Cerebrospinal fluid promotes survival and astroglial differentiation of adult human neural progenitor cells but inhibits proliferation and neuronal differentiation

Background  

Neural stem cells (NSCs) are a promising source for cell replacement therapies for neurological diseases. Growing evidence suggests an important role of cerebrospinal fluid (CSF) not only on neuroectodermal cells during brain development but also on the survival, proliferation and fate specification of NSCs in the adult brain. Existing in vitro studies focused on embryonic cell lines and embryonic CSF. We therefore studied the effects of adult human leptomeningeal CSF on the behaviour of adult human NSCs (ahNSCs).     

Calponin is expressed by subpopulations of connective tissue cells but not olfactory ensheathing cells in the neonatal olfactory mucosa

Background  

Debate has been ongoing on the relative merits of olfactory ensheathing cells (OECs) and Schwann cells as candidates for transplant-mediate repair of CNS lesions. Both glial cells exhibit similar molecular and cellular properties and to date there has been no antigenic marker identified that can clearly distinguish the two cell types. This inability to distinguish between the two cells types prevents confirmation of a controversial statement that cultures of OECs are contaminated with Schwann cells. Recently, proteomic analysis of foetal OECs and adult Schwann cells identified an actin-binding protein, calponin, as a specific marker for OECs. However, at the same time a recent report suggested that adult OECs do not express calponin. It was not clear if this discrepancy was due to methodology, as cells had to be treated with proteinase K to maximize calponin staining or developmental differences with only foetal/neonatal OECs expressing calponin. For this reason we have examined calponin expression in the peripheral olfactory system of embryonic and neonatal rats in vivo and from cells in vitro to assess if calponin is expressed in a developmental manner.     

Transcriptome analysis in primary neural stem cells using a tag cDNA amplification method

Background  

Neural stem cells (NSCs) can be isolated from the adult mammalian brain and expanded in culture, in the form of cellular aggregates called neurospheres. Neurospheres provide an in vitro model for studying NSC behaviour and give information on the factors and mechanisms that govern their proliferation and differentiation. They are also a promising source for cell replacement therapies of the central nervous system. Neurospheres are complex structures consisting of several cell types of varying degrees of differentiation. One way of characterising neurospheres is to analyse their gene expression profiles. The value of such studies is however uncertain since they are heterogeneous structures and different populations of neurospheres may vary significantly in their gene expression.     

Epidermal growth factor (EGF) withdrawal masks gene expression differences in the study of pituitary adenylate cyclase-activating polypeptide (PACAP) activation of primary neural stem cell proliferation

Background  

The recently discovered adult neural stem cells, which maintain continuous generation of new neuronal and glial cells throughout adulthood, are a promising and expandable source of cells for use in cell replacement therapies within the central nervous system. These cells could either be induced to proliferate and differentiate endogenously, or expanded and differentiated in culture before being transplanted into the damaged site of the brain. In order to achieve these goals effective strategies to isolate, expand and differentiate neural stem cells into the desired specific phenotypes must be developed. However, little is known as yet about the factors and mechanisms influencing these processes. It has recently been reported that pituitary adenylate cyclase-activating polypeptide (PACAP) promotes neural stem cell proliferation both in vivo and in vitro.     

Multimodal investigations of trans-endothelial cell trafficking under condition of disrupted blood-brain barrier integrity

Background  

Stem cells or immune cells targeting the central nervous system (CNS) bear significant promises for patients affected by CNS disorders. Brain or spinal cord delivery of therapeutic cells is limited by the blood-brain barrier (BBB) which remains one of the recognized rate-limiting steps. Osmotic BBB disruption (BBBD) has been shown to improve small molecule chemotherapy for brain tumors, but successful delivery of cells in conjunction with BBBD has never been reported.     

Lentivirus-mediated transgene delivery to the hippocampus reveals sub-field specific differences in expression

Background  

In the adult hippocampus, the granule cell layer of the dentate gyrus is a heterogeneous structure formed by neurons of different ages, morphologies and electrophysiological properties. Retroviral vectors have been extensively used to transduce cells of the granule cell layer and study their inherent properties in an intact brain environment. In addition, lentivirus-based vectors have been used to deliver transgenes to replicative and non-replicative cells as well, such as post mitotic neurons of the CNS. However, only few studies have been dedicated to address the applicability of these widespread used vectors to hippocampal cells in vivo. Therefore, the aim of this study was to extensively characterize the cell types that are effectively transduced in vivo by VSVg-pseudotyped lentivirus-based vectors in the hippocampus dentate gyrus.     

