Expression of Neuronal Markers in Differentiated Marrow Stromal Cells and CD133+ Stem-Like Cells

The immunomodulatory effects of mesenchymal stromal cell-based therapy in human and animal models of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic systemic autoimmune inflammatory disease with no absolute cure. Although the exact etiopathogenesis of SLE is still enigmatic, it has been well demonstrated that a combination of genetic predisposition and environmental factors trigger a disturbance in immune responses and thereby participate in the development of this condition. Almost all available therapeutic strategies in SLE are primarily based on the administration of immunosuppressive drugs and are not curative. Mesenchymal stromal cells (MSCs) are a subset of non-hematopoietic adult stem cells that can be isolated from many adult tissues and are increasingly recognized as immune response modulating agents. MSC-mediated inhibition of immune responses is a complex mechanism that involves almost every aspect of the immune response. MSCs suppress the maturation of antigen-presenting cells (DC and MQ), proliferation of T cells (Th1, T17, and Th2), proliferation and immunoglobulin production of B cells, the cytotoxic activity of CTL and NK cells in addition to increasing regulatory cytokines (TGF-β and IL10), and decreasing inflammatory cytokines (IL17, INF-ϒ, TNF-α, and IL12) levels. MSCs have shown encouraging results in the treatment of several autoimmune diseases, in particular SLE. This report aims to review the beneficial and therapeutic properties of MSCs; it also focuses on the results of animal model studies, preclinical studies, and clinical trials of MSC therapy in SLE from the immunoregulatory aspect.

An Update on the Therapeutic Potential of Stem Cells

The seeming setbacks noted for stem cells underscore the need for experimental studies for safe and efficacious application to patients. Both clinical and experimental researchers have gained valuable knowledge on the characteristics of stem cells, and their behavior in different microenvironment. This introductory chapter focuses on adult mesenchymal stem cells (MSCs) based on the predominance in the clinic. MSCs can be influenced by inflammatory mediators to exert immune suppressive properties, commonly referred to as "licensing." Interestingly, while there are questions if other stem cells can be delivered across allogeneic barrier, there is no question on the ability of MSCs to provide this benefit. This property has been a great advantage since MSCs could be available for immediate application as "off-the-shelf" stem cells for several disorders, tissue repair and gene/drug delivery. Despite the benefit of MSCs, it is imperative that research continues with the various types of stem cells. The method needed to isolate these cells is outlined in this book. In parallel, safety studies are needed; particularly links to oncogenic event. In summary, this introductory chapter discusses several potential areas that need to be addressed for safe and efficient delivery of stem cells, and argue for the incorporation of microenvironmental factors in the studies. The method described in this chapter could be extrapolated to the field of chimeric antigen receptor T-cells (CAR-T). This will require application to stem cell hierarchy of memory T-cells.

Improved stem cell therapy of spinal cord injury using GDNF-overexpressed bone marrow stem cells in a rat model

The use of stem cell base therapy as an effective strategy for the treatment of spinal cord injury (SCI) is very promising. Although some strategy has been made to generate neural-like cells using bone marrow mesenchymal stem cells (BMSCs), the differentiation strategies are still inefficiently. For this purpose, we improved the therapeutic outcome with utilize both of N-neurotrophic factor derived Gelial cells (GDNF) gene and differentiation medium that induce the BMSCs into the neural-like cells. The differentiated GDNF overexpressed BMSCs (BMSCs-GDNF) were injected on the third day of post-SCI. BBB score test was performed for four weeks. Two weeks before the end of BBB, biotin dextranamin was injected intracrebrally and at the end of the fourth week, the tissue was stained. BBB scores were significantly different in BMSCs-GDNF injected and control animals. Significant difference in axon counting was observed in BMSCs-GDNF treated animals compared to the control group. According to the results, differentiated BMSCs-GDNF showed better results in comparison to the BMSCs without genetic modification. This study provides a new strategy to investigate the role of simultaneous in stem cell and gene therapy for future neural-like cells transplantation base therapies for SCI.

