Study on the Role of MicroRNA-214 in the Rehabilitation of Cartilage in Mice with Exercise-Induced Traumatic Osteoarthritis

Abstract

This study aimed to explore the possible relationship between the expression of Micro RNA-214 (miR-214) and the pathogenesis and recovery in mice with post-traumatic osteoarthritis (PTOA). In this study, 40 male C57BL/6 mice were randomly divided into five groups: model control (MC) group, model (M) group, rehabilitation control (RC) group, model + rehabilitation (M + R) group, and model + convalescent (M + C) group. Four weeks of high-intensity treadmill exercise (HITE) and 4 weeks of moderate-intensity treadmill exercise (MITE) were implemented for PTOA modeling and rehabilitation, respectively. In vitro, 10% elongation mechanical strain was used for IL-1β stimulated chondrocytes. We found that compared with the MC group, there was a significant increase in the aspect of inflammation and catabolism while a dramatic fall in miR-214 expression was observed in the M group. After the 4 weeks of MITE, the level of inflammation and metabolism, as well as miR-214 expression, was partially reversed in the M + R group compared with the M + C group. The expression of miR-214 decreased dramatically after chondrocyte stimulation by IL-1β and then increased significantly after 10% strain was applied to IL-1β-treated cells. These results suggest that a suitable mechanical load can increase the expression of miR-214, and that miR-214 may play a chondroprotective effect in the development of OA.

Keywords: articular cartilage; miR-214; post-traumatic osteoarthritis; treadmill exercise.

Figure 1

Changes in the weights of mice at different ages in each group. (A) Changes in the weight of mice in the MC and M groups; (B) Changes in the weight of mice in the RC, the M + R, and M + C groups. (n = 8, Comparison within M group: ^▲ p < 0.05; comparison between MC and M groups: * p < 0.05; comparison between M + R and M + C groups: ^# p < 0.05).

Figure 2

Histological evaluation of joint tissue sections by HE and safranin O staining. (A) HE stained histological images of the knee joints; A(1): HE staining for MC group; A(2): HE staining for M group; A(3): HE staining for RC group; A(4): HE staining for M + R group; A(5): HE staining for M + C group; A(6): The Mankin score of each group; (B) Safranin-O-Fast Green stained histological images of the knee joints of mice; B(1): Safranin-O-Fast Green staining for MC group; B(2): Safranin-O-Fast Green staining for M group; B(3): Safranin-O-Fast Green staining for RC group; B(4): Safranin-O-Fast Green staining for M + R group; B(5): Safranin-O-Fast Green staining for M + C group; B(6): The Mankin score of each group. The red arrow indicates the site of cartilage damage. (n = 8, * p < 0.05, ** p < 0.01.).

Figure 3

3D reconstruction of the subchondral bone of the femoral condyle by micro-CT.

Figure 4

The gene expression of metabolic and inflammatory factors of knee joint cartilage. (A,B) the expression of COL2A mRNA; (C,D) the expression of ACAN mRNA; (E,F) the expression of TNF-α mRNA; (G,H) the expression of MMP-13 mRNA (n = 8, * p < 0.05, ** p < 0.01.)

Figure 5

The expression of mouse cartilage miR-214 and its related downstream genes. (A,B) the expression of miR-214; (C,D) the expression of Wnt1 mRNA; (E, F) the expression of β-catenin mRNA. (n = 8, * p < 0.05, ** p < 0.01.)

Figure 6

Toluidine blue O staining for chondrocytes.

Figure 7

Cell viability of chondrocyte stimulated with IL-1β at different concentrations: comparison between 0.1 ng/mL and 10 ng/mL. (** p < 0.01).

Figure 8

RNA expression of metabolic, inflammatory factors and miR-214 of chondrocyte. NC: Control group, IL-1β 0 h: IL-1β+ 0 h strain, IL-1β 1 h: IL-1β+ 1 h strain, IL-1β 1 h: IL-1β+ 1 h strain, IL-1β 2 h: IL-1β+ 2 h strain, IL-1β 4 h: IL-1β+ 4 h strain (n = 4, * p < 0.05, ** p < 0.01.)

Figure 9

Protein expression of metabolic factors of chondrocytes. NC: Control group, IL-1β 0 h: IL-1β+ 0 h strain, IL-1β 1 h: IL-1β+ 1 h strain, IL-1β 1 h: IL-1β+ 1 h strain, IL-1β 2 h: IL-1β+ 2 h strain, IL-1β 4 h: IL-1β+ 4 h strain (n = 4, * p < 0.05).