We first applied the genome edited silkworm silk (GE-silk) to interpret X-ray fiber diagram, and implied a great potential for the application of genome editing technology to the structural study of silk. The origin of a weak meridional layer-line streak with a spacing of ∼21 Å, observed in the X-ray fiber diagram of Bombyx mori silkworm silk, has been widely believed but not experimentally proven to be a period of the pseudostructure associated with the occurrence of serine residues at regular intervals in a hexapeptide repeating unit -G-A-G-A-G-S-. The above hypothesis was experimentally demonstrated from X-ray measurements of GE-silk.

Human urine-derived stem cells (hUSCs) show multipotential differentiation ability and can differentiate into mesodermal cell lineages. Interstitial cells of Cajal-like cells (ICC-LCs) are crucial for the pace-making function of spontaneous contraction in the bladder. However, the mechanisms by which hUSCs generate ICC-LCs have not been elucidated. In this study, we developed a strategy for directional differentiation of hUSCs into ICC-LCs. hUSCs were transfected with lentiviral vectors encoding c-Kit, stem cell factor (SCF), hyperpolarization activated cyclic nucleotide gated potassium channel 4 (HCN4), and 5-azacytidine induced 2 (AZI2) genes, and the cells were cultured for an additional 7 days in specific medium. The expression of the surface marker c-Kit on ICC-LCs was determined at 7 days after transfection. hUSCs were successfully expanded and transfected with the four lentiviral vectors. hUSCs transfected with lentiviral-c-Kit, lentiviral-HCN4, and lentiviral-AZI2 showed higher expression of c-Kit 7 days after transfection, but only the lentiviral-HCN4-transfected cells showed morphological alterations in ICC-LCs. These cells also displayed visible HCN current amplitude and density. This approach may provide a new strategy for the treatment of underactive bladder.