A 3D-printed osteochondral scaffold with a dual biomimetic design of spatially organized lotus-radial microchannels and bioinspired nano-mineral precursors for efficient osteochondral regeneration

Abstract Osteochondral defects present substantial clinical challenges due to the complex, multilayered structure and distinct physiological properties of cartilage and subchondral bone. Here, we report a three-dimensional (3D)-printed osteochondral scaffold featuring a dual biomimetic design that integrates vertically oriented microchannels with bioinspired nano-mineral precursors. Specifically, a multifunctional hierarchical construct was developed by incorporating ultrasmall (∼1 nm) polymer-induced liquid precursor-modified amorphous calcium phosphate (nCaP) into a GelMA-based matrix. Using digital light processing-based 3D printing, a biphasic scaffold with spatially defined architectures was fabricated, consisting of a pure GelMA upper layer featuring combined lotus-like and radial pore distributions to emulate the cartilage microenvironment, and a nCaP/GelMA lower layer with lotus-like pore architecture to support subchondral bone regeneration. Notably, in contrast to conventional inorganic fillers such as nanohydroxyapatite (nHAp), the incorporation of ultrasmall nCaP nanoclusters did not adversely affect photopolymerization behavior or printing fidelity, thereby enabling high-resolution fabrication. Beyond structural advantages, nCaP incorporation markedly enhanced the bioactivity of the scaffold. Compared with nHAp, nCaP significantly promoted the recruitment and osteogenic differentiation of endogenous bone marrow-derived mesenchymal stem cells, while also facilitating extracellular matrix deposition, mineralization, and angiogenesis. Transcriptomic analysis further indicated that these effects were associated with the upregulation of angiogenic factor EGFL6, suppression of inflammation-related TNFSF14/NF- κ B signaling, and activation of the PI3K–Akt pathway. Collectively, both in vitro and in vivo evaluations demonstrated that the nCaP/GelMA scaffold achieved improved tissue integration, restoration of hierarchical architecture, and enhanced mechanical performance compared with control groups. These findings underscore the potential of dual biomimetic scaffold design as an effective strategy for osteochondral regeneration.