Grafted neural stem cells migrate to substantia nigra and improve behavior in Parkinsonian rats

Transplantation of human neural stem cell prevents symptomatic motor behavior disability in a rat model of Parkinson's disease

Parkinson's disease (PD) is a ubiquitous brain cell degeneration disease and presents a significant therapeutic challenge. By injecting 6-hydroxydopamine (6-OHDA) into the left medial forebrain bundle, rats were made to exhibit PD-like symptoms and treated by intranasal administration of a low-dose (2 × 105) or high-dose (1 × 106) human neural stem cells (hNSCs). Apomorphine-induced rotation test, stepping test, and open field test were implemented to evaluate the motor behavior and high-performance liquid chromatography was carried out to detect dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), serotonin, and 5-hydroxyindole-3-acetic acid in the striatum of rats. Animals injected with 6-OHDA showed significant motor function deficits and damaged dopaminergic system compared to the control group, which can be restored by hNSCs treatment. Treatment with hNSCs significantly increased the tyrosine hydroxylase-immunoreactive cell count in the substantia nigra of PD animals. Moreover, the levels of neurotransmitters exhibited a significant decline in the striatum tissue of animals injected with 6-OHDA when compared to that of the control group. However, transplantation of hNSCs significantly elevated the concentration of DA and DOPAC in the injured side of the striatum. Our study offered experimental evidence to support prospects of hNSCs for clinical application as a cell-based therapy for PD.

Research progress of neural stem cells as a source of dopaminergic neurons for cell therapy in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease, the most characteristic pathological feature is the progressive loss of dopaminergic (DA) neurons in the substantia nigra pars compactus (SNpc) of the mesencephalon, along with reduced dopamine content in the striatum. Researchers have been searching for drugs and therapies to treat PD in decades. However, no approach could stop the progression of the disease, and even some of them caused adverse clinical side effects. PD has a well-defined lesion. Therefore, it is considered to be one of the most curable central nervous system diseases by cell replacement treatment. Fetal ventral mesencephalic tissue transplantation has been used to treat patients with PD and obtained positive treatment results. However, ethical issues, such as limited donor tissue, and side effects including graft-induced dyskinesias, limit its clinical applications. Neural stem cell (NSC) transplantation is a viable therapy choice because it possesses multipotency, self-renewal ability, and differentiation into DA neurons, which may substitute for lost DA neurons and slow down the neurodegenerative process in PD. Studies that investigated the delivery of NSCs by using animal models of PD revealed survival, migration, and even amelioration of behavioral deficits. Here, the research progress of NSCs or NSC-derived DA neurons in treating PD was reviewed, and the practicability of present manufacturing processes for clinical testing was considered. This review is expected to offer ideas for practical strategies to solve the present technical and biological problems related to the clinical application of NSCs in PD.

Therapeutic Effect of BDNF-Overexpressing Human Neural Stem Cells (F3.BDNF) in a Contusion Model of Spinal Cord Injury in Rats

The most common type of spinal cord injury is the contusion of the spinal cord, which causes progressive secondary tissue degeneration. In this study, we applied genetically modified human neural stem cells overexpressing BDNF (brain-derived neurotrophic factor) (F3.BDNF) to determine whether they can promote functional recovery in the spinal cord injury (SCI) model in rats. We transplanted F3.BDNF cells via intrathecal catheter delivery after a contusion of the thoracic spinal cord and found that they were migrated toward the injured spinal cord area by MR imaging. Transplanted F3.BDNF cells expressed neural lineage markers, such as NeuN, MBP, and GFAP and were functionally connected to the host neurons. The F3.BDNF-transplanted rats exhibited significantly improved locomotor functions compared with the sham group. This functional recovery was accompanied by an increased volume of spared myelination and decreased area of cystic cavity in the F3.BDNF group. We also observed that the F3.BDNF-transplanted rats showed reduced numbers of Iba1- and iNOS-positive inflammatory cells as well as GFAP-positive astrocytes. These results strongly suggest the transplantation of F3.BDNF cells can modulate inflammatory cells and glia activation and also improve the hyperalgesia following SCI.

