Cinnamaldehyde-Chitosan Nanoparticles Protect Fibroblasts from High-Glucose-Induced Apoptosis via PI3K/AKT Pathway Activation

Hyperglycemia disrupts wound healing in diabetes partly by promoting fibroblast apoptosis. This study aimed to evaluate whether cinnamaldehyde-chitosan nanoparticles (CCNPs) can inhibit high-glucose-induced fibroblasts apoptosis, and to determine whether this effect involves modulation of the PI3K/AKT pathway. CCNPs were synthesized using a modified ionic-gelation method and characterized by Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM). Murine embryonic fibroblasts cell line (NIH-3T3) were allocated to 6 groups: 2 control groups-normal glucose (NG, 5.5 mM glucose) and high glucose (HG, 30 mM glucose)-and 4 treatment groups that were pretreated with metformin (50 µM) or CCNPs (12.5, 25 and 50 µM) prior to 24 h of HG exposure. After 24 h of treatment, PI3K and phosphorylated-AKT levels in the cell lysates were quantified using ELISA, and fibroblasts apoptosis was assessed and quantified by Annexin V-PI flow cytometry. Synthesized CCNPs exhibited spherical morphology with an average diameter of 214.8 ± 54.0 nm, a polydispersity index (PDI) of 0.419, and a ζ-potential of +66.2 mV. High glucose exposure significantly increased the proportion of late apoptotic cells and reduced PI3K and p-AKT expression, compared with NG group (p < 0.05). Meanwhile, CCNPs at all tested concentrations significantly reduced late apoptotic cell percentages in a concentration-dependent manner, whereas only CCNPs at 50 µM significantly restored both PI3K and p-AKT levels. These findings suggest that CCNPs mitigate high-glucose-induced fibroblast apoptosis and is likely associated with the activation of PI3K/AKT pathway. This study provides preliminary in vitro evidence supporting a potential fibroblast-protective role of CCNPs under hyperglycemic conditions. Limitations of this study include the short-term in-vitro design and the absence of a direct comparison between CCNPs versus cinnamaldehyde only. Future studies should incorporate longer exposure durations, pathway-specific inhibitor, and in-vivo validation.