Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder, affecting over 8.5 million people worldwide. The aggregation of α-Synuclein (α-syn) into pathological oligomers and fibrils, known as Lewy bodies, is central to the pathogenesis and progression of PD. Pathologic α-syn seeds induce further aggregation, propagating throughout neurons and causing cytotoxicity and neurodegeneration. Cationic arginine-rich peptides (CARPs) are gaining attention due to their diverse neuroprotective effects and protein anti-aggregatory properties, establishing them as a promising therapeutic avenue for PD. Available PD therapies are palliative, failing to address the underlying a-syn pathology. This study aims to characterise both intracellular a-syn aggregation and intercellular a-syn propagation (uptake) in vitro, and investigate the therapeutic potential of the CARP, R18D (18-mer of D-arginine), to prevent these processes. To mimic PD pathology, a-syn aggregate overexpression is induced in the rodent neuronal cell-culture model through two approaches: administration of a-syn seed and MG-132, a proteasome inhibitor. To investigate a-syn aggregation inhibition by R18D, neuronal cultures receive R18D treatment at various concentrations and are monitored 48 hours later. Any changes induced by R18D are quantified using homogenous time-resolved fluorescence. To investigate a-syn uptake inhibition by R18D, α-syn seeds are treated with R18D and introduced to neuronal cultures where uptake is directly visualised using confocal microscopy. Preliminary HTRF results and confocal image analysis suggest R18D may reduce a-syn aggregation and uptake. R18D represents a novel therapeutic approach to reduce key processes of α-syn pathology and may be critical in halting or slowing the aggressive progression of PD.