Bone Marrow Stromal Cells for Repair of the Spinal Cord: Towards Clinical Application

Stem cells have been recognized and intensively studied for their potential use in restorative approaches for degenerative diseases and traumatic injuries. In the central nervous system (CNS), stem cell-based strategies have been proposed to replace lost neurons in degenerative diseases such as Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis (Lou Gehrig's disease), or to replace lost oligodendrocytes in demyelinating diseases such as multiple sclerosis. Stem cells have also been implicated in repair of the adult spinal cord. An impact to the spinal cord results in immediate damage to tissue including blood vessels, causing loss of neurons, astrocytes, and oligodendrocytes. In time, more tissue nearby or away from the injury site is lost due to secondary injury. In case of relatively minor damage to the cord some return of function can be observed, but in most cases the neurological loss is permanent. This review will focus on in vitro and in vivo studies on the use of bone marrow stromal cells (BMSCs), a heterogeneous cell population that includes mesenchymal stem cells, for repair of the spinal cord in experimental injury models and their potential for human application. To optimally benefit from BMSCs for repair of the spinal cord it is imperative to develop in vitro techniques that will generate the desired cell type and/or a large enough number for in vivo transplantation approaches. We will also assess the potential and possible pitfalls for use of BMSCs in humans and ongoing clinical trials.

The expression of neurogenic markers after neuronal induction of chorion-derived mesenchymal stromal cells

OBJECTIVES

Chorion is a tissue of early embryologic period that is discarded after delivery. It might be the potential source of mesenchymal stromal cells (MSCs) that can be used for research and eventually for therapeutic studies. At present, the biological properties and the differentiation capacity of chorion-derived MSCs are still poorly characterised. The objective of this study is to characterise and explore the differentiating potential of chorion-derived MSCs towards the neuronal lineages.

METHODS

Chorionic membrane was digested with enzyme and cultured in Dulbecco's Modified Eagle's medium supplemented with 10% fetal bovine serum. The expression of MSC markers was examined using flow cytometry. The adipogenic, osteogenic and neurogenic differentiation were examined by culturing in appropriate induction media. The expression of neuronal markers was determined by immunofluorescence and quantitative real time-PCR.

RESULTS

Chorion-derived MSCs were easily expanded up to 20 passages. They were positive for MSC markers (CD73, CD90 and CD105), and negative for haematopoietic markers (CD34 and CD45). Chorion-derived MSCs could differentiate into several mesodermal-lineages including adipocytes and osteoblasts. Moreover, chorion-derived MSCs could differentiate into neuronal-like cells as characterised by cell morphology and the presence of neural markers including MAP-2, glial fibrillary acidic protein (GFAP) and beta-tubulin III.

DISCUSSION

Chorion-derived MSCs can be readily obtained and expanded in culture. These cells also have transdifferentiation capacity as evidenced by their neuronal differentiation potential. Therefore, chorion can be used as an alternative source of MSCs for stem cell therapy in nervous system disorders.

Umbilical cord-derived mesenchymal stem cells retain immunomodulatory and anti-oxidative activities after neural induction

The immunomodulatory and anti-oxidative activities of differentiated mesenchymal stem cells contribute to their therapeutic efficacy in cell-replacement therapy. Mesenchymal stem cells were isolated from human umbilical cord and induced to differentiate with basic fibroblast growth factor, nerve growth factor, epidermal growth factor, brain-derived neurotrophic factor and forskolin. The mesenchymal stem cells became rounded with long processes and expressed the neural markers, Tuj1, neurofilament 200, microtubule-associated protein-2 and neuron-specific enolase. Nestin expression was significantly reduced after neural induction. The expression of immunoregulatory and anti-oxidative genes was largely unchanged prior to and after neural induction in mesenchymal stem cells. There was no significant difference in the effects of control and induced mesenchymal stem cells on lymphocyte proliferation in co-culture experiments. However, the expression of human leukocyte antigen-G decreased significantly in induced neuron-like cells. These results suggest that growth factor-based methods enable the differentiation of mesenchymal stem cell toward immature neuronal-like cells, which retain their immunomodulatory and anti-oxidative activities.

Derivation of neural stem cells from human adult peripheral CD34+ cells for an autologous model of neuroinflammation

Proinflammatory factors from activated T cells inhibit neurogenesis in adult animal brain and cultured human fetal neural stem cells (NSC). However, the role of inhibition of neurogenesis in human neuroinflammatory diseases is still uncertain because of the difficulty in obtaining adult NSC from patients. Recent developments in cell reprogramming suggest that NSC may be derived directly from adult fibroblasts. We generated NSC from adult human peripheral CD34+ cells by transfecting the cells with Sendai virus constructs containing Sox2, Oct3/4, c-Myc and Klf4. The derived NSC could be differentiated to glial cells and action potential firing neurons. Co-culturing NSC with activated autologous T cells or treatment with recombinant granzyme B caused inhibition of neurogenesis as indicated by decreased NSC proliferation and neuronal differentiation. Thus, we have established a unique autologous in vitro model to study the pathophysiology of neuroinflammatory diseases that has potential for usage in personalized medicine.

