軟骨缺損後的再生與修復一直是臨床治療上的挑戰。由於關節軟骨缺乏血管、細胞密度低，且細胞遷移與增殖能力較低，受損後通常難以自行恢復原有的組織結構與力學功能。近年來，水膠因具有高含水量及類似細胞外基質的三維結構，已廣泛應用於軟骨組織工程。然而，水膠支架仍面臨力學支撐不足、結構穩定性不佳、降解行為難以控制，以及促進幹細胞軟骨分化能力有限等問題。甲基丙烯醯化明膠（gelatin methacryloyl, GelMA）水膠具有可光交聯、生物相容性良好及材料性質可調控等特性，但單獨使用時仍可能面臨力學強度不足的問題。鍶離子（Sr²⁺）為化學性質與鈣離子相近的二價陽離子，並被認為可調控軟骨基質生成、軟骨相關基因表現及局部細胞反應，而其生物效應可能受濃度與釋放行為影響。因此，本研究旨在將不同濃度的鍶離子添加於 GelMA 光交聯水膠中，並以脂肪來源幹細胞（adipose-derived stem cells, ADSCs）作為細胞來源，系統性評估其材料與力學性質、細胞相容性及軟骨分化相關反應，以探討其應用於軟骨組織工程的潛力。
本研究製備含不同濃度鍶離子的 GelMA 水膠支架，鍶離子濃度分別設定為 0.1、1、10 與 30 mM，並以純 GelMA 作為對照組。材料分析顯示，鍶離子可分布於水膠支架中，且隨鍶離子濃度提高，水膠孔洞結構逐漸緻密，膨潤能力下降，而抗壓性能與酵素降解後的結構完整性則呈提升趨勢。各組水膠皆維持可接受的細胞相容性，並可支持 ADSCs 在材料表面附著。軟骨分化相關結果顯示，較高濃度的鍶離子配方整體上具有較高的軟骨相關基因表現與硫酸化糖胺聚醣沉積量；然而，30 mM 組亦呈現略高的肥大分化相關基因表現，且後期細胞存活率較低。相較之下，10 mM 組在支架穩定性、力學性質、細胞相容性、軟骨相關基因表現、基質累積及肥大分化相關表現之間呈現較佳的整體平衡，顯示在本研究測試濃度與實驗條件下，含 10 mM Sr²⁺ 的 GelMA 配方具有作為軟骨組織工程光交聯水膠支架的應用潛力。

Cartilage regeneration remains a major clinical challenge because articular cartilage is avascular, has low cellularity, and exhibits limited cell migration and proliferation, resulting in poor intrinsic repair capacity. Hydrogels have been widely investigated for cartilage tissue engineering because of their highwater content and extracellular matrix-like three-dimensional architecture. However, insufficient mechanical support, inadequate structural stability, poorly controlled degradation, and limited capacity to promote stem cell chondrogenesis remain important limitations. Gelatin methacryloyl (GelMA) is a photocrosslinkable and biocompatible hydrogel with tunable properties, although GelMA alone may provide insufficient mechanical strength. Strontium ions (Sr²⁺) are divalent cations with chemical properties like those of calcium ions and have been reported to modulate cartilage matrix formation, chondrogenic gene expression, and local cellular responses. Nevertheless, these biological effects may depend on Sr²⁺ concentration and release behavior. Therefore, this study incorporated 0.1, 1, 10, and 30 mM Sr²⁺ into GelMA hydrogels and systematically evaluated their material and mechanical properties, cytocompatibility, and chondrogenic responses using adipose-derived stem cells (ADSCs).
GelMA hydrogels containing 0.1, 1, 10, or 30 mM Sr²⁺ were successfully fabricated, with pristine GelMA serving as the control. Increasing Sr²⁺ concentration produced a more compact pore structure, reduced swelling, enhanced compressive mechanical performance, and improved structural integrity following enzymatic degradation. All formulations maintained acceptable cytocompatibility and supported ADSC attachment. Formulations containing higher Sr²⁺ concentrations generally exhibited greater chondrogenic gene expression and sulfated glycosaminoglycan accumulation. However, the 30 mM group also showed slightly higher expression of hypertrophy-associated genes and lower late-stage cell viability. Among the tested formulations, the GelMA formulation containing 10 mM Sr²⁺ exhibited the most balanced overall profile in terms of scaffold stability, mechanical properties, cytocompatibility, chondrogenic gene expression, matrix accumulation, and hypertrophy-associated responses. These findings suggest that, among the concentrations evaluated in this study, the 10 mM Sr²⁺ formulation has potential as a photocrosslinked hydrogel scaffold for cartilage tissue engineering.

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