Extensive neuroprotection by choroid plexus transplants in excitotoxin lesioned monkeys

Single nuclei RNA-seq reveals a medium spiny neuron glutamate excitotoxicity signature prior to the onset of neuronal death in an ovine Huntington's disease model

Huntington's disease (HD) is a neurodegenerative genetic disorder caused by an expansion in the CAG repeat tract of the huntingtin (HTT) gene resulting in behavioural, cognitive, and motor defects. Current knowledge of disease pathogenesis remains incomplete, and no disease course-modifying interventions are in clinical use. We have previously reported the development and characterisation of the OVT73 transgenic sheep model of HD. The 73 polyglutamine repeat is somatically stable and therefore likely captures a prodromal phase of the disease with an absence of motor symptomatology even at 5-years of age and no detectable striatal cell loss. To better understand the disease-initiating events we have undertaken a single nuclei transcriptome study of the striatum of an extensively studied cohort of 5-year-old OVT73 HD sheep and age matched wild-type controls. We have identified transcriptional upregulation of genes encoding N-methyl-D-aspartate (NMDA), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainate receptors in medium spiny neurons, the cell type preferentially lost early in HD. Further, we observed an upregulation of astrocytic glutamate uptake transporters and medium spiny neuron GABAA receptors, which may maintain glutamate homeostasis. Taken together, these observations support the glutamate excitotoxicity hypothesis as an early neurodegeneration cascade-initiating process but the threshold of toxicity may be regulated by several protective mechanisms. Addressing this biochemical defect early may prevent neuronal loss and avoid the more complex secondary consequences precipitated by cell death.

Rodent Models of Huntington's Disease: An Overview

Huntington's disease (HD) is an autosomal-dominant inherited neurological disorder caused by a genetic mutation in the IT15 gene. This neurodegenerative disorder is caused by a polyglutamine repeat expansion mutation in the widely expressed huntingtin (HTT) protein. HD is characterized by the degeneration of basal ganglia neurons and progressive cell death in intrinsic neurons of the striatum, accompanied by dementia and involuntary abnormal choreiform movements. Animal models have been extensively studied and have proven to be extremely valuable for therapeutic target evaluations. They reveal the hallmark of the age-dependent formation of aggregates or inclusions consisting of misfolded proteins. Animal models of HD have provided a therapeutic strategy to treat HD by suppressing mutant HTT (mHTT). Transgenic animal models have significantly increased our understanding of the molecular processes and pathophysiological mechanisms underlying the HD behavioral phenotype. Since effective therapies to cure or interrupt the course of the disease are not yet available, clinical research will have to make use of reliable animal models. This paper reviews the main studies of rodents as HD animal models, highlighting the neurological and behavioral differences between them. The choice of an animal model depends on the specific aspect of the disease to be investigated. Toxin-based models can still be useful, but most experimental hypotheses depend on success in a genetic model, whose choice is determined by the experimental question. There are many animal models showing similar HD symptoms or pathologies. They include chemical-induced HDs and genetic HDs, where cell-free and cell culture, lower organisms (such as yeast, Drosophila, C. elegans, zebrafish), rodents (mice, rats), and non-human primates are involved. These models provide accessible systems to study molecular pathogenesis and test potential treatments. For developing more effective pharmacological treatments, better animal models must be available and used to evaluate the efficacy of drugs.

From Pathogenesis to Therapeutics: A Review of 150 Years of Huntington's Disease Research

Huntington's disease (HD) is a debilitating neurodegenerative genetic disorder caused by an expanded polyglutamine-coding (CAG) trinucleotide repeat in the huntingtin (HTT) gene. HD behaves as a highly penetrant dominant disorder likely acting through a toxic gain of function by the mutant huntingtin protein. Widespread cellular degeneration of the medium spiny neurons of the caudate nucleus and putamen are responsible for the onset of symptomology that encompasses motor, cognitive, and behavioural abnormalities. Over the past 150 years of HD research since George Huntington published his description, a plethora of pathogenic mechanisms have been proposed with key themes including excitotoxicity, dopaminergic imbalance, mitochondrial dysfunction, metabolic defects, disruption of proteostasis, transcriptional dysregulation, and neuroinflammation. Despite the identification and characterisation of the causative gene and mutation and significant advances in our understanding of the cellular pathology in recent years, a disease-modifying intervention has not yet been clinically approved. This review includes an overview of Huntington's disease, from its genetic aetiology to clinical presentation and its pathogenic manifestation. An updated view of molecular mechanisms and the latest therapeutic developments will also be discussed.

Cell Encapsulation and 3D Bioprinting for Therapeutic Cell Transplantation

The promise of cell therapy has been augmented by introducing biomaterials, where intricate scaffold shapes are fabricated to accommodate the cells within. In this review, we first discuss cell encapsulation and the promising potential of biomaterials to overcome challenges associated with cell therapy, particularly cellular function and longevity. More specifically, cell therapies in the context of autoimmune disorders, neurodegenerative diseases, and cancer are reviewed from the perspectives of preclinical findings as well as available clinical data. Next, techniques to fabricate cell-biomaterials constructs, focusing on emerging 3D bioprinting technologies, will be reviewed. 3D bioprinting is an advancing field that enables fabricating complex, interconnected, and consistent cell-based constructs capable of scaling up highly reproducible cell-biomaterials platforms with high precision. It is expected that 3D bioprinting devices will expand and become more precise, scalable, and appropriate for clinical manufacturing. Rather than one printer fits all, seeing more application-specific printer types, such as a bioprinter for bone tissue fabrication, which would be different from a bioprinter for skin tissue fabrication, is anticipated in the future.

Development of the brain ventricular system from a comparative perspective

The brain ventricular system (BVS) consists of brain ventricles and channels filled with cerebrospinal fluid (CSF). Disturbance of CSF flow has been linked to scoliosis and neurodegenerative diseases, including hydrocephalus. This could be due to defects of CSF production by the choroid plexus or impaired CSF movement over the ependyma dependent on motile cilia. Most vertebrates have horizontal body posture. They retain additional evolutionary innovations assisting CSF flow, such as the Reissner fiber. The causes of hydrocephalus have been studied using animal models including rodents (mice, rats, hamsters) and zebrafish. However, the horizontal body posture reduces the effect of gravity on CSF flow, which limits the use of mammalian models for scoliosis. In contrast, fish swim against the current and experience a forward-to-backward mechanical force akin to that caused by gravity in humans. This explains the increased popularity of the zebrafish model for studies of scoliosis. "Slit-ventricle" syndrome is another side of the spectrum of BVS anomalies. It develops because of insufficient inflation of the BVS. Recent advances in zebrafish functional genetics have revealed genes that could regulate the development of the BVS and CSF circulation. This review will describe the BVS of zebrafish, a typical teleost, and vertebrates in general, in comparative perspective. It will illustrate the usefulness of the zebrafish model for developmental studies of the choroid plexus (CP), CSF flow and the BVS.

