ETD

• Amyotrophic Lateral Sclerosis
• Assembloids
• Connectoids
• Disease Modelling
• Organoids

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by the loss of both upper and lower motor neurons. It often manifests alongside frontotemporal dementia (FTD), presenting with both neuropsychiatric and motor symptoms. ALS most commonly occurs sporadically; however, familial forms have been reported, involving genes such as chromosome 9 open reading frame 72 (C9ORF72), superoxide dismutase 1 (SOD1), TAR DNA-binding protein (TARDBP), and fused in sarcoma (FUS). Among these, the C9ORF72 hexanucleotide repeat expansion is the most common genetic cause. 
Historically, ALS has been studied using postmortem cell cultures and histological sections derived from patient samples. However, these methods primarily reflect end-stage disease, limiting insight into the progressive evolution of neurodegeneration and complicating the development of effective therapeutic interventions. Animal models represent another important approach, offering the advantage of recapitulating disease progression and enabling behavioural assessment. Nevertheless, they fail to fully capture the complete spectrum of ALS pathology, reproducing only selected pathological and behavioural features. 
In recent years, the use of organoids and higher-order assemblies derived from human induced pluripotent stem cells (hiPSCs) has emerged as a promising strategy for studying neurodegenerative diseases. These models can recapitulate many aspects of disease pathology in a more comprehensive manner, while avoiding some of the ethical limitations associated with animal and postmortem studies. 
In the context of C9ORF72 hexanucleotide repeat expansion, both gain-of-function and loss-of-function mechanisms appear to contribute significantly to disease pathology. These include the disruption of nuclear protein localization, impairment of axonal trafficking, dysfunction of ion channels and membrane transporters, synaptic abnormalities, and network-level disturbances, all of which contribute to the disease phenotype. Despite advances from postmortem, animal, and cellular studies, the true progression of disease in complex human-derived systems such as organoids remains poorly understood. 
The aim of this study is to advance the understanding of subcellular disease-related protein aggregates, including both classical and non-classical proteins; to characterize dipeptide repeat expansions; and to investigate electrophysiological and morphological axonal pathologies. This will be achieved through the generation of organoids derived from C9ORF72 hexanucleotide repeat expansion patient cells and isogenic controls.