κ-Carrageenan-Based Hydrogels Support Viability and Odontogenic Differentiation of Stem Cells From the Apical Papilla
International Dental Journal
Introduction and Aims
Immature teeth with pulp necrosis remain challenging because conventional root canal treatment does not restore pulp-dentin vitality. Hydrogel scaffolds for regenerative endodontics should support stem cell viability and provide a microenvironment favourable for dentin-pulp regeneration. This study evaluated κ-Carrageenan (κC)-based hydrogels, with and without gelatin, as scaffolds for stem cells from the apical papilla (SCAP), and examined how formulation-dependent properties influenced SCAP viability and odontogenic differentiation.
Methods
Hydrogels were prepared as 1% gelatin, 1.5% κC, 2.5% κC, 1.5% κC+gelatin (κCG) and 2.5% κCG, with cells cultured without hydrogel as a control. Physicochemical characterisation included scanning electron microscopy, Fourier-transform infrared spectroscopy, rheology, degradation and swelling at days 1, 3, 7 and 14. SCAP were isolated and characterised using flow cytometry. Cell viability, metabolic activity, spreading, migration, alkaline phosphatase activity, Alizarin Red S staining and qPCR of differentiation-related markers were also assessed.
Results
The hydrogels showed formulation-dependent microstructure, degradation, swelling and viscoelastic properties. κC-containing formulations behaved as viscoelastic solids, and 2.5% κCG exhibited the highest storage modulus and lowest Tan (δ). SCAP remained predominantly viable in all groups. Gelatin-containing hydrogels improved long-term cytocompatibility and greater cell spreading compared to lower-concentration κC alone. Migration was comparable across groups. During differentiation, κC-containing formulations showed higher alkaline phosphatase activity and mineral deposition, with increased late-stage mineralisation observed in 2.5% κCG. Gene expression analysis indicated early upregulation of RUNX2 and BSP and increased late-stage expression of OPN, OCN, DMP1 and DSPP, with a more evident maturation-associated response in 2.5% κCG.
Conclusion
κC-based hydrogels supported SCAP viability and promoted odontogenic differentiation in vitro. Gelatin incorporation improved late-stage mineralisation and odontogenic marker expression, with 2.5% κCG demonstrating the most favourable overall response.
Clinical Relevance
κC-gelatin hydrogels may serve as promising scaffold candidates for dentin-pulp regenerative strategies by supporting SCAP survival and odontogenic maturation within a tunable hydrogel microenvironment.
Introduction and Aims