Characterization of TRPV4-mediated signaling pathways in an optimized human choroid plexus epithelial cell line

The objectives of these studies were twofold: 1) to characterize the human choroid plexus papilloma (HIBCPP) cell line as a model of the blood-cerebrospinal fluid barrier (BCSFB) via morphology, tightness, and polarization of transporters in choroid plexus epithelia (CPe), and 2) to utilize Ussing-style electrophysiology to elucidate signaling pathways associated with the activation of the transient receptor potential vanilloid 4 (TRPV4) channel involved in cerebrospinal fluid (CSF) secretion. RT-PCR was implemented to determine gene expression of cell fate markers, junctional complex proteins, and transporters of interest. Scanning electron microscopy and confocal three-dimensional renderings of cultures grown on permeable supports were utilized to delineate the morphology of the brush border, junctional complexes, and polarization of key transporters. Electrophysiology was used to understand and explore TRPV4-mediated signaling in the HIBCPP cell line, considering both short-circuit current (Isc) and conductance responses. HIBCPP cells grown under optimized culture conditions exhibited minimal multilayering, developed an intermediate resistance monolayer, retained differentiation properties, and expressed, and correctly localized, junctional proteins and native transporters. We found that activation of TRPV4 resulted in a robust, multiphasic change in electrogenic ion flux and increase in conductance accompanied by substantial fluid secretion. This response appears to be modulated by a number of different effectors, implicating phospholipase C (PLC), protein kinase C (PKC), and phosphoinositide 3-kinase (PI3K) in TRPV4-mediated ion flux. The HIBCPP cell line is a representative model of the human BCSFB, which can be utilized for studies of transporter function, intracellular signaling, and regulation of CSF production.

Experimental approaches for manipulating choroid plexus epithelial cells

Choroid plexus (ChP) epithelial cells are crucial for the function of the blood-cerebrospinal fluid barrier (BCSFB) in the developing and mature brain. The ChP is considered the primary source and regulator of CSF, secreting many important factors that nourish the brain. It also performs CSF clearance functions including removing Amyloid beta and potassium. As such, the ChP is a promising target for gene and drug therapy for neurodevelopmental and neurological disorders in the central nervous system (CNS). This review describes the current successful and emerging experimental approaches for targeting ChP epithelial cells. We highlight methodological strategies to specifically target these cells for gain or loss of function in vivo. We cover both genetic models and viral gene delivery systems. Additionally, several lines of reporters to access the ChP epithelia are reviewed. Finally, we discuss exciting new approaches, such as chemical activation and transplantation of engineered ChP epithelial cells. We elaborate on fundamental functions of the ChP in secretion and clearance and outline experimental approaches paving the way to clinical applications.

Neuroinflammation in Huntington's Disease: A Starring Role for Astrocyte and Microglia

Huntington's disease (HD) is a neurodegenerative genetic disorder caused by a CAG repeat expansion in the huntingtin gene. HD causes motor, cognitive, and behavioral dysfunction. Since no existing treatment affects the course of this disease, new treatments are needed. Inflammation is frequently observed in HD patients before symptom onset. Neuroinflammation, characterized by the presence of reactive microglia, astrocytes and inflammatory factors within the brain, is also detected early. However, in comparison to other neurodegenerative diseases, the role of neuroinflammation in HD is much less known. Work has been dedicated to altered microglial and astrocytic functions in the context of HD, but less attention has been given to glial participation in neuroinflammation. This review describes evidence of inflammation in HD patients and animal models. It also discusses recent knowledge on neuroinflammation in HD, highlighting astrocyte and microglia involvement in the disease and considering anti-inflammatory therapeutic approaches.

Mesenchymal Stem Cell-Induced Anti-Neuroinflammation Against Traumatic Brain Injury

Traumatic brain injury (TBI) is a pervasive and damaging form of acquired brain injury (ABI). Acute, subacute, and chronic cell death processes, as a result of TBI, contribute to the disease progression and exacerbate outcomes. Extended neuroinflammation can worsen secondary degradation of brain function and structure. Mesenchymal stem cell transplantation has surfaced as a viable approach as a TBI therapeutic due to its immunomodulatory and regenerative features. This article examines the role of inflammation and cell death in ABI as well as the effectiveness of bone marrow-derived mesenchymal stem/stromal cell (BM-MSC) transplants as a treatment for TBI. Furthermore, we analyze new studies featuring transplanted BM-MSCs as a neurorestorative and anti-inflammatory therapy for TBI patients. Although clinical trials support BM-MSC transplants as a viable TBI treatment due to their promising regenerative characteristics, further investigation is imperative to uncover innovative brain repair pathways associated with cell-based therapy as stand-alone or as combination treatments.

Energy Metabolism Analysis of Three Different Mesenchymal Stem Cell Populations of Umbilical Cord Under Normal and Pathologic Conditions

Human umbilical cord mesenchymal stem cells (hUC-MSCs) are a pivotal source of therapeutically active cells for regenerative medicine due to their multipotent differentiation potential, immunomodulatory and anti-inflammatory proprieties, as well as logistical collection advantages without ethical concerns. However, it remains poorly understood whether MSCs from different compartments of the human umbilical cord are therapeutically superior than others. In this study, MSCs were isolated from Wharton’s jelly (WJ-MSCs), perivascular region (PV-MSCs) and cord lining (CL-MSCs) of hUC. These cells expressed the mesenchymal markers (CD90, CD73), stemness marker (OCT4), endothelial cell adhesion molecular marker (CD146), and the monocyte/macrophage marker (CD14) found within the MSC population implicated as a key regulator of inflammatory responses to hypoxia, was displayed by WJ-, PV-, and CL-MSCs respectively. A direct consequence of oxygen and glucose deprivation during stroke and reperfusion is impaired mitochondrial function that contributes to cellular death. Emerging findings of mitochondria transfer provide the basis for the replenishment of healthy mitochondria as a strategy for the treatment of stroke. Cell Energy Phenotype and Mito Stress tests were performed the energy metabolic profile of the three MSC populations and their mitochondrial function in both ambient and OGD cell culture conditions. PV-MSCs showed the highest mitochondrial activity. CL-MSCs were the least affected by OGD/R condition, suggesting their robust survival in ischemic environment. In this study, MSC populations in UC possess comparable metabolic capacities and good survival under normal and hypoxic conditions suggesting their potential as transplantable cells for mitochondrial-based stem cell therapy in stroke and other ischemic diseases.

Mitochondrial activity of human umbilical cord mesenchymal stem cells

Human umbilical cord mesenchymal stem cells (hUC-MSCs) serve as a potential cell-based therapy for degenerative disease. They provide immunomodulatory and anti-inflammatory properties, multipotent differentiation potential and are harvested with no ethical concern. It is unknown whether MSCs collected from different areas of the human umbilical cord elicit more favorable effects than others. Three MSC populations were harvested from various regions of the human umbilical cord: cord lining (CL-MSCs), perivascular region (PV-MSCs), and Wharton's jelly (WJ-MSCs). Mesenchymal markers (CD90 and CD73) were expressed by all three cell populations. Stemness marker (OCT4), endothelial cell adhesion molecular marker (CD146), and monocyte-macrophage marker (CD14) were expressed by WJ-MSCs, PV-MSCs, and CL-MSCs, respectively. Stroke presents with oxygen and glucose deprivation and leads to dysfunctional mitochondria and consequently cell death. Targeting the restoration of mitochondrial function in the stroke brain through mitochondrial transfer may be effective in treating stroke. In vitro exposure to ambient and OGD conditions resulted in CL-MSCs number decreasing the least post-OGD/R exposure, and PV-MSCs exhibiting the greatest mitochondrial activity. All three hUC-MSC populations presented similar metabolic activity and survival in normal and pathologic environments. These characteristics indicate hUC-MSCs potential as a potent therapeutic in regenerative medicine.

