Development of stem cell-based therapy for Parkinson's disease

Development of In Vitro Parkinson's Disease Model Mediated by MPP+ and α-Synuclein Using Wharton's Jelly Mesenchymal Stem Cells

MAIN PROBLEM

The mechanism behind Parkinson's disease (PD) is still unclear, and a cure to stop its progression is yet to be found. This is mainly due to the lack of effective human PD models. To address this, we generated an in vitro PD model using Wharton's jelly-derived mesenchymal stem cells (WJMSCs).

METHODS

WJMSCs were isolated from the umbilical cord using an enzymatic method. MSCs were characterized by RT-PCR, immunofluorescence, and trilineage differentiation. MSCs were differentiated into dopaminergic neuron-like cells (DAN) and further degenerated by treating them with either MPP+ iodide or the A53T mutated α-synuclein variant. Gene expression analysis by qRT-PCR and protein analysis by immunofluorescence, flow cytometry, and ELISA were performed. Assays to measure LDH, ROS, NO, GSH, and mitochondrial membrane potential were also performed after degeneration.

RESULTS

WJMSCs were positive for MSC markers and were able to differentiate into adipocytes, chondrocytes, and osteocytes. DAN obtained after the differentiation of WJMSCs for 48 h expressed neuronal markers such as synapsin 1, neuropilin, neurofilament, and MAPT along with dopaminergic markers such as Nurr1, DAT, TH, DDC, and KCNJ6 and were functionally active. Upon degeneration of DAN by MPP+ or A53T, elevated levels of SNCA and downregulation of TH, Nurr1, DAT, and KCNJ6 were observed. Furthermore, increased expression of α-SYN was detected at the protein level as well. Finally, reduction in mitochondrial membrane potential and GSH levels along with an increase in intracellular ROS, nitrite production, and LDH levels confirmed that the in vitro PD-like model exhibited the molecular characteristics of PD.

CONCLUSION

This model is rapid, cost-efficient, and effective for understanding the molecular mechanisms of the disease and can also be used for screening of emerging therapeutics for PD.

Biology, Pathology, and Targeted Therapy of Exosomal Cargoes in Parkinson's Disease: Advances and Challenges

Parkinson's disease (PD) involves the loss of dopamine neurons and accumulation of alpha-synuclein (α-syn), leading to Lewy bodies. While α-syn-targeting immunotherapies show promise, clinical application is challenging. Emerging strategies include nano-platforms for targeted delivery and imaging, and cell-based therapies with patient-specific dopaminergic neurons, aiming to enhance treatment effectiveness despite challenges. Exosome-based methodologies are emerging as a promising area of research in PD due to their role in the spread of α-syn pathology. Exosomes are small extracellular vesicles that can carry misfolded α-syn and transfer it between cells, contributing to the progression of PD. They can be isolated from biological fluids such as blood and cerebrospinal fluid, making them valuable biomarkers for the disease. Additionally, engineering exosomes to deliver therapeutic agents, including small molecules, RNA, or proteins, offers a novel approach for targeted therapy, capitalizing on their natural ability to cross the blood-brain barrier (BBB). Ongoing studies are evaluating the safety and efficacy of these engineered exosomes in clinical settings. This review explores the role of exosomes in PD, focusing on their potential for diagnosis, treatment, and understanding of pathology. It highlights advancements and future directions in using exosomes as biomarkers and therapeutic tools.

Progress in direct reprogramming of dopaminergic cell replacement therapy

Parkinson's disease (PD) is a gradual neurodegenerative disease. While drug therapy and surgical treatments have been the primary means of addressing PD, they do not offer a cure, and the risks associated with surgical treatment are high. Recent advances in cell reprogramming have given rise to new prospects for the treatment of Parkinson's disease (PD), with induced pluripotent stem cells (iPSCs), induced dopamine neurons (iDNs), and induced neural stem cells (iNSCs) being created. These cells can potentially be used in the treatment of Parkinson's disease. On the other hand, this article emphasizes the limits of iPSCs and iNSCs in the context of Parkinson's disease treatment, as well as approaches for direct reprogramming of somatic cells into iDNs. The paper will examine the benefits and drawbacks of directly converting somatic cells into iDNs.

Perinatal Tissue-Derived Stem Cells: An Emerging Therapeutic Strategy for Challenging Neurodegenerative Diseases

Over the past 20 years, stem cell therapy has been considered a promising option for treating numerous disorders, in particular, neurodegenerative disorders. Stem cells exert neuroprotective and neurodegenerative benefits through different mechanisms, such as the secretion of neurotrophic factors, cell replacement, the activation of endogenous stem cells, and decreased neuroinflammation. Several sources of stem cells have been proposed for transplantation and the restoration of damaged tissue. Over recent decades, intensive research has focused on gestational stem cells considered a novel resource for cell transplantation therapy. The present review provides an update on the recent preclinical/clinical applications of gestational stem cells for the treatment of protein-misfolding diseases including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS). However, further studies should be encouraged to translate this promising therapeutic approach into the clinical setting.

Want of Wnt in Parkinson's disease: Could sFRP disrupt interplay between Nurr1 and Wnt signaling?

Nuclear receptor related 1 (Nurr1) is a transcription factor known to regulate the development and maintenance of midbrain dopaminergic (mDA) neurons. Reports have confirmed that defect or obliteration of Nurr1 results in neurodegeneration and motor function impairment leading to Parkinson's disease (PD). Studies have also indicated that Nurr1 regulates the expression of alpha-synuclein (α-SYN) and mutations in Nurr1 cause α-SYN overexpression, thereby increasing the risk of PD. Nurr1 is modulated via various pathways including Wnt signaling pathway which is known to play an important role in neurogenesis and deregulation of it contributes to PD pathogenesis. Both Wnt/β-catenin dependent and independent pathways are implicated in the activation of Nurr1 and subsequent downregulation of α-SYN. This review highlights the interaction between Nurr1 and Wnt signaling pathways in mDA neuronal development. We further hypothesize how modulation of Wnt signaling pathway by its antagonist, secreted frizzled related proteins (sFRPs) could be a potential route to treat PD.

