FROM ORGANOIDS TO CONNECTIVITY: A NOVEL APPROACH TO MODELING THE HUMAN CORTICOSPINAL TRACT.

This thesis aims to model the human corticospinal tract (CST) using cortical organoids (hCOs) and spinal cord organoids (hSpOs) derived from human iPSCs. Two complementary strategies were employed: (1) contact-based fusion of hCOs and hSpOs to form cortico-spinal assembloids, and (2) connectoid-based modeling using microfluidic chips to study long-range axonal connectivity. The spinal organoids were developed using an accelerated protocol and validated by the expression of motor neuron markers, while cortical organoids were assessed for layer-specific neuronal identity. Connectivity was evaluated across different microdevice platforms, including a custom 3D-printed chip (MED160), agarose-based systems, and PDMS microfluidic devices. Together, these models provide an in vitro platform to investigate CST development, axonal guidance, and applications in regeneration and disease modeling.