An Examination of Mobile Spinal Cord Stimulators on Treating Parkinson Disease

In animal models of Parkinson disease (PD), spinal cord stimulation (SCS) exhibits neuroprotective effects. Recent advancements in SCS technology, most importantly mobile stimulators, allow for the conventional limitations of SCS such as limited stimulation time and restricted animal movements to be bypassed, offering potential avenues for improved clinical translation to PD patients. Small devices that could deliver continuous SCS to freely moving parkinsonian rats were shown to significantly improve behavior, preserve neurons and fibers in the substantia Nigra/striatum, reduce microglia infiltration, and increase laminin-positive area of the cerebral cortex. Through possible anti-inflammatory and angiogenic mechanisms, it has been demonstrated that there are behavioral and histological benefits to continuous SCS in a time-dependent manner. This review will discuss the benefits of this technology as well as focus on the limitations of current animal models.

Long-Term Continuous Cervical Spinal Cord Stimulation Exerts Neuroprotective Effects in Experimental Parkinson's Disease

BACKGROUND

Spinal cord stimulation (SCS) exerts neuroprotective effects in animal models of Parkinson's disease (PD). Conventional stimulation techniques entail limited stimulation time and restricted movement of animals, warranting the need for optimizing the SCS regimen to address the progressive nature of the disease and to improve its clinical translation to PD patients.

OBJECTIVE

Recognizing the limitations of conventional stimulation, we now investigated the effects of continuous SCS in freely moving parkinsonian rats.

METHODS

We developed a small device that could deliver continuous SCS. At the start of the experiment, thirty female Sprague-Dawley rats received the dopamine (DA)-depleting neurotoxin, 6-hydroxydopamine, into the right striatum. The SCS device was fixed below the shoulder area of the back of the animal, and a line from this device was passed under the skin to an electrode that was then implanted epidurally over the dorsal column. The rats were divided into three groups: control, 8-h stimulation, and 24-h stimulation, and behaviorally tested then euthanized for immunohistochemical analysis.

RESULTS

The 8- and 24-h stimulation groups displayed significant behavioral improvement compared to the control group. Both SCS-stimulated groups exhibited significantly preserved tyrosine hydroxylase (TH)-positive fibers and neurons in the striatum and substantia nigra pars compacta (SNc), respectively, compared to the control group. Notably, the 24-h stimulation group showed significantly pronounced preservation of the striatal TH-positive fibers compared to the 8-h stimulation group. Moreover, the 24-h group demonstrated significantly reduced number of microglia in the striatum and SNc and increased laminin-positive area of the cerebral cortex compared to the control group.

CONCLUSIONS

This study demonstrated the behavioral and histological benefits of continuous SCS in a time-dependent manner in freely moving PD animals, possibly mediated by anti-inflammatory and angiogenic mechanisms.

Mesenchymal stem cell therapy alleviates the neuroinflammation associated with acquired brain injury

Ischemic stroke and traumatic brain injury (TBI) comprise two particularly prevalent and costly examples of acquired brain injury (ABI). Following stroke or TBI, primary cell death and secondary cell death closely model disease progression and worsen outcomes. Mounting evidence indicates that long‐term neuroinflammation extensively exacerbates the secondary deterioration of brain structure and function. Due to their immunomodulatory and regenerative properties, mesenchymal stem cell transplants have emerged as a promising approach to treating this facet of stroke and TBI pathology. In this review, we summarize the classification of cell death in ABI and discuss the prominent role of inflammation. We then consider the efficacy of bone marrow–derived mesenchymal stem/stromal cell (BM‐MSC) transplantation as a therapy for these injuries. Finally, we examine recent laboratory and clinical studies utilizing transplanted BM‐MSCs as antiinflammatory and neurorestorative treatments for stroke and TBI. Clinical trials of BM‐MSC transplants for stroke and TBI support their promising protective and regenerative properties. Future research is needed to allow for better comparison among trials and to elaborate on the emerging area of cell‐based combination treatments.

Organ Culture and Grafting of Choroid Plexus into the Ventricular CSF of Normal and Hydrocephalic HTx Rats

Choroid plexus (CP) may aid brain development and repair by secreting growth factors and neurotrophins for CSF streaming to ventricular and subventricular zones. Disrupted ventricular/subventricular zone progenitors and stem cells lead to CNS maldevelopment. Exploring models, we organ cultured the CP and transplanted fresh CP into a lateral ventricle of postnatal hydrocephalic (hyHTx) and nonhydrocephalic (nHTx) rats. After 60 days in vitro, the cultured choroid ependyma formed spherical rings with beating cilia. Cultured CP expressed endocytotic caveolin 1 and apical aquaporin 1 and absorbed horseradish peroxidase from medium. Transthyretin secretory protein was secreted by organ-cultured CP into medium throughout 60 days in vitro. Fresh CP, surviving at 1 week after lateral ventricle implantation of nHTx or hyHTx did not block CSF flow. Avascular 1-week transplants in vivo expressed caveolin 1, aquaporin 1, and transthyretin, indicating that grafted CP may secrete trophic proteins but not CSF. Our findings encourage further exploration on CP organ culture and grafting for translational strategies. Because transplanted CP, though not producing CSF, may secrete beneficial molecules for developing brain injured by hydrocephalus, we propose that upon CP removal in hydrocephalus surgery, the fractionated tissue could be transplanted back (ventricular autograft).

Altered secretory and neuroprotective function of the choroid plexus in progressive multiple sclerosis

The choroid plexus (CP) is a key regulator of the central nervous system (CNS) homeostasis through its secretory, immunological and barrier properties. Accumulating evidence suggests that the CP plays a pivotal role in the pathogenesis of multiple sclerosis (MS), but the underlying mechanisms remain largely elusive. To get a comprehensive view on the role of the CP in MS, we studied transcriptomic alterations of the human CP in progressive MS and non-neurological disease controls using RNA sequencing. We identified 17 genes with significantly higher expression in progressive MS patients relative to that in controls. Among them is the newly described long non-coding RNA HIF1A-AS3. Next to that, we uncovered disease-affected pathways related to hypoxia, secretion and neuroprotection, while only subtle immunological and no barrier alterations were observed. In an ex vivo CP explant model, a subset of the upregulated genes responded in a similar way to hypoxic conditions. Our results suggest a deregulation of the Hypoxia-Inducible Factor (HIF)-1 pathway in progressive MS CP. Importantly, cerebrospinal fluid levels of the hypoxia-responsive secreted peptide PAI-1 were higher in MS patients with high disability relative to those with low disability. These findings provide for the first time a complete overview of the CP transcriptome in health and disease, and suggest that the CP environment becomes hypoxic in progressive MS patients, highlighting the altered secretory and neuroprotective properties of the CP under neuropathological conditions. Together, these findings provide novel insights to target the CP and promote the secretion of neuroprotective factors into the CNS of progressive MS patients.

