Prostaglandin E2 affects proliferation and collagen synthesis by human patellar tendon fibroblasts

Objective: To determine the effect of prostaglandin E-2 on proliferation and collagen synthesis by human patellar tendon fibroblasts. Design and Setting: Controlled laboratory study. Methods: Human patellar tendon fibroblasts were treated with different concentrations (1, 10, 100 ng/mL) of prostaglandin E-2 in cultures. Fibroblasts without prostaglandin E-2 treatment were used as the control group. The fibroblast proliferation and collagen synthesis were measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and Sircol collagen assay, respectively. Main Outcome Measured: Changes in proliferation and collagen production of human patellar tendon fibroblasts. Results: At 1 ng/mL of prostaglandin E2, there was no significant effect on fibroblast proliferation compared with the control group. At concentrations of 10 ng/mL and 100 ng/mL prostaglandin E2, however, fibroblast proliferation significantly decreased, by 7.3% (P = 0.002) and 10.8% (P < 0.0001), respectively, compared with the control group. At I ng/mL of prostaglandin E, collagen production of the tendon fibroblasts was unaffected. However, at both 10 ng/mL and 106 ng/mL prostaglandin E,, collagen production was significantly decreased, by 45.2% (P < 0.0001) and 45.7% (P < 0.0001), respectively, compared with the control group. The levels of collagen production between these 2 dosages did not differ significantly. Conclusions: Prostaglandin E2 affects the proliferation of and collagen production by human patellar tendon fibroblasts in a dosage-dependent manner. Clinical Relevance: Based on these in vitro findings, we speculate that production of prostaglandin E2 in tendons might play some role in the acellularity and matrix disorganization seen in exercise-induced tendinopathy.