Characterization of substantia nigra neurogenesis in homeostasis and dopaminergic degeneration: beneficial effects of the microneurotrophin BNN-20

Background

Loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) underlines much of the pathology of Parkinson’s disease (PD), but the existence of an endogenous neurogenic system that could be targeted as a therapeutic strategy has been controversial. BNN-20 is a synthetic, BDNF-mimicking, microneurotrophin that we previously showed to exhibit a pleiotropic neuroprotective effect on the dopaminergic neurons of the SNpc in the “weaver” mouse model of PD. Here, we assessed its potential effects on neurogenesis.

Methods

We quantified total numbers of dopaminergic neurons in the SNpc of wild-type and “weaver” mice, with or without administration of BNN-20, and we employed BrdU labelling and intracerebroventricular injections of DiI to evaluate the existence of dopaminergic neurogenesis in the SNpc and to assess the origin of newborn dopaminergic neurons. The in vivo experiments were complemented by in vitro proliferation/differentiation assays of adult neural stem cells (NSCs) isolated from the substantia nigra and the subependymal zone (SEZ) stem cell niche to further characterize the effects of BNN-20.

Results

Our analysis revealed the existence of a low-rate turnover of dopaminergic neurons in the normal SNpc and showed, using three independent lines of experiments (stereologic cell counts, BrdU and DiI tracing), that the administration of BNN-20 leads to increased neurogenesis in the SNpc and to partial reversal of dopaminergic cell loss. The newly born dopaminergic neurons, that are partially originated from the SEZ, follow the typical nigral maturation pathway, expressing the transcription factor FoxA2. Importantly, the pro-cytogenic effects of BNN-20 were very strong in the SNpc, but were absent in other brain areas such as the cortex or the stem cell niche of the hippocampus. Moreover, although the in vitro assays showed that BNN-20 enhances the differentiation of NSCs towards glia and neurons, its in vivo administration stimulated only neurogenesis.

Conclusions

Our results demonstrate the existence of a neurogenic system in the SNpc that can be manipulated in order to regenerate the depleted dopaminergic cell population in the “weaver” PD mouse model. Microneurotrophin BNN-20 emerges as an excellent candidate for future PD cell replacement therapies, due to its area-specific, pro-neurogenic effects.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02398-3.

Stem cell in neurodegenerative disorders; an emerging strategy

Neurodegenerative disorders are a diversity of disorders, surrounding Alzheimer's (AD), Parkinson's (PD), Huntington's diseases (HD), and amyotrophic lateral sclerosis (ALS) accompanied by some other less common diseases generally characterized by either developed deterioration of central or peripheral nervous system structurally or functionally. Today, with the viewpoint of an increasingly aging society, the number of patients with neurodegenerative diseases and sociomedical burdens will spread intensely. During the last decade, stem cell technology has attracted great attention for treating neurodegenerative diseases worldwide because of its unique attributes. As acknowledged, there are several categories of stem cells being able to proliferate and differentiate into various cellular lineages, highlighting their significance in the context of regenerative medicine. In preclinical models, stem cell therapy using mesenchymal stem/stromal cells (MSCs), hematopoietic stem cells (HSCs), and neural progenitor or stem cells (NPCs or NSCs) along with pluripotent stem cells (PSCs)-derived neuronal cells could elicit desired therapeutic effects, enabling functional deficit rescue partially. Regardless of the noteworthy progress in our scientific awareness and understanding of stem cell biology, there still exist various challenges to defeat. In the present review, we provide a summary of the therapeutic potential of stem cells and discuss the current status and prospect of stem cell strategy in neurodegenerative diseases, in particular, AD, PD, ALS, and HD.

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.

