Optimized gradient of lyophilized platelet-rich plasma in biomimetic 3D-printed triphasic scaffold based on alginate and gelatin for osteochondral tissue engineering.

This study developed a 3D-printed, triphasic (subchondral bone, calcified, and articular cartilage) scaffold using biological macromolecule-based bioinks to support the chondrogenic differentiation of bone marrow-derived mesenchymal stem cells (BM-MSCs). A subchondral bone layer was formed by blending various concentrations of graphene oxide (GO) (1% and 2% w/w) into an alginate (Alg) and gelatin (Gel) bioink, two natural biopolymers known for their biocompatibility and biodegradability. Following mechanical and biocompatibility assessments, the 1% GO concentration was selected and applied consistently through the subchondral and calcified cartilage layers. In contrast, the gradient of lyophilized platelet-rich plasma (PRP) powder was adjusted to 1%, 2%, and 3% (w/v) to more accurately replicate the characteristics of calcified and articular cartilage. Triphasic scaffolds with different PRP gradients were evaluated for water absorption, biodegradability, rheological behavior, stem cell viability, and chondroinductive activity. The results indicated that 3D-printed triphasic scaffolds containing 1% or 2% PRP exhibited favorable biomechanical properties, with no significant differences between the two concentrations. However, scaffolds with 2% PRP facilitated the attachment, proliferation, and survival of BM-MSCs, as indicated by an increase in the expression of cartilage-related genes and enhanced production of glycosaminoglycan (GAG), as confirmed through real-time PCR and Alcian Blue staining, respectively.