Nanofibers Regulate Single Bone Marrow Stem Cell Osteogenesis via FAK/RhoA/YAP1 Pathway

Understanding cell-material interactions is a prerequisite for the development of bio-inspired materials for tissue regeneration. While nanofibrous biomaterials have been widely used in tissue regeneration, the effects of nanofibrous architecture on stem cell behaviors are largely ambiguous because the previous biomaterial systems used for nanofiber-cell interactions could not exclude the interference of cell-cell interactions. In this study, we developed a unique micropatterning technology to confine one single stem cell in a microisland of the nanofibrous micropatterned matrix; therefore, eliminating any potential intercellular communications. The nanofibrous micropatterned matrix, which mimicked both the physical architecture and chemical composition of natural extracellular matrix, was fabricated by a combination of electrospinning, chemical crosslinking, and UV-initiated photolithography. Compared to the non-nanofibrous architecture, a bone marrow mesenchymal stem cell (BMSC) cultured on the nanofibrous microisland exhibited a more in vivo-like morphology, a smaller spreading area, less focal adhesion, and fewer stress fibers. The BMSC cultured on the nanofibrous microisland also had higher alkaline phosphatase activity, indicating nanofibrous architecture promoted BMSC differentiation. A mechanistic study reveals that nanofibers regulate single BMSC osteogenesis via the FAK/RhoA/YAP1 pathway. The nanofibrous micropatterned matrix developed in this study is an excellent platform to promote the fundamental understanding of cell-matrix interactions, ultimately provide valuable insights for the development of novel bio-inspired scaffolds for tissue regeneration.