Intranasal Administration of Mesenchymal Stem Cells Ameliorates the Abnormal Dopamine Transmission System and Inflammatory Reaction in the R6/2 Mouse Model of Huntington Disease

Intrastriatal administration of mesenchymal stem cells (MSCs) has shown beneficial effects in rodent models of Huntington disease (HD). However, the invasive nature of surgical procedure and its potential to trigger the host immune response may limit its clinical use. Hence, we sought to evaluate the non-invasive intranasal administration (INA) of MSC delivery as an effective alternative route in HD. GFP-expressing MSCs derived from bone marrow were intranasally administered to 4-week-old R6/2 HD transgenic mice. MSCs were detected in the olfactory bulb, midbrain and striatum five days post-delivery. Compared to phosphate-buffered saline (PBS)-treated littermates, MSC-treated R6/2 mice showed an increased survival rate and attenuated circadian activity disruption assessed by locomotor activity. MSCs increased the protein expression of DARPP-32 and tyrosine hydroxylase (TH) and downregulated gene expression of inflammatory modulators in the brain 7.5 weeks after INA. While vehicle treated R6/2 mice displayed decreased Iba1 expression and altered microglial morphology in comparison to the wild type littermates, MSCs restored both, Iba1 level and the thickness of microglial processes in the striatum of R6/2 mice. Our results demonstrate significantly ameliorated phenotypes of R6/2 mice after MSCs administration via INA, suggesting this method as an effective delivering route of cells to the brain for HD therapy.

Regenerative medicine for Parkinson's disease using differentiated nerve cells derived from human buccal fat pad stem cells

The purpose of this study was to evaluate the utility of human adipose stem cells derived from the buccal fat pad (hBFP-ASCs) for nerve regeneration. Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive death of dopaminergic neurons. PD is a candidate disease for cell replacement therapy because it has no fundamental therapeutic methods. We examined the properties of neural-related cells induced from hBFP-ASCs as a cell source for PD treatment. hBFP-ASCs were cultured in neurogenic differentiation medium for about 2 weeks. After the morphology of hBFP-ASCs changed to neural-like cells, the medium was replaced with neural maintenance medium. Cells differentiated from hBFP-ASCs showed neuron-like structures and expressed neuron markers (β3-tubulin, neurofilament 200, and microtubule-associated protein 2), an astrocyte marker (glial fibrillary acidic protein), or dopaminergic neuron-related marker (tyrosine hydroxylase). Induced neural cells were transplanted into a 6-hydroxydopamine (6-OHDA)-lesioned rat hemi-parkinsonian model. At 4 weeks after transplantation, 6-OHDA-lesioned rats were subjected to apomorphine-induced rotation analysis. The transplanted cells survived in the brain of rats as dopaminergic neural cells. No tumor formation was found after cell transplantation. We demonstrated differentiation of hBFP-ASCs into neural cells, and that transplantation of these neural cells improved the symptoms of model rats. Our results suggest that neurons differentiated from hBFP-ASCs would be applicable to cell replacement therapy of PD.

Transplanted Neural Stem Cells: Playing a Neuroprotective Role by Ceruloplasmin in the Substantia Nigra of PD Model Rats?

Although mounting evidence suggests that ceruloplasmin (CP) deficiency and iron deposition are pivotal factors responsible for exacerbating demise of dopaminergic neurons in the substantia nigra (SN) of the Parkinsonism and neural stem cells (NSCs) are believed to be excellent candidates for compensating the lost dopaminergic neurons, there are few researches to explore the change of CP expression and of iron deposition in the pathological microenvironment of SN after NSCs transplantation and the ability of grafted NSCs to differentiate directionally into dopaminergic neurons under the changed homeostasis. With substantia nigral stereotaxic technique and NSCs transplantation, we found that tyrosine hydroxylase and CP expression decreased and iron deposition increased in the lesioned SN after 6-OHDA administration compared with control, while tyrosine hydroxylase and CP expression increased and iron deposition decreased after NSCs transplantation compared to 6-OHDA administration alone. Only a small number of embedding NSCs are able to differentiate into dopaminergic neurons. These results suggest that grafted NSCs have an influence on improving the content of CP expression, which may play a neuroprotective role by decreasing iron deposition and ameliorating damage of dopaminergic neurons and possibly underline the iron-related common mechanism of Parkinson's disease and Wilson's disease.

