Figure 4.

Improved stem-cell transplantation at cartilage-injury sites by 3D-IHI nanoscaffold. (a) Schematic diagram illustrating the surgical process and timeline of cartilage repair. Macroscopic views of the cartilage defects filled with TGFβ–BMSC–IHI nanoscaffold and the controls. The degradation of MnO₂ NTs and the regeneration process could be monitored via MRI. (b) To identify our transplanted cells, BMSCs were genetically labeled with a green fluorescent protein (GFP). Scale bar: 100 μm. (c) The dramatically reduced red fluorescent signals of the ROS probe revealed that MnO₂ NTs in the IHI nanoscaffold could effectively scavenge ROS in the defect area. Promoted cell proliferation was confirmed by the higher expression of proliferative marker Ki67 immunostaining. Scale bar: 50 μm. (d) The TGFβ–BMSC–IHI nanoscaffold could retain a significantly higher amount of cells after transplantation compared to other cell-transplantation groups by quantifying the number of remaining GFP⁺ cells in (c). (e) Histogram of the fluorescence intensity of ROS probe showed the effective consumption of ROS in the MnO₂ NTs containing groups. (f) Quantification of Ki67⁺ cells in the defects. The quantifications in (e) and (f) were generated based on the fluorescence intensities in (c). All data are presented as mean ± SD (n = 5). ^*P < 0.05, ^**P < 0.01, ^***P < 0.001.