Cell therapy: the final frontier for treatment of neurological diseases

Neurodegenerative diseases are devastating because they cause increasing loss of cognitive and physical functions and affect an estimated 1 billion individuals worldwide. Unfortunately, no drugs are currently available to halt their progression, except a few that are largely inadequate. This mandates the search of new treatments for these progressively degenerative diseases. Neural stem cells (NSCs) have been successfully isolated, propagated, and characterized from the adult brains of mammals, including humans. The confirmation that neurogenesis occurs in the adult brain via NSCs opens up fresh avenues for treating neurological problems. The proof-of-concept studies demonstrating the neural differentiation capacity of stem cells both in vitro and in vivo have raised widespread enthusiasm toward cell-based interventions. It is anticipated that cell-based neurogenic drugs may reverse or compensate for deficits associated with neurological diseases. The increasing interest of the private sector in using human stem cells in therapeutics is evidenced by launching of several collaborative clinical research activities between Pharma giants and research institutions or small start-up companies. In this review, we discuss the major developments that have taken place in this field to position stem cells as a prospective candidate drug for the treatment of neurological disorders.

MicroRNAs as markers for neurally committed CD133+/CD34+ stem cells derived from human umbilical cord blood

Neural differentiation of the CD133+/CD34+ subpopulation of human umbilical cord blood stem cells was investigated, and neuro-miR (mir-9 and mir-124) expression was examined. An efficient induction protocol for neural differentiation of hematopoietic stem cells together with the exclusion of retinoic acid in this process was also studied. Transcription of some neural markers such as microtubule-associated protein-2, beta-tubulin III, and neuron-specific enolase was evaluated by real-time PCR, immunocytochemistry, and western blotting. Increased expression of neural indicators in the treated cells confirmed the appropriate neural differentiation, which supported the high efficiency of our defined neuronal induction protocol. Verified high expression of neuro-miRNAs along with neuronal specific proteins not only strengthens the regulatory role of miRNAs in determining stem cell fate but also introduces these miRNAs as novel indicators of neural differentiation. These data highlight the prominent therapeutic potential of hematopoietic stem cells for use in cell therapy of neurodegenerative diseases.

The remyelination Philosopher's Stone: stem and progenitor cell therapies for multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease that leads to oligodendrocyte loss and subsequent demyelination of the adult central nervous system (CNS). The pathology is characterized by transient phases of recovery during which remyelination can occur as a result of resident oligodendroglial precursor and stem/progenitor cell activation. However, myelin repair efficiency remains low urging the development of new therapeutical approaches that promote remyelination activities. Current MS treatments target primarily the immune system in order to reduce the relapse rate and the formation of inflammatory lesions, whereas no therapies exist in order to regenerate damaged myelin sheaths. During the last few years, several transplantation studies have been conducted with adult neural stem/progenitor cells and glial precursor cells to evaluate their potential to generate mature oligodendrocytes that can remyelinate axons. In parallel, modulation of the endogenous progenitor niche by neural and mesenchymal stem cell transplantation with the aim of promoting CNS progenitor differentiation and myelination has been studied. Here, we summarize these findings and discuss the properties and consequences of the various molecular and cell-mediated remyelination approaches. Moreover, we address age-associated intrinsic cellular changes that might influence the regenerative outcome. We also evaluate the extent to which these experimental treatments might increase the regeneration capacity of the demyelinated human CNS and hence be turned into future therapies.

Current thoughts on the therapeutic potential of stem cell

Stem cells are considered as potential therapy for inflammatory disorders, tissue repair, and gene delivery, among others. The heterogeneity of a disease and the underlying disorder of a patient bring up the question on the method by which stem cells should be delivered. This summary discusses potential complex interactions among mediators at sites to tissue insults with stem cells. The chapter selects mesenchymal stem cells (MSCs) as a model, although the discussion is relevant to all stem cells. The review examines how MSCs and their differentiated cells can develop cross communication with soluble factors and cells within the region of tissue damage. Inflammatory cytokines, IL-1, TNFα, and TGFβ are selected to explain how they can affect the responses of MSCs, while predisposing the stem cells to oncogenic event. By understanding the varied functions of MSCs, one will be able to intervene to form a balance in functions, ultimately to achieve safety and efficient application. Cytokines can affect the expression of pluripotent genes such as REST and Oct-4. REST is a critical gene in the decision of a cell to express or repress neural genes. Since cytokines can affect microRNAs, the review incorporates this family of molecules as mediators of cytokine effects. IFNγ, although an inflammatory mediator, is central to the expression of MHC-II on MSCs. Therefore, it is included to discuss its role in the transplantation of stem cells across allogeneic barrier. In summary, this chapter discusses several potential areas that need to be addressed for safe and efficient delivery of stem cells, and argue for the incorporation of microenvironmental factors in the studies.

