Parkinson's Disease Phenotypes in Patient Neuronal Cultures and Brain Organoids Improved by 2-Hydroxypropyl-ß-Cyclodextrin Treatment.

BACKGROUND: The etiology of Parkinson's disease (PD) is only partially understood despite the fact that environmental causes, risk factors, and specific gene mutations are contributors to the disease. Biallelic mutations in the phosphatase and tensin homolog (PTEN)-induced putative kinase 1 (PINK1) gene involved in mitochondrial homeostasis, vesicle trafficking, and autophagy are sufficient to cause PD. OBJECTIVES: We sought to evaluate the difference between controls' and PINK1 patients' derived neurons in their transition from neuroepithelial stem cells to neurons, allowing us to identify potential pathways to target with repurposed compounds. METHODS: Using two-dimensional and three-dimensional models of patients' derived neurons we recapitulated PD-related phenotypes. We introduced the usage of midbrain organoids for testing compounds. Using Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated protein 9 (Cas9), we corrected the point mutations of three patients' derived cells. We evaluated the effect of the selected compound in a mouse model. RESULTS: PD patient-derived cells presented differences in their energetic profile, imbalanced proliferation, apoptosis, mitophagy, and a reduced differentiation efficiency to tyrosine hydroxylase positive (TH+) neurons compared to controls' cells. Correction of a patient's point mutation ameliorated the metabolic properties and neuronal firing rates as well as reversing the differentiation phenotype, and reducing the increased astrocytic levels. Treatment with 2-hydroxypropyl-ß-cyclodextrin increased the autophagy and mitophagy capacity of neurons concomitant with an improved dopaminergic differentiation of patient-specific neurons in midbrain organoids and ameliorated neurotoxicity in a mouse model. CONCLUSION: We show that treatment with a repurposed compound is sufficient for restoring the impaired dopaminergic differentiation of PD patient-derived cells. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Long-term hyperglycemia aggravates α-synuclein aggregation and dopaminergic neuronal loss in a Parkinson's disease mouse model.

BACKGROUND: Growing evidence suggests an association between Parkinson's disease (PD) and diabetes mellitus (DM). At the cellular level, long-term elevated levels of glucose have been shown to lead to nigrostriatal degeneration in PD models. However, the underlying mechanism is still unclear. Previously, we have elucidated the potential of type 2 diabetes mellitus (T2DM) in facilitating PD progression, involving aggregation of both alpha-synuclein (α-syn) and islet amyloid polypeptide in the pancreatic and brain tissues. However, due to the complicated effect of insulin resistance on PD onset, the actual mechanism of hyperglycemia-induced dopaminergic degeneration remains unknown. METHODS: We employed the type 1 diabetes mellitus (T1DM) model induced by streptozotocin (STZ) injection in a transgenic mouse line (BAC-α-syn-GFP) overexpressing human α-syn, to investigate the direct effect of elevated blood glucose on nigrostriatal degeneration. RESULTS: STZ treatment induced more severe pathological alterations in the pancreatic islets and T1DM symptoms in α-syn-overexpressing mice than in wild-type mice, at one month and three months after STZ injections. Behavioral tests evaluating motor performance confirmed the nigrostriatal degeneration. Furthermore, there was a marked decrease in dopaminergic profiles and an increase of α-syn accumulation and Serine 129 (S129) phosphorylation in STZ-treated α-syn mice compared with the vehicle-treated mice. In addition, more severe neuroinflammation was observed in the brains of the STZ-treated α-syn mice. CONCLUSION: Our results solidify the potential link between DM and PD, providing insights into how hyperglycemia induces nigrostriatal degeneration and contributes to pathogenic mechanisms in PD.

Differential seeding and propagating efficiency of α-synuclein strains generated in different conditions.