Culture Model for Non-human Primate Choroid Plexus

While there are murine and rat choroid plexus epithelial cell cultures, a translationally relevant model for choroid plexus activation and function is still lacking. The rhesus macaque is the gold standard for modeling viral infection and activation of CNS, including HIV-associated neurocognitive disorders. We have developed a rhesus macaque choroid plexus epithelial cell culture model which we believe to be suitable for studies of inflammation associated with viral infection of the CNS. Epithelial morphology and function were assessed using vimentin, phalloidin, the tight junction protein zonula-occludens-1 (ZO-1), and focal adhesion kinase (FAK). Choroid plexus epithelial cell type was confirmed using immunofluorescence with two proteins highly expressed in the choroid plexus: transthyretin and α-klotho. Finally, barrier properties of the model were monitored using pro- and anti-inflammatory mediators (TNF-α, the TLR2 agonist PamCys3K, and dexamethasone). When pro-inflammatory TNF-α was added to the xCelligence wells, there was a decrease in barrier function, which decreased in a step-wise fashion with each additional administration. This barrier function was repaired upon addition of the steroid dexamethasone. The TLR2 agonist PAM3CysK increased barrier functions in TNF-α treated wells. We have presented a model of the blood-CSF barrier that will allow study into pro- and anti-inflammatory conditions in the brain, while simultaneously measuring real time changes to epithelial cells.

Longitudinal characterization of cognitive and motor deficits in an excitotoxic lesion model of striatal dysfunction in non-human primates

As research progresses in the understanding of the molecular and cellular mechanisms underlying neurodegenerative diseases like Huntington's disease (HD) and expands towards preclinical work for the development of new therapies, highly relevant animal models are increasingly needed to test new hypotheses and to validate new therapeutic approaches. In this light, we characterized an excitotoxic lesion model of striatal dysfunction in non-human primates (NHPs) using cognitive and motor behaviour assessment as well as functional imaging and post-mortem anatomical analyses. NHPs received intra-striatal stereotaxic injections of quinolinic acid bilaterally in the caudate nucleus and unilaterally in the left sensorimotor putamen. Post-operative MRI scans showed atrophy of the caudate nucleus and a large ventricular enlargement in all 6 NHPs that correlated with post-mortem measurements. Behavioral analysis showed deficits in 2 analogues of the Wisconsin card sorting test (perseverative behavior) and in an executive task, while no deficits were observed in a visual recognition or an episodic memory task at 6 months following surgery. Spontaneous locomotor activity was decreased after lesion and the incidence of apomorphine-induced dyskinesias was significantly increased at 3 and 6 months following lesion. Positron emission tomography scans obtained at end-point showed a major deficit in glucose metabolism and D2 receptor density limited to the lesioned striatum of all NHPs compared to controls. Post-mortem analyses revealed a significant loss of medium-sized spiny neurons in the striatum, a loss of neurons and fibers in the globus pallidus, a unilateral decrease in dopaminergic neurons of the substantia nigra and a loss of neurons in the motor and dorsolateral prefrontal cortex. Overall, we show that this robust NHP model presents specific behavioral (learning, execution and retention of cognitive tests) and metabolic functional deficits that, to the best of our knowledge, are currently not mimicked in any available large animal model of striatal dysfunction. Moreover, we used non-invasive, translational techniques like behavior and imaging to quantify such deficits and found that they correlate to a significant cell loss in the striatum and its main input and output structures. This model can thus significantly contribute to the pre-clinical longitudinal evaluation of the ability of new therapeutic cell, gene or pharmacotherapy approaches in restoring the functionality of the striatal circuitry.

Stem cell therapy for neurological disorders: A focus on aging

Age-related neurological disorders continue to pose a significant societal and economic burden. Aging is a complex phenomenon that affects many aspects of the human body. Specifically, aging can have detrimental effects on the progression of brain diseases and endogenous stem cells. Stem cell therapies possess promising potential to mitigate the neurological symptoms of such diseases. However, aging presents a major obstacle for maximum efficacy of these treatments. In this review, we discuss current preclinical and clinical literature to highlight the interactions between aging, stem cell therapy, and the progression of major neurological disease states such as Parkinson's disease, Huntington's disease, stroke, traumatic brain injury, amyotrophic lateral sclerosis, multiple sclerosis, and multiple system atrophy. We raise important questions to guide future research and advance novel treatment options.

An update on intracerebral stem cell grafts

INTRODUCTION

Primary neurological disorders are notoriously debilitating and deadly, and over the past four decades stem cell therapy has emerged as a promising treatment. Translation of stem cell therapies from the bench to the clinic requires a better understanding of delivery protocols, safety profile, and efficacy in each disease. Areas covered: In this review, benefits and risks of intracerebral stem cell transplantation are presented for consideration. Milestone discoveries in stem cell applications are reviewed to examine the efficacy and safety of intracerebral stem cell transplant therapy for disorders of the central nervous system and inform design of translatable protocols for clinically feasible stem cell-based treatments. Expert commentary: Intracerebral administration, compared to peripheral delivery, is more invasive and carries the risk of open brain surgery. However, direct cell implantation bypasses the blood-brain barrier and reduces the first-pass effect, effectively increasing the therapeutic cell deposition at its intended site of action. These benefits must be weighed with the risk of graft-versus-host immune response. Rigorous clinical trials are underway to assess the safety and efficacy of intracerebral transplants, and if successful will lead to widely available stem cell therapies for neurologic diseases in the coming years.

Rutin as a Potent Antioxidant: Implications for Neurodegenerative Disorders

A wide range of neurodegenerative diseases (NDs), including Alzheimer's disease, Parkinson's disease, Huntington's disease, and prion diseases, share common mechanisms such as neuronal loss, apoptosis, mitochondrial dysfunction, oxidative stress, and inflammation. Intervention strategies using plant-derived bioactive compounds have been offered as a form of treatment for these debilitating conditions, as there are currently no remedies to prevent, reverse, or halt the progression of neuronal loss. Rutin, a glycoside of the flavonoid quercetin, is found in many plants and fruits, especially buckwheat, apricots, cherries, grapes, grapefruit, plums, and oranges. Pharmacological studies have reported the beneficial effects of rutin in many disease conditions, and its therapeutic potential in several models of NDs has created considerable excitement. Here, we have summarized the current knowledge on the neuroprotective mechanisms of rutin in various experimental models of NDs. The mechanisms of action reviewed in this article include reduction of proinflammatory cytokines, improved antioxidant enzyme activities, activation of the mitogen-activated protein kinase cascade, downregulation of mRNA expression of PD-linked and proapoptotic genes, upregulation of the ion transport and antiapoptotic genes, and restoration of the activities of mitochondrial complex enzymes. Taken together, these findings suggest that rutin may be a promising neuroprotective compound for the treatment of NDs.

