Silk Fibroin Based Biomaterials And Its Application In Urethral Reconstruction

In many cases,such as infection,inflammation,trauma,and congenital diseases,can cause urethral defect or stricture needing the urethral reconstruction treatment.There are many researches before trying to solve the clinical problems.And tissue engineering show a promise.Tissue engineering urethral tissue has been emerging in recent years,including biomaterials,seeding methods and the seed cells to composite materials planting method,is one of the three crucial factors.For solving those problems,we compared the different seeding technology of constructing tissue-engineered urethra in vitro and the feasibility analysis of tongue mucosa as a source of cells for tissue engineering.Based on some key technologies of the compositing methods,we explored the possibility of constructing tissue-engineered urethra best.First tongue mucosa epithelial cells and muscle cells were isolated,the the two cells were seeded using four different compositing methods: sandwich composite group,the laminated composite group,static-dynamic compound and centrifugal composite group.The study found that the tongue mucosa can be used as a sources of seed cells for tissue-engineered urethra;Each method has its advantages and disadvantages.Then this study first proposed useing calcium peroxide on silk fibroin composite materials,making its have the ability to release oxygen for a long time,and thus be more suitable for subsequent reconstruction on research and clinical application.Because this materials was based on the protein biological film,layered cocultured methods of was used for this experiment in vitro to construct tissue-engineered urethra,and verified by animal experiments.Although this protein biological film can be used to successfully repair urethral defect,the protein biological film is thinner needing the surrounding tissue supply,so this film maynot be suitable for posterior urethral repair,therefore we should further explore the silk fibroin modified in order for the application of the posterior urethral reconstruction.And through the analysis of the posterior urethral structure,the currently available reconstructive procedures are insufficient due to a lack of the appropriate scaffolds that would support the needs of various cell types.To address this problem,we developed a bilayer scaffold comprising a microporous network(silk fibroin [SF])and a nanoporous bacterial cellulose(BC)scaffold and evaluated its feasibility and potential for long-segment urethral regeneration in a dog model.The data presented in this study demonstrate the feasibility of developing 3-D bilayer scaffolds with both microporous structures and nanotextured surfaces via stationary cultivation of Gluconacetobacter xylinus using an SF microporous scaffold as a template.The bilayer SF-BC scaffold can provide several advantages and add functionality to the scaffold.The nanotextured BC layer was designed to prevent the erosion of toxic substances in urine and is conducive to the proliferation of epithelial cells.The microporous SF layer was conducive for cells to migrate in vitro,and tissue could grow in through the mesh and integrate with surrounding tissues.This study provides preclinical evidence that cell-seeded scaffolds can be used in the reconstruction of 5-cm urethral defects.