Fig. 3. Histological evaluation for cartilage degeneration in CCR5^−/− and WT mice.

The sham-operated side of both CCR5^−/− (A) and WT (B) mice after DMM showed normal cartilage with no osteophyte formation at 8-weeks after DMM. Following DMM at 8-weeks, decreased articular cartilage degeneration (complete arrow) in CCR5^−/− (C) compared to WT mice (D) was observed. Osteophyte formation was also observed on the medial side in both CCR5^−/− and WT mice (arrowhead). The sum OA score from all four quadrants of five sections from each level with eight levels from each knee was based on cartilage damage and shows that CCR5^−/− mice develop less OA compared to WT mice after surgery only at 8-weeks (N = 14 for WT, N = 16 for CCR5^−/−) (G) and 12-weeks (N = 6 each genotype) (I) but not at 4-weeks post-surgery (N = 16 for WT, N = 14 for CCR5^−/−) (E). Pair-wise comparison showed that the summed OA score was found to be significantly lower in DMM knees of CCR5^−/− compared to WT mice at 8- (P < 0.01; 95% CI = 5.52–20.02 in CCR5^−/−) and 12-weeks (P < 0.01; 95% CI = 1.10–1.86 in CCR5^−/−) post-surgery. A maximum score (F, H, J) representing highest score from all sectioned levels for a given knee indicates that DMM knees have significant more OA score in both CCR5^−/− and WT mice compared to sham knees. It was also shown that there was no significant difference between CCR5^−/− mice and WT mice for maximum OA score at any time point post-surgery. MFC = medial femoral condyle; LFC = lateral femoral condyle; MM = medial meniscus; LM = lateral meniscus; T = Tibia. Images in the left panel have magnification of 40× and scale bar = 300 µm while images in the right panel have magnification of 100× and scale bar = 100 µm. Higher magnification images of the selected box showed right to the lower magnification images. Asterisks (*) indicate P < 0.05. Graphs represent mean ± 95% CI.