**5. Conclusion**

422 Biomaterials – Physics and Chemistry

Porous scaffols made by silk fibroin can be formed into different pore size and porosity, which could meet the needs of different histocytes during repairing process. Porous structure is also helpful to the exchange of nutrient substance among different parts of

Biological material will be treated as foreign matter when implanted in the body, even if its biocompatibility is perfectly good. Therefore, foreign body reaction will be inevitable surrounding the material. The strength and extent of foreign body reaction are closely related to its biocompatibility and biodegradablity. So, we evaluate the tissue reaction and material change after implantation by fibrous encapsulation, granulation formation,tissue fibrosis, type of inflammantary cells, tissue necrosis and tissue ingrowth, morphological

We found that wet porous fibroin scaffold was soft in texture, and could be easily cut into different forms to fit the need of implantation while the operation was performed. Tissue reaction around the materials was slight when we removed the scaffold, and the surface of the material was wrapped up by semitransparent fibrous membranes. The porous fibroin scaffolds were eosinophilic stained by HE. Its surface was irregular. And there are lacunes of different size inside the material. Chronic inflammation reaction occurred, mainly lymphocytes and macrophages could be found around the material. And fibrous capsule could be observed. After two weeks of implantation, blood capillary could be found proliferate into the lacuna of the material, and the fibroblasts also attached to the irregular surface of the material. These phenomena became more and more obvious as time went by, which showed that the surface texture of porous fibroin was favourable for interstitial cell to grow on. Moreover, the porous structure of the scaffold made the material permeable, which could probably cause the exchange of the nutrition and metabolite through the scaffold that lead to

Because the fibroin scaffolds were formed by protein and could hardly be separated from surrounding tissues, histopathology observation was performed after experiment instead of quantitative determination. During eight-weeks' observation, the scaffold disintegration started from the fourth week. But there was still no obvious change inside the scaffold structure until the eighth week, which indicated to us that we should set the observation period much longer to get more information about the degradation of fibroin porous scaffold in further research. We didn't make effective statistical analysis about the quantity and type of inflammatory cells surrounding the scaffold for the number of samples was too small. Moreover, according to the requirements of different tissue repair, the pore size and porosity of porous scaffolds should be different. And materials with different structure may cause different result in tissue reaction, tissue regeneration and material degradation. These

2 2 yes lymphocyte and macrophageno no yes 4 2 yes lymphocyte and macrophageyes no yes 6 2 yes lymphocyte and macrophageyes no yes 8 2 yes mosly macrophage yes no yes

scaffolds. So we choose the porous silk fibroin scaffold as the research object.

active tissue ingrowth. This may also be a plus factor for tissue regeneration.

are also challenging questions that need to be considered in further experiment.

disaggregation

tissue necrosis tissue ingrowth

number fibrationinflammatory cell type Scaffold

Time (week)

section

Table 2. histopathology observation

changes and disaggregation of the scaffolds.

To sum up, porous silk fibroin scaffold shows good histocyte attachment and has good histocompatibility. The Porous silk fibroin scaffold can degradate in vivo, but more study should be made on the mechanism and degradation products.
