Genetically modified non-human primate models for research on neurodegenerative diseases.

Neurodegenerative diseases (NDs) are a group of debilitating neurological disorders that primarily affect elderly populations and include Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS). Currently, there are no therapies available that can delay, stop, or reverse the pathological progression of NDs in clinical settings. As the population ages, NDs are imposing a huge burden on public health systems and affected families. Animal models are important tools for preclinical investigations to understand disease pathogenesis and test potential treatments. While numerous rodent models of NDs have been developed to enhance our understanding of disease mechanisms, the limited success of translating findings from animal models to clinical practice suggests that there is still a need to bridge this translation gap. Old World non-human primates (NHPs), such as rhesus, cynomolgus, and vervet monkeys, are phylogenetically, physiologically, biochemically, and behaviorally most relevant to humans. This is particularly evident in the similarity of the structure and function of their central nervous systems, rendering such species uniquely valuable for neuroscience research. Recently, the development of several genetically modified NHP models of NDs has successfully recapitulated key pathologies and revealed novel mechanisms. This review focuses on the efficacy of NHPs in modeling NDs and the novel pathological insights gained, as well as the challenges associated with the generation of such models and the complexities involved in their subsequent analysis.

Cath-KP, a novel peptide derived from frog skin, prevents oxidative stress damage in a Parkinson's disease model.

Parkinson's disease (PD) is a neurodegenerative condition that results in dyskinesia, with oxidative stress playing a pivotal role in its progression. Antioxidant peptides may thus present therapeutic potential for PD. In this study, a novel cathelicidin peptide (Cath-KP; GCSGRFCNLFNNRRPGRLTLIHRPGGDKRTSTGLIYV) was identified from the skin of the Asiatic painted frog ( Kaloula pulchra). Structural analysis using circular dichroism and homology modeling revealed a unique αßß conformation for Cath-KP. In vitro experiments, including free radical scavenging and ferric-reducing antioxidant analyses, confirmed its antioxidant properties. Using the 1-methyl-4-phenylpyridinium ion (MPP +)-induced dopamine cell line and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice, Cath-KP was found to penetrate cells and reach deep brain tissues, resulting in improved MPP +-induced cell viability and reduced oxidative stress-induced damage by promoting antioxidant enzyme expression and alleviating mitochondrial and intracellular reactive oxygen species accumulation through Sirtuin-1 (Sirt1)/Nuclear factor erythroid 2-related factor 2 (Nrf2) pathway activation. Both focal adhesion kinase (FAK) and p38 were also identified as regulatory elements. In the MPTP-induced PD mice, Cath-KP administration increased the number of tyrosine hydroxylase (TH)-positive neurons, restored TH content, and ameliorated dyskinesia. To the best of our knowledge, this study is the first to report on a cathelicidin peptide demonstrating potent antioxidant and neuroprotective properties in a PD model by targeting oxidative stress. These findings expand the known functions of cathelicidins, and hold promise for the development of therapeutic agents for PD.

PINK1 gene mutation by pair truncated sgRNA/Cas9-D10A in cynomolgus monkeys.

Mutations of PTEN-induced kinase I (PINK1) cause early-onset Parkinson's disease (PD) with selective neurodegeneration in humans. However, current PINK1 knockout mouse and pig models are unable to recapitulate the typical neurodegenerative phenotypes observed in PD patients. This suggests that generating PINK1 disease models in non-human primates (NHPs) that are close to humans is essential to investigate the unique function of PINK1 in primate brains. Paired single guide RNA (sgRNA)/Cas9-D10A nickases and truncated sgRNA/Cas9, both of which can reduce off-target effects without compromising on-target editing, are two optimized strategies in the CRISPR/Cas9 system for establishing disease animal models. Here, we combined the two strategies and injected Cas9-D10A mRNA and two truncated sgRNAs into one-cell-stage cynomolgus zygotes to target the PINK1 gene. We achieved precise and efficient gene editing of the target site in three newborn cynomolgus monkeys. The frame shift mutations of PINK1 in mutant fibroblasts led to a reduction in mRNA. However, western blotting and immunofluorescence staining confirmed the PINK1 protein levels were comparable to that in wild-type fibroblasts. We further reprogramed mutant fibroblasts into induced pluripotent stem cells (iPSCs), which showed similar ability to differentiate into dopamine (DA) neurons. Taken together, our results showed that co-injection of Cas9-D10A nickase mRNA and sgRNA into one-cell-stage cynomolgus embryos enabled the generation of human disease models in NHPs and target editing by pair truncated sgRNA/Cas9-D10A in PINK1 gene exon 2 did not impact protein expression.