Neural stem cells and strategies for the regeneration of the central nervous system

The adult mammalian central nervous system (CNS), especially that of adult humans, is a representative example of organs that do not regenerate. However, increasing interest has focused on the development of innovative therapeutic methods that aim to regenerate damaged CNS tissue by taking advantage of recent advances in stem cell and neuroscience research. In fact, the recapitulation of normal neural development has become a vital strategy for CNS regeneration. Normal CNS development is initiated by the induction of stem cells in the CNS, i.e., neural stem cells (NSCs). Thus, the introduction or mobilization of NSCs could be expected to lead to CNS regeneration by recapitulating normal CNS development, in terms of the activation of the endogenous regenerative capacity and cell transplantation therapy. Here, the recent progress in basic stem cell biology, including the author’s own studies, on the prospective identification of NSCs, the elucidation of the mechanisms of ontogenic changes in the differentiation potential of NSCs, the induction of neural fate and NSCs from pluripotent stem cells, and their therapeutic applications are summarized. These lines of research will, hopefully, contribute to a basic understanding of the nature of NSCs, which should in turn lead to feasible strategies for the development of ideal “stem cell therapies” for the treatment of damaged brain and spinal cord tissue.     

A novel three-dimensional system to study interactions between endothelial cells and neural cells of the developing central nervous system

Background  

During angiogenesis in the developing central nervous system (CNS), endothelial cells (EC) detach from blood vessels growing on the brain surface, and migrate into the expanding brain parenchyma. Brain angiogenesis is regulated by growth factors and extracellular matrix (ECM) proteins secreted by cells of the developing CNS. In addition, recent evidence suggests that EC play an important role in establishing the neural stem cell (NSC) niche. Therefore, two-way communication between EC and neural cells is of fundamental importance in the developing CNS. To study the interactions between brain EC and neural cells of the developing CNS, a novel three-dimensional (3-D) murine co-culture system was developed. Fluorescent-labelled brain EC were seeded onto neurospheres; floating cellular aggregates that contain NSC/neural precursor cells (NPC) and smaller numbers of differentiated cells. Using this system, brain EC attachment, survival and migration into neurospheres was evaluated and the role of integrins in mediating the early adhesive events addressed.     

Neuronal expression of muskelin in the rodent central nervous system

Background  

The kelch repeat protein muskelin mediates cytoskeletal responses to the extracellular matrix protein thrombospondin 1, (TSP1), that is known to promote synaptogenesis in the central nervous system (CNS). Muskelin displays intracellular localization and affects cytoskeletal organization in adherent cells. Muskelin is expressed in adult brain and has been reported to bind the Cdk5 activator p39, which also facilitates the formation of functional synapses. Since little is known about muskelin in neuronal tissues, we here analysed the tissue distribution of muskelin in rodent brain and analysed its subcellular localization using cultured neurons from multiple life stages.     

Signalling crosstalk in FGF2-mediated protection of endothelial cells from HIV-gp120

Background  

The blood brain barrier (BBB) is the first line of defence of the central nervous system (CNS) against circulating pathogens, such as HIV. The cytotoxic HIV protein, gp120, damages endothelial cells of the BBB, thereby compromising its integrity, which may lead to migration of HIV-infected cells into the brain. Fibroblast growth factor 2 (FGF2), produced primarily by astrocytes, promotes endothelial cell fitness and angiogenesis. We hypothesized that treatment of human umbilical vein endothelial cells (HUVEC) with FGF2 would protect the cells from gp120-mediated toxicity via endothelial cell survival signalling.     

Differentiation of human bone marrow stem cells into cells with a neural phenotype: diverse effects of two specific treatments

Background  

It has recently been demonstrated that the fate of adult cells is not restricted to their tissues of origin. In particular, it has been shown that bone marrow stem cells can give rise to cells of different tissues, including neural cells, hepatocytes and myocytes, expanding their differentiation potential.     

Neural stem cells from protein tyrosine phosphatase sigma knockout mice generate an altered neuronal phenotype in culture

Background  

The LAR family Protein Tyrosine Phosphatase sigma (PTPσ) has been implicated in neuroendocrine and neuronal development, and shows strong expression in specific regions within the CNS, including the subventricular zone (SVZ). We established neural stem cell cultures, grown as neurospheres, from the SVZ of PTPσ knockout mice and sibling controls to determine if PTPσ influences the generation and the phenotype of the neuronal, astrocyte and oligodendrocyte cell lineages.     

