The effects of aging, antiinflammatory drugs, and ultrasound on the in vitro response of tendon tissue

We investigated the effects of aging and various treatments on rat patellar tendon using an in vitro model. In the first part of the study, the H-3-thymidine and H-3-proline incorporation rates at 12 and 24 hours were determined in transected patellar tendon explants from young (21 days), intermediate age (8 to 10 weeks), and older (4 to 6 months) rats. In the second part, the same incorporation rates were measured in the older tendon explants in response to treatment with control medium, medium with a high and low concentration of indomethacin, and medium with a high and low concentration of dexamethasone. Finally, the effects of ultrasound treatment were measured and compared with a sham ultrasound treatment. The results indicated an age-dependent response of the tendon. The youngest specimens consistently showed the highest incorporation rates. The addition of a high concentration of dexamethasone resulted in a small negative effect on the H-3-thymidine incorporation. Ultrasound and indomethacin had no significant effects. This study indicates that aging is associated with a lower metabolic activity of tendon. In this model, currently used treatment methods failed to result in direct positive effects on tendon tissue, and a high concentration of dexamethasone appeared to have a small negative effect.