Investigation of oxidized alginate-gelatin-based hydrogels enriched with magnesium for cartilage tissue engineering

Abstract

Cartilage is an aneural and avascular tissue with limited self-healing capacity, which requires external intervention upon injury. Since the 1990s, tissue engineering has emerged as a promising regenerative strategy, which can surpass the limitations of conventional treatments. Hydrogels, as highly hydrated polymer networks, are widely utilized in tissue engineering due to their structural and biochemical similarity to the native extracellular matrix (ECM). Among them, alginate dialdehyde-gelatin-based (ADA-GEL) hydrogels have gained attention for their biocompatibility and biodegradability. Recent studies have demonstrated that magnesium ions enhance chondral regeneration, yet their integration into ADA-GEL hydrogels remains unexplored. In this study, Mg²⁺-releasing ADA-GEL-based hydrogels were developed incorporating magnesium carbonate (MgCO₃) at concentrations ranging from 0.5 to 20 mg/mL, and the effect of the MgCO₃ concentration on resulting hydrogel properties was investigated comprehensively. Morphological analysis revealed suitable pore sizes of 100 – 300 μm across all formulations. Furthermore, increasing the MgCO₃ concentration led to improved mechanical properties and tailorable Mg²⁺ ion release and hydrogel degradation in vitro. The investigation of cell-material interactions showed a beneficial effect of released Mg²⁺ ions on the proliferation of chondrogenic ATDC5 cells, highlighting the potential of Mg²⁺ enrichment of ADA-GEL-based hydrogels for cartilage tissue engineering approaches.

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Materials

Sodium alginate (VIVAPHARM®, PH176) derived from Laminaria hyperborean was obtained from JRS PHARMA GmbH & Co. KG (Rosenberg, Germany). The dialysis membranes (MWCO: 6–8 kDa, diameter 32 mm, Spectra/Por®) and sterile syringe filters (Rotilabo, PVDF) were purchased from Carl Roth GmbH + Co. KG, Germany. Microbial transglutaminase (ACTIVA WM, specific enzyme activity of 85–135 U g−1) was obtained from Ajinomoto Co., Inc. (Japan). Dulbecco’s Phosphate Buffered Saline (DPBS, [−] CaCl2, [−] MgCl2), Hanks’ Balanced Salt Solution (HBSS, [+] CaCl2, [+] MgCl2, Gibco), Dulbecco’s Modified Eagle Medium (DMEM, 4.5 g/L glucose, Gibco), DMEM/F-12 (Gibco), penicillin/streptomycin (PS), fetal bovine serum (FBS), Calcein-AM, DAPI, and Phalloidin (Invitrogen) were purchased from Thermo Fisher Scientific Inc. (Germany). All other chemicals were purchased from Sigma-Aldrich (Germany) if not specified otherwise.

Lisa Schöbel, Utku Özdemir, Aldo R. Boccaccini, Investigation of oxidized alginate-gelatin-based hydrogels enriched with magnesium for cartilage tissue engineering, Materials Today Chemistry, Volume 49, 2025, 103030, ISSN 2468-5194, https://doi.org/10.1016/j.mtchem.2025.103030.

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