Proceedings: cell therapies for Parkinson's disease from discovery to clinic

Linalool, a Fragrance Compound in Plants, Protects Dopaminergic Neurons and Improves Motor Function and Skeletal Muscle Strength in Experimental Models of Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by the gradual loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc), resulting in reduced dopamine levels in the striatum and eventual onset of motor symptoms. Linalool (3,7-dimethyl-1,6-octadien-3-ol) is a monoterpene in aromatic plants exhibiting antioxidant, antidepressant, and anti-anxiety properties. The objective of this study is to evaluate the neuroprotective impacts of linalool on dopaminergic SH-SY5Y cells, primary mesencephalic and cortical neurons treated with 1-methyl-4-phenylpyridinium ion (MPP+), as well as in PD-like mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Cell viability, α-tubulin staining, western blotting, immunohistochemistry and behavioral experiments were performed. In MPP+-treated SH-SY5Y cells, linalool increased cell viability, reduced neurite retraction, enhanced antioxidant defense by downregulation of apoptosis signaling (B-cell lymphoma 2 (Bcl-2), cleaved caspase-3 and poly ADP-ribose polymerase (PARP)) and phagocyte NADPH oxidase (gp91phox), as well as upregulation of neurotrophic signaling (brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF)) and nuclear factor-erythroid 2 related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) pathway. In MPP+-treated primary mesencephalic neurons, linalool enhanced the expressions of tyrosine hydroxylase (TH), Sirtuin 1 (SirT1), and parkin. In MPP+-treated primary cortical neurons, linalool upregulated protein expression of SirT1, γ-Aminobutyric acid type A-α1 (GABAA-α1), and γ-Aminobutyric acid type B (GABAB). In PD-like mice, linalool attenuated the loss of dopamine neurons in SNpc. Linalool improved the motor and nonmotor behavioral deficits and muscle strength of PD-like mice. These findings suggest that linalool potentially protects dopaminergic neurons and improves the impairment symptoms of PD.

Embryonic Stem Cells in Clinical Trials: Current Overview of Developments and Challenges

The first isolation of human embryonic stem cells (hESC) reported in the late 90s opened a new window to promising possibilities in the fields of human developmental biology and regenerative medicine. Subsequently, the differentiation of hESC lines into different precursor cells showed their potential in treating different incurable diseases. However, this promising field has consistently had remarkable ethical and experimental limitations. This paper is a review of clinical trial studies dealing with hESC and their advantages, limitations, and other specific concerns. Some of the hESC limitations have been solved, and several clinical trial studies are ongoing so that recent clinical trials have strived to improve the clinical applications of hESC, especially in macular degeneration and neurodegenerative diseases. However, regarding hESC-based therapy, several important issues need more research and discussion. Despite considerable studies to Date, hESC-based therapy is not available for conventional clinical applications, and more studies and data are needed to overcome current clinical and ethical limitations. When all the limitations of Embryonic stem cells (ESC) are wholly resolved, perhaps hESC can become superior to the existing stem cell sources. This overview will be beneficial for understanding the standard and promising applications of cell and tissue-based therapeutic approaches and for developing novel therapeutic applications of hESC.

Conditioned Medium of Human Menstrual Blood-Derived Endometrial Stem Cells Protects Against MPP+-Induced Cytotoxicity in vitro

Mesenchymal stem cells (MSCs) showed the potential to treat Parkinson’s disease (PD). However, it is unknown whether the conditioned medium of human menstrual blood-derived endometrial stem cells (MenSCs-CM) has the function to alleviate syndromes of PD. In this study, human neuroblastoma SH-SY5Y cells were exposed to neurotoxicant 1-methyl-4-phenylpyridinium (MPP⁺) for inducing a range of response characteristics of PD. After culturing this cell model with 24 h/48 h collected MenSCs-CM for different days, cell viability, pro-inflammation cytokines, mitochondrial membrane potential (ΔΨm), oxidative stress, and cell apoptosis were detected. Finally, protein assay was performed to detect 12 kinds of neurotrophic factors inside MenSCs-CM. Our results showed that MPP⁺ caused SH-SY5Y cell viability reduction as an increasing dose and time dependent manner. MPP⁺ treatment resulted in inflammation, mitochondrial dysfunction, reactive oxygen species (ROS) production accumulation, and apoptosis of SH-SY5Y at its IC50 concentration. Forty-eight hours-collected MenSCs-CM and culturing with the MPP⁺-treated SH-SY5Y for 2 days are the optimized condition to increase cell viability. Besides, MenSCs-CM was efficacious against MPP⁺ induced inflammation, ΔΨm loss, ROS generation, and it could significantly decrease cells numbers in late apoptosis stage. What’s more, protein assay showed that MenSCs-CM contained various neuroprotective factors. Our study provided the first evidence that MenSCs-CM has a protective effect on MPP⁺-induced cytotoxicity in various aspects, and firstly showed that MenSCs can release at least 12 kinds of neurotrophic factors to medium, which may contribute to the protective function of MenSCs-CM to treat PD. This research enlightening that MenSCs-CM is beneficial in the therapy for PD and probably also for other neurodegenerative diseases.

Primate stem cells: bridge the translation from basic research to clinic application

A growing body of literature has shown that stem cells are very effective for the treatment of degenerative diseases in rodents but these exciting results have not translated to clinical practice. The difference results from the divergence in genetic, metabolic, and physiological phenotypes between rodents and humans. The high degree of similarity between non-human primates (NHPs) and humans provides the most accurate models for preclinical studies of stem cell therapy. Using a NHP model to understand the following key issues, which cannot be addressed in humans or rodents, will be helpful for extending stem cell applications in the basic science and the clinic. These issues include pluripotency of primate stem cells, the safety and efficiency of stem cell therapy, and transplantation procedures of stem cells suitable for clinical translation. Here we review studies of the above issues in NHPs and current challenges of stem cell applications in both basic science and clinical therapies. We propose that the use of NHP models, in particular combining the serial production and transplantation procedures of stem cells is the most useful for preclinical studies designed to overcome these challenges.