3D-bioprinted gum karaya hydrogels with photocurable and stem cell recruitment properties for accelerating cartilage...

Directional migration and differentiation of stem cells in situ are necessary for cartilage tissue regeneration. To regenerate cartilage tissue similar to natural one, transplanted scaffolds are required to have favorable stiffness, biocompatibility, and the ability to recruit and induce stem cells. Herein, a three-dimensional (3D) bio-printed Gum Karaya Methacrylate (GK-MA) bioink functionalized with EPLQLKM (E7) peptide was developed to form GK-MA-E7 hydrogel for cartilage tissue engineering applications. Among them, GK-MA exhibits desirable mechanical strength and biosafety, while the E7 peptide acts as an anchoring site for the recruitment of bone marrow mesenchymal stem cells (BMSCs). The physicochemical properties of the bioink can be precisely regulated by adjusting the photopolymerization conditions. Compared to Gum karaya (GK) and GK-MA scaffolds, the GK-MA-E7 construct significantly enhances the biological behavior of BMSCs, as reflected in improved adhesion, proliferation, homing efficiency, and chondrogenic commitment. These effects are corroborated by a pronounced increase in glycosaminoglycan (GAG) deposition and the elevated transcription of cartilage-specific markers such as Col2a1, SOX9, Col1a1, and ACAN. Further, the photo-cross-linkable 3D-printed GK-MA-E7 hydrogels embedded with BMSCs led to notable cartilage regeneration in vivo by the end of the 8-week therapeutic regimen, with the score elevated to approximately three times that of the control group. This work proposes an alternative approach for the development of photo-cross-linkable, biodegradable, and injectable scaffolds derived from native polysaccharides, offering the potential for minimally invasive strategies in cartilage tissue regeneration.