Proof of Concept Studies Exploring the Safety and Functional Activity of Human Parthenogenetic-Derived Neural Stem Cells for the Treatment of Parkinson's Disease

Recent studies indicate that human pluripotent stem cell (PSC)-based therapies hold great promise in Parkinson's disease (PD). Clinical studies have shown that grafted fetal neural tissue can achieve considerable biochemical and clinical improvements in PD. However, the source of fetal tissue grafts is limited and ethically controversial. Human parthenogenetic stem cells offer a good alternative because they are derived from unfertilized oocytes without destroying viable human embryos and can be used to generate an unlimited supply of neural stem cells for transplantation. Here we evaluate for the first time the safety and engraftment of human parthenogenetic stem cell-derived neural stem cells (hpNSCs) in two animal models: 6-hydroxydopamine (6-OHDA)-lesioned rodents and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated nonhuman primates (NHPs). In both rodents and nonhuman primates, we observed successful engraftment and higher dopamine levels in hpNSC-transplanted animals compared to vehicle control animals, without any adverse events. These results indicate that hpNSCs are safe, well tolerated, and could potentially be a source for cell-based therapies in PD.

Dorsal root ganglion progenitors differentiate to gamma-aminobutyric acid- and choline acetyltransferase-positive neurons

This study examined the isolation and differentiation of dorsal root ganglion progenitor cells for therapeutic use in neurodegenerative diseases. Rat embryonic dorsal root ganglia progenitors were isolated and purified using the differential adhesion method combined with cytosine arabinoside treatment. After culture in serum-free medium supplemented with B27, basic fibroblast growth factor and epidermal growth factor, these cells remained viable and survived for more than 18 months in vitro. Most cells differentiated to neurons that were immunoreactive for gamma-aminobutyric acid and choline acetyltransferase as detected by immunohistochemical staining. In addition, nerve growth factor and neurotrophic tyrosine kinase receptor expression were also observed in dorsal root ganglion progenitors and differentiated cells. K252a, an inhibitor that blocks nerve growth factor-induced signaling, inhibited cell survival, suggesting the possible existence of a nerve growth factor autocrine loop in these proliferating cells.

Extracellular matrices, artificial neural scaffolds and the promise of neural regeneration

Over last 20 years, extracellular matrices have been shown to be useful in promoting tissue regeneration. Recently, they have been used and have had success in achieving neurogenesis. Recent developments in extracellular matrix design have allowed their successful in vivo incorporation to engender an environment favorable for neural regeneration in animal models. Promising treatments under investigation include manipulation of the intrinsic extracellular matrix and incorporation of engineered naometer-sized scaffolds through which inhibition of molecules serving as barriers to neuroregeneration and delivery of neurotrophic factors and/or cells for successful tissue regeneration can be achieved. Further understanding of the changes incurred within the extracellular matrix following central nervous system injury will undoubtedly help design a clinically efficacious extracellular matrix scaffold that can mitigate or reverse neural degeneration in the clinical setting.