Nonhuman Primate Models of Huntington's Disease and Their Application in Translational Research

Huntington's disease (HD) is a monogenic, autosomal dominant inherited fatal disease that affects 1 in 10,000 people worldwide. Given its unique genetic characteristics, HD would appear as one of the most straightforward neurodegenerative diseases to replicate in animal models. Indeed, mutations in the HTT gene have been used to generate a variety of animal models that display differential pathologies and have significantly increased our understanding of the pathological mechanisms of HD. However, decades of efforts have also shown the complexity of recapitulating the human condition in other species. Here we describe the three different types of models that have been generated in nonhuman primate species, stating their advantages and limitations and attempt to give a critical perspective of their translational value to test the efficacy of novel therapeutic strategies. Obtaining construct, phenotypic, and predictive validity has proven to be challenging in most animal models of human diseases. In HD in particular, it is hard to assess the predictive validity of a new therapeutic strategy when no effective "benchmark" treatment is available in the clinic. In this light, only phenotypic/face validity and construct validity are discussed.

Transplants of Encapsulated Rat Choroid Plexus Cells Exert Neuroprotection in a Rodent Model of Huntington's Disease

Choroid plexus (CP) epithelial cells secrete several neurotrophic factors and have been used in transplantation studies designed to impart neuroprotection against central nervous system (CNS) trauma. In the present study, CP was isolated from adult rats, encapsulated within alginate microcapsules, and transplanted unilaterally into the rat striatum. Three days later, unilateral injections of quinolinic acid (QA; 225 nmol) were made into the ipsilateral striatum to mimic the pathology observed in Huntington's disease (HD). After surgery, animals were tested for motor function using the placement test. Rats receiving CP transplants were significantly less impaired on this test. Nissl-stained sections demonstrated that CP transplants significantly reduced the volume of the striatal lesion produced by QA. Quantitative analysis of striatal neurons further demonstrated that choline acetyltransferase-immunoreactive, but not diaphorase-positive, neurons were protected by CP transplants. These data demonstrate that transplanted CP cells can be used to protect striatal neurons from excitotoxic damage and that the pattern of neuroprotection varies across specific neuronal populations.

In Vitro Culture Duration does Not Impact the Ability of Encapsulated Choroid Plexus Transplants to Prevent Neurological Deficits in an Excitotoxin-Lesioned Rat Model of Huntington's Disease

Delivery of neurotrophic molecules to the CNS is a potential treatment strategy for preventing the neuronal loss accompanying many neurological disorders. Choroid plexus (CP) epithelial cells secrete a cocktail of neurotrophic factors, and encapsulated CP transplants are neuroprotective in animal models of stroke and Huntington's disease (HD). Prior to clinical use, it is essential to identify and optimize parameters such as the length of time that transplant products such as encapsulated CP can be maintained. In the present study, neonatal porcine CP was encapsulated within alginate microcapsules and maintained in vitro for 1, 2, or 7 months. The encapsulated cells remained viable (>80%) at all time points and were transplanted unilaterally into the rat striatum. Seven days later, the same animals received unilateral injections of quinolinic acid (QA; 225 nmol) adjacent to the implant site. Separate groups of animals served as controls and received QA alone. After surgery, animals were periodically evaluated for weight loss and were tested for motor function 14 days post-QA. In controls, QA lesions produced a significant loss of body weight and impaired function of the contralateral forelimb. In contrast, implants of CP were potently neuroprotective as rats receiving CP transplants did not lose body weight and were not significantly impaired when tested for motor function. These benefits were independent of the length of time that the cells were held in vitro and demonstrate that the potential potency of alginate encapsulated CP cells can be retained for extremely long periods of time in vitro.

In Vitro Exposure of Cultured Porcine Choroid Plexus Epithelial Cells to Immunosuppressant, Anti-Inflammatory, and Psychoactive Drugs

Delivery of neurotrophic molecules to the CNS is a potential treatment for preventing the neuronal loss in neurological disorders such as Huntington's disease (HD). Choroid plexus (CP) epithelial cell transplants secrete several neurotrophic factors and are neuroprotective in rat and monkey animal models of HD. HD patients receiving CP transplants would likely receive a course of immunosuppressant/anti-inflammatory treatment postsurgery and would remain on psychoactive medications to treat their motor, psychiatric, and emotional symptoms. Therefore, we examined whether CP epithelial cells are impacted by incubation with cyclosporine A (CsA), dexmethasone, haloperidol, fluoxetine, and carbamezapine. In each case, DNA was quantified to determine cell number, a formazen dye-based assay was used to quantify cell metabolism, and vascular endothelial growth factor (VEGF) levels were measured as a marker of protein secretion. Except for the highest dose of fluoxetine, none of the drugs tested exerted any detrimental effect on cell number. Incubation with CsA or dexamethasone did not have any consistent significant effect on VEGF secretion or cell metabolism. Carbamazepine was without effect while only the highest dose of haloperidol tested modestly lowered cell metabolism. VEGF secretion and cell metabolism was not measurable from CP cells exposed to 100 μM fluoxetine. These data continue to support the potential use of CP transplants in HD.

Alginate-based microcapsules generated with the coaxial electrospray method for clinical application

Alginate-based microencapsulation of cells has made a significant impact on the fields of regenerative medicine and tissue engineering mainly because of its ability to provide immunoisolation for the encapsulated material. This characteristic has allowed for the successful transplantation of non-autologous cells in several clinical trials for life threatening conditions, such as diabetes, myocardial infarction, and neurodegenerative disorders. Methods for alginate hydrogel microencapsulation have been well developed for various types of cells and can generate microcapsules of different diameters, degradation time, and composition. It appears the most prominent and successful method in clinical applications is the coaxial electrospray method, which can be used to generate both homogenous and non-homogeneous microcapsules with uniform size on the order of 100 μm. The present review aims to discuss why alginate hydrogel is an ideal biomaterial for the encapsulation of cells, how alginate-based microcapsules are generated, and methods of modifying the microcapsules for specific clinical treatments. This review will also discuss clinical applications that have utilized alginate-based microencapsulation in the treatment of diabetes, ischemic heart disease, and neurodegenerative diseases.

Primary Choroid Plexus Tissue for Use in Cellular Therapy

The choroid plexus (CP) has been explored as a cellular therapeutic due to its broad-ranging secretome and demonstrated longevity in a variety of encapsulation modalities. While the CP organ is normally involved in disease repair processes in the brain, the range of indications that could potentially be ameliorated with exogenous CP therapy is widespread, including diseases of the central nervous system, hearing loss, chronic wounds, and others. The CP can be isolated from animal sources and digested into a highly purified epithelial culture that can withstand encapsulation and transplantation. Its epithelium can adapt to different microenvironments, and depending on culture conditions, can be manipulated into various three-dimensional configurations with distinct gene expression profiles. The cocktail of proteins secreted by the CP can be harvested in culture, and purified forms of these extracts have been evaluated in topical applications to treat poorly healing wounds. When encapsulated, the epithelial clusters can be maintained for extended durations in vitro with minimal impact on potency. A treatment for Parkinson's disease utilizing encapsulated porcine CP has been developed and is currently being evaluated in a Phase I clinical trial. The current chapter serves to summarize recent experience with CP factor delivery, and provides a description of the relevant materials and methods employed in these studies.

