3D-bioprinted gelatin methacryloyl hydrogel culture system emulating the oviduct environment for enhanced preimplantation embryo development

Oviducts have specific biomechanical properties that support fertilization and preimplantation embryo development, both of which are essential for successful pregnancy. However, conventional plastic-based human embryo culture does not recapitulate the biomechanical environment of the oviduct. Therefore, oviduct mimic culture systems that accurately emulate biophysical conditions for reproductive cells are a significant unmet clinical need. In the present study, we designed a threedimensional (3D)-bioprinted optimal soft hydrogel system that accurately mimics the oviduct environment and investigated signaling factors during embryo development. We developed an oviduct tube-mimic hydrogel culture dish using gelatin methacryloyl (GelMA) 3D-bioprinted hydrogel. Quantitative assessment of hydrogel mechanical properties depended on the stiffness of the GelMA 3D-bioprinted hydrogel. Embryo quality was evaluated based on cleavage speed and blastocyst ratio on the GelMA hydrogel. Whole-transcriptome next-generation sequencing (NGS) analysis of embryos was used to identify biomechanical signaling factors. Our findings revealed that 10 kPa GelMA hydrogel culture conditions performed better with respect to development speed, blastocyst ratio, and hatching ratio than the control condition. Whole transcriptome NGS revealed up-regulation of mRNA processing genes and protein transport genes by the 7 and 10 kPa hydrogels. Furthermore, the inner cell mass and the number of Oct4+ + cells were significantly higher in blastocysts cultured on 10 kPa hydrogel dishes than in those cultured on conventional hard plastic dishes. These findings demonstrate that optimized oviduct-mimic hydrogel-based 3D GelMA culture dishes could improve in vitro embryo development. Hence, 3D GelMA culture dishes may be useful as human embryo culture systems for assisted reproductive techniques.