Kartogenin-loaded liposomes coated with alkylated hyaluronic acid for stimulated chondrogenic differentiation.

Kartogenin (KGN) is a potent inducer of chondrogenic differentiation, but its biomedical application is limited by poor aqueous solubility and the lack of efficient delivery systems. In this study, hybrid nanosystems composed of KGN-loaded liposomes (LK) coated with amphiphilic hyaluronic acid (HA) derivatives were developed to combine favorable carrier properties with HA-mediated biological targeting. Native HA was hydrophobically modified with dodecyl (C12) or octadecyl (C18) chains at low or high degrees of substitution (DS), yielding three amphiphilic derivatives: HAC12L, HAC18L, and HAC18H. Polymer-coated liposomes were characterized by dynamic light scattering and ζ-potential measurements, while lipid bilayer organization was evaluated by differential scanning calorimetry (DSC) and cryogenic transmission electron microscopy (cryo-TEM). Increasing hydrophobic modification enhanced polymer-liposome association and altered liposome surface organization. HAC18H provided the strongest KGN retention but also introduced greater membrane heterogeneity. All HA derivatives exhibited good cytocompatibility toward human umbilical cord Wharton's jelly mesenchymal stem cells (hUC-MSCs) within the concentration range of 1-40 µg/mL, and polymer coating reduced the cytotoxicity of KGN-loaded liposomes compared with uncoated systems. In a 14-day stimulation model, the hybrid formulations induced structure- and dose-dependent upregulation of chondrogenic markers (SOX9, ACAN, COL2A1) with minimal induction of COL1A1, consistent with activation of early chondrogenic differentiation pathways. Among the tested systems, LK-HAC18L exhibited the most balanced chondrogenic profile, as assessed by combined gene expression, lineage specificity, and CD44 receptor engagement. Overall, these findings indicate that controlled hydrophobic modification of HA modestly modulates KGN release behavior while influencing its biological activity, providing a promising platform for cartilage regeneration applications.