Stereotaxic Surgical Targeting of the Nonhuman Primate Caudate and Putamen: Gene Therapy for Huntington's Disease

Stereotaxic surgery is an invaluable tool to deliver a variety of gene therapy constructs to the nonhuman primate caudate and putamen in preclinical studies for the genetic, neurodegenerative disorder, Huntington's disease (HD). Here we describe in detail how to perform this technique beginning with a pre-surgical magnetic resonance imaging scan to determine surgical coordinates followed by the stereotaxic surgical injection technique. In addition, we include methodology of a full necropsy including brain and peripheral tissue removal and a standard immunohistochemical technique to visualize the injected gene therapy agent.

Proliferation of cultured mouse choroid plexus epithelial cells

The choroid plexus (ChP) epithelium is a multifunctional tissue found in the ventricles of the brain. The major function of the ChP epithelium is to produce cerebrospinal fluid (CSF) that bathes and nourishes the central nervous system (CNS). In addition to the CSF, ChP epithelial cells (CPECs) produce and secrete numerous neurotrophic factors that support brain homeostasis, such as adult hippocampal neurogenesis. Accordingly, damage and dysfunction to CPECs are thought to accelerate and intensify multiple disease phenotypes, and CPEC regeneration would represent a potential therapeutic approach for these diseases. However, previous reports suggest that CPECs rarely divide, although this has not been extensively studied in response to extrinsic factors. Utilizing a cell-cycle reporter mouse line and live cell imaging, we identified scratch injury and the growth factors insulin-like growth factor 1 (IGF-1) and epidermal growth factor (EGF) as extrinsic cues that promote increased CPEC expansion in vitro. Furthermore, we found that IGF-1 and EGF treatment enhances scratch injury-induced proliferation. Finally, we established whole tissue explant cultures and observed that IGF-1 and EGF promote CPEC division within the intact ChP epithelium. We conclude that although CPECs normally have a slow turnover rate, they expand in response to external stimuli such as injury and/or growth factors, which provides a potential avenue for enhancing ChP function after brain injury or neurodegeneration.

Developments in intracerebral stem cell grafts

The field of stem cell therapy has emerged as a promising research area for brain repair. Optimizing the safety and efficacy of the therapy for clinical trials will require revisiting transplantation protocols. The cell delivery route stands as a key translational item that warrants careful consideration in facilitating the success of stem cell therapy in the clinic. Intracerebral administration, compared to peripheral route, requires an invasive procedure to directly implant stem cells into injured brain. Although invasive, intracerebral transplantation circumvents the prohibitive blood brain barrier in allowing grafted cells when delivered peripherally to penetrate the brain and reach the discreet damaged brain tissues. This review will highlight milestone discoveries in cell therapy for neurological disorders, with emphasis on intracerebral transplantation in relevant animal models and provide insights necessary to optimize the safety and efficacy of cell therapy for the treatment of Parkinson's disease, Huntington's disease, stroke and traumatic brain injury.

Advances in cell encapsulation technology and its application in drug delivery

INTRODUCTION

Cell encapsulation technology has improved enormously since it was proposed 50 years ago. The advantages offered over other alternative systems, such as the prevention of repetitive drug administration, have triggered the use of this technology in multiple therapeutic applications.

AREAS COVERED

In this article, improvements in cell encapsulation technology and strategies to overcome the drawbacks that prevent its use in the clinic have been summarized and discussed. Different studies and clinical trials that have been performed in several therapeutic applications have also been described.

EXPERT OPINION

The authors believe that the future translation of this technology from bench to bedside requires the optimization of diverse aspects: i) biosafety, controlling and monitoring cell viability; ii) biocompatibility, reducing pericapsular fibrotic growth and hypoxia suffered by the graft; iii) control over drug delivery; iv) and the final scale up. On the other hand, an area that deserves more attention is the cryopreservation of encapsulated cells as this will facilitate the arrival of these biosystems to the clinic.

Choroid plexus in developmental and evolutionary perspective

The blood-cerebrospinal fluid boundary is present at the level of epithelial cells of the choroid plexus. As one of the sources of the cerebrospinal fluid (CSF), the choroid plexus (CP) plays an important role during brain development and function. Its formation has been studied largely in mammalian species. Lately, progress in other model animals, in particular the zebrafish, has brought a deeper understanding of CP formation, due in part to the ability to observe CP development in vivo. At the same time, advances in comparative genomics began providing information, which opens a possibility to understand further the molecular mechanisms involved in evolution of the CP and the blood-cerebrospinal fluid boundary formation. Hence this review focuses on analysis of the CP from developmental and evolutionary perspectives.

Choroid plexus implants rescue Alzheimer's disease-like pathologies by modulating amyloid-β degradation

The choroid plexuses (CP) release numerous biologically active enzymes and neurotrophic factors, and contain a subpopulation of neural progenitor cells providing the capacity to proliferate and differentiate into other types of cells. These characteristics make CP epithelial cells (CPECs) excellent candidates for cell therapy aiming at restoring brain tissue in neurodegenerative illnesses, including Alzheimer's disease (AD). In the present study, using in vitro approaches, we demonstrated that CP were able to diminish amyloid-β (Aβ) levels in cell cultures, reducing Aβ-induced neurotoxicity. For in vivo studies, CPECs were transplanted into the brain of the APP/PS1 murine model of AD that exhibits advanced Aβ accumulation and memory impairment. Brain examination after cell implantation revealed a significant reduction in brain Aβ deposits, hyperphosphorylation of tau, and astrocytic reactivity. Remarkably, the transplantation of CPECs was accompanied by a total behavioral recovery in APP/PS1 mice, improving spatial and non-spatial memory. These findings reinforce the neuroprotective potential of CPECs and the use of cell therapies as useful tools in AD.

Transplantation of induced pluripotent stem cells improves functional recovery in Huntington's disease rat model

The purpose of this study was to determine the functional recovery of the transplanted induced pluripotent stem cells in a rat model of Huntington's disease with use of 18F-FDG microPET/CT imaging.

METHODS

In a quinolinic acid-induced rat model of striatal degeneration, induced pluripotent stem cells were transplanted into the ipsilateral lateral ventricle ten days after the quinolinic acid injection. The response to the treatment was evaluated by serial 18F-FDG PET/CT scans and Morris water maze test. Histological analyses and Western blotting were performed six weeks after stem cell transplantation.

RESULTS

After induced pluripotent stem cells transplantation, higher 18F-FDG accumulation in the injured striatum was observed during the 4 to 6-weeks period compared with the quinolinic acid-injected group, suggesting the metabolic recovery of injured striatum. The induced pluripotent stem cells transplantation improved learning and memory function (and striatal atrophy) of the rat in six week in the comparison with the quinolinic acid-treated controls. In addition, immunohistochemical analysis demonstrated that transplanted stem cells survived and migrated into the lesioned area in striatum, and most of the stem cells expressed protein markers of neurons and glial cells.