Neural stem/progenitor cell transplantation for cortical visual impairment in neonatal brain injured patients

The purpose of this study was to investigate the clinical efficacy of neural stem/progenitor cell (NS/PC) transplantation to treat severe cortical visual impairment (CVI), a sequela of neonatal brain injury. Fifty-two patients with cerebral injury and CVI were randomly divided into two groups: the treatment group (n = 25, with the median age of 18 months) and the control group (n = 27, with the median age of 19.5 months). The treatment group received intracerebroventricular transplantation of human NS/PCs and rehabilitation training. The control group received rehabilitation only. The visual function was assessed by Holt's method at various time points after transplantation. One in five patients with fundus abnormalities accompanied by blindness regained light perception. The visual functions of 75% of the patients with normal fundus were improved by one level or more in a 2-year follow-up. The median efficacy appeared 60 days posttransplantation. The total effective rate of cell transplantation on visual improvement was 64% (16 patients of 25), among which one blind patient regained light perception, five (31.2%) CVI patients improved by one level, and 10 (62.5%) improved by more than one level. Functional magnetic resonance imaging (fMRI) in a subpopulation of patients showed enhanced signals in the occipital lobe, visual pathway, and apical lobe after transplantation. In the control group, four patients with fundus abnormalities showed no improvement. Nine of 23 CVI patients with normal fundus improved visual function by more than one level. At the 2-year follow-up, no blind patients showed visual improvement. The total effective rate was 33.33% (9 of 27 patients). Among those showing visual improvement in the control group, six patients (66.67%) improved by one level, and three (33.33%) by more than one level. The median efficacy occurred in 365 days. Human NS/PC transplantation is effective to treat patients with severe CVI after neonatal brain injury. Compared with the traditional rehabilitation training, cell transplantation showed not only earlier visual improvement but also higher improvement rates and degrees. This article is published as part of the International Association of Neurorestoratology (IANR) supplement issue of Cell Transplantation.

Cell based therapy in Parkinsonism

Parkinson's disease (PD) is a synucleinopathy-induced chronic progressive neurodegenerative disorder, worldwide affecting about 5 million humans. As of yet, actual therapies are symptomatic, and neuroprotective strategies are an unmet need. Due to their capability to transdifferentiate, to immune modulate and to increase neuroplasticity by producing neurotrophic factors, adult stem cells (ASC) might fill this gap. Preclinical research in 6-hydroxydopamine (6-OHDA) and/or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) lesioned animals established persistent improvements of motor behavior after ASC-treatment. Histological/histochemical measurements in these animals evidenced an intracerebral applied ASC-induced increase of Tyrosine Hydroxylase-positive (TH+) cells with increased striatal dopamine levels, suggesting cell rescue. Likewise, clinical experience with subventricular applied ASCs in PD patients, although limited, is encouraging, evidencing neurorescue especially during the early phase of the disease. In multiple system atrophy (MSA) or progressive supranuclear palsy (PSP) patients, though, only marginal reduced progression of natural progression could be established after subventricular or intravasal ASC implantations.

Effects of neural progenitor cell transplantation in children with severe cerebral palsy

Cerebral palsy (CP) is a chronic nervous system disease that severely damages the physical and developmental health of children. Traditional treatment brings about only improvement of mild to moderate CP, but severe CP still lacks effective interventions. To explore safety and efficacy of using neural progenitor cells (NPCs) to treat CP in children, we performed NPC transplantation in 45 patients with severe CP by injecting NPCs derived from aborted fetal tissue into the lateral ventricle. Gross motor function measures (GMFM), the Peabody Developmental Motor Scale-Fine Motor (PDMS-FM) test, and a unified survey questionnaire designed specifically for children with CP were used to evaluate neurological function of the patients. Motor development was significantly accelerated within the first month after cell transplantation, but the rate of improvement gradually slowed to preoperative levels. However, after 1 year, the developmental level in each functional sphere (gross motor, fine motor, and cognition) of the treatment group was significantly higher compared to the control group. No delayed complications of this therapy were noted. These results suggest that NPC transplantation is a safe and effective therapeutic method for treating children with severe CP.