Cellular rejuvenation: molecular mechanisms and potential therapeutic interventions for diseases

The ageing process is a systemic decline from cellular dysfunction to organ degeneration, with more predisposition to deteriorated disorders. Rejuvenation refers to giving aged cells or organisms more youthful characteristics through various techniques, such as cellular reprogramming and epigenetic regulation. The great leaps in cellular rejuvenation prove that ageing is not a one-way street, and many rejuvenative interventions have emerged to delay and even reverse the ageing process. Defining the mechanism by which roadblocks and signaling inputs influence complex ageing programs is essential for understanding and developing rejuvenative strategies. Here, we discuss the intrinsic and extrinsic factors that counteract cell rejuvenation, and the targeted cells and core mechanisms involved in this process. Then, we critically summarize the latest advances in state-of-art strategies of cellular rejuvenation. Various rejuvenation methods also provide insights for treating specific ageing-related diseases, including cellular reprogramming, the removal of senescence cells (SCs) and suppression of senescence-associated secretory phenotype (SASP), metabolic manipulation, stem cells-associated therapy, dietary restriction, immune rejuvenation and heterochronic transplantation, etc. The potential applications of rejuvenation therapy also extend to cancer treatment. Finally, we analyze in detail the therapeutic opportunities and challenges of rejuvenation technology. Deciphering rejuvenation interventions will provide further insights into anti-ageing and ageing-related disease treatment in clinical settings.

The effect of dopaminergic neuron transplantation and melatonin co-administration on oxidative stress-induced cell death in Parkinson's disease

A gradual degeneration of the striatum and loss of nigral dopamine cells are characteristic of Parkinson's disease. Nowadays, combination therapy for neurodegenerative disease is considered. This study aimed to investigate the effects of melatonin and dopaminergic neurons derived from adipose tissue stem cells (ADSCs) in a rat model of Parkinson's disease. Parkinson's disease was induced in rats using neurotoxin 6-Hydroxydopamine. The treatment was performed using melatonin and dopaminergic neurons transplantation. Subsequently, behavioral tests, western blot analysis for Caspase-3 expression, GSH (Glutathione) content and stereology analysis for the volume and cell number of substantia nigra and striatum were performed. Treatment with melatonin and dopaminergic neuron transplantation increased the number of neurons in substantia nigra and striatum while the number of glial cell and the volume of substantia nigra and striatum did not show significant change between groups. Western blot analysis for caspase 3 indicated the significant differences between groups. The results also indicated the increased level of glutathione (GSH) content in treatment groups. this study showed that combination therapy with melatonin and dopaminergic neurons could greatly protect the neurons, reduce oxidative stress and improve the symptoms of PD.

Stem Cell-based and Advanced Therapeutic Modalities for Parkinson's Disease: A Risk-effectiveness Patient-centered Analysis

Treatment of Parkinson's disease (PD), the second most prevalent neurodegenerative disorder, is currently considered a challenging issue since it causes substantial disability, poor quality of life, and mortality. Despite remarkable progress in advanced conventional therapeutic interventions, the global burden of the disease has nearly doubled, prompting us to assess the riskeffectiveness of different treatment modalities. Each protocol could be considered as the best alternative treatment depending on the patient's situation. Prescription of levodopa, the most effective available medicine for this disorder, has been associated with many complications, i.e., multiple episodes of "off-time" and treatment resistance. Other medications, which are typically used in combination with levodopa, may have several adverse effects as well. As a result, the therapies that are more in line with human physiology and make the least interference with other pathways are worth investigating. On the other hand, remaining and persistent symptoms after therapy and the lack of effective response to the conventional approaches have raised expectations towards innovative alternative approaches, such as stem cell-based therapy. It is critical to not overlook the unexplored side effects of innovative approaches due to the limited number of research. In this review, we aimed to compare the efficacy and risk of advanced therapies with innovative cell-based and stemcell- based modalities in PD patients. This paper recapitulated the underlying factors/conditions, which could lead us to more practical and established therapeutic outcomes with more advantages and few complications. It could be an initial step to reconsider the therapeutic blueprint for patients with Parkinson's disease.

Polyphenols and Stem Cells for Neuroregeneration in Parkinson's Disease and Amyotrophic Lateral Sclerosis

Parkinson's disease (PD) and Amyotrophic lateral sclerosis (ALS) are neurological disorders, pathologically characterized by chronic degeneration of dopaminergic neurons and motor neurons respectively. There is still no cure or effective treatment against the disease progression and most of the treatments are symptomatic. The present review offers an overview of the different factors involved in the pathogenesis of these diseases. Subsequently, we focused on the recent advanced studies of dietary polyphenols and stem cell therapies, which have made it possible to slow down the progression of neurodegeneration. To date, stem cells and different polyphenols have been used for the directional induction of neural stem cells into dopaminergic neurons and motor neurons. We have also discussed their involvement in the modulation of different signal transduction pathways and growth factor levels in various in vivo and in vitro studies. Likewise stem cells, polyphenols also exhibit the potential of neuroprotection by their anti-apoptotic, anti-inflammatory, anti-oxidant properties regulating the growth factors levels and molecular signaling events. Overall this review provides a detailed insight into recent strategies that promise the use of polyphenol with stem cell therapy for the possible treatment of PD and ALS.

Brain Delivery of Curcumin Through Low-Intensity Ultrasound-Induced Blood-Brain Barrier Opening via Lipid-PLGA Nanobubbles

Background

Parkinson's disease (PD) is a progressive neurodegenerative disorder. Owing to the presence of blood-brain barrier (BBB), conventional pharmaceutical agents are difficult to the diseased nuclei and exert their action to inhibit or delay the progress of PD. Recent literatures have demonstrated that curcumin shows the great potential to treat PD. However, its applications are still difficult in vivo due to its poor druggability and low bioavailability through the BBB.

Methods

Melt-crystallization methods were used to improve the solubility of curcumin, and curcumin-loaded lipid-PLGA nanobubbles (Cur-NBs) were fabricated through encapsulating the curcumin into the cavity of lipid-PLGA nanobubbles. The bubble size, zeta potentials, ultrasound imaging capability and drug encapsulation efficiency of the Cur-NBs were characterized by a series of analytical methods. Low-intensity focused ultrasound (LIFU) combined with Cur-NB was used to open the BBB to facilitate curcumin delivery into the deep brain of PD mice, followed by behavioral evaluation for the treatment efficacy.

