Reliable Harvest of Injectable Human Mesenchymal Stem Cell Sheets by Modulating Cell-Substrate Adhesion Strength.

Cell sheet engineering has emerged as a promising scaffold-free strategy in cell-based therapeutics, preserving essential cell-cell and cell-extracellular matrix (ECM) interactions. To enable minimally invasive delivery, a key challenge relies on making the cell sheets compatible with injection-based administration without subjecting sensitive cells to physical or thermal stresses. This study addresses a reliable method for controlling cell sheet dimensions by combining differential cell adhesion-guided micropatterning along with an isothermal detachment method. The surface composition of a copolymer, poly(ethylene glycol dimethacrylate-co-hydroxyethyl methacrylate) is delicately controlled via initiated chemical vapor deposition to ensure intact cell adhesion and rapid cell detachment under isothermal condition. The optimized surface further allows hydrophobic microcontact printing for creating micron-sized sheets. Human mesenchymal stem cell sheets harvested with this method show preserved ECM without compromising cell viability after both detachment and injection. Moreover, the injected cell sheets substantially enhance the angiogenic potential of human umbilical vein endothelial cells, demonstrating the sustained therapeutic activity of the cell sheet after injection. It is believed that this approach has great potential to broaden the scope of cell sheet engineering, serving as a robust platform for regenerative medicine.