[Effect of mechanical tension on expressions of RhoA/Rho associated protein kinases in rat tendon stem cells in vitro].

Objective: To investigate the effect of different mechanical tensions on the expressions of RhoA/Rho associated protein kinases (ROCK) in rat tendon stem cells (TSCs).
Methods: TSCs were isolated from the tendon tissue of male Sprague Dawley rats (aged, 2-3 months; weighing, 200-250 g) by enzymatic digestion method and cultured for 2-3 passages, then seeded on micro groovdishes. The 4% (4% stretch group) and 8% (8% stretch group) mechanical stretching was performed for 4 hours every day at 1 Hz. After 1, 2, and 3 days, the protein and mRNA expressions of RhoA and ROCK were measured by Western blot and real-time quantitative PCR. The cell proliferation was measured by cell counting kit 8. The cells were not stretched as control group.
Results: The TSCs at passage 2 showed a cobble-stone shape and aggregation growth; TSCs seeded on micro groovdishes showed random growth, and the cells grew along the stretching direction after mechanical stretching. The mRNA expressions of RhoA and ROCK in control group, 4%, and 8% stretch groups showed an increasing tendency at 1, 2, and 3 days, showing significant difference between groups (P < 0.05). The protein expressions of RhoA and ROCK in 4% and 8% stretch groups were similar to those in control group at 1 day (P > 0.05), but the expressions in 4% and 8% stretch groups showed an increasing tendency at 2 and 3 days, which were significantly higher than those in control group (P < 0.05). The cell proliferation of 8% stretch group was significantly lower than that of 4% stretch group and control group at each time point (P < 0.05), but no significant difference was found between 4% stretch group and control group (P > 0.05).
Conclusion: The expressions of RhoA and ROCK of rat TSCs are positively correlated with stretch intensity. So RhoA/ROCK may be an important molecule in TSCs after mechanical stretching.