Results

The solubility of curcumin was improved by melt-crystallization methods, with 2627-fold higher than pure curcumin. The resulting Cur-NBs have a nanoscale size about 400 nm and show excellent contrast imaging performance. Curcumin drugs encapsulated into Cur-NBs could be effectively released when Cur-NBs were irradiated by LIFU at the optimized acoustic pressure, achieving 30% cumulative release rate within 6 h. Importantly, Cur-NBs combined with LIFU can open the BBB and locally deliver the curcumin into the deep-seated brain nuclei, significantly enhancing efficacy of curcumin in the Parkinson C57BL/6J mice model in comparison with only Cur-NBs and LIFU groups.

Conclusion

In this work, we greatly improved the solubility of curcumin and developed Cur-NBs for brain delivery of curcumin against PD through combining with LIFU-mediating BBB. Cur-NBs provide a platform for these potential drugs which are difficult to cross the BBB to treat PD disease or other central nervous system (CNS) diseases.

Current Approaches and Molecular Mechanisms for Directly Reprogramming Fibroblasts Into Neurons and Dopamine Neurons

Parkinson's disease is mainly caused by specific degeneration of dopaminergic neurons (DA neurons) in the substantia nigra of the middle brain. Over the past two decades, transplantation of neural stem cells (NSCs) from fetal brain-derived neural stem cells (fNSCs), human embryonic stem cells (hESCs), and induced pluripotent stem cells (iPSCs) has been shown to improve the symptoms of motor dysfunction in Parkinson's disease (PD) animal models and PD patients significantly. However, there are ethical concerns with fNSCs and hESCs and there is an issue of rejection by the immune system, and the iPSCs may involve tumorigenicity caused by the integration of the transgenes. Recent studies have shown that somatic fibroblasts can be directly reprogrammed to NSCs, neurons, and specific dopamine neurons. Directly induced neurons (iN) or induced DA neurons (iDANs) from somatic fibroblasts have several advantages over iPSC cells. The neurons produced by direct transdifferentiation do not pass through a pluripotent state. Therefore, direct reprogramming can generate patient-specific cells, and it can overcome the safety problems of rejection by the immune system and teratoma formation related to hESCs and iPSCs. However, there are some critical issues such as the low efficiency of direct reprogramming, biological functions, and risks from the directly converted neurons, which hinder their clinical applications. Here, the recent progress in methods, mechanisms, and future challenges of directly reprogramming somatic fibroblasts into neurons or dopamine neurons were summarized to speed up the clinical translation of these directly converted neural cells to treat PD and other neurodegenerative diseases.

From Transcriptome to Behavior: Intranasal Injection of Late Passage Human Olfactory Stem Cells Displays Potential in a Rat Model of Parkinson's Disease

Parkinson's disease (PD) is one of the most common neurodegenerative disorders, which is caused by the loss of dopaminergic (DAergic) neurons. Thus, cell replacement therapy (CRT) might be regarded as an alternative therapy to effectively treat motor functional defects in PD patients. Human olfactory ectomesenchymal stem cells (OE-MSCs) are a novel type of mesenchymal stem cells (MSCs) with a strong tendency to differentiate into DAergic neurons. However, there are various barriers to successful CRT including the proliferation capacity of stem cells at higher passage numbers as well as the route of stem cell delivery. In this regard, we aimed to explore the efficacy of late passage OE-MSC administration through the intranasal (IN) route in PD rat models. Herein, the proliferation capacity of OE-MSCs was compared at early and late passage numbers; then, the results were validated via RNA sequencing analysis. Subsequently, the efficacy of IN injection of late passage OE-MSC in PD models was evaluated. The results manifested the absence of noticeable differences in proliferation capacity and signaling pathways in OE-MSCs at early and late passage numbers. Moreover, it was found that the IN administration of OE-MSCs with a high passage number substantially increased the levels of DAergic markers and improved the motor function in rat models of PD. Overall, our findings suggested that OE-MSCs with a high passage number are a promising CRT candidate due to their fundamental potential to provide a large number of cells with an enormous proliferation capacity. Moreover, they exhibit the high efficiency of IN administration as a noninvasive route of late-passage OE-MSC delivery for CRT, particularly for PD.

Regenerative Stem Cell Therapy for Neurodegenerative Diseases: An Overview

Neurodegenerative diseases resulting from the progressive loss of structure and/or function of neurons contribute to different paralysis degrees and loss of cognition and sensation. The lack of successful curative therapies for neurodegenerative disorders leads to a considerable burden on society and a high economic impact. Over the past 20 years, regenerative cell therapy, also known as stem cell therapy, has provided an excellent opportunity to investigate potentially powerful innovative strategies for treating neurodegenerative diseases. This is due to stem cells' capability to repair injured neuronal tissue by replacing the damaged or lost cells with differentiated cells, providing a conducive environment that is in favor of regeneration, or protecting the existing healthy neurons and glial cells from further damage. Thus, in this review, the various types of stem cells, the current knowledge of stem-cell-based therapies in neurodegenerative diseases, and the recent advances in this field are summarized. Indeed, a better understanding and further studies of stem cell technologies cause progress into realistic and efficacious treatments of neurodegenerative disorders.

Progress in clinical trials of stem cell therapy for cerebral palsy

Cerebral palsy is the most common disease in children associated with lifelong disability in many countries. Clinical research has demonstrated that traditional physiotherapy and rehabilitation therapies cannot alone cure cerebral palsy. Stem cell transplantation is an emerging therapy that has been applied in clinical trials for a variety of neurological diseases because of the regenerative and unlimited proliferative capacity of stem cells. In this review, we summarize the design schemes and results of these clinical trials. Our findings reveal great differences in population characteristics, stem cell types and doses, administration methods, and evaluation methods among the included clinical trials. Furthermore, we also assess the safety and efficacy of these clinical trials. We anticipate that our findings will advance the rational development of clinical trials of stem cell therapy for cerebral palsy and contribute to the clinical application of stem cells.