Neural differentiation potential of human bone marrow-derived mesenchymal stromal cells: misleading marker gene expression

Background  

In contrast to pluripotent embryonic stem cells, adult stem cells have been considered to be multipotent, being somewhat more restricted in their differentiation capacity and only giving rise to cell types related to their tissue of origin. Several studies, however, have reported that bone marrow-derived mesenchymal stromal cells (MSCs) are capable of transdifferentiating to neural cell types, effectively crossing normal lineage restriction boundaries. Such reports have been based on the detection of neural-related proteins by the differentiated MSCs. In order to assess the potential of human adult MSCs to undergo true differentiation to a neural lineage and to determine the degree of homogeneity between donor samples, we have used RT-PCR and immunocytochemistry to investigate the basal expression of a range of neural related mRNAs and proteins in populations of non-differentiated MSCs obtained from 4 donors.     

Laminin enhances the growth of human neural stem cells in defined culture media

Background  

Human neural stem cells (hNSC) have the potential to provide novel cell-based therapies for neurodegenerative conditions such as multiple sclerosis and Parkinson's disease. In order to realise this goal, protocols need to be developed that allow for large quantities of hNSC to be cultured efficiently. As such, it is important to identify factors which enhance the growth of hNSC. In vivo, stem cells reside in distinct microenvironments or niches that are responsible for the maintenance of stem cell populations. A common feature of niches is the presence of the extracellular matrix molecule, laminin. Therefore, this study investigated the effect of exogenous laminin on hNSC growth.     

BrdU-positive cells in the neonatal mouse hippocampus following hypoxic-ischemic brain injury

Background  

Mechanisms that affect recovery from fetal and neonatal hypoxic-ischemic (H-I) brain injury have not been fully elucidated. The incidence of intrapartum asphyxia is approximately 2.5%, but the occurrence of adverse clinical outcome is much lower. One of the factors which may account for this relatively good outcome is the process of neurogenesis, which has been described in adult animals. We used a neonatal mouse model to assess new cells in the hippocampus after H-I injury.     

The effect of mesenchymal stem cell transplantation on the recovery of bladder and hindlimb function after spinal cord contusion in rats

Background  

Mesenchymal stem cells are widely used for transplantation into the injured spinal cord in vivo model and for safety, many human clinical trials are continuing to promote improvements of motor and sensory functions after spinal cord injury. Yet the exact mechanism for these improvements remains undefined. Neurogenic bladder following spinal cord injury is the main problem decreasing the quality of life for patients with spinal cord injury, but there are no clear data using stem cell transplantation for the improvement of neurogenic bladder for in vivo studies and the clinical setting.     

Notch signaling is required for maintaining stem-cell features of neuroprogenitor cells derived from human embryonic stem cells

Background  

Studies have provided important findings about the roles of Notch signaling in neural development. Unfortunately, however, most of these studies have investigated the neural stem cells (NSCs) of mice or other laboratory animals rather than humans, mainly owing to the difficulties associated with obtaining human brain samples. It prompted us to focus on neuroectodermal spheres (NESs) which are derived from human embryonic stem cell (hESC) and densely inhabited by NSCs. We here investigated the role of Notch signaling with the hESC-derived NESs.     

Adaptation of NS cells growth and differentiation to high-throughput screening-compatible plates

Background  

There is an urgent need of neuronal cell models to be applied to high-throughput screening settings while recapitulating physiological and/or pathological events occurring in the Central Nervous System (CNS). Stem cells offer a great opportunity in this direction since their self renewal capacity allows for large scale expansion. Protocols for directed differentiation also promise to generate populations of biochemically homogenous neuronal progenies. NS (Neural Stem) cells are a novel population of stem cells that undergo symmetric cell division in monolayer and chemically defined media, while remaining highly neurogenic.     

Neurospheres from rat adipose-derived stem cells could be induced into functional Schwann cell-like cells in vitro

Background  

Schwann cells (SC) which are myelin-forming cells in peripheral nervous system are very useful for the treatment of diseases of peripheral nervous system and central nervous system. However, it is difficult to obtain sufficient large number of SC for clinical use, so alternative cell systems are desired.     

Neurotrophin and Trk expression by cells of the human lamina cribrosa following oxygen-glucose deprivation

Background  

Ischemia within the optic nerve head (ONH) may contribute to retinal ganglion cell (RGC) loss in primary open angle glaucoma (POAG). Ischemia has been reported to increase neurotrophin and high affinity Trk receptor expression by CNS neurons and glial cells. We have previously demonstrated neurotrophin and Trk expression within the lamina cribrosa (LC) region of the ONH. To determine if ischemia alters neurotrophin and Trk protein expression in cells from the human LC, cultured LC cells and ONH astrocytes were exposed to 48 hours of oxygen-glucose deprivation (OGD). Also cells were exposed to 48 hours of OGD followed by 24 hours of recovery in normal growth conditions. Cell number, neurotrophin and Trk receptor protein expression, neurotrophin secretion, and Trk receptor activation were examined.