Current challenges for the advancement of neural stem cell biology and transplantation research

Transplantation of neural stem cells (NSC) is hoped to become a promising primary or secondary therapy for the treatment of various neurodegenerative disorders of the central nervous system (CNS), as demonstrated by multiple pre-clinical animal studies in which functional recovery has already been demonstrated. However, for NSC therapy to be successful, the first challenge will be to define a transplantable cell population. In the first part of this review, we will briefly discuss the main features of ex vivo culture and characterisation of NSC. Next, NSC grafting itself may not only result in the regeneration of lost tissue, but more importantly has the potential to improve functional outcome through many bystander mechanisms. In the second part of this review, we will briefly discuss several pre-clinical studies that contributed to a better understanding of the therapeutic potential of NSC grafts in vivo. However, while many pre-clinical animal studies mainly report on the clinical benefit of NSC grafting, little is known about the actual in vivo fate of grafted NSC. Therefore, the third part of this review will focus on non-invasive imaging techniques for monitoring cellular grafts in the brain under in vivo conditions. Finally, as NSC transplantation research has evolved during the past decade, it has become clear that the host micro-environment itself, either in healthy or injured condition, is an important player in defining success of NSC grafting. The final part of this review will focus on the host environmental influence on survival, migration and differentiation of grafted NSC.

A review of the role of stem cells in the development and treatment of glioma

The neurosurgical management of patients with intrinsic glial cancers is one of the most rapidly evolving areas of practice. This has been fuelled by advances in surgical technique not only in cytoreduction but also in drug delivery. Further innovation will depend on a deeper understanding of the biology of the disease and an appreciation of the limitations of current knowledge. Here we review the controversial topic of cancer stem cells applied to glioma to provide neurosurgeons with a working overview. It is now recognised that the adult human brain contains regionally specified cell populations capable of self-renewal that may contribute to tumour growth and maintenance following accumulated mutational change. Tumour cells adapted to maintain growth demonstrate some stem-like characteristics and as such constitute a legitimate therapeutic target. Cellular reprogramming technologies raise the potential of developing stem cells as novel surgical tools to target disease and possibly ameliorate some of the consequences of treatment. Achieving these goals remains a significant challenge to neurosurgical oncologists, not least in challenging how we think about treating brain cancer. This review will briefly examine our understanding of adult stem cells within the brain, the evidence that they contribute to the development of brain tumours as tumour-initiating cells, and the potential implications for therapy. It will also look at the role stem cells may play in the future management of glioma.

Adult human olfactory epithelial-derived progenitors: a potential autologous source for cell-based treatment for Parkinson's disease

Human adult olfactory epithelial-derived neural progenitors (hONPs) can differentiate along several neural lineages in response to morphogenic signals in vitro. A previous study optimized the transfection paradigm for the differentiation of hONPs to dopaminergic neurons. This study engrafted cells modified by the most efficient transfection paradigm for dopaminergic neural restriction and pretransfected controls into a unilateral neurotoxin, 6-hydroxydopamine-induced parkinsonian rat model. Approximately 35% of the animals engrafted with hONPs had improved behavioral recovery as demonstrated by the amphetamine-induced rotation test, as well as a corner preference and cylinder paw preference, over a period of 24 weeks. The pre- and post-transfected groups produced equivalent responses, indicating that the toxic host environment supported hONP dopaminergic differentiation in situ. Human fibroblasts used as a cellular control did not diminish the parkinsonian rotational deficits at any point during the study. Increased numbers of tyrosine hydroxylase (TH)-positive cells were detected in the engrafted brains compared with the fibroblast-implanted and medium-only controls. Engrafted TH-positive hONPs were detected for a minimum of 6 months in vivo; they were multipolar, had long processes, and migrated beyond their initial injection sites. Higher dopamine levels were detected in the striatum of behaviorally improved animals than in equivalent regions of their nonrecovered counterparts. Throughout these experiments, no evidence of tumorigenicity was observed. These results support our hypothesis that human adult olfactory epithelial-derived progenitors represent a unique autologous cell type with promising potential for future use in a cell-based therapy for patients with Parkinson's disease.

