Cell Therapy in Parkinson's Disease: Host Brain Repair Machinery Gets a Boost From Stem Cell Grafts

Probing Gut Participation in Parkinson's Disease Pathology and Treatment via Stem Cell Therapy

Accumulating evidence suggests the critical role of the gut-brain axis (GBA) in Parkinson's disease (PD) pathology and treatment. Recently, stem cell transplantation in transgenic PD mice further implicated the GBA's contribution to the therapeutic effects of transplanted stem cells. In particular, intravenous transplantation of human umbilical-cord-blood-derived stem/progenitor cells and plasma reduced motor deficits, improved nigral dopaminergic neuronal survival, and dampened α-synuclein and inflammatory-relevant microbiota and cytokines in both the gut and brain of mouse and rat PD models. That the gut robustly responded to intravenously transplanted stem cells and prompted us to examine in the present study whether direct cell implantation into the gut of transgenic PD mice would enhance the therapeutic effects of stem cells. Contrary to our hypothesis, results revealed that intragut transplantation of stem cells exacerbated motor and gut motility deficits that corresponded with the aggravated expression of inflammatory microbiota, cytokines, and α-synuclein in both the gut and brain of transgenic PD mice. These results suggest that, while the GBA stands as a major source of inflammation in PD, targeting the gut directly for stem cell transplantation may not improve, but may even worsen, functional outcomes, likely due to the invasive approach exacerbating the already inflamed gut. The minimally invasive intravenous transplantation, which likely avoided worsening the inflammatory response of the gut, appears to be a more optimal cell delivery route to ameliorate PD symptoms.

Neuroprotective Effects of the Neural-Induced Adipose-Derived Stem Cell Secretome against Rotenone-Induced Mitochondrial and Endoplasmic Reticulum Dysfunction

Mesenchymal stem cells (MSCs) have therapeutic effects on neurodegenerative diseases (NDDs) known by their secreted molecules, referred to as the “secretome”. The mitochondrial complex I inhibitor, rotenone (ROT), reproduces α-synuclein (α-syn) aggregation seen in Parkinson’s disease (PD). In this present study, we examined the neuroprotective effects of the secretome from neural-induced human adipose tissue-derived stem cells (NI-ADSC-SM) during ROT toxicity in SH-SY5Y cells. Exposure to ROT significantly impaired the mitophagy by increased LRRK2, mitochondrial fission, and endoplasmic reticulum (ER) stress (ERS). ROT also increased the levels of calcium (Ca2+), VDAC, and GRP75, and decreased phosphorylated (p)-IP3R Ser1756/total (t)-IP3R1. However, NI-ADSC-SM treatment decreased Ca2+ levels along with LRRK2, insoluble ubiquitin, mitochondrial fission by halting p-DRP1 Ser616, ERS by reducing p-PERK Thr981, p-/t-IRE1α, p-SAPK, ATF4, and CHOP. In addition, NI-ADSC-SM restored the mitophagy, mitochondrial fusion, and tethering to the ER. These data suggest that NI-ADSC-SM decreases ROT-induced dysfunction in mitochondria and the ER, which subsequently stabilized tethering in mitochondria-associated membranes in SH-SY5Y cells.

Inflammatory gut as a pathologic and therapeutic target in Parkinson’s disease

Parkinson’s disease (PD) remains a significant unmet clinical need. Gut dysbiosis stands as a PD pathologic source and therapeutic target. Here, we assessed the role of the gut-brain axis in PD pathology and treatment. Adult transgenic (Tg) α-synuclein-overexpressing mice served as subjects and were randomly assigned to either transplantation of vehicle or human umbilical cord blood-derived stem cells and plasma. Behavioral and immunohistochemical assays evaluated the functional outcomes following transplantation. Tg mice displayed typical motor and gut motility deficits, elevated α-synuclein levels, and dopaminergic depletion, accompanied by gut dysbiosis characterized by upregulation of microbiota and cytokines associated with inflammation in the gut and the brain. In contrast, transplanted Tg mice displayed amelioration of motor deficits, improved sparing of nigral dopaminergic neurons, and downregulation of α-synuclein and inflammatory-relevant microbiota and cytokines in both gut and brain. Parallel in vitro studies revealed that cultured dopaminergic SH-SY5Y cells exposed to homogenates of Tg mouse-derived dysbiotic gut exhibited significantly reduced cell viability and elevated inflammatory signals compared to wild-type mouse-derived gut homogenates. Moreover, treatment with human umbilical cord blood-derived stem cells and plasma improved cell viability and decreased inflammation in dysbiotic gut-exposed SH-SY5Y cells. Intravenous transplantation of human umbilical cord blood-derived stem/progenitor cells and plasma reduced inflammatory microbiota and cytokine, and dampened α-synuclein overload in the gut and the brain of adult α-synuclein-overexpressing Tg mice. Our findings advance the gut-brain axis as a key pathological origin, as well as a robust therapeutic target for PD.

