Scaffolds Decorated by In Vivo Environment Improve Cell Proliferation and Wound Healing

Abstract

Modification to surface texture of biomaterials, protein adsorption and interactions of biomaterials and cells have been studied in vitro for several decades in tissue engineering. However, few reports focus on the decoration of in vivo environment to implanted biomaterials and the effects of the decoration on cells proliferation and wound healing. In this study, we used porous silk fibroin materials and poly (vinyl alcohol) (PVA) sponges as dermal substitutes for dermis regeneration in rats. In addition, both materials were harvested at 3 days after implantation and used for cell culture. The decoration of in vivo environment to biomaterials, namely the organization of extracellular matrix (ECM) in the materials, was observed through scanning electron microscope (SEM), transmission electron microscope (TEM) and histology. Furthermore, if the in vivo decoration can support fibroblast viability and proliferation in vitro and improve wound healing in vivo has been examined via MTT assay and histology. Besides, the effects of surface chemical composition and surface texture of the materials on the in vivo decoration have been assessed and discussed. The results showed that the deposition of proteins and organization of ECM (collagen fibers as the indicator) in the materials have been detected at 3 days after implantation. However, no cells could be found at this time. MTT assay suggested that cells seeded on the decorated PVA sponges had significantly higher viability than those seeded on the undecorated ones (PVA sponges). The histological analysis showed that fibrous encapsulation formed around PVA sponges at 3 days after implantation while even distribution of collagen fibers was seen in the porous silk fibroin materials, and that the fibrous encapsulation in PVA sponges existed at 18 days after implantation. Newly formed tissues containing functional blood vessels could be found in both materials, but the moderate infiltration of inflammatory cells and the interstices between PVA sponges and the newly formed tissues could be found in PVA sponges at 18 days after implantation. In conclusion, the implanted materials are firstly decorated by in vivo environment through the protein adsorption and the organization of ECM. This process plays a key role in improving cell proliferation and subsequent wound healing in vivo. Furthermore, the smooth surfaces in the porous silk fibroin materials have been more biocompatible to extracellular proteins compared to the rough surfaces in PVA sponges. Therefore, this study might provide insights into the selection of raw materials and the control of surface texture during development of biomaterials with better biocompatibility.