Figure 3

Histological assessment of the cartilaginous repair tissue. (A) Representative images are shown of the tissue sections of rat knees stained with haematoxylin and eosin (H&E), toluidine blue and following immunolocalisation for human mitochondrial antigen (HMA). A greater extent of defect fill with areas of prominent metachromatic staining of GAG deposition was observed in the defects transplanted with CD271+ MSCs compared to defects transplanted with PA MSCs and the Alpha Chondro Shield scaffold alone. The presence of human cells was confirmed by immunolocalization of HMA as indicated by brown punctate staining (red arrows) around the PGA fibres (yellow asterisks) of the scaffold in the cell-treated groups, but not in scaffold alone group. Greater vascularisation was seen in the defects transplanted with PA MSCs and the Alpha Chondro Shield scaffold alone compared to defects transplanted with CD271+ MSCs. Scare bars: H&E top row and toluidine blue = 200 µm; HMA = 10 µm; H&E bottom row = 50 µm. (B) There was a significantly lower overall histological score, indicative of better repair tissue, in defects transplanted with CD271+ MSCs compared with the control group. Data shown are means ± SDs. **p < 0.01.