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Distinct tissue responses to porous silk fibroin scaffolds (PSFSs) and polyvinyl alcohol (PVA) sponges in vivo

Selection of raw materials for biomedical materials has been one of the focuses on development of biomaterials. In this study, we used porous silk fibroin scaffolds (PSFSs) prepared by freeze drying method and polyvinyl alcohol (PVA) sponges which have similar macro-structure such as average pore size and porosity. Both materials were implanted in femoral muscles of rats, and the biocompatibility of both materials has been examined by histological observation and scoring method. Moreover, the biodegradation rates of both materials have been compared by a computer-assisted image analysis method. The results showed that PSFSs have better biocompatibility than PVA sponges in terms of deposition of collagen matrix, remodeling of extracellular matrix (ECM), infiltration of inflammatory cells, tissues formation and angiogenesis. However, PVA sponges evoked heavy and lasting infiltration of inflammatory cells, and the moderate infiltration lasted up to 23 days after the implantation. In summary, silk fibroin, as a natural protein, has incomparable biocompatibility for ECM organization and tissues formation, and thus has promising applications in tissue engineering and artificial organ.