Effect of primary cilia on growth plate chondrocyte proliferation of young rats with chronic renal insufficiency
Objective: To observe the effect of primary cilia on growth plate chondrocyte proliferation of young rats with chronic renal insufficiency (CRI).
Methods: Male 2-week-old Sprague-Dawley rats were randomly divided into two groups (with 10 in each group): Sham group (only left ureter was exposed) and CRI group (left ureter was ligated). Rats were sacrificed 2 weeks after operation and the total length of tibia was measured. Histological sections of tibia were taken to observe the chondrocytes of growth plate proliferative region and the expression rate of primary cilia. Chondrocytes from growth plate in two groups were isolated and cultured in vitro to P3 generation and the chondrocyte proliferation rate at 24 h were detected. The primary cilia expression rate and cilia length of chondrocytes were measured. Western blot was used to detect the expression of intraflagellar transport 88 (IFT88) protein and the gray scale was analyzed.
Results: The total length of tibia was shorter in CRI group [(35.84±4.56) mm vs (42.33±3.44) mm, P=0.002]. The results of tibial histological section showed that chondrocytes of growth plate proliferative region were unorganized and the number of chondrocyte with columnar structure was less in CRI group (2.71±1.10 vs 7.68±1.32, P<0.001). The primary cilia expression rate of chondrocytes was higher in CRI group [(35.53±7.41)% vs (18.31±5.12)%, P<0.001]. The chondrocyte proliferation rate at 24 h was lower in CRI group [(11.38±6.10)% vs (24.35±8.46)%, P=0.001]. The primary cilia expression rate of chondrocytes was higher in CRI group [(60.12±7.86)% vs (32.17±8.97)%, P<0.001], and the primary cilia length of chondrocytes was longer in CRI group [(3.54±1.61) μm vs (1.96±0.82) μm, P=0.012]. The protein IFT88 was more highly expressed in CRI group (0.47±0.23 vs 0.17±0.10, P=0.001).
Conclusion: The primary cilia expression rate of growth plate chondrocytes was higher in the rats with CRI, resulting in decreased chondrocyte proliferation rate and growth retardation of tibial growth plate.