Fib@PEGDA/GelMA hydrogel as a light-curing thin-layer matrix for RPE cell growth and function

Retinal degenerative diseases, including age-related macular degeneration and retinitis pigmentosa, are leading causes of blindness globally, characterized by progressive degeneration of retinal pigment epithelium (RPE) and photoreceptor (PR) cells. Despite advancements, current therapies have not substantially arrested disease progression. Cell replacement therapy using healthy RPE and PR cells holds promise but faces obstacles such as poor cell survival, inadequate integration, and transplantation difficulties. To address these issues, tissue engineering combined with 3D printing has become a focal point. This study investigates the use of four hydrogels-GelMA, HAMA, AlgMA, and PEGDA-and their various crosslinked combinations for creating hydrogel thin-layer matrices conducive to RPE cell growth. PEGDA/GelMA hydrogel demonstrated optimal support for cell spreading and proliferation, which is not achievable with hydrogels matrices of other formulations. The relationship between the mechanical properties of PEGDA/GelMA hydrogels and cell growth was further refined. PEGDA600-20 hydrogel with a compressive modulus of 1245.07 ± 20.79 kPa was selected based on time-course viability assays, leading to the development of the optimized Fib@PEGDA/GelMA hydrogel exhibited exceptional biocompatibility. Compared to PEGDA/GelMA, CCK-8 assays demonstrated significantly improved relative cell viability at 24 h, 48 h, and 72 h, with increases of 17.73 ± 1.22%, 14.54 ± 3.63%, and 19.04 ± 2.31%, respectively on Fib@PEGDA/GelMA matrix. qRT-PCR results indicated a mitigation of epithelial-mesenchymal transition (EMT), as evidenced by downregulation of EMT markers (CDH2, COL1A1, and FN1), accompanied by reduced IL-6 levels. Fib@PEGDA/GelMA hydrogel enhanced phagocytic activity in ARPE-19 cells and promoted functional expression in hiPSC-RPEs. Additionally, the hydrogel showed favorable<i>in vivo</i>biocompatibility following subcutaneous implantation of RCS rats at 1, 2, and 4 weeks post-implantation evidenced by HE and Masson's staining. This system offers a promising bioink for 3D-printed retinal cell scaffolds and paves the way for future advancements in cell replacement therapies for retinal degenerative diseases.