Gut-Brain Axis as a PD Pathologic Source and Therapeutic Target. The PD murine model of α-synuclein overexpression at around 8 weeks of age manifests gut dysbiosis, characterized by inflammation-specific microbiota and cytokines, which can trigger brain neurodegeneration, especially dopaminergic depletion reminiscent of PD pathology. Targeting the dysbiotic gut via intravenous hUCB stem cell transplantation can render gut homeostasis and sequester peripheral as well as central inflammation, leading to brain repair and amelioration of PD behavioral and histological deficits.

Combination of Stem Cells and Rehabilitation Therapies for Ischemic Stroke

Stem cell transplantation with rehabilitation therapy presents an effective stroke treatment. Here, we discuss current breakthroughs in stem cell research along with rehabilitation strategies that may have a synergistic outcome when combined together after stroke. Indeed, stem cell transplantation offers a promising new approach and may add to current rehabilitation therapies. By reviewing the pathophysiology of stroke and the mechanisms by which stem cells and rehabilitation attenuate this inflammatory process, we hypothesize that a combined therapy will provide better functional outcomes for patients. Using current preclinical data, we explore the prominent types of stem cells, the existing theories for stem cell repair, rehabilitation treatments inside the brain, rehabilitation modalities outside the brain, and evidence pertaining to the benefits of combined therapy. In this review article, we assess the advantages and disadvantages of using stem cell transplantation with rehabilitation to mitigate the devastating effects of stroke.

Stem Cells for Aging-Related Disorders

This review captures recent advances in biological and translational research on stem cells. In particular, we discuss new discoveries and concepts regarding stem cell treatment of aging-related disorders. A myriad of stem cell sources exists, from hematopoietic to mesenchymal and neural cell lineages. We examine current applications of exogenous adult bone marrow-derived stem cells as an effective and safe transplantable cell source, as well as the use of electrical stimulation to promote endogenous neurogenesis for Parkinson's disease. We also explore the potential of transplanting exogenous umbilical cord blood cells and mobilizing host resident stem cells in vascular dementia and aging. In addition, we assess the ability of small molecules to recruit resident stem cells in Alzheimer's disease. Finally, we evaluate mechanisms of action recently implicated in stem cell therapy, such as the role of long non-coding RNAs, G-protein coupled receptor 5, and NeuroD1. Our goal is to provide a synopsis of recent milestones regarding the application of stem cells in aging.

Induced neural stem cells from human patient-derived fibroblasts attenuate neurodegeneration in Niemann-Pick type C mice

Background

Niemann-Pick disease type C (NPC) is caused by the mutation of NPC genes, which leads to the abnormal accumulation of unesterified cholesterol and glycolipids in lysosomes. This autosomal recessive disease is characterized by liver dysfunction, hepatosplenomegaly, and progressive neurodegeneration. Recently, the application of induced neural stem cells (iNSCs), converted from fibroblasts using specific transcription factors, to repair degenerated lesions has been considered a novel therapy.

Objectives

The therapeutic effects on NPC by human iNSCs generated by our research group have not yet been studied in vivo; in this study, we investigate those effects.

