New Hyaluronic Acid-Based Bioengineered 3D Scaffold: Fabrication and Potential for Oocyte In Vitro Maturation

Oocyte in vitro maturation (IVM) is a valuable tool in human and animal reproduction, but its efficiency remains lower than that obtainable in vivo, partly due to suboptimal used culture conditions. This study aimed to evaluate the effects of adding hyaluronic acid (HA) to spherical alginate-based 3D scaffolds to better mimic the native ovarian intrafollicular microenvironment. HA (2 or 4 mg/mL) was incorporated into an alginate/collagen I/granulosa cell matrix to fabricate bioengineered microbeads, which were characterized for morphology, microstructure and mechanical properties. Sheep cumulus-oocyte complexes were encapsulated and cultured for 24 h in such microbeads for IVM and subsequent IVEC. HA-enriched scaffolds displayed sphericity, stability, concentration-dependent reduction in pore size and slight increase in stiffness. In scaffolds with 2 mg/mL HA, cumulus cell expansion, metaphase II and embryo cleavage rates were significantly improved compared to controls, scaffolds without HA and 4 mg/mL HA. Apoptosis levels in cumulus and granulosa cells were significantly lower with 2 mg/mL HA. SEM imaging suggested cell-driven extracellular matrix (ECM) remodelling during IVM. These results indicate that 2 mg/mL HA provides the optimal balance between structural support and mechanical compliance, promoting oocyte maturation. Further studies are needed to elucidate the underlying molecular mechanisms.