Challenges and translational considerations of mesenchymal stem/stromal cell therapy for Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta and the presence of Lewy bodies, which gives rise to motor and non-motor symptoms. Unfortunately, current therapeutic strategies for PD merely treat the symptoms of the disease, only temporarily improve the patients' quality of life, and are not sufficient for completely alleviating the symptoms. Therefore, cell-based therapies have emerged as a novel promising therapeutic approach in PD treatment. Mesenchymal stem/stromal cells (MSCs) have arisen as a leading contender for cell sources due to their regenerative and immunomodulatory capabilities, limited ethical concerns, and low risk of tumor formation. Although several studies have shown that MSCs have the potential to mitigate the neurodegenerative pathology of PD, variabilities in preclinical and clinical trials have resulted in inconsistent therapeutic outcomes. In this review, we strive to highlight the sources of variability in studies using MSCs in PD therapy, including MSC sources, the use of autologous or allogenic MSCs, dose, delivery methods, patient factors, and measures of clinical outcome. Available evidence indicates that while the use of MSCs in PD has largely been promising, conditions need to be standardized so that studies can be effectively compared with one another and experimental designs can be improved upon, such that this body of science can continue to move forward.

Stem Cell-Based Therapies for Parkinson Disease

Parkinson disease (PD) is a neurological movement disorder resulting primarily from damage to and degeneration of the nigrostriatal dopaminergic pathway. The pathway consists of neural populations in the substantia nigra that project to the striatum of the brain where they release dopamine. Diagnosis of PD is based on the presence of impaired motor features such as asymmetric or unilateral resting tremor, bradykinesia, and rigidity. Nonmotor features including cognitive impairment, sleep disorders, and autonomic dysfunction are also present. No cure for PD has been discovered, and treatment strategies focus on symptomatic management through restoration of dopaminergic activity. However, proposed cell replacement therapies are promising because midbrain dopaminergic neurons have been shown to restore dopaminergic neurotransmission and functionally rescue the dopamine-depleted striatum. In this review, we summarize our current understanding of the molecular pathogenesis of neurodegeneration in PD and discuss the development of new therapeutic strategies that have led to the initiation of exploratory clinical trials. We focus on the applications of stem cells for the treatment of PD and discuss how stem cell research has contributed to an understanding of PD, predicted the efficacy of novel neuroprotective therapeutics, and highlighted what we believe to be the critical areas for future research.

Functional dopaminergic neurons derived from human chorionic mesenchymal stem cells ameliorate striatal atrophy and improve behavioral deficits in Parkinsonian rat model

Human chorionic mesenchymal stem cells (HCMSCs) have been recognized as a desirable choice for cell therapy in neurological disorders such as Parkinson's disease (PD). Due to invaluable features of HCMSCs including their immunomodulatory and immunosuppressive properties, easily accessible and less differentiated compared to other types of MSCs, HCMSCs provide a great hope for regenerative medicine. Thus, the purpose of this study was to determine the in vitro and in vivo efficacy of HCMSCs-derived dopaminergic (DA) neuron-like cells with regard to PD. Initially, HCMSCs were isolated and underwent a 2-week DA differentiation, followed by in vitro assessments, using quantitative real-time polymerase chain reaction, immunocytochemistry, patch clamp recording, and high-performance liquid chromatography. In addition, the effects of implanted HCMSCs-derived DA neuron-like cells on the motor coordination along with stereological alterations in the striatum of rat models of PD were investigated. Our results showed that under neuronal induction, HCMSCs revealed neuron-like morphology, and expressed neuronal and DA-specific genes, together with DA release. Furthermore, transplantation of HCMSCs-derived DA neurons into the striatum of rat models of PD, augmented performance. Besides, it prevented reduction of striatal volume, dendritic length, and the total number of neurons, coupled with a diminished level of cleaved caspase-3. Altogether, these findings suggest that HCMSCs could be considered as an attractive strategy for cell-based therapies in PD.

Advancement in the modelling and therapeutics of Parkinson's disease

Since the discovery of L-dopa in the middle of the 20th century (1960s), there is not any neuroprotective therapy available although significant development has been made in the treatment of symptomatic Parkinson's disease (PD). Neurological disorders like PD can be modelled in animals so as to recapitulates most of the symptoms seen in PD patients. In aging population, PD is the second most common neurodegenerative disease after Alzheimer's disease, even though significant outcomes have been achieved in PD research yet it still is a mystery to solve the treatments for PD. In the last two decades, PD models have provided enhanced precision into the understanding of the process of PD disease, its etiology, pathology, and molecular mechanisms behind it. Furthermore, at the same time as cellular models have helped to recognize specific events, animal models, both toxic and genetic, have replicated almost all of the hallmarks of PD and are very helpful for testing and finding new strategies for neuroprotection. Recently, in both classical and newer models, major advances have been done in the modelling of supplementary PD features have come into the light. In this review, we have try to provide an updated summary of the characteristics of these models related to in vitro and in vivo models, animal models for PD, stem cell model for PD, newer 3D model as well as the strengths and limitations of these most popular PD models.

Uncovering the Pharmacological Mechanism of Stemazole in the Treatment of Neurodegenerative Diseases Based on a Network Pharmacology Approach

Stemazole exerts potent pharmacological effects against neurodegenerative diseases and protective effects in stem cells. However, on the basis of the current understanding, the molecular mechanisms underlying the effects of stemazole in the treatment of Alzheimer's disease and Parkinson's disease have not been fully elucidated. In this study, a network pharmacology-based strategy integrating target prediction, network construction, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, and molecular docking was adopted to predict the targets of stemazole relevant to the treatment of neurodegenerative diseases and to further explore the involved pharmacological mechanisms. The majority of the predicted targets were highly involved in the mitogen-activated protein kinase (MAPK) signaling pathway. RAC-alpha serine/threonine-protein kinase (AKT1), caspase-3 (CASP3), caspase-8 (CASP8), mitogen-activated protein kinase 8 (MAPK8), and mitogen-activated protein kinase 14 (MAPK14) are the core targets regulated by stemazole and play a central role in its anti-apoptosis effects. This work provides a scientific basis for further elucidating the mechanism underlying the effects of stemazole in the treatment of neurodegenerative diseases.