Methods

We used an NPC mouse model to efficiently evaluate the therapeutic effect of iNSCs, because neurodegeneration progress is rapid in NPC. In addition, application of human iNSCs from NPC patient-derived fibroblasts in an NPC model in vivo can give insight into the clinical usefulness of iNSC treatment. The iNSCs, generated from NPC patient-derived fibroblasts using the SOX2 and HMGA2 reprogramming factors, were transplanted by intracerebral injection into NPC mice.

Results

Transplantation of iNSCs showed positive results in survival and body weight change in vivo. Additionally, iNSC-treated mice showed improved learning and memory in behavior test results. Furthermore, through magnetic resonance imaging and histopathological assessments, we observed delayed neurodegeneration in NPC mouse brains.

Conclusions

iNSCs converted from patient-derived fibroblasts can become another choice of treatment for neurodegenerative diseases such as NPC.

Role of IL-6 in the regulation of neuronal development, survival and function

The pleiotropic cytokine interleukin-6 (IL-6) is emerging as a molecule with both beneficial and destructive potentials. It can exert opposing actions triggering either neuron survival after injury or causing neurodegeneration and cell death in neurodegenerative or neuropathic disorders. Importantly, neurons respond differently to IL-6 and this critically depends on their environment and whether they are located in the peripheral or the central nervous system. In addition to its hub regulator role in inflammation, IL-6 is recently emerging as an important regulator of neuron function in health and disease, offering exciting possibilities for more mechanistic insight into the pathogenesis of mental, neurodegenerative and pain disorders and for developing novel therapies for diseases with neuroimmune and neurogenic pathogenic components.

Applying hiPSCs and Biomaterials Towards an Understanding and Treatment of Traumatic Brain Injury

Traumatic brain injury (TBI) is the leading cause of disability and mortality in children and young adults and has a profound impact on the socio-economic wellbeing of patients and their families. Initially, brain damage is caused by mechanical stress-induced axonal injury and vascular dysfunction, which can include hemorrhage, blood-brain barrier disruption, and ischemia. Subsequent neuronal degeneration, chronic inflammation, demyelination, oxidative stress, and the spread of excitotoxicity can further aggravate disease pathology. Thus, TBI treatment requires prompt intervention to protect against neuronal and vascular degeneration. Rapid advances in the field of stem cells (SCs) have revolutionized the prospect of repairing brain function following TBI. However, more than that, SCs can contribute substantially to our knowledge of this multifaced pathology. Research, based on human induced pluripotent SCs (hiPSCs) can help decode the molecular pathways of degeneration and recovery of neuronal and glial function, which makes these cells valuable tools for drug screening. Additionally, experimental approaches that include hiPSC-derived engineered tissues (brain organoids and bio-printed constructs) and biomaterials represent a step forward for the field of regenerative medicine since they provide a more suitable microenvironment that enhances cell survival and grafting success. In this review, we highlight the important role of hiPSCs in better understanding the molecular pathways of TBI-related pathology and in developing novel therapeutic approaches, building on where we are at present. We summarize some of the most relevant findings for regenerative therapies using biomaterials and outline key challenges for TBI treatments that remain to be addressed.

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.

Gutting the brain of inflammation: A key role of gut microbiome in human umbilical cord blood plasma therapy in Parkinson's disease model

Current therapies for Parkinson's disease (PD), including L‐3,4‐dihydroxyphenylalanine (L‐DOPA), and clinical trials investigating dopaminergic cell transplants, have generated mixed results with the eventual induction of dyskinetic side effects. Although human umbilical cord blood (hUCB) stem/progenitor cells present with no or minimal capacity of differentiation into mature dopaminergic neurons, their transplantation significantly attenuates parkinsonian symptoms likely via bystander effects, specifically stem cell graft‐mediated secretion of growth factors, anti‐inflammatory cytokines, or synaptic function altogether promoting brain repair. Recognizing this non‐cell replacement mechanism, we examined here the effects of intravenously transplanted combination of hUCB‐derived plasma into the 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP)‐induced rat model of PD. Animals received repeated dosing of either hUCB‐derived plasma or vehicle at 3, 5 and 10 days after induction into MPTP lesion, then behaviourally and immunohistochemically evaluated over 56 days post‐lesion. Compared to vehicle treatment, transplantation with hUCB‐derived plasma significantly improved motor function, gut motility and dopaminergic neuronal survival in the substantia nigra pars compacta (SNpc), which coincided with reduced pro‐inflammatory cytokines in both the SNpc and the intestinal mucosa and dampened inflammation‐associated gut microbiota. These novel data directly implicate a key pathological crosstalk between gut and brain ushering a new avenue of therapeutically targeting the gut microbiome with hUCB‐derived stem cells and plasma for PD.

