Modeling Parkinson's disease using human midbrain organoids

With increasing prevalence, neurodegenerative disorders present a major challenge
for medical research and public health. Despite years of investigation, significant
knowledge gaps exist, which impede the development of disease-modifying therapies.
The development of tools to model both physiological and pathological
human brains greatly enhanced our ability to study neurological disorders. Brain
organoids, derived from human induced pluripotent stem cells (iPSCs), hold unprecedented
promise for biomedical research to unravel novel pathological mechanisms
of a multitude of brain disorders. As brain proxies, these models bridge
the gap between traditional 2D cell cultures and animal models. Owing to their
human origin, hiPSC-derived organoids can recapitulate features that cannot be
modeled in animals by virtue of differences in species.
Parkinson’s disease (PD) is a human-specific neurodegenerative disorder. The
major manifestations are the consequence of degenerating dopaminergic neurons
(DANs) in the midbrain. The disease has a multifactorial etiology and a multisystemic
pathogenesis and pathophysiology. In this thesis, we used state-of-the-art
technologies to develop a human midbrain organoid (hMO) model with a great
potential to study PD. hMOs were generated from iPSC-derived neural precursor
cells, which were pre-patterned to the midbrain/hindbrain region. hMOs contain
multiple midbrain-specific cell types, such as midbrain DANs, as well as astrocytes
and oligodendrocytes. We could demonstrate features of neuronal maturation
such as myelination, synaptic connections, spontaneous electrophysiological activity
and neural network synchronicity. We further developed a neurotoxin-induced
PD organoid model and set up a high-content imaging platform coupled with machine
learning classification to predict neurotoxicty. Patient-derived hMOs display
PD-relevant pathomechanisms, indicative of neurodevelopmental deficits. hMOs
as novel in vitro models open up new avenues to unravel PD pathophysiology and
are powerful tools in biomedical research.