Neovascularization of Porous Silk Fibroin Films(PSFFs) as Dermis Substitutes Implanted in Rats

Abstract

Neovascularization in biomaterials plays a key role in wound healing. In this paper, porous silk fibroin films (PSFFs) whose structure was optimized, as dermis substitutes, were implanted in the back skin of rats for recovery of dermis loss. Results showed that a thin layer of loose connective tissue had formed at the interface between PSFFs and subcutaneous tissues, in which abundant blood vessels could be observed at 24 h after surgery. Whereafter the newly formed connective tissue thickened and the number of microvessels in the tissue increased. Furthermore, a few microvessels could be seen in PSFFs at day 5, most of which were capillaries. By day 10, the density of microvessels in PSFFs increased to a peak while the percentage of capillary decreased. At day 23, both the density of microvessels and the percentage of capillary was almost equal to those of normal tissues. In summary, wound healing with PSFFs as dermis substitutes is the neovascularization process of PSFFs. The process includes three major steps: (1) new formation and growth of loose connective tissue into the pores of PSFFs, (2) proliferation and migration of fibroblasts and endothelial cells, and (3) formation of functional microvessels and their networks.