In Vitro Study of the Anti-inflammatory and Antifibrotic Activity of Tannic Acid-Coated Curcumin-Loaded Nanoparticles in Human Tenocytes

Tendinitis is a tendon disorder related to inflam-mation and pain, due to an injury or overuse of the tissue, which is hypocellular and hypovascular, leading to limited repair which occurs in a disorganized deposition of extracellular matrix that leads to scar formation and fibrosis, ultimately resulting in impaired tendon integrity. Current conventional treatments are limited and often ineffective, highlighting the need for new therapeutic strategies. In this work, acetalated-dextran nanoparticles (AcDEX NPs) loaded with curcumin and coated with tannic acid (TA) are developed to exploit the anti-inflammatory and anti-fibrotic properties of the two compounds. For this purpose, a microfluidic technique was used in order to obtain particles with a precise size distribution, aiming to decrease the batch-to-batch variability for possible future clinical translation. Coating with TA increased not only the stability of the nanosystem in different media but also enhanced the interaction and the cell-uptake in primary human tenocytes and KG-1 macrophages. The nanosystem exhibited good biocompatibility toward these cell types and a good release profile in an inflammatory environment. The efficacy was demonstrated by real-time quantitative polymerase chain reaction, in which the curcumin loaded in the particles showed good anti-inflammatory properties by decreasing the expression of NF-icb and TA-coated NPs showing anti-fibrotic effect, decreasing the gene expression of TGF-fi. Overall, due to the loading of curcumin and TA in the AcDEX NPs, and their synergistic activity, this nanosystem has promising properties for future application in tendinitis.