Abstract:
Background Cartilage defects often induce chondrocyte senescence. Current research primarily focuses on the infiltration of normal chondrocytes within tissue-engineered scaffolds, with studies on the infiltration of senescent chondrocytes remaining insufficient. Objective To investigate the altered infiltration capacity of senescent chondrocytes and to enhance their infiltration within scaffolds by optimizing scaffold structure via an ice recrystallization technology. Methods The differences in cell infiltration between senescent chondrocytes and normal chondrocytes within conventional ice-templated gelatin scaffolds were examined using confocal microscopy scanning and reconstruction. The pore size and porosity of the scaffolds were measured by scanning electron microscopy. The compressive modulus of the scaffold material was evaluated using a uniaxial compression test. The effect of the scaffold material on the survival rate of senescent chondrocytes was assessed by live/dead staining. The proliferative activity of senescent chondrocytes on the scaffold material was measured using the CCK-8 assay and EdU staining. Cell morphology and infiltration behavior of senescent chondrocytes in the two types of scaffolds were observed via cytoskeleton/nucleus staining. The in vivo effect of the scaffold material on promoting cartilage defect repair was evaluated using a rat cartilage defect model. Results Compared to normal chondrocytes, senescent chondrocytes exhibited a significantly weakened infiltration capacity within conventional ice-templated gelatin scaffolds(P<0.01). The pore size of the gelatin scaffold prepared by the ice crystal recrystallization method (21.1 ± 2.7 μm) was significantly larger than that of the conventional ice-templated scaffold (8.0 ± 1.6 μm) (P<0.001), while also exhibiting higher porosity (P<0.05). The compressive modulus of ice recrystallized scaffolds (16.5 ± 4.5 kPa) was significantly higher than that of conventional ice-templated scaffolds (6.2 ± 1.5 kPa) (P<0.05). Live/Dead staining, CCK-8 assay, and EdU staining indicated that scaffold extracts did not significantly inhibit cell viability (P>0.05). Cell morphology observations showed that the ice recrystallized gelatin scaffold enhanced the adhesion of senescent chondrocytes. After 4 and 14 days of culture, the infiltration depth of senescent chondrocytes was significantly greater in ice recrystallized scaffolds compared to conventional ones (Day 4: 132 ± 13.7 μm vs. 41 ± 6.2 μm, P<0.001; Day 14: 1336.1 ± 80.0 μm vs. 929.3 ± 105.0 μm, P<0.01). The rat cartilage defect model demonstrated that the ice recrystallized gelatin scaffold significantly promoted cartilage repair (P<0.001). Conclusion The infiltration capacity of senescent chondrocytes within gelatin scaffolds is diminished. A novel gelatin scaffold fabricated by the ice recrystallization method can enhance the infiltration of senescent chondrocytes and promote the repair and healing of cartilage defects.