Objective: To study the effects of the periosteum,synovium and cartilage tissues on the gene expressions of proteoglycan, collagen II, and nuclear factor kappa B (NF-kappaB) and to investigate the different effects of these tissues on cartilage regeneration.
Methods: In 20 New Zealand white rabbits, 20 cartilage explants were taken from the knee joints in each rabbit, the size of which was 4 mm x 4 mm x 4 mm. All the cartilages were divided into the following 4 groups and cultured for 7 days: Group A, with 5 pieces (2 mm x 2 mm) of the synovium of the knee joints in each dish; Group B, with 5 pieces (2 mm x 2 mm) of the periosteum in each dish; Group C, with 5 pieces (2 mm x 2 mm x 2 mm) of the cartilage in each dish; and Group D, with no addition of other tissues (control group). RNA was extracted from the cells of the cartilage explants (4 mm x 4 mm x 4 mm) in all the dishes. The gene expressions of proteoglycan, collagen II and NF-kappaB were defected by a reverse transcription-polymerase chain reaction (RT-PCR).
Results: In group A, the gene expression of proteoglycan was significantly decreased. The relative density of this gene expression had a significant difference when compared with that in group D (1.09 +/- 0.21 vs. 1.25 +/- 0.25, P < 0.05); the gene expressions of collagen I and NF-kappaB were also decreased, but they had no significant differences when compared with those in group D (P > 0.05). In group B, the gene expressions of proteoglycan, collagen II, and NF-kappaB were significantly increased. The relative densities of these gene expressions were 1.60 +/- 0.26, 1.57 +/- 0.24, and 4.20 +/- 2.22, respectively, which had significant differences when compared with those in group D (P < 0.05). In group C, the relative density of the gene expression of collagen II was 1.43 +/- 0.28, which had a significant difference when compared with that in group D (P < 0.05), but the relative densities of the gene expressions of proteoglycan and NF-kappaB had no significant differences when compared with those in group D (P > 0.05).
Conclusion: The results indicate that the periosteum can up-regulate the gene expressions of proteoglycan, collagen II and NF-kappaB. The NF-kappaB is likely to be an important nuclear transcription factor related to cartilage regeneration. The results also suggest that the periosteum may be better in facilitating the cartilage repair and regeneration in clinical practice.