INTRODUCTION: Aging is characterized by progressive molecular and epigenetic changes, including heterochromatin disorganization and impaired stress responses, which contribute to the onset of neurodegenerative disorders such as Parkinson’s disease (PD). Epigenetic deregulation, in particular, has emerged as a central mechanism underlying age-related neuronal dysfunction. Experimental models that recapitulate these changes are essential for understanding the mechanisms driving neurodegeneration.

AIM(S): The study aimed to establish a cellular model of neuronal aging using D-galactose and to assess age-related molecular and epigenetic alterations in dopaminergic neurons derived from hiPSCs

METHOD(S): Dopaminergic neurons were differentiated from human-induced pluripotent stem cells (hiPSCs) and exposed to D-galactose (15 mg/mL) for five days. Epigenetic changes were analyzed using immunofluorescent staining for heterochromatin-associated proteins HP1γ and H3K9me3. Evaluations included cellular senescence, viability, oxidative stress levels, mitochondrial performance, and transcriptional activity.

RESULTS: Exposure to D-galactose induced a marked reduction in chromatin compaction, as evidenced by significantly lower levels of HP1γ and H3K9me3. Neurons displayed heightened oxidative stress, diminished mitochondrial functionality, and suppressed expression of mitochondrial biogenesis regulators including PGC1a and NRF1. The senescence-associated gene P16 showed increased expression. Additionally, dopaminergic neuronal markers TH and MAP2 expression declined significantly, accompanied by upregulation of the pro-apoptotic gene BAX.

CONCLUSIONS: This model demonstrates that D-galactose induces an aging-like phenotype in dopaminergic neurons, marked by epigenetic disorganization, mitochondrial dysfunction, loss of dopaminergic markers, and senescence-associated gene expression.

FINANCIAL SUPPORT: The study was supported by Mossakowski Medical Research Institute, Polish Academy of Sciences - Research Fund grant no. FBW 032/2022