Biological implications and limitations of a cynomolgus monkey with naturally occurring Parkinson's disease.

We recently identified a cynomolgus monkey with naturally occurring Parkinson's disease (PD), indicating that PD may not be a uniquely human disease (Li et al, 2020). In our previous study, four lines of evidence, including typical PD clinical symptoms, pharmacological responses, pathological hallmarks, and genetic mutations, strongly supported the identification of a monkey with spontaneous PD (Figure 1). To the best of our knowledge, this is the first reported case of naturally developed PD in animals. This suggests that PD is not a disease restricted to humans, with its existence in a non-human primate providing a novel evolutionary angle for understanding PD. As a close relative to humans (Buffalo et al, 2019; Phillips et al, 2014; Yan et al, 2011), this rare case of PD in another primate species provides solid evidence that monkeys are ideal candidates for the development of a genuine "animal version of PD", with conserved etiology and pathogenesis (Li et al, 2020). Furthermore, it allows us to compare similarities and differences in PD development between species and to understand PD pathogenesis from an evolutionary point of view.

Herba Cistanche (Rou Cong Rong): A Review of Its Phytochemistry and Pharmacology.

Herba Cistanche, known as Rou Cong Rong in Chinese, is a very valuable Chinese herbal medicine that has been recorded in the Chinese Pharmacopoeia. Rou Cong Rong has been extensively used in clinical practice in traditional herbal formulations and has also been widely used as a health food supplement for a long time in Asian countries such as China and Japan. There are many bioactive compounds in Rou Cong Rong, the most important of which are phenylethanoid glycosides. This article summarizes the up-to-date information regarding the phytochemistry, pharmacology, processing, toxicity and safety of Rou Cong Rong to reveal its pharmacodynamic basis and potential therapeutic effects, which could be of great value for its use in future research.

Neuroprotective effect of biosynthesised gold nanoparticles synthesised from root extract of Paeonia moutan against Parkinson disease - In vitro &In vivo model.

Parkinson disease is one of the most common neurological movement disorders affecting geriatric population. Biosynthesized gold nanoparticles are the ideal alternatives spotlighted by many researchers to treat various diseases. In the present study we synthesized gold nanoparticles using the root extract of Paeonia mountan, woody trees which are used in traditional Chinese medicine to be prescribed for diverse diseases. The synthesis of gold nanoparticles was confirmed with UV-Vis spectroscopic analysis and characterized using FTIR, HR-TEM, EDAX and XRD analysis. The cytotoxicity property of synthesized gold nanoparticles was assessed using MTT assay in the murine microglial BV2 cells. The neuroprotective effect of synthesized gold nanoparticles in inflammatory agent lipopolysaccharides triggered murine microglial BV2 cells was evaluated using nitric oxide, prostaglandin E2 and inflammatory cytokines assays such as IL-6&IL-1ß. Further to confirm in vivo effect of synthesized nanoparticles, the nanoparticles were treated to Parkinson induced C57BL/6 mice. Behavioral, biochemical and molecular analysis were performed to estimate the potency of synthesized gold nanoparticles against the Parkinson induction in mice model. Our characterization results prove the gold nanoparticles synthesized using Paeonia mountan fulfills the requirement of ideal nanodrug and it potentially inhibited the inflammation in in vitro murine microglial BV2. The results of in vivo experiments authentically confirm gold nanoparticles synthesized using Paeonia mountan alleviates the neuroinflammation and improves the motor coordination in Parkinson induced mice.

De novo tetrahydrobiopterin biosynthesis is impaired in the inflammed striatum of parkin(-/-) mice.

Parkinson's disease (PD), the second-most prevalent neurodegenerative disease, is primarily characterized by neurodegeneration in the substantia nigra pars compacta, resulting in motor impairment. Loss-of-function mutations in parkin are the major cause of the early onset familial form of the disease. Although rodents deficient in parkin (parkin(-/-) ) have some dopaminergic system dysfunction associated with central oxidative stress and energy metabolism deficiencies, these animals only display nigrostriatal pathway degeneration under inflammatory conditions. This study investigated the impact of the inflammatory stimulus induced by lypopolisaccharide (LPS) on tetrahydrobiopterin (BH4) synthesizing enzymes (de novo and salvage pathways), since this cofactor is essential for dopamine synthesis. The mitochondrial content and architecture was investigated in the striatum of LPS-exposed parkin(-/-) mice. As expected, the LPS (0.33 mg/kg; i.p.) challenge compromised spontaneous locomotion and social interaction with juvenile parkin(-/-) and WT mice. Moreover, the genotype impacted the kinetics of the investigation of the juvenile. The inflammatory scenario did not induce apparent changes in mitochondrial ultrastructure; however, it increased the quantity of mitochondria, which were of smaller size, and provoked the perinuclear distribution of the organelle. Furthermore, the BH4 de novo biosynthetic pathway failed to be up-regulated in the LPS challenge, a well-known stimulus for its activation. The LPS treatment increased sepiapterin reductase (SPR) expression, suggesting compensation by the salvage pathway. This might indicate that dopamine synthesis is compromised in parkin(-/-) mice under inflammatory conditions. Finally, this scenario impaired the striatal expression of the transcription factor BDNF, possibly favoring cell death.

