Effect of Low-Molecular-Weight Hyaluronate-Based Nanoparticles on the In Vitro Expression of Cartilage Markers

Hyaluronic acid (HA) is a key component of synovial fluid as it plays a crucial role in joint physiology. Its biological activity is influenced by molecular weight, local concentration, and persistence in joints. High-molecular-weight HA has a consolidated history of clinical use, whereas little is known about the metabolic effect of low-molecular-weight hyaluronate on cartilage differentiation. This study explores the potential of HA-based nanoparticles (NPs) on chondrocytes differentiation in vitro. Starting from 25 kDa and 250 kDa sodium hyaluronate solutions, two types of NPs were prepared by antisolvent precipitation in ethanol. The resulting NPs were dried in the presence of dipalmitoyl phosphatidylcholine, a natural synovial fluid component, then applied on an in vitro model of horse articular chondrocytes: no toxicity was observed and NPs prepared from 250 kDa HA promoted chondrocyte differentiation to a larger extent with respect to corresponding HA solutions, as evidenced by increased gene expression of chondrogenic markers (<i>Col2a1</i> and <i>Sox9</i>) and reduced expression of dedifferentiation markers (<i>Col1a1</i> and <i>Runx2</i>). These findings suggest that HA-based NPs are more effective at promoting the cellular internalization of the molecule and the differentiation of chondrocytes in vitro and could be a promising platform for drug delivery and cartilage repair.