Stability of neural differentiation in human adipose derived stem cells by two induction protocols

There are some evidences for suggesting that adipose derived stem cells (ADSCs) can be differentiated to the fate of neural cell type. ADSCs can be expanded rapidly in vitro and can be obtained by a less invasive method. In this study, we attempted to compare the stability of neural differentiation in human ADSCs by using two induction protocols. Isolated ADSCs were induced into neural-like cells using diverse effects of two specific procedures. For protocol 1, ADSCs were induced by chemical induction. In protocol 2, ADSCs were treated for sphere formation. Then, the singled cells were cultured in neurobasal media supplemented with special components. Differentiated ADSCs were evaluated for Nestin, MAP2 and GFAP expression by immunocytochemistry and semi quantitative RT-PCR techniques. Moreover, MTT assay was employed to detect cell viability and proliferation. Immunocytochemical analysis of both protocols demonstrated that ADSCs had large expression of the neural-specific markers. In RT-PCR, protocol 1 showed the highest percentage of MAP2 expression, but with time passing, the neural like state was reversible. Protocol 2 found with express of Nestin at week 1, however MAP2 and GFAP expression increased after 3 weeks. The neural-like cells produced by protocol 1 led to the further cell death. Comparative analysis showed that neural-like cell differentiation of ADSCs in chemical induction protocol was rapid but transitory, while it was approximately steady in neurosphere formation protocol.

Glioblastoma-dependent differentiation and angiogenic potential of human mesenchymal stem cells in vitro

Tumor angiogenesis is of central importance in the malignancy of glioblastoma multiforme (GBM). As previously shown, human mesenchymal stem cells (hMSC) migrate towards GBM and are incorporated into tumor microvessels. However, phenotype and function of recruited hMSC remain unclear. We evaluated the differentiation and angiogenic potential of hMSC after stimulation with glioblastoma-conditioned medium in vitro. Immunostaining with endothelial, smooth muscle cell and pericyte markers was used to analyze hMSC differentiation in different concentrations of tumor-conditioned medium (CM), and the angiogenic potential was evaluated by matrigel-based tube-formation assay (TFA). Immunofluorescence staining revealed that tumor-conditioned hMSC (CM-hMSC) expressed CD 151, VE-cadherin, desmin, α-smooth muscle actin, nestin, and nerval/glial antigen 2 (NG2) in a CM concentration-dependent manner, whereas no expression of von-Willebrand factor (vWF) and smooth myosin could be detected. These findings are indicative of GBM-dependent differentiation of hMSC into pericyte-like cells, rather than endothelial or smooth muscle cells. Furthermore, TFA of hMSC and CM-hMSC revealed CM-dependent formation of capillary-like networks, which differed substantially from those formed by human endothelial cells (HUVEC), also implying pericyte-like tube formation. These results are indicative of GBM-derived differentiation of hMSC into pericyte-like mural cells, which might contribute to the neovascularization and stabilization of tumor vessels.

An efficient method for generation of neural-like cells from adult human bone marrow-derived mesenchymal stem cells

BACKGROUND

Stem cell-based therapies to repair and replace lost neural cells are a highly promising treatment for CNS diseases. Bone marrow (BM)-derived mesenchymal stem cells (MSCs) have great potential as therapeutic agents against neurological maladies, since they have the ability to differentiate into neural phenotypes and can be readily isolated and expanded for autotransplantation with no risk of rejection. In our previous studies, we demonstrated that neural cells could be efficiently generated from mouse BM-derived MSCs by exposing cells to epigenetic modifiers and a neural environment. The main idea of this approach was the reactivation of pluripotency-associated genes in MSCs before exposing them to neural-inducing factors.

AIM

In this study, we used a similar approach to efficiently generate neural cells from human BM-derived MSCs.