Effects of neonatal neural progenitor cell implantation on adult neuroanatomy and cognition in the Ts65Dn model of Down syndrome

As much of the aberrant neural development in Down syndrome (DS) occurs postnatally, an early opportunity exists to intervene and influence life-long cognitive development. Recent success using neural progenitor cells (NPC) in models of adult neurodegeneration indicate such therapy may be a viable option in diseases such as DS. Murine NPC (mNPC, C17.2 cell line) or saline were implanted bilaterally into the dorsal hippocampus of postnatal day 2 (PND 2) Ts65Dn pups to explore the feasibility of early postnatal treatment in this mouse model of DS. Disomic littermates provided karyotype controls for trisomic pups. Pups were monitored for developmental milestone achievement, and then underwent adult behavior testing at 14 weeks of age. We found that implanted mNPC survived into adulthood and migrated beyond the implant site in both karyotypes. The implantation of mNPC resulted in a significant increase in the density of dentate granule cells. However, mNPC implantation did not elicit cognitive changes in trisomic mice either neonatally or in adulthood. To the best of our knowledge, these results constitute the first assessment of mNPC as an early intervention on cognitive ability in a DS model.

Prospect of cell therapy for Parkinson's disease

The hallmark of Parkinson's disease is on-going degeneration of dopaminergic neurons in the substantia nigra, which may be due to various etiologies. Various approaches to alleviate symptoms are available, such as life-long pharmacological intervention, deep brain stimulation, and transplantation of dopaminergic neuron-containing fetal tissue. However, each of these approaches has a disadvantage. Several studies have shown that various kinds of stem cells, induced pluripotent stem cells, and other cells can differentiate into dopaminergic neurons and may be promising for treating Parkinson's disease in the future. Therefore, this review addresses those cells in terms of their prospects in cell therapy for Parkinson's disease. In addition, the need for safety and efficacy studies, various cell delivery modes and sites, and possible side effects will be discussed.

Reversal of chlorpyrifos neurobehavioral teratogenicity in mice by allographic transplantation of adult subventricular zone-derived neural stem cells

Neurobehavioral teratogenicity can be reversed with transplantation of neural stem cells. However, the usefulness of this therapy would be greatly enhanced by employing adult stem cells. In pursuit of this this goal, we developed a model that uses subventricular zone (SVZ) cells. HS/Ibg mice were exposed prenatally to chlorpyrifos on gestational days 9-18 (3 mg/kg/day, SC) in order to induce deficits in their performance in the Morris water maze test. Both the control and the exposed offspring were transplanted with SVZ cells (or vehicle) on postnatal day 35; this actually represents an allogenic transplantation, because the HS/Ibg strain is a heterogeneous stock. The transplanted cells were later observed in the host brain by DiI tracing, and their initial differentiation to cholinergic neurons and astrocytes was ascertained. On postnatal day 80, animals that had been exposed prenatally to chlorpyrifos displayed impaired Morris water maze performance, requiring more time to reach the platform. Transplantation of adult SVZ-derived neural stem cells (NSC) reversed the deficits. Applying autologous transplantation provides an important demonstration that the methodological obstacles of immunological rejection and the ethical concerns related to using embryonic stem cells may be successfully bypassed in developing stem cell therapies for neurodevelopmental disorders.

Age and sex differences in neural stem cell transplantation: a descriptive study in rats

Purpose

The purpose of this study was to determine whether neural stem cell (NSC) sexual dimorphism previously demonstrated in vitro translates in vivo in NSC transplantation experiments and constitutes a defining factor of the transplantation outcome.

Methods

NSCs isolated from the subventricular zone of 2-day-old or 20-month-old male and female rats were grown as neurospheres prior to being transplanted in the striatum of 2-day-old or 20-month-old male and female recipient animals. The outcome of the transplantation and the NSC differentiation status were analyzed 8 weeks later by assessing the expression of the markers doublecortin (DCX) for neuroblasts, glial fibrillary acidic protein (GFAP) for astrocytes, nestin for stem cells, and choline acetyltransferase (ChAT) for neuronal cholinergic phenotype by immunofluorescence.

