Intra-Articular Injections of Polyphenols Protect Articular Cartilage from Inflammation-Induced Degradation: Suggesting a Potential Role in Cartilage Therapeutics

Natarajan V, Madhan B, Tiku ML · PLoS One

The protection is chemical rather than anti-inflammatory: the polyphenols bind and crosslink cartilage collagen the way tannins tan hide, raising the explants' thermal denaturation point by 12 to 17 °C and cutting collagenase digestion from 72% to 25 to 29%. In the rats the injections did not change paw swelling or the onset of arthritis, yet histological cartilage damage scores were lower whether given before or after induction. The authors frame the result as an argument for polyphenols as an injected cartilage therapeutic rather than as a dietary one.

Population

Bovine cartilage explants, and 42 female rats with collagen-induced arthritis

Intervention

EGCG or tannic acid injected into the knee, 300 μg per dose in five doses, before or after arthritis was induced

Comparator

Vehicle

Limitations

Intra-articular delivery, in a rheumatoid rather than osteoarthritic model, and the framing itself concedes that the dietary route is the problem; histology came from three rats per group. Funded by India's CSIR.