Omics data integration suggests a potential idiopathic Parkinson's disease signature.

peer reviewedThe vast majority of Parkinson's disease cases are idiopathic. Unclear etiology and multifactorial nature complicate the comprehension of disease pathogenesis. Identification of early transcriptomic and metabolic alterations consistent across different idiopathic Parkinson's disease (IPD) patients might reveal the potential basis of increased dopaminergic neuron vulnerability and primary disease mechanisms. In this study, we combine systems biology and data integration approaches to identify differences in transcriptomic and metabolic signatures between IPD patient and healthy individual-derived midbrain neural precursor cells. Characterization of gene expression and metabolic modeling reveal pyruvate, several amino acid and lipid metabolism as the most dysregulated metabolic pathways in IPD neural precursors. Furthermore, we show that IPD neural precursors endure mitochondrial metabolism impairment and a reduced total NAD pool. Accordingly, we show that treatment with NAD precursors increases ATP yield hence demonstrating a potential to rescue early IPD-associated metabolic changes

Treating Parkinson's Disease with Human Bone Marrow Mesenchymal Stem Cell Secretome: A Translational Investigation Using Human Brain Organoids and Different Routes of In Vivo Administration.

peer reviewedParkinson's disease (PD) is the most common movement disorder, characterized by the progressive loss of dopaminergic neurons from the nigrostriatal system. Currently, there is no treatment that retards disease progression or reverses damage prior to the time of clinical diagnosis. Mesenchymal stem cells (MSCs) are one of the most extensively studied cell sources for regenerative medicine applications, particularly due to the release of soluble factors and vesicles, known as secretome. The main goal of this work was to address the therapeutic potential of the secretome collected from bone-marrow-derived MSCs (BM-MSCs) using different models of the disease. Firstly, we took advantage of an optimized human midbrain-specific organoid system to model PD in vitro using a neurotoxin-induced model through 6-hydroxydopamine (6-OHDA) exposure. In vivo, we evaluated the effects of BM-MSC secretome comparing two different routes of secretome administration: intracerebral injections (a two-site single administration) against multiple systemic administration. The secretome of BM-MSCs was able to protect from dopaminergic neuronal loss, these effects being more evident in vivo. The BM-MSC secretome led to motor function recovery and dopaminergic loss protection; however, multiple systemic administrations resulted in larger therapeutic effects, making this result extremely relevant for potential future clinical applications

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

Millifluidic culture improves human midbrain organoid vitality and differentiation

Human midbrain-specific organoids (hMOs) serve as an experimental in vitro model for studying the pathogenesis of Parkinson's disease (PD). In hMOs, neuroepithelial stem cells (NESCs) give rise to functional midbrain dopaminergic (mDA) neurons that are selectively degenerating during PD. A limitation of the hMO model is an under-supply of oxygen and nutrients to the densely packed core region, which leads eventually to a "dead core". To reduce this phenomenon, we applied a millifluidic culture system that ensures media supply by continuous laminar flow. We developed a computational model of oxygen transport and consumption in order to predict oxygen levels within the hMOs. The modelling predicts higher oxygen levels in the hMO core region under millifluidic conditions. In agreement with the computational model, a significantly smaller "dead core" was observed in hMOs cultured in a bioreactor system compared to those ones kept under conventional shaking conditions. Comparing the necrotic core regions in the organoids with those obtained from the model allowed an estimation of the critical oxygen concentration necessary for ensuring cell vitality. Besides the reduced "dead core" size, the differentiation efficiency from NESCs to mDA neurons was elevated in hMOs exposed to medium flow. Increased differentiation involved a metabolic maturation process that was further developed in the millifluidic culture. Overall, bioreactor conditions that improve hMO quality are worth considering in the context of advanced PD modelling

Derivation of Human Midbrain-Specific Organoids from Neuroepithelial Stem Cells

Research on human brain development and neurological diseases is limited by the lack of advanced experimental in vitro models that truly recapitulate the complexity of the human brain. Here, we describe a robust human brain organoid system that is highly specific to the midbrain derived from regionally patterned neuroepithelial stem cells. These human midbrain organoids contain spatially organized groups of dopaminergic neurons, which make them an attractive model for the study of Parkinson’s disease. Midbrain organoids are characterized in detail for neuronal, astroglial, and oligodendrocyte differentiation. Furthermore, we show the presence of synaptic connections and electrophysiological activity. The complexity of this model is further highlighted by the myelination of neurites. The present midbrain organoid system has the potential to be used for advanced in vitro disease modeling and therapy development

Neural Stem Cells of Parkinson's Disease Patients Exhibit Aberrant Mitochondrial Morphology and Functionality

Summary: Emerging evidence suggests that Parkinson's disease (PD), besides being an age-associated disorder, might also have a neurodevelopment component. Disruption of mitochondrial homeostasis has been highlighted as a crucial cofactor in its etiology. Here, we show that PD patient-specific human neuroepithelial stem cells (NESCs), carrying the LRRK2-G2019S mutation, recapitulate key mitochondrial defects previously described only in differentiated dopaminergic neurons. By combining high-content imaging approaches, 3D image analysis, and functional mitochondrial readouts we show that LRRK2-G2019S mutation causes aberrations in mitochondrial morphology and functionality compared with isogenic controls. LRRK2-G2019S NESCs display an increased number of mitochondria compared with isogenic control lines. However, these mitochondria are more fragmented and exhibit decreased membrane potential. Functional alterations in LRRK2-G2019S cultures are also accompanied by a reduced mitophagic clearance via lysosomes. These findings support the hypothesis that preceding mitochondrial developmental defects contribute to the manifestation of the PD pathology later in life. : Walter, Bolognin and colleagues show the detection of mitochondrial phenotypes in NESCs derived from Parkinson's disease (PD) patients carrying the LRRK2-G2019S mutation. This supports the use of stem cells as a relevant model to study PD-associated mitochondrial defects associated to PD. Keywords: Parkinson's disease, LRRK2, neurodevelopment, stem cells, mitochondria, autophagy, mitophag