Quality Standards of Stem Cell Sources for Clinical Treatment of Neurodegenerative Diseases

A large number of experimental and clinical studies have shown that cell transplantation has therapeutic effects for PD, AD and other neurodegenerative diseases or damages. Good Manufacturing Practice (GMP) guidance must be defined to produce clinical-grade cells for transplantation to the patients. Standardized quality and clinical preparation procedures of the transplanted cells will ensure the therapeutic efficacy and reduce the side-effect risk of cell therapy. Here we review the cell quality standards governing the clinical transplantation of stem cells for neurodegenerative diseases to clinical practitioners. These quality standards include cell quality control, minimal suggested cell doses for undergoing cell transplantation, documentation of procedure and therapy, safety evaluation, efficacy evaluation, policy of repeated treatments, not charging the patients for unproven therapies, basic principles of cell therapy, and publishing responsibility.

The cell repair research for Parkinson’s disease: A systematic review

Background and Objective:

Parkinson’s disease (PD) is a common neurodegenerative disease. Previous studies have demonstrated the effect of cell-based therapies, but their clinical efficacy and safety have not been evaluated. This review protocol aimed to systematically evaluate the effect of stem cell therapy in patients with PD and to develop an evidence base for guiding policy and practice.

Methods:

PubMed, Embase, MedlinePlus, The Lancet and Brain were searched over the period January 2001 to October 2019. The keywords used for searching were "Parkinson’s disease" and "cell therapy" and "mesenchymal stem cells" and "embryonic stem cells" and "brain-derived neural stem cells" and "neural progenitor cells" . The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement and a measurement tool, Assessment of Multiple Systematic Reviews (AMSTAR), to assess systematic reviews were used to assess the reporting quality and methodological quality. Data extracted included study details, participant details, intervention details and outcome.

Results:

Nine valid research papers were screened out by systematic analysis. These nine studies were carried out in different countries, with different populations and cell types. According to evaluation methods used, all of the transplantation therapies reported can improve the symptoms of PD patients.

Conclusions:

Cell transplantation is a potential treatment option for PD. More studies with strict study design, larger sample sizes, and longer follow-up are needed in the future.

Stem Cell Therapy for Parkinson's Disease

Parkinson's disease (PD) is one of the most common neurodegenerative diseases caused by specific degeneration and loss of dopamine neurons in substantia nigra of the midbrain. PD is clinically characterized by motor dysfunctions and non-motor symptoms. Even though the dopamine replacement can improve the motor symptoms of PD, it cannot stop the neural degeneration and disease progression. Electrical deep brain stimulation (DBS) to the specific brain areas can improve the symptoms, but it eventually loses the effectiveness. Stem cell transplantation provides an exciting potential for the treatment of PD. Current available cell sources include neural stem cells (NSCs) from fetal brain tissues, human embryonic stem cells (hESCs) isolated from blastocyst, and induced pluripotent stem cells (iPSCs) reprogrammed from the somatic cells such as the fibroblasts and blood cells. Here, we summarize the research advance in experimental and clinical studies to transplant these cells into animal models and clinical patients, and specifically highlight the studies to use hESCs /iPSCs-derived dopaminergic precursor cells and dopamine neurons for the treatment of PD, at last propose future challenges for developing clinical-grade dopaminergic cells for treating the PD.

Novel Approach to Stem Cell Therapy in Parkinson's Disease

In this commentary we discuss International Stem Cell Corporation's (ISCO's) approach to developing a pluripotent stem cell based treatment for Parkinson's disease (PD). In 2016, ISCO received approval to conduct the world's first clinical study of a pluripotent stem cell based therapy for PD. The Australian regulatory agency Therapeutic Goods Administration (TGA) and the Melbourne Health's Human Research Ethics Committee (HREC) independently reviewed ISCO's extensive preclinical data and granted approval for the evaluation of a novel human parthenogenetic derived neural stem cell (NSC) line, ISC-hpNSC, in a PD phase 1 clinical trial ( ClinicalTrials.gov NCT02452723). This is a single-center, open label, dose escalating 12-month study with a 5-year follow-up evaluating a number of objective and patient-reported safety and efficacy measures. A total of 6 years of safety and efficacy data will be collected from each patient. Twelve participants are recruited in this study with four participants per single dose cohort of 30, 50, and 70 million ISC-hpNSC. The grafts are placed bilaterally in the caudate nucleus, putamen, and substantia nigra by magnetic resonance imaging-guided stereotactic surgery. Participants are 30-70 years old with idiopathic PD ≤13 years duration and unified PD rating scale motor score (Part III) in the "OFF" state ≤49. This trial is fully funded by ISCO with no economic involvement from the patients. It is worth noting that ISCO underwent an exhaustive review process and successfully answered the very comprehensive, detailed, and specific questions posed by the TGA and HREC. The regulatory/ethic review process is based on applying scientific and clinical expertise to decision-making, to ensure that the benefits to consumers outweigh any risks associated with the use of medicines or novel therapies.

Pharmacokinetics and absolute oral bioavailability of stemazole by UPLC-MS/MS and its bio-distribution through tritium labeling

The small molecule, stemazole, has significant therapeutic effects on neurodegenerative diseases, such as Alzheimer's disease (AD), due to its neuroprotective effects and remarkable survival-promoting activity in stem cells. However, pharmacokinetic properties of stemazole were unclear. In this study, a rapid and effective ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed to detect stemazole. The detector was operated in the positive-ion mode with an electrospray ionization (ESI) interface in multiple reaction monitoring (MRM) mode. Chromatographic separation was performed on an Acquity UPLC^® BEH C₁₈ column with gradient elution. Stemazole was extracted from plasma following a one-step protein precipitation method. The method was fully validated for its selectivity, specificity, and sensitivity. The calibration curve range of 5-1125 ng/mL showed good linearity for stemazole. Intra-day and inter-day precision rates were less than 10%, and accuracy ranged from 95.87% to 105.23%. The pharmacokinetic profiles were illustrated through the newly developed method for the first time. The absolute oral bioavailability of stemazole is 32.10%. Therefore, it is feasible as an oral medication, which greatly facilitates its broad application. The biological distribution of tritium-labeled stemazole in mice was studied, and the results showed that stemazole was absorbed rapidly and distributed widely, mainly in the liver and kidneys. A specific amount was also detected in the brain, which provides a prerequisite for the use of stemazole to treat neurodegenerative diseases. This work represents first description of the pharmacokinetics, bioavailability, and tissue distribution of stemazole and will lay the foundation for further investigation and drug development.

