Experimental study on the effect of different concentrations of macrophage inhibitory cytokine-1 on the proliferation and metabolism of elderly chondrocytes

Objective To observe the effect of different concentrations of macrophage inhibitory cytokine (MIC)-1 on proliferation of old chondrocytes. Methods The serum and the cartilage specimens of the young and the old were collected respectively, and the content of MIC-1 in serum and cartilage was detected. Human chondrocytes were cultured, the control group was treated with culture medium alone, and the culture medium of the experimental group contained recombinant human MIC-1 protein at different concentrations, including 10 ng/ml in experimental group 1, 100 ng/ml in experimental group 2 and 200 ng/ml in experimental group 3. After 48 h of culture, the proliferation of chondrocytes was detected by EdU, and the expression of pSmad2 Smad2 and Col2 in chondrocytes was detected by Western blot and Quantitative real time polymerase chain reaction (qRT-PCR). T test was used for comparison between the two groups. The single factor analysis of variance (ANOVA) and Tukey method were used for the multi-group comparison. Results The relative expression level of MIC-1 protein in serum of young people (0.89±0.11) was higher than that of old people (0.48±0.12), and the difference was statistically significant (t=2.58, P<0.05). The percentage of EdU positive cells in the control group was (26.8±1.5)%, that in the experimental group 1 was (26.2±1.6)%, that in the experimental group 2 was (35.2±1.8)%, and that in the experimental group 3 was (45.6±2.7)%. The difference between groups was statistically significant (F=21.45, P<0.01). The relative expression level of pSmad2 protein was significantly different between groups (F=18.32, P<0.01), among which, experimental group 2(1.25±0.11) and experimental group 3(0.93±0.22) were higher than control group (0.54±0.10), respectively. There were statistically significant differences in Col2 protein relative expression between groups (F=17.90, P<0.01), with experimental group 2(1.28±0.14) and experimental group 3(1.74±0.14) being higher than control group (0.80±0.04), respectively. The relative expression level of Col2 mRNA was significantly different between groups (F=17.90, P<0.01), with experimental group 2(1.13±0.16) and experimental group 3(1.65±0.15) being higher than control group (0.49±0.10). Conclusion The MIC-1 content of the serum and the cartilage in young people is higher than that in old people, and MIC-1 can promote the proliferation of chondrocytes in old. Key words: Aged; Chondrocytes; Osteoarthritis; Macrophages