CONCLUSION

Our findings show that induced pluripotent stem cells can survive, differentiate to functional neurons and improve partial striatal function and metabolism after implantation in a rat Huntington's disease model.

Carriers in cell-based therapies for neurological disorders

There is a pressing need for long-term neuroprotective and neuroregenerative therapies to promote full function recovery of injuries in the human nervous system resulting from trauma, stroke or degenerative diseases. Although cell-based therapies are promising in supporting repair and regeneration, direct introduction to the injury site is plagued by problems such as low transplanted cell survival rate, limited graft integration, immunorejection, and tumor formation. Neural tissue engineering offers an integrative and multifaceted approach to tackle these complex neurological disorders. Synergistic therapeutic effects can be obtained from combining customized biomaterial scaffolds with cell-based therapies. Current scaffold-facilitated cell transplantation strategies aim to achieve structural and functional rescue via offering a three-dimensional permissive and instructive environment for sustainable neuroactive factor production for prolonged periods and/or cell replacement at the target site. In this review, we intend to highlight important considerations in biomaterial selection and to review major biodegradable or non-biodegradable scaffolds used for cell transplantation to the central and peripheral nervous system in preclinical and clinical trials. Expanded knowledge in biomaterial properties and their prolonged interaction with transplanted and host cells have greatly expanded the possibilities for designing suitable carrier systems and the potential of cell therapies in the nervous system.

Encapsulated cell therapy for neurodegenerative diseases: from promise to product

Delivering therapeutic molecules, including trophic factor proteins, across the blood brain barrier to the brain parenchyma to treat chronic neurodegenerative diseases remains one of the great challenges in biology. To be effective, delivery needs to occur in a long-term and stable manner at sufficient quantities directly to the target region in a manner that is selective but yet covers enough of the target site to be efficacious. One promising approach uses cellular implants that produce and deliver therapeutic molecules directly to the brain region of interest. Implanted cells can be precisely positioned into the desired region and can be protected from host immunological attack by encapsulating them and by surrounding them within an immunoisolatory, semipermeable capsule. In this approach, cells are enclosed within a semiporous capsule with a perm selective membrane barrier that admits oxygen and required nutrients and releases bioactive cell secretions while restricting passage of larger cytotoxic agents from the host immune defense system. Recent advances in human cell line development have increased the levels of secreted therapeutic molecules from encapsulated cells, and membrane extrusion techniques have led to the first ever clinical demonstrations of long-term survival and function of encapsulated cells in the brain parenchyma. As such, cell encapsulation is capable of providing a targeted, continuous, de novo synthesized source of very high levels of therapeutic molecules that can be distributed over significant portions of the brain.

Secretion of BDNF and GDNF from free and encapsulated choroid plexus epithelial cells

Choroid plexus epithelial cells secrete numerous biologically active neurotrophic factors, which may be beneficial to the transplantation site. Encapsulated cells are often used in tissue transplantation. The present study was conducted to investigate the effect of encapsulation on the secretory function of choroid plexus epithelial cells. Neonatal rat choroid plexus epithelial cells were primarily cultured. After 9 days of culture, the cells were distributed into two groups, and one group of cells was encapsulated in vitro. The initial culture conditions such as cell numbers and medium volumes were the same. Supernatants in the free and encapsulated choroid plexus epithelial cells were collected at the time points of day 1 through day 7. Quantitative determination of the BDNF and GDNF levels was performed by enzyme-linked immunosorbent assay to assess the secretory function of the cells in the two forms. Statistical analyses were performed using a Student t test. P<0.05 was set to indicate statistical significance. A very similar secretion pattern was observed in both groups. In the first 4 days of encapsulation, the release of BDNF and GDNF in the encapsulated cells was significantly lower than that in the free cells, while the difference diminished after day 5. This in vitro study demonstrates that the secretion of BDNF and GDNF in encapsulated choroid plexus epithelial cells is different from that in non-encapsulated cells in the early stage of encapsulation treatment, whereas it is similar in the later stage.

Primary culture of choroid plexuses from neonate rats containing progenitor cells capable of differentiation

BACKGROUND

The choroid plexuses, which could secrete a number of neurotrophins, have recently been used in transplantation in central nervous system diseases.

AIMS

To study the mechanism of nerve regeneration in the central nervous system by grafting choroid plexus tissues.

STUDY DESIGN

Animal experimentation.

METHODS

The choroid plexuses from the lateral ventricles of neonatal rats were cultured in adherent culture, and immunocytochemical methods were used to analyse the progenitor cells on days 2, 6, and 10 after seeding.

RESULTS

Expression of both nestin and glial fibrillary acidic protein was observed in small cell aggregates on day 2 in primary culture. Most of the nestin-positive cells on day 6 were immunoreactive to glial fibrillary acidic protein antibody. No cells expressing nestin or glial fibrillary acidic protein were seen on day 10.

CONCLUSION

These experimental results indicate that the choroid plexus contains a specific cell population - progenitor cells. Under in vitro experimental conditions, the progenitor cells differentiated into choroid plexus epithelial cells but did not form neurons or astrocytes.

Phosphodiesterases: Regulators of cyclic nucleotide signals and novel molecular target for movement disorders

Movement disorders rank among the most common neurological disorders. During the last two decades substantial progress has been made in understanding of the pathological basis of these disorders. Although, several mechanisms have been proposed, downregulation of cyclic nucleotide mediated signaling cascade has consistently been shown to contribute to the striatal dysfunctioning as seen in movement disorders. Thus, counteracting dysregulated cyclic nucleotide signaling has been considered to be beneficial in movement disorders. Cyclic nucleotide phosphodiesterases (PDEs) are the enzymes responsible for the breakdown of cyclic nucleotides and upregulation in PDE activity has been reported in various movement disorders. Thus, PDE inhibition is considered to be a novel strategy to restore cerebral cyclic nucleotide levels and their downstream signalling cascade. Indeed, various PDE inhibitors have been tested pre-clinically and were reported to be neuroprotective in various neurodegenerative disorders associated with movement disabilities. In this review, we have discussed a putative role of PDE inhibitors in movement disorders and associated abnormalities.

Therapeutic applications of encapsulated cells

The synergy of some promising advances in the fields of cell therapy and biomaterials together with improvements in the fabrication of more refined and tailored microcapsules for drug delivery have triggered the progress of cell encapsulation technology. Cell microencapsulation involves immobilizing the transplanted cells within a biocompatible scaffold surrounded by a membrane in attempt to isolate the cells from the host immune attack and enhance or prolong their function in vivo. This technology represents one strategy which aims to overcome the present difficulties related to local and systemic controlled release of drugs and growth factors as well as to organ graft rejection and thus the requirements for use of immunomodulatory protocols or immunosuppressive drugs. This chapter gives an overview of the current situation of cell encapsulation technology as a controlled drug delivery system, and the essential requirements of the technology, some of the therapeutic applications, the challenges, and the future directions under investigation are highlighted.