Novel Targets for Parkinson's Disease: Addressing Different Therapeutic Paradigms and Conundrums

Parkinson's disease (PD) is a neurodegenerative disease that is pathologically characterized by degeneration of dopamine neurons in the substantia nigra pars compacta (SNpc). PD leads to clinical motor features that include rigidity, tremor, and bradykinesia. Despite multiple available therapies for PD, the clinical features continue to progress, and patients suffer progressive disability. Many advances have been made in PD therapy which directly target the cause of the disease rather than providing symptomatic relief. A neuroprotective or disease modifying strategy that can slow or cease clinical progression and worsening disability remains as a major unmet medical need for PD management. The present review discusses potential novel therapies for PD that include recent interventions in the form of immunomodulatory techniques and stem cell therapy. Further, an introspective approach to identify numerous other novel targets that can alleviate PD pathogenesis and enable physicians to practice multitargeted therapy and that may provide a ray of hope to PD patients in the future are discussed.

Soluble epoxide hydrolase plays a key role in the pathogenesis of Parkinson's disease

Parkinson's disease (PD) is characterized as a chronic and progressive neurodegenerative disorder, and the deposition of specific protein aggregates of α-synuclein, termed Lewy bodies, is evident in multiple brain regions of PD patients. Although there are several available medications to treat PD symptoms, these medications do not prevent the progression of the disease. Soluble epoxide hydrolase (sEH) plays a key role in inflammation associated with the pathogenesis of PD. Here we found that MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)-induced neurotoxicity in the mouse striatum was attenuated by subsequent repeated administration of TPPU, a potent sEH inhibitor. Furthermore, deletion of the sEH gene protected against MPTP-induced neurotoxicity, while overexpression of sEH in the striatum significantly enhanced MPTP-induced neurotoxicity. Moreover, the expression of the sEH protein in the striatum from MPTP-treated mice or postmortem brain samples from patients with dementia of Lewy bodies (DLB) was significantly higher compared with control groups. Interestingly, there was a positive correlation between sEH expression and phosphorylation of α-synuclein in the striatum. Oxylipin analysis showed decreased levels of 8,9-epoxy-5Z,11Z,14Z-eicosatrienoic acid in the striatum of MPTP-treated mice, suggesting increased activity of sEH in this region. Interestingly, the expression of sEH mRNA in human PARK2 iPSC-derived neurons was higher than that of healthy control. Treatment with TPPU protected against apoptosis in human PARK2 iPSC-derived dopaminergic neurons. These findings suggest that increased activity of sEH in the striatum plays a key role in the pathogenesis of neurodegenerative disorders such as PD and DLB. Therefore, sEH may represent a promising therapeutic target for α-synuclein-related neurodegenerative disorders.

Stem Cell Therapy: Repurposing Cell-Based Regenerative Medicine Beyond Cell Replacement

Stem cells exhibit simple and naive cellular features, yet their exact purpose for regenerative medicine continues to elude even the most elegantly designed research paradigms from developmental biology to clinical therapeutics. Based on their capacity to divide indefinitely and their dynamic differentiation into any type of tissue, the advent of transplantable stem cells has offered a potential treatment for aging-related and injury-mediated diseases. Recent laboratory evidence has demonstrated that transplanted human neural stem cells facilitate endogenous reparative mechanisms by initiating multiple regenerative processes in the brain neurogenic areas. Within these highly proliferative niches reside a myriad of potent regenerative molecules, including anti-inflammatory cytokines, proteomes, and neurotrophic factors, altogether representing a biochemical cocktail vital for restoring brain function in the aging and diseased brain. Here, we advance the concept of therapeutically repurposing stem cells not towards cell replacement per se, but rather exploiting the cells' intrinsic properties to serve as the host brain regenerative catalysts.