Outmost Cationic Surface Charge of Layer-by-Layer Films Prevent Endothelial Cells Migration in Three-dimensional Tissues

Tissues and organs possess an organized cellular arrangement that enables their unique functions. However, conventional three-dimensional (3D) encapsulation techniques fail to recapitulate this complexity due to the cell migration during cell culture. In biological tissues, basement membranes (BMs) are essential to mechanically support cellular organization. In this study, we found that positively-charged outmost surface of multilayered nanofilms, fabricated through LbL assembly of poly-L-lysine (PLL) and dextran (Dex) via hydrogen bonds, stimulated the barrier functions of BMs. This type of artificial BMs (A-BMs) demonstrate enhanced barrier properties in comparison to other type ofA-BMs composed of BM component such as collagen type IV and laminin. Such an enhancement is potentially associated with the outmost positive layer, which inhibits the sprouting of endothelial cells (ECs) and effectively prevents EC migration over a 14-day period, aligning with the regeneration timeline of natural BMs in 3D tissues. In the end, 3D organized vascular channels are successfully engineered through the sequential processes of spreading smooth muscle cells (SMCs), in-situ assembly of PLL/Dex nanofilms and endothelialization of ECs, which would provide a reliable platform for evaluating the efficacy of drugs, investigating nanotoxicology, and advancing the development of regenerative medicine.