Protective Effect of Curcumin Against Oxidative Stress-Induced Injury in Rats with Parkinson's Disease Through the Wnt/ ß-Catenin Signaling Pathway.

BACKGROUND/AIMS: The study aimed to investigate the protective effect of curcumin against oxidative stress-induced injury of Parkinson's disease (PD) through the Wnt/ß-catenin signaling pathway in rats. METHODS: The successfully established PD rat models and normal healthy rats were randomly assigned into the 6-hydroxydopamine (6-OHDA), the curcumin (Cur) and the control groups. Immunohistochemistry was used to detect the positive expression of tyrosine hydroxylase (TH), dopamine transporter (DAT) and glial fibrillary acidic protein (GFAP). Deutocerebrum primary cells were extracted and classified into the control, 6-OHDA, Cur (5, 10, 15 µmol/L), Dickkopf-1 (DKK-1) and Cur + DKK-1 groups. MTT assays, adhesion tests and TUNEL staining were used to assess cell viability, adhesion and apoptosis, respectively. Western blotting and qRT-PCR were used to examine the protein and mRNA expressions of Wnt3a and ß-catenin and the c-myc and cyclinD1 mRNA expressions. RESULTS: TH and DAT expressions in the Cur group were elevated and GFAP was reduced compared with the 6-OHDA group. Curcumin enhanced viability, survival and adhesion and attenuated apoptosis of deutocerebrum primary cells by activating the Wnt/ß-catenin signaling pathway. Higher Wnt3a and ß-catenin mRNA and protein expressions and c-myc and cyclinD1 mRNA expressions, enhanced superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) contents, decreased malondialdehyde (MDA) content and elevated mitochondrial membrane potential (∆ψm) were found in the 10 and 15 µmol/L Cur groups compared with the 6-OHDA group. However, opposite tendencies were found in the Cur + DKK-1 group compared to the 10 µmol/L Cur group. CONCLUSION: This study suggests that curcumin could protect against oxidative stress-induced injury in PD rats via the Wnt/ß-catenin signaling pathway.

Practical Stereology Applications for the Pathologist.

Qualitative histopathology is the gold standard for routine examination of morphological tissue changes in the regulatory or academic environment. The human eye is exceptional for pattern recognition but often cannot detect small changes in quantity. In cases where detection of subtle quantitative changes is critical, more sensitive methods are required. Two-dimensional histomorphometry can provide additional quantitative information and is quite useful in many cases. However, the provided data may not be referent to the entire tissue and, as such, it makes several assumptions, which are sources of bias. In contrast, stereology is design based rather than assumption based and uses stringent sampling methods to obtain accurate and precise 3-dimensional information using geometrical and statistical principles. Recent advances in technology have made stereology more approachable and practical for the pathologist in both regulatory and academic environments. This review introduces pathologists to the basic principles of stereology and walks the reader through some real-world examples for the application of these principles in the workplace.

Aminochrome induces dopaminergic neuronal dysfunction: a new animal model for Parkinson's disease.

L-Dopa continues to be the gold drug in Parkinson's disease (PD) treatment from 1967. The failure to translate successful results from preclinical to clinical studies can be explained by the use of preclinical models which do not reflect what happens in the disease since these induce a rapid and extensive degeneration; for example, MPTP induces a severe Parkinsonism in only 3 days in humans contrasting with the slow degeneration and progression of PD. This study presents a new anatomy and develops preclinical model based on aminochrome which induces a slow and progressive dysfunction of dopaminergic neurons. The unilateral injection of aminochrome into rat striatum resulted in (1) contralateral rotation when the animals are stimulated with apomorphine; (2) absence of significant loss of tyrosine hydroxylase-positive neuronal elements both in substantia nigra and striatum; (3) cell shrinkage; (4) significant reduction of dopamine release; (5) significant increase in GABA release; (6) significant decrease in the number of monoaminergic presynaptic vesicles; (7) significant increase of dopamine concentration inside of monoaminergic vesicles; (8) significant increase of damaged mitochondria; (9) significant decrease of ATP level in the striatum (10) significant decrease in basal and maximal mitochondrial respiration. These results suggest that aminochrome induces dysfunction of dopaminergic neurons where the contralateral behavior can be explained by aminochrome-induced ATP decrease required both for anterograde transport of synaptic vesicles and dopamine release. Aminochrome could be implemented as a new model neurotoxin to study Parkinson's disease.

