# Hyaluronic Acid Microplates for Intra-articular Lubrication and Cartilage Protection in Post-traumatic Osteoarthritis

## TL;DR

This paper introduces hyaluronic acid microparticles that reduce joint inflammation and protect cartilage in osteoarthritis, offering a long-lasting treatment option.

## Contribution

The study presents engineered hyaluronic acid microparticles with tunable mechanical properties for sustained intra-articular lubrication and inflammation reduction.

## Key findings

- μHA microparticles reduced proinflammatory cytokine production in human chondrocytes under oxidative stress.
- In a 3D OA cartilage model, μHA decreased glycosaminoglycan release and MMP-13 activity.
- A single μHA injection in mice lowered synovial inflammation in a post-traumatic OA model.

## Abstract

Osteoarthritis (OA) is the most common joint disorder,
characterized
by a vicious cycle of synovial inflammation and cartilage degradation.
Intra-articular injection of hyaluronic acid (HA)-based products,
one of the currently available treatments, provides only temporary
symptomatic relief without addressing the underlying inflammation.
Here, we engineered several configurations of 20 × 5 μm
square-shaped HA-based hydrogel microparticles (μHA) by photopolymerizing
HA–methacrylate chains within a sacrificial template. The μHA
mechano-pharmacological properties were tuned by adjusting the HA
concentration, molecular weight, and degree of methacrylation, resulting
in microparticles with a Young’s modulus ranging from a few
tens (30 kPa) to a few hundred (200 kPa) kilopascals; a structure
stable for over a month under oxidative stress conditions; and reduced
friction in simulated synovial fluids. Under H2O2-induced oxidative conditions, μHA decreased the production
of proinflammatory cytokines (IL-6, IL-1β, and TNF-α)
in human chondrocytes to basal levels. In a three-dimensional OA cartilage
model, μHA reduced glycosaminoglycan release and matrix metalloproteinase-13
activity, demonstrating chondroprotective effects. In a rigorous murine
model of early-stage post-traumatic OA, a single intra-articular injection
of μHA lowered proinflammatory gene expression in the synovium
to basal levels. In summary, μHA offers a drug-free approach
to managing OA by enhancing lubrication and reducing inflammation,
providing a sustained therapeutic activity over several weeks.