Light-Triggered PET-RAFT Polymerization Transiently Suppresses MSC Differentiation and Alters Cellular Mechanics

Abstract Mesenchymal stem cells (MSCs) hold immense promise for regenerative medicine, but premature differentiation during ex vivo expansion can limit their utility. Here, we applied light-triggered photoinduced electron transfer-reversible addition–fragmentation chain transfer (PET-RAFT) polymerization to transiently suppress the differentiation of mouse bone marrow-derived MSCs (mBMSCs). Under the selected conditions, PET-RAFT treatment significantly increases cellular stiffness while simultaneously disrupting F-actin organization and Paxillin distribution. This mechanical remodeling effectively inhibits both osteogenic and adipogenic differentiation, even in the presence of induction media, as evidenced by the suppression of key markers such as RUNX-2, alkaline phosphatase (ALPL), and Collagen Type I. Mechanistically, this lineage arrest of MSCs is mediated through the downregulation of the p38 phosphorylation and plectin expression, whereas β-catenin levels remained comparable across groups. After 15 passages, the treated cell population recovered osteogenic differentiation capacity comparable to controls. These findings present a strategy for transiently suppressing MSC differentiation, addressing a critical bottleneck in the ex vivo expansion of cells for cell-based therapies.