Long-term stimulation of the subthalamic nucleus in hemiparkinsonian rats: neuroprotection of dopaminergic neurons.

OBJECT: The goal of this study was to evaluate the neuroprotective effects conferred by long-term electrical stimulation of the subthalamic nucleus (STN) against degeneration of dopaminergic neurons by assessing motor functional and immunohistological findings in hemiparkinsonian rats. METHODS: In 13 of 25 rats, a concentric microelectrode was stereotactically implanted into the right STN under the guidance of extracellular microelectrode recording. After this had been done the animals were given an injection of 6-hydroxydopamine (6-OHDA) into the right striatum. Seven of the rats received continuous stimulation (frequency 130 Hz, intensity 80-100 microA) for 2 weeks (Group A); the other six did not receive any stimulation during this period (Group B). Twelve rats did not receive electrode implantation and underwent 6-OHDA injection only; these animals served as a control group (Group C). After 2 weeks, motor function in the rats was evaluated by conducting an amphetamine-induced rotation test. Finally, tyrosine hydroxylase-immunoreactive neurons in the pars compacta of the substantia nigra (SNc) were counted to evaluate the extent of degeneration of dopaminergic neurons. Ipsilateral rotation was significantly decreased in Group A, regardless of the effects of stimulation delivered during the test (p < 0.05). Rats in Group B demonstrated typical circling as did those in Group C, except that on stimulation Group B rats immediately stopped circling or changed direction. Tyrosine hydroxylase-immunoreactive neurons in the SNc were significantly preserved in the animals in Group A, whereas neurons in animals in Groups B and C were moderately depleted (p < 0.01). CONCLUSIONS: Acutely, STN stimulation improved rotation symmetry in rats with moderate SNc degeneration. When STN stimulation had been applied for the preceding 2 weeks, motor function was better and SNc neural degeneration was significantly milder. Subthalamic nucleus stimulation thus appears to protect dopaminergic neurons in this hemiparkinsonian model, in addition to improving motor function in these animals.

Therapeutic gene transfer with herpes-based vectors: studies in Parkinson's disease and motor nerve regeneration.

We have examined the possibility of using herpes simplex virus (HSV)-based vectors to prevent neuronal cell death and enhance functional recovery after injury. In the 6-hydroxydopamine (6-OHDA) model of Parkinson's disease (PD) and after proximal spinal root injury, direct stereotactic injection of HSV-based vectors constructed to express the glial cell derived neurotrophic factor (GDNF) or the anti-apoptotic peptide Bcl-2 prevented neuronal death and enhanced recovery. Gene transfer may be useful in the treatment of neurologic disorders in which neuronal cell death occurs in a restricted anatomic distribution.

Complications of a trophic xenotransplant approach in parkinsonian monkeys.

Various restorative cell transplantation strategies have been investigated to substitute for lost dopamine (DA) neurons or to enhance DA synthesis in Parkinson's disease. Intracerebral implantation of engineered cells encapsulated in a semipermeable polymer membrane constitutes one way to deliver bioactive substances unable to cross the blood-brain barrier while avoiding the need for long-term immunosuppression. Glial cell line-derived neurotrophic factor (GDNF) has shown trophic effects on DA neurons but effective and sustained delivery within the brain parenchyma remains problematic. The long-term efficacy and late complications of a xenotransplant approach utilizing GDNF-expressing encapsulated baby hamster kidney (BHK) cells were examined. Each of five MPTP-lesioned parkinsonian cynomolgus monkeys received five devices containing active or inert cells grafted bilaterally in the striatum in a two-stage procedure 9 months apart and animals were sacrificed 4 months later for analyses. No definite motor benefit was observed, DA levels were comparable between GDNF- and control cell-implanted striata, and tyrosine hydroxylase (TH) immunoreactivity in the substantia nigra showed no consistent recovery. Cell viability and GDNF synthesis in the explanted devices were negligible. The brain tissue surrounding all implants showed an intense immune reaction with prominent "foreign body" inflammatory infiltrates. Membrane biophysics, the cell type used, and the extended period of time the devices remained in situ may have contributed to the negative outcome and should be addressed in future investigations using this approach.