Engineering cartilaginous constructs by integrating umbilical cord–derived mesenchymal stem cell spheroids and localized mineral ion delivery in 3D hydrogel

The engineering three-dimensional (3D) cartilage tissue from mesenchymal stem cells is often obstructed by diffusion limitations, uncontrolled signal delivery, and hypertrophic differentiation following chondrogenesis. We herein report a 3D cartilaginous construct by encapsulation of spheroids of human umbilical cord-derived MSCs (hUCSCs) within in Gelatin methacryloyl hydrogels where the mineral-coated fibers (MFs) were integrated within the spheroid for localized ion delivery, thereby alleviating diffusion limitations. Through the intrinsic properties of hUCSCs, this system achieved robust chondrogenesis while minimizing hypertrophic progression. MFs led to a greater than threefold upregulation in chondrogenic gene expression and enhanced deposition of chondrogenic extracellular matrix in hUCSC spheroids, without concomitant increases in hypertrophic markers or matrix components. Comparative analysis revealed that hUCSCs exhibited superior chondrogenic potential and reduced hypertrophic gene expression relative to human bone marrow-derived MSCs. These findings highlight the potential of the MFs-incorporated composite spheroids-laden hydrogels as a novel biomimetic strategy for stable cartilage biofabrication, as they selectively promote hUCSC chondrogenic differentiation while mitigating hypertrophic maturation in a controlled 3D microenvironment.