Comparison of phenotypic markers and neural differentiation potential of human bone marrow stromal cells from the cranial bone and iliac crest

Cellular therapies represent a new frontier in the treatment of neurological diseases. Accumulating evidence from preclinical studies of animal models suggests that mesenchymal stromal cells (MSCs), also known as mesenchymal stem cells, are an effective therapy for neurological diseases. In this study, we established human MSC lines from both cranial bone marrow (cBMMSCs) and iliac crest bone marrow (iBMMSCs) from the same donors and found that cBMMSCs show higher expression of neural crest-associated genes than iBMMSCs. Moreover, as observed in both mRNA and protein assays, neurogenic-induced cells from cBMMSCs expressed significantly higher levels of neural markers, such as NESTIN, SLUG, SOX9, and TWIST, than those from iBMMSCs. Thus, cBMMSCs showed a greater tendency than iBMMSCs to differentiate into neuron-like cells.

Stem Cell Transplantation and Physical Exercise in Parkinson's Disease, a Literature Review of Human and Animal Studies

The absence of effective and satisfactory treatments that contribute to repairing the dopaminergic damage caused by Parkinson's Disease (PD) and the limited recovery capacity of the nervous system are troubling issues and the focus of many research and clinical domains. Recent advances in the treatment of PD through stem cell (SC) therapy have recognized their promising restorative and neuroprotective effects that are implicated in the potentiation of endogenous mechanisms of repair and contribute to functional locomotor improvement. Physical exercise (PE) has been considered an adjuvant intervention that by itself induces beneficial effects in patients and animal models with Parkinsonism. In this sense, the combination of both therapies could provide synergic or superior effects for motor recovery, in contrast with their individual use. This review aims to provide an update on recent progress and the potential effectiveness of SC transplantation and PE for the treatment of locomotor deficits in PD. It has reviewed the neuropathological pathways involved in the classical motor symptoms of this condition and the mechanisms of action described in experimental studies that are associated with locomotor enhancement through exercise, cellular transplantation, and their union in some neurodegenerative conditions.

Secretome of Undifferentiated Neural Progenitor Cells Induces Histological and Motor Improvements in a Rat Model of Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder that results from the death of dopamine (DA) neurons. Over recent years, differentiated or undifferentiated neural stem cells (NSCs) transplantation has been widely used as a means of cell replacement therapy. However, compelling evidence has brought attention to the array of bioactive molecules produced by stem cells, defined as secretome. As described in the literature, other cell populations have a high‐neurotrophic activity, but little is known about NSCs. Moreover, the exploration of the stem cell secretome is only in its initial stages, particularly as applied to neurodegenerative diseases. Thus, we have characterized the secretome of human neural progenitor cells (hNPCs) through proteomic analysis and investigated its effects in a 6‐hydroxidopamine (6‐OHDA) rat model of PD in comparison with undifferentiated hNPCs transplantation. Results revealed that the injection of hNPCs secretome potentiated the histological recovery of DA neurons when compared to the untreated group 6‐OHDA and those transplanted with cells (hNPCs), thereby supporting the functional motor amelioration of 6‐OHDA PD animals. Additionally, hNPCs secretome proteomic characterization has revealed that these cells have the capacity to secrete a wide range of important molecules with neuroregulatory actions, which are most likely support the effects observed. Overall, we have concluded that the use of hNPCs secretome partially modulate DA neurons cell survival and ameliorate PD animals’ motor deficits, disclosing improved results when compared to cell transplantation approaches, indicating that the secretome itself could represent a route for new therapeutic options for PD regenerative medicine. stem cells translational medicine2018;7:829–838

The Efficacy of Graphene Foams for Culturing Mesenchymal Stem Cells and Their Differentiation into Dopaminergic Neurons

The implantation of stem cells in vivo is the ideal approach for the restoration of normal life functions, such as replenishing the decreasing levels of affected dopaminergic (DA) neurons during neurodegenerative disease conditions. However, combining stem cells with biomaterial scaffolds provides a promising strategy for engineering tissues or cellular delivery for directed stem cell differentiation as a means of replacing diseased/damaged tissues. In this study, mouse mesenchymal stem cells (MSCs) were differentiated into DA neurons using sonic hedgehog, fibroblast growth factor, basic fibroblast growth factor, and brain-derived neurotrophic factor, while they were cultured within collagen-coated 3D graphene foams (GF). The differentiation into DA neurons within the collagen-coated GF and controls (collagen gels, plastic) was confirmed using β-III tubulin, tyrosine hydroxylase (TH), and NeuN positive immunostaining. Enhanced expression of β-III tubulin, TH, and NeuN and an increase in the average neurite extension length were observed when cells were differentiated within collagen-coated GF in comparison with collagen gels. Furthermore, these graphene-based scaffolds were not cytotoxic as MSC seemed to retain viability and proliferated substantially during in vitro culture. In summary, these results suggest the utility of 3D graphene foams towards the differentiation of DA neurons from MSC, which is an important step for neural tissue engineering applications.

Intrastriatal transplantation of stem cells from human exfoliated deciduous teeth reduces motor defects in Parkinsonian rats

BACKGROUND

This study explored the neural differentiation and therapeutic effects of stem cells from human exfoliated deciduous teeth (SHED) in a rat model of Parkinson's disease (PD).

METHODS

The SHED were isolated from fresh dental pulp and were induced to differentiate to neurons and dopamine neurons by inhibiting similar mothers against dpp (SMAD) signaling with Noggin and increase conversion of dopamine neurons from SHED with CHIR99021, Sonic Hedgehog (SHH) and FGF8 in vitro. The neural-primed SHED were transplanted to the striatum of 6-hydroxydopamine (6-OHDA)-induced PD rats to evaluate their neural differentiation and functions in vivo.