METHOD

Neural induction was achieved by exposing cells simultaneously to inhibitors of DNA methylation and histone deacetylation, and pharmacological agents that increase cAMP levels.

RESULTS

The expression of pluripotency and neural markers was confirmed with immunocytochemistry, western blot and real-time PCR. ELISA studies showed that these neurally induced-human MSCs cells released the neurotrophic factors glial cell-derived neurotrophic factor and brain-derived neurotrophic factor.

CONCLUSION

Human MSCs that are neurally modified with this methodology could be a useful source of cells for CNS repair and regeneration.

Neural differentiation of human adipose tissue-derived stem cells

While adult stem cells can be induced to transdifferentiate into multiple lineages of cells or tissues, their plasticity and utility for human therapy remains controversial. In this chapter, we describe methods for the transdifferentiation of human adipose tissue-derived stem cells (ASCs) along neural lineages using in vitro and in vivo systems. The in vitro neural differentiation of ASCs has been reported by several groups using serum-free cytokine induction, butylated hydroxyanisole (BHA) chemical induction, and neurosphere formation in combination with the cytokines, such as brain-derived neurotrophic factor (BDNF) and basic fibroblast growth factor (bFGF). For in vivo neurogenic induction, ASCs are treated with BDNF and bFGF to form neurospheres in vitro and then delivered directly to the brain. In this chapter, several detailed protocols for the effective neurogenic induction of ASCs in vitro and in vivo are described. The protocols described herein can be applied to further molecular and mechanistic studies of neurogenic induction and differentiation of ASCs. In addition, these methods can be useful for differentiating ASCs for therapeutic intervention in central nervous system disorders.

Lentiviral vector-mediated knockdown of the NG2 [corrected] proteoglycan or expression of neurotrophin-3 promotes neurite outgrowth in a cell culture model of the glial scar

BACKGROUND

Following spinal cord injury, a highly inhibitory environment for axonal regeneration develops. One of the main sources of this inhibition is the glial scar that is formed after injury by reactive astrocytes. The inhibitory environment is mainly a result of chondroitin sulphate proteoglycans (CSPGs). NG2, [corrected] one of the main inhibitory CSPGs, is up-regulated following spinal cord injury.

METHODS

Small interfering RNA (siRNA) was designed to target NG2 and this short hairpin RNA (shRNA) was cloned into a lentiviral vector (LV). The neurotrophic factor neurotrophin-3 (NT-3) promotes the growth and survival of developing neurites and has also been shown to aid regeneration. NT-3 was also cloned into a LV. In vitro assessment of these vectors using a coculture system of dorsal root ganglia (DRG) neurones and Neu7 astrocytes was carried out. The Neu7 cell line is a rat astrocyte cell line that overexpresses NG2, thereby mimicking the inhibitory environment following spinal cord injury.

RESULTS AND DISCUSSION

These experiments show that both the knockdown of NG2 via shRNA and over-expression of NT-3 can significantly increase neurite growth, although a combination of both vectors did not confer any additional benefit over the vectors used individually. These LVs show promising potential for growth and survival of neurites in injured central nervous system tissue (CNS).

Immunohistochemical analysis of developmental neural antigen expression in the balloon cells of focal cortical dysplasia

Balloon cells (BC) are the histological hallmarks of focal cortical dysplasia (FCD). Expression of the neural stem cell surface marker CD133 and other developmental markers was studied in the BC of FCD using formalin-fixed paraffin-embedded tissue from nine patients with FCD. Labeling indexes were calculated for all antibodies. BC were easily identified at the gray-white matter junction and they extended into the white matter. Immunoreactivity in BC was found for the following antigens in nine patients: CD133 (six patients; 22.2 ± 7.7%), CD34 (two patients; 0.4 ± 0.3%), nestin (nine patients; 37.6 ± 8.5%), vimentin (eight patients; 59.2 ± 8.7%), glial fibrillary acid protein (six patients; 34.3 ± 10.4%), microtubule-associated protein 2 (four patients; 8.3 ± 5.0%), neurofilament-middle/high (five patients; 10.2 ± 4.6%) and synaptophysin (three patients; 4.2 ± 3.3%). Neuronal nuclei (NeuN, neuron specific nuclear protein) was not expressed in BC of any patient. The results of this study suggest that BC in patients with FCD originate from glioneuronal precursor cells and that developmental defects of neuronal and glial specifications are important in the histogenesis of FCD.

