In Situ Hydrogelation of Cellular Monolayers Enables Conformal Biomembrane Functionalization for Xeno-Free Feeder Substrate Engineering.

The intricate biochemical functionalities of cellular membranes have inspired numerous strategies for deriving and anchoring cell-surface components onto solid substrates for biological studies, biosensor applications, and tissue engineering. However, introducing conformal and right-side-out cell membrane coverage onto planar substrates requires cumbersome multi-step protocols that can be limited by significant device-to-device variability. Here, we demonstrate a facile approach for biomembrane functionalization of planar substrates by subjecting confluent cellular monolayer to intracellular hydrogel polymerization. The resulting cell-gel hybrid, herein termed GELL, exhibits extraordinary stability and retains the structural integrity, membrane fluidity, membrane protein mobility, and topology of living cells. In assessing the utility of GELL layers as a tissue engineering feeder substrate for stem cell maintenance, GELL feeder prepared from primary mouse embryonic fibroblasts (MEFs) not only preserves stemness of murine stem cells but also exhibits advantages over live feeder cells owing to the GELL's inanimate, non-metabolizing nature. Leveraging the versatility of the intracellular gelation approach, we further show the preparation of xeno-free feeder substrate devoid of non-human components with HeLa cells. With the hydrogelation process eliminating the safety and contamination concerns of the immortalized cells, the inanimate HeLa GELL feeder layer effectively sustains the growth and stemness of both murine and human induced pluripotent stem cells (iPSCs). The study highlights a novel bio-functionalization strategy that introduces new opportunities for tissue engineering and other biomedical applications. This article is protected by copyright. All rights reserved.