RESULTS

These SHED were efficiently differentiated to neurons (62.7%) and dopamine neurons (42.3%) through a newly developed method. After transplantation, the neural-induced SHED significantly improved recovery of the motor deficits of the PD rats. The grafted SHED were differentiated into neurons (61%), including dopamine neurons (22.3%), and integrated into the host rat brain by forming synaptic connections. Patch clamp analysis showed that neurons derived from grafted SHED have the same membrane potential profile as dopamine neurons, indicating these cells are dopamine neuron-like cells. The potential molecular mechanism of SHED transplantation in alleviating motor deficits of the rats is likely to be mediated by neuronal replacement and immune-modulation as we detected the transplanted dopamine neurons and released immune cytokines from SHED.

CONCLUSION

Using neural-primed SHED to treat PD showed significant restorations of motor deficits in 6-OHDA-induced rats. These observations provide further evidence that SHED can be used for cell-based therapy of PD.

Generation of Human Neural Stem Cells by Direct Phenotypic Conversion

Human neural stem cells (hNSC) are multipotent adult stem cells. Various studies are underway worldwide to identify new methods for treatment of neurological diseases using hNSC. This chapter summarizes the latest research trends in and fields for application of patient-specific hNSC using direct phenotypic conversion technology. The aim of the study was to analyze the advantages and disadvantages of current technology and to suggest relevant directions for future hNSC research.

Assessing the Efficacy of Cell Transplantation for Parkinson's Disease: A Patient-Centered Approach

BACKGROUND

Evidence from a growing number of preclinical studies indicate that recently discovered stem cell lines may be translated into viable cellular therapies for people with Parkinson's disease.

OBJECTIVES

In a brief but critical review, we examine the use of primary and secondary outcome measures currently used to evaluate the efficacy of cellular therapies.

METHODS

The current practice of relying on a single primary outcome measure does not appear to provide the evidence required for demonstrating the robust, life-changing recovery anticipated with the successful implementation of cellular therapies.

RESULTS

We propose a 360-degree assessment protocol, which includes co-primary and composite outcome measures to provide accurate and comprehensive evidence of treatment efficacy, from the perspectives of both the researchers and the patients.

Current understanding of the molecular mechanisms in Parkinson's disease: Targets for potential treatments

Gradual degeneration and loss of dopaminergic neurons in the substantia nigra, pars compacta and subsequent reduction of dopamine levels in striatum are associated with motor deficits that characterize Parkinson’s disease (PD). In addition, half of the PD patients also exhibit frontostriatal-mediated executive dysfunction, including deficits in attention, short-term working memory, speed of mental processing, and impulsivity. The most commonly used treatments for PD are only partially or transiently effective and are available or applicable to a minority of patients. Because, these therapies neither restore the lost or degenerated dopaminergic neurons, nor prevent or delay the disease progression, the need for more effective therapeutics is critical. In this review, we provide a comprehensive overview of the current understanding of the molecular signaling pathways involved in PD, particularly within the context of how genetic and environmental factors contribute to the initiation and progression of this disease. The involvement of molecular chaperones, autophagy-lysosomal pathways, and proteasome systems in PD are also highlighted. In addition, emerging therapies, including pharmacological manipulations, surgical procedures, stem cell transplantation, gene therapy, as well as complementary, supportive and rehabilitation therapies to prevent or delay the progression of this complex disease are reviewed.

The epigenetic component of the brain response to electromagnetic stimulation in Parkinson's Disease patients: A literature overview

Modulations of epigenetic machinery, namely DNA methylation pattern, histone modification, and non-coding RNAs expression, have been recently included among the key determinants contributing to Parkinson's Disease (PD) aetiopathogenesis and response to therapy. Along this line of reasoning, a set of experimental findings are highlighting the epigenetic-based response to electromagnetic (EM) therapies used to alleviate PD symptomatology, mainly Deep Brain Stimulation (DBS) and Transcranial Magnetic Stimulation (TMS). Notwithstanding the proven efficacy of EM therapies, the precise molecular mechanisms underlying the brain response to these types of stimulations are still far from being elucidated. In this review we provide an overview of the epigenetic changes triggered by DBS and TMS in both PD patients and neurons from different experimental animal models. Furthermore, we also propose a critical overview of the exposure modalities currently applied, in order to evaluate the technical robustness and dosimetric control of the stimulation, which are key issues to be carefully assessed when new molecular findings emerge from experimental studies. Bioelectromagnetics. 39:3-14, 2018. © 2017 Wiley Periodicals, Inc.

Stem Cell Technology for (Epi)genetic Brain Disorders

Despite the enormous efforts of the scientific community over the years, effective therapeutics for many (epi)genetic brain disorders remain unidentified. The common and persistent failures to translate preclinical findings into clinical success are partially attributed to the limited efficiency of current disease models. Although animal and cellular models have substantially improved our knowledge of the pathological processes involved in these disorders, human brain research has generally been hampered by a lack of satisfactory humanized model systems. This, together with our incomplete knowledge of the multifactorial causes in the majority of these disorders, as well as a thorough understanding of associated (epi)genetic alterations, has been impeding progress in gaining more mechanistic insights from translational studies. Over the last years, however, stem cell technology has been offering an alternative approach to study and treat human brain disorders. Owing to this technology, we are now able to obtain a theoretically inexhaustible source of human neural cells and precursors in vitro that offer a platform for disease modeling and the establishment of therapeutic interventions. In addition to the potential to increase our general understanding of how (epi)genetic alterations contribute to the pathology of brain disorders, stem cells and derivatives allow for high-throughput drugs and toxicity testing, and provide a cell source for transplant therapies in regenerative medicine. In the current chapter, we will demonstrate the validity of human stem cell-based models and address the utility of other stem cell-based applications for several human brain disorders with multifactorial and (epi)genetic bases, including Parkinson's disease (PD), Alzheimer's disease (AD), fragile X syndrome (FXS), Angelman syndrome (AS), Prader-Willi syndrome (PWS), and Rett syndrome (RTT).

