Genetic Manipulation of Mammalian Cells in Microphysiological Hydrogels.

Engineering functional 3D tissue constructs is essential for developing advanced organ-like systems, with applications ranging from fundamental biological research to drug testing. The generation of complex multicellular structures requires the integration of external geometric and mechanical cues with the ability to activate genetic programs that regulate and stimulate cellular self-organization. Here, it is demonstrated that gelatin methacryloyl (GelMA) hydrogels serve as effective matrices for 3D cell culture, supporting both in situ genetic manipulation and cell growth. HEK293T cells embedded in GelMA remained viable and proliferated over 16 days, forming clusters within the matrix. Efficient gene delivery is achieved in the 3D hydrogel environment using both plasmid DNA and mRNA as gene vectors. Furthermore, in situ prime editing is applied to induce permanent genetic modifications in embedded cells. To achieve spatially confined gene expression, gel-embedded channels are introduced that allowed localized stimulation via doxycycline perfusion through a Tet-On system. These findings demonstrate the feasibility of integrating gene delivery, inducible expression, and spatial control within GelMA-based hydrogels, establishing a versatile framework for engineered 3D cell systems with programmable genetic activity.