Microencapsulating and Banking Living Cells for Cell-Based Medicine

A major challenge to the eventual success of the emerging cell-based medicine such as tissue engineering, regenerative medicine, and cell transplantation is the limited availability of the desired cell sources. This challenge can be addressed by cell microencapsulation to overcome the undesired immune response (i.e., to achieve immunoisolation) so that non-autologous cells can be used to treat human diseases, and by cell/tissue preservation to bank living cells for wide distribution to end users so that they are readily available when needed in the future. This review summarizes the status quo of research in both cell microencapsulation and banking the microencapsulated cells. It is concluded with a brief outlook of future research directions in this important field.

Human mesenchymal stem cells prolong survival and ameliorate motor deficit through trophic support in Huntington's disease mouse models

We investigated the therapeutic potential of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) in Huntington's disease (HD) mouse models. Ten weeks after intrastriatal injection of quinolinic acid (QA), mice that received hBM-MSC transplantation showed a significant reduction in motor function impairment and increased survival rate. Transplanted hBM-MSCs were capable of survival, and inducing neural proliferation and differentiation in the QA-lesioned striatum. In addition, the transplanted hBM-MSCs induced microglia, neuroblasts and bone marrow-derived cells to migrate into the QA-lesioned region. Similar results were obtained in R6/2-J2, a genetically-modified animal model of HD, except for the improvement of motor function. After hBM-MSC transplantation, the transplanted hBM-MSCs may integrate with the host cells and increase the levels of laminin, Von Willebrand Factor (VWF), stromal cell-derived factor-1 (SDF-1), and the SDF-1 receptor Cxcr4. The p-Erk1/2 expression was increased while Bax and caspase-3 levels were decreased after hBM-MSC transplantation suggesting that the reduced level of apoptosis after hBM-MSC transplantation was of benefit to the QA-lesioned mice. Our data suggest that hBM-MSCs have neural differentiation improvement potential, neurotrophic support capability and an anti-apoptotic effect, and may be a feasible candidate for HD therapy.

Controlled delivery systems: from pharmaceuticals to cells and genes

During the last few decades, a fair amount of scientific investigation has focused on developing novel and efficient drug delivery systems. According to different clinical needs, specific biopharmaceutical carriers have been proposed. Micro- and nanoparticulated systems, membranes and films, gels and even microelectronic chips have been successfully applied in order to deliver biopharmaceuticals via different anatomical routes. The ultimate goal is to deliver the potential drugs to target tissues, where regeneration or therapies (chemotherapy, antibiotics, and analgesics) are needed. Thereby, the bioactive molecule should be protected against environmental degradation. Delivery should be achieved in a dose- and time-correct manner. Drug delivery systems (DDS) have been conceived to provide improvements in drug administration such as ability to enhance the stability, absorption and therapeutic concentration of the molecules in combination with a long-term and controlled release of the drug. Moreover, the adverse effects related with some drugs can be reduced, and patient compliance could be improved. Recent advances in biotechnology, pharmaceutical sciences, molecular biology, polymer chemistry and nanotechnology are now opening up exciting possibilities in the field of DDS. However, it is also recognized that there are several key obstacles to overcome in bringing such approaches into routine clinical use. This review describes the present state-of-the-art DDS, with examples of current clinical applications, and the promises and challenges for the future in this innovative field.

Functional modulation of choroid plexus epithelial clusters in vitro for tissue repair applications

One of the primary obstacles in the restoration or repair of damaged tissues is the temporospatial orchestration of biological and physiological events. Cellular transplantation is an important component of tissue repair as grafted cells can serve as replacement cells or as a source of secreted factors. But few, if any, primary cells can perform more than a single tissue repair function. Epithelial cells, derived from the choroid plexus (CP), are an exception to this rule, as transplanted CP is protective and regenerative in animal models as diverse as CNS degeneration and dermal wound repair. They secrete a myriad of proteins with therapeutic potential as well as matrix and adhesion factors, and contain responsive cytoskeletal components potentially capable of precise manipulation of cellular and extracellular niches. Here we isolated CP from neonatal porcine lateral ventricles and cultured the cells under a variety of conditions to specifically modulate tissue morphology (2D vs. 3D) and protein expression. Using qRT-PCR analysis, transmission electron microscopy, and gene microarray studies we demonstrate a fine level of control over CP epithelial cell clusters opening further opportunities for exploration of the therapeutic potential of this unique tissue source.

Company profile: Tissue regeneration for diabetes and neurological diseases at Living Cell Technologies

Living Cell Technologies’ (LCT’s) cell-based therapeutic for Type 1 diabetes, DIABECELL®, comprises encapsulated porcine insulin-producing cells. DIABECELL is presently in a Phase II clinical trial in New Zealand following positive early results. The cells are implanted into the abdomen to replace the patient’s pancreatic β-islet cells that have been lost as a result of autoimmune disease. LCT is also developing brain choroid plexus cells for the treatment of neurologic diseases. The aim is to enhance the brain’s natural repair mechanism by implanting cells releasing neurotrophins. Choroid plexus cell implants alleviate disease in animal models of Parkinson’s disease, Huntington’s disease and stroke. LCT encapsulates all cells in alginate, permitting implantation without using immunosuppressive drugs.

Use of Encapsulated Stem Cells to Overcome the Bottleneck of Cell Availability for Cell Therapy Approaches

Nowadays cell-based therapy is rarely in clinical practice because of the limited availability of appropriate cells. To apply cells therapeutically, they must not cause any immune response wherefore mainly autologous cells have been used up to now. The amount of vital cells in patients is limited, and under certain circumstances in highly degenerated tissues no vital cells are left. Moreover, the extraction of these cells is connected with additional surgery; also the expansion in vitro is difficult. Other approaches avoid these problems by using allo-or even xenogenic cells. These cells are more stable concerning their therapeutic behavior and can be produced in stock. To prevent an immune response caused by these cells, cell encapsulation (e.g. with alginate) can be performed. Certain studies showed that encapsulated allo- and xenogenic cells achieve promising results in treatment of several diseases. For such cell therapy approaches, stem cells, particularly mesenchymal stem cells, are an interesting cell source. This review deals on the one hand with the use of encapsulated cells, especially stem cells, in cell therapy and on the other hand with bioreactor systems for the expansion and differentiation of mesenchymal stem cells in reproducible and sufficient amounts for potential clinical use.

Microencapsulated choroid plexus epithelial cell transplants for repair of the brain

The choroid plexuses (CPs) play pivotal roles in basic aspects of neural function including maintaining the extracellular milieu of the brain by actively modulating chemical exchange between the CSF and brain parenchyma, surveying the chemical and immunological status of the brain, detoxifying the brain, secreting a nutritive "cocktail" of polypeptides and participating in repair processes following trauma. Even modest changes in the CP can have far reaching effects and changes in the anatomy and physiology of the CP have been linked to several CNS diseases. It is also possible that replacing diseased or transplanting healthy CP might be useful for treating acute and chronic brain diseases. Here we describe the wide-ranging functions of the CP, alterations of these functions in aging and neurodegeneration and recent demonstrations of the therapeutic potential of transplanted microencapsulated CP for neural trauma.