To study the variation of CD105+/CD166+ cells and its multilineage potential in early osteoarthritis (OA) cartilage so as to lay a foundation for cartilage repair and pathologic cartilage remodeling in arthritis.
The knee OA model was established in the right knee of 30 adult New Zealand rabbits (8-12 months old). The chondrocytes were harvested from normal cartilage of the left knee (group A), OA cartilage of the right knee at 2 weeks (group B), at 4 weeks (group C), and at 8 weeks (group D) after modeling, and BMSCs were used in group E for the expression of CD105 and CD166. The percentage of CD105+/CD166+ cells in each group was counted by flow cytometry, and CD105+/CD166+ cells were isolated and purified by magnetic-activated cell sorting. The expressions of CD105 and CD166 were observed in 5 groups by laser scanning confocal microscope. Chondrogenesis, osteogenesis, and adipogenesis were evaluated with Alcian blue cytochemistry and collagen type II immunohistochemistry, by detecting the deposition of calcium, and with oil red O staining, respectively.
The percentage of CD105+/CD166+ cells in group A, B, C, and D was significantly lower than that in group E (P < 0.05); it was significantly higher in groups B, C, and D than in group A (P < 0.05), and in group D than in groups B and C (P < 0.05), but no significant difference was found between groups B and C (P > 0.05). Laser scanning confocal microscope results confirmed the expressions of CD105+ and CD166+ cells in groups A, B, C, D, and E, no obvious difference in expression was shown among 5 groups. At 1 week after chondrogenic induction, positive expressions of proteoglycan and collagen type II were observed in 5 groups, no obvious difference was noticed among 5 groups. At 2 weeks after osteogenic induction, calcium level in group E was significantly higher than that in groups A, B, C, and D (P < 0.05), but no significant different was found among groups A, B, C, and D (P > 0.05). At 4 weeks after adipogenic induction, there were more red lipid droplets in group E than in groups A, B, C, and D.
CD105+/CD166+ cells in early OA cartilage increase, which show chondrogenic differentiation potential.