ObjectiveTo isolate and identify the cartilage progenitor cells (CPCs) from normal cartilage, and to explore the influence of interleukin 1β (IL-1β) in different concentrations on its chondrogenesis. MethodsCPCs were isolated from normal cartilage of adult New Zealand white rabbit with the fibronectin adhesion assay;the cell phenotype was identified;and the cloning and differentiation of CPCs were observed. CPCs were incubated with H-DMEM in group A, with chondrogenic induced medium in group B, with chondrogenic induced medium+0.1 ng/mL IL-1β in group C and chondrogenic induced medium+1.0 ng/mL IL-1β in group D for 3 weeks. The histology, biochemistry, and real-time fluorescence quantitative PCR were performed to observe the effect of IL-1β on the chondrgenic differentiation. ResultsThe CPCs from normal cartilage expressed positively stem cell phenotype, which have similar ability of cloning and differentiation to stem cells. The cell pellets in groups C and D were significantly smaller than those in group B, and cell showed hypertrophic morphology change. There were more expressions of collagen type Ⅱ and collagen type X in group B than in group A, in group B than in groups C and D, and in group C than group D with Safranin O staining. The biochemistry results showed that collagen type Ⅱ content, glycosaminoglycan (GAG) content, and the ratio of GAG/DNA were significantly lower in groups C and D than in group B (P<0.05), and in group D than in group C (P<0.05);but the DNA content was significantly higher in groups C and D than in group B (P<0.05), and no significant difference between groups C and D (P>0.05). The real-time fluorescence quantitative PCR results showed that the relative mRNA expressions of collagen type Ⅱ, collagen type X, and Sox-9 were significantly lower in groups C and D than in group B (P<0.05), and in group D than in group C (P<0.05), but the relative mRNA expressions of Runx-2 and matrix metalloproteinase 13 were significantly higher in groups C and D than in group B (P<0.05), and in group D than in group C (P<0.05). ConclusionThere are CPCs having the character of stem cells in normal cartilage, and they have the capability of cloning and potential differentiation. IL-1β can inhibit the chondrogenesis of CPCs, and possibly promote the osteogenic differentiation.