Results

No NSCs were detected in the brain of rat pups 8 weeks after transplantation. However, the endogenous neurogenesis was dramatically increased in a sex-dependent manner. These data suggest that the transplanted NSCs may have triggered endogenous neurogenesis by the intermediate growth factors they may have produced or the production they may have induced. However, NSCs transplanted into the striatum of adult rats were detectable at week 8. NSC survival was dependent on the sex and age of the donor and the recipient. Some of the transplanted cells were found to express DCX, GFAP, and ChAT, supporting an ongoing differentiation process toward astroglial and neuronal cholinergic phenotypes.

Conclusion

The outcome of the NSC transplantation was highly dependent on the sex and age of the combination donor/recipient. Data generated from our work may allow us in the future to answer the question “What NSCs and for whom?” and consequently lead to the optimization of the grafting process and improvement of the clinical prognosis.

Clinical potential of intravenous neural stem cell delivery for treatment of neuroinflammatory disease in mice?

While neural stem cells (NSCs) are widely expected to become a therapeutic agent for treatment of severe injuries to the central nervous system (CNS), currently there are only few detailed preclinical studies linking cell fate with experimental outcome. In this study, we aimed to validate whether IV administration of allogeneic NSC can improve experimental autoimmune encephalomyelitis (EAE), a well-established animal model for human multiple sclerosis (MS). For this, we cultured adherently growing luciferase-expressing NSCs (NSC-Luc), which displayed a uniform morphology and expression profile of membrane and intracellular markers, and which displayed an in vitro differentiation potential into neurons and astrocytes. Following labeling with green fluorescent micron-sized iron oxide particles (f-MPIO-labeled NSC-Luc) or lentiviral transduction with the enhanced green fluorescent protein (eGFP) reporter gene (NSC-Luc/eGFP), cell implantation experiments demonstrated the intrinsic survival capacity of adherently cultured NSC in the CNS of syngeneic mice, as analyzed by real-time bioluminescence imaging (BLI), magnetic resonance imaging (MRI), and histological analysis. Next, EAE was induced in C57BL/6 mice followed by IV administration of NSC-Luc/eGFP at day 7 postinduction with or without daily immunosuppressive therapy (cyclosporine A, CsA). During a follow-up period of 20 days, the observed clinical benefit could be attributed solely to CsA treatment. In addition, histological analysis demonstrated the absence of NSC-Luc/eGFP at sites of neuroinflammation. In order to investigate the absence of therapeutic potential, BLI biodistribution analysis of IV-administered NSC-Luc/eGFP revealed cell retention in lung capillaries as soon as 1-min postinjection, resulting in massive inflammation and apoptosis in lung tissue. In summary, we conclude that IV administration of NSCs currently has limited or no therapeutic potential for neuroinflammatory disease in mice, and presumably also for human MS. However, given the fact that grafted NSCs have an intrinsic survival capacity in the CNS, their therapeutic exploitation should be further investigated, and-in contrast to several other reports-will most likely be highly complex.

Stem cell potential in Parkinson's disease and molecular factors for the generation of dopamine neurons

Parkinson's disease (PD) involves the loss of dopamine (DA) neurons, making it the most expected neurodegenerative disease to be treated by cell replacement therapy. Stem cells are a promising source for cell replacement therapy due to their ability to self-renew and their pluripotency/multipotency that allows them to generate various types of cells. However, it is challenging to derive midbrain DA neurons from stem cells. Thus, in this review, I will discuss the molecular factors that are known to play critical roles in the generation and survival of DA neurons. The developmental process of DA neurons and functions of extrinsic soluble factors and homeodomain proteins, forkhead box proteins, proneural genes, Nurr1 and genes involved in epigenetic control are discussed. In addition, different types of stem cells that have potential for future cell replacement therapy are reviewed.