Ninety-day Local Tolerability and Toxicity Study of ND0612, a Novel Formulation of Levodopa/Carbidopa, Administered by Subcutaneous Continuous Infusion in Minipigs

A 90-day study in Göttingen minipigs was conducted to test the local tolerability and systemic toxicity of ND0612, a novel aqueous solution of carbidopa (CD)/levodopa (LD) intended for the treatment of Parkinson's disease by continuous subcutaneous administration using a discrete infusion pump. To evaluate tissue site reactions, we used a unique study design involving multiple infusion sites to evaluate the effect of dose per site (270/63, 360/45, and 360/84 mg LD/CD), volume of infusion per site (4.5 and 6 ml per site), formulation concentration (60/14 and 60/7.5 mg/ml LD/CD), daily rate of infusion per site (240 μl/hr for16 hr and 80 μl/hr for 8 hr, 320 μl/hr for 16 hr and 100 μl/hr for 8 hr, or 750 μl/hr for 8 hr), frequency (once every 5, 10, 15, or 20 days), and number of infusions (4, 6, or 9) to the same infusion site. No systemic adverse effects were observed. Histopathological changes at infusion sites started with localized minimal necrosis and acute inflammation that progressed to subacute and chronic inflammatory and reparative changes with evidence of progressive recovery following the final infusion. None of the infusion site effects were judged to be adverse, and clinical exposures to ND0612 are not expected to result in adverse responses.

Combining NT3-overexpressing MSCs and PLGA microcarriers for brain tissue engineering: A potential tool for treatment of Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder that characterized by destruction of substantia nigrostriatal pathway due to the loss of dopaminergic (DA) neurons. Regardless of substantial efforts for treatment of PD in recent years, an effective therapeutic strategy is still missing. In a multidisciplinary approach, bone marrow derived mesenchymal stem cells (BMSCs) are genetically engineered to overexpress neurotrophin-3 (nt-3 gene) that protect central nervous system tissues and stimulates neuronal-like differentiation of BMSCs. Poly(lactic-co-glycolic acid) (PLGA) microcarriers are designed as an injectable scaffold and synthesized via double emulsion method. The surface of PLGA microcarriers are functionalized by collagen as a bioadhesive agent for improved cell attachment. The results demonstrate effective overexpression of NT-3. The expression of tyrosine hydroxylase (TH) in transfected BMSCs reveal that NT-3 promotes the intracellular signaling pathway of DA neuron differentiation. It is also shown that transfected BMSCs are successfully attached to the surface of microcarriers. The presence of dopamine in peripheral media of cell/microcarrier complex reveals that BMSCs are successfully differentiated into dopaminergic neuron. Our approach that sustains presence of growth factor can be suggested as a novel complementary therapeutic strategy for treatment of Parkinson disease.

Stem cell therapies in age-related neurodegenerative diseases and stroke

Aging, a complex process associated with various structural, functional and metabolic changes in the brain, is an important risk factor for neurodegenerative diseases and stroke. These diseases share similar neuropathological changes, such as the formation of misfolded proteins, oxidative stress, loss of neurons and synapses, dysfunction of the neurovascular unit (NVU), reduction of self-repair capacity, and motor and/or cognitive deficiencies. In addition to gray matter dysfunction, the plasticity and repair capacity of white matter also decrease with aging and contribute to neurodegenerative diseases. Aging not only renders patients more susceptible to these disorders, but also attenuates their self-repair capabilities. In addition, low drug responsiveness and intolerable side effects are major challenges in the prevention and treatment of senile diseases. Thus, stem cell therapies-characterized by cellular plasticity and the ability to self-renew-may be a promising strategy for aging-related brain disorders. Here, we review the common pathophysiological changes, treatments, and the promises and limitations of stem cell therapies in age-related neurodegenerative diseases and stroke.

Therapeutic Potential of Induced Neural Stem Cells for Parkinson's Disease

Parkinson's disease (PD) is a chronic, neurodegenerative disorder that results from the loss of cells in the substantia nigra (SN) which is located in the midbrain. However, no cure is available for PD. Recently, fibroblasts have been directly converted into induced neural stem cells (iNSCs) via the forced expression of specific transcription factors. Therapeutic potential of iNSC in PD has not been investigated yet. Here, we show that iNSCs directly converted from mouse fibroblasts enhanced functional recovery in an animal model of PD. The rotational behavior test was performed to assess recovery. Our results indicate that iNSC transplantation into the striatum of 6-hydroxydopamine (6-OHDA)-injected mice can significantly reduce apomorphine-induced rotational asymmetry. The engrafted iNSCs were able to survive in the striatum and migrated around the medial forebrain bundle and the SN pars compacta. Moreover, iNSCs differentiated into all neuronal lineages. In particular, the transplanted iNSCs that committed to the glial lineage were significantly increased in the striatum of 6-OHDA-injected mice. Engrafted iNSCs differentiated to dopaminergic (DA) neurons and migrated into the SN in the 6-OHDA lesion mice. Therefore, iNSC transplantation serves as a valuable tool to enhance the functional recovery in PD.

Advances in Stem Cell Research- A Ray of Hope in Better Diagnosis and Prognosis in Neurodegenerative Diseases

Neurodegeneration and neurodegenerative disorders have been a global health issue affecting the aging population worldwide. Recent advances in stem cell biology have changed the current face of neurodegenerative disease modeling, diagnosis, and transplantation therapeutics. Stem cells also serve the purpose of a simple in-vitro tool for screening therapeutic drugs and chemicals. We present the application of stem cells and induced pluripotent stem cells (iPSCs) in the field of neurodegeneration and address the issues of diagnosis, modeling, and therapeutic transplantation strategies for the most prevalent neurodegenerative disorders. We have discussed the progress made in the last decade and have largely focused on the various applications of stem cells in the neurodegenerative research arena.

A Critical Evaluation of the Methodological Obstacles to Translating Cell-Based Research Into an Effective Treatment for People With Parkinson's Disease

The remarkable scientific and technological advances in the field of cell research have not been translated into viable restorative therapies for brain disorders. In this article, we examine the best available evidence for the clinical efficacy of reconstructive intracerebral transplantation in people with Parkinson's disease (PD), with the aim of identifying methodological obstacles to the translation process. The major stumbling block is the fact that the potential contributions of people with neural grafts and the effects of the physical and social environment in which they recover have not been adequately investigated and applied to advancing the clinical stages of the research program. We suggest that the biopsychosocial model along with emerging evidence of targeted rehabilitation can provide a useful framework for conducting research and evaluation that will ensure the best possible outcomes following intracerebral transplantation for PD.