast) were examined for adherence and growth on the nets by confocal laser microscopy after staining of the cells with calcein-AM and by electron microscopy. All the cells readily adhered and spread over the individual fibers of the nets. Most of the cells were able to grow and survive on the nets for at least 7 weeks and growth not only covered the individual fibers of the net but generally bridged the gaps between individual fibers forming tissue-like structures. Scanning electron microscopic examination of the nets demonstrated a tight association of individual cells with the fibers and nets examined after removal of cells showed no evidence that the growth of cells in any way changed the structure of the fibers. Thus, silk fibroin nets are highly human cell-compatible and should be a useful new scaffolding biomaterial applicable for a wide range of target tissues in addition to supporting endothelial cells required for the vascularization of the newly formed tissue.