MUSEOS DE LA SEDA / SILK MUSEUMS

products of silkworm have applications in the traditional Asian medicine. The body of the larvae accumulates metabolites of high biological value that come from the mulberry leaves, their only source of food. The powder obtained from larvae after freeze drying presents good properties in terms of the reduction of glucose levels in blood and in the improvement of symptoms of metabolic syndrome, such as is described in the scientific literature. It is also known that the silk peptides are effective in the control of diabetes in animal models, through the protective effect of pancreatic beta cells. It is also important to mention the extensive use of silk proteins as active compounds in the field of cosmetics. The fibroin has a demonstrated effect on wound healing and regenerative of skin cells. And the sericin has a demonstrated effect improving the skin hydration. Both proteins are incorporated as actives in creams, once extracted or as hydrolysates of the cocoon. In ad- dition to this, the oil obtained through the application of pressure to the chrysalides con- tains fatty acids of recognised biological activity and is also used for skin care. But from all the diverse non-textile applications of silk, the most interesting at present is its application as a biomaterial for Tissue Engineering and Regenerative Medicine. A biomaterial is a material of chemical or biological origin that interacts with animal tissues for different applications, usually, as prosthetics. The development of new bio- materials has shown a decisive impulse in the last decade, starting from the discovery of the existence and properties of the stem cells. These are undifferentiated cells that under certain stimulus provided by specific growth factors, differentiate to form cell types of the different tissues and organs. This discovery led to the development of a new paradigm in biomedical research, the Tissue Engineering. Starting from the new knowledge about the localization, proliferation and differentiation of stem cells, it is possible now to obtain these cells from their different niches (fat, bone marrow, etc.) in a patient. Thus, after their growth, it is expected to form a specific tissue and use it for a substitution of a defective or absent tissue or organ. There is no risk of rejection, given the autologous origin of the cells. However, this procedure requires an essential component, which is a two or three-dimensional scaffold, to act as a physical support for the cells, guiding their growth to obtain the desired shape of the tissue structure. The search of biomaterials appropriate for this application is very intense, and has produced a wide diversity of materials and configurations for that function. However, in an unexpected and fortunate way, a series of experiments made by the research group of Prof. David L. Kaplan in Tufts University (Boston, USA), revealed that the fibroin of silk is one of the most adequate biomaterial for the fabrication of scaffolds for the growth and differentiation of stem cells. At present, after 20 years of development, silk fibroin is very well stablished as a versatile and efficient biomaterial in the fields of Tissue Engineering and Regenerative Medicine. 3.1) Properties of the silk fibroin as biomaterial What are the characteristics that make silk fibroin suitable as a biomaterial? The most important one could be its biocompatibility. The contact of fibroin with tissues does not produce foreign body reaction, nor rejection. This fact explains the long history of use of silk sutures in surgery for centuries. The implanted fibroin structures experiment a slow degradation to its peptides and amino acids, due to the action of proteases. Another im- portant feature of fibroin is that its surface presents reactive chemical amino and carboxyl 61