BACKGROUND: Accumulation of alpha-synuclein (α-syn) is a main pathological hallmark of Parkinson's and related diseases, which are collectively known as synucleinopathies. Growing evidence has supported that the same protein can induce remarkably distinct pathological progresses and disease phenotypes, suggesting the existence of strain difference among α-syn fibrils. Previous studies have shown that α-syn pathology can propagate from the peripheral nervous system (PNS) to the central nervous system (CNS) in a "prion-like" manner. However, the difference of the propagation potency from the periphery to CNS among different α-syn strains remains unknown and the effect of different generation processes of these strains on the potency of seeding and propagation remains to be revealed in more detail. METHODS: Three strains of preformed α-syn fibrils (PFFs) were generated in different buffer conditions which varied in pH and ionic concentrations. The α-syn PFFs were intramuscularly (IM) injected into a novel bacterial artificial chromosome (BAC) transgenic mouse line that expresses wild-type human α-syn, and the efficiency of seeding and propagation of these PFFs from the PNS to the CNS was evaluated. RESULTS: The three strains of α-syn PFFs triggered distinct propagation patterns. The fibrils generated in mildly acidic buffer led to the most severe α-syn pathology, degeneration of motor neurons and microgliosis in the spinal cord. CONCLUSIONS: The different α-syn conformers generated in different conditions exhibited strain-specific pathology and propagation patterns from the periphery to the CNS, which further supports the view that α-syn strains may be responsible for the heterogeneity of pathological features and disease progresses among synucleinopathies.

Positron imaging for verification of irradiation field during radiotherapy.

AIM OF STUDY: The present study was designed to investigate the application of positron images from photonuclear reactions to verify the location of targeted radiation in vivo. MATERIALS AND METHODS: The phantom study was conducted with distilled water, porcine muscle, porcine adipose tissue, and graphite; these subjects were irradiated separately with 50 MV photons generated by an MM50 Racetrack Microtron. The positron emission activity was measured using a Geiger counter, and the radioactive decay curves for each of the irradiated materials were then established. The positron emission tomography (PET) images of the three tissue models were also achieved using the same radiation conditions. The in vivo PET imaging study was also conducted in tumor-bearing rabbits. RESULTS: Our results demonstrated that the PET imaging could be used to verify the position of the irradiation field in vivo. The dose distribution images of photonuclear reactions of 11 C and 15 O were uniform, using 2-Gy 50 MV photons. CONCLUSIONS: The factors influencing the half-life of radiation activity in various tissues were different from the first order kinetic reaction in physics.

Protoporphyrin IX catalyzed hydrogen peroxide to generate singlet oxygen.

AIM: To study the role of protoporphyrin IX (pPIX) in mitochondrial metabolism of hydrogen peroxide (H2O2). METHODS: O2 (-) specific fluorescent markers DMA (9,10-dimerthylanthracence) and SOSG (Singlet Oxygen Sensor Green reagent) were used for measurement of singlet oxygen ((1)O2). Catalyzing conversion of H2O2 into (1)O2 by pPIX was monitored in vitro under varied H2O2 content, temperature, and PH value in the reaction. Ex vivo mitochondrial model was used to analyze effects of ferrochelatase (FECH) and high energy X-rays on this catalytic reaction. RESULTS: In complete dark, measurable (1)O2 was generated when 1.5 mM of H2O2 was incubated with 24 µM of pPIX H2O2 at 37°C for 3 hours. Mitochondrial yield of H2O2 was 0.11±0.03 nmole/mg/min. Mitochondrial FECH significantly improve the catalytic ability of pPIX converting H2O2 into (1)O2. At presence of high-energy X-ray, incubation of 14.4 µM of pPIX with 0.54 µM of H2O2 also generated (1)O2, during which the fluorescence density of 1.05 µM of DMA decreased by 41.5% (P < 0.05). This conversion was not observed when pPIX was replaced with structurally similar hematoporphyrin. CONCLUSION: pPIX can catalyze conversion of H2O2 into (1)O2.