• Angelman Syndrome
• chitosan
• Nanomedicine
• nose-brain delivery
• polymeric nanoparticles

Angelman syndrome (AS) is a severe neurodevelopmental disorder characterized by intellectual disability, frequent seizures, speech impairment and developmental delay. It is caused by the loss of function of the maternally inherited UBE3A gene in neurons. UBE3A plays a key role in neurodevelopment. Proper UBE3A expression, in fact, is essential in normal brain development: its increase causes autism like disorders while its lack leads to Angelman syndrome. Today the most promising therapeutic approach for AS is the unsilencing of the paternal UBE3A allele by targeting a long non-coding UBE3A-antisense transcript via antisense oligonucleotides (ASOs). This approach offers the advantage of restoring UBE3A protein levels without risking over-expression.
ASOs are short single-stranded nucleic acids molecules capable of modulating gene expression, for example by binding to RNA and leading it to degradation.
It is challenging to develop treatments targeting the central nervous system (CNS) due to the presence of the blood brain barrier (BBB). Several drugs, such as ASOs, are usually administrated intrathecally. Given the highly invasive nature of intrathecal administration, over the past few decades, nano vectors and intranasal delivery has been proposed as viable alternative.
Polymeric nanoparticles (NPs), characterized by their sub-micrometer size, can be used to transport molecules to the CNS and are well-suited for administration via intranasal route. Mucoadhesion is a fundamental aspect of intranasal drug delivery because can enhance the resistance time of the active principle in the nasal cavity, boosting drug adsorption and efficiency. Chitosan (CHI), a natural polymer, possesses inherent mucoadhesive properties, making it an ideal candidate due to its natural origin, biocompatibility, and biodegradability, aligning perfectly with the purpose.
The aim of this work is to provide a new strategy for brain delivery of antisense oligonucleotides based on NPs made of biocompatible, FDA-approved natural polymers, via non invasive intranasal route. Here, three different formulations for the nose-brain delivery of ASOs have been developed and investigated:
1) CHI NPs formed with 2,6-pyridinecarboxylic acid as crosslinker;
2) NPs of poly(lactide-co-glicolide) (PLGA) functionalised with glucosamine, the monomer of CHI;
3) CHI-ASOs polyplexes, complexes formed through ionic interactions between the positively charged CHI polymer and negatively charged DNA molecules.
These formulations have been refined and asses to evaluate their size, and surface charge through Dynamic Light Scattering (DLS), as well as their cytotoxicity profile via in vitro testing on human nasal and neuronal cells. Lastly, ASOs encapsulation efficiency of each formulation was evaluated.