Both interleukin-3 and interleukin-6 are necessary for better ex vivo expansion of CD133+ cells from umbilical cord blood

Umbilical cord blood (UCB), an ideal source for transplantable hematopoietic stem cells (HSC), is readily available and is rich in progenitor cells. Identification of conditions favoring UCB-HSC ex vivo expansion and of repopulating potential remains a major challenge in hematology. CD133+ cells constitute an earlier, less-differentiated HSC group with a potentially higher engraftment capacity. The presence of SCF, Flt3-L, and TPO are essential for CD133+ and/or CD34+ cells ex vivo expansion; however, IL-3 and IL-6 influence has not yet been clearly established. We investigated this influence on CD133+ cells from UCB ex vivo expansion and the effect of these cytokines upon cell phenotype. Immediately after isolation an 85% of CD133+ cell purity was obtained, diminishing after 4 and 8 days of ex vivo expansion. CD133+ fold-increase was higher using IMDM with SCF, Flt3-L, and TPO (BM)+IL-3 or BM+IL-3+IL-6 on day 8 (13.83- and 17.47-fold increase, respectively). BM+IL-6 presented no significant difference from BM alone. We demonstrated that 5.1% of the CD133+ cells expressed IL-6 receptor (IL-6R) after isolation. After 4 and 8 days in culture, the percentage of CD133+ cells that expressed IL-6R was as follows: BM alone (9.8% and 22.02%, respectively); BM+IL-3 (8.33% and 16.74%); BM+IL-6 (9.2% and 17.67%); and BM+IL-3+IL-6 (12.5% and 61.20%). Cell cycle analysis revealed quiescent cells after isolation, 95.5% CD133+ cells in the G0/G1 phase. Regardless of culture period or cytokine incubation, CD133+ cell cycle altered to 70% of CD133+ in the G0/G1 phase. Colony-forming unit (CFU) doubled in BM+IL-3+IL-6 after 8 days of incubation compared with BM group. SOX-2 and NANOG-relative gene expression was detected on day 0 after isolation. BM+IL-6 prevented the decrease in NANOG and SOX-2 gene expression level compared to BM+IL-3 or BM+IL-3+IL-6 incubated cells. Our results indicated that UCB-isolated CD133+ cells were better ex vivo expanded in the presence of SCF, Flt3-L, TPO, IL-3+IL-6. IL-3 probably promotes higher CD133+ cell expansion and IL-6 maintains immature phenotype.

High expression of large-conductance Ca2+-activated K+ channel in the CD133+ subpopulation of SH-SY5Y neuroblastoma cells

Solid tumors contain a population of cancer stem cells (CSCs), and CD133 is widely used as a CSCs marker. We investigated the differences between CD133(+) and CD133(-) cells from the neuroblastoma cell line SH-SY5Y in terms of the expressions of voltage-gated ion channels. A CD133(+) enriched (>60%) population was isolated, and a subsequent whole-cell voltage-clamp study showed that these cells predominantly express TEA-sensitive outward K(+) currents (I(K,TEA)) and TTX-sensitive voltage-gated inward Na(+) currents (I(Na)). Cell-attached single channel recordings demonstrated higher density of large-conductance (155pS) channel in CD133(+) cells than in CD133(-) cells. The TEA-sensitivity and single channel conductance indicated the large-conductance Ca(2+)-activated K(+) channels (BK(Ca)). Furthermore, RT-PCR analysis of 22 transcripts of voltage-gated ion channels in SH-SY5Y cells showed the expressions of Cav1.3, Kir2.1, Kv1.4, Kv2.1, Kv4.2, Kv7.1, BK(Ca), and Nav1.7, and those of BK(Ca) and Nav1.7 were higher in CD133(+) than in CD133(-) cells. In addition, the increase of cytosolic Ca(2+) concentration ([Ca(2+)](c)) in response to ionomycin (a Ca(2+) ionophore) was higher and more sustained in CD133(+) than in CD133(-) cells. Plausibly membrane hyperpolarization via BK(Ca) might be responsible for the augmented Ca(2+) influx observed in CD133(+) cells. The physiological implications of the differential expression of BK(Ca) and Nav1.7 in CSCs require further investigation.

Functional neural differentiation of human adipose tissue-derived stem cells using bFGF and forskolin

Background

Adult mesenchymal stem cells (MSCs) derived from adipose tissue have the capacity to differentiate into mesenchymal as well as endodermal and ectodermal cell lineage in vitro. We characterized the multipotent ability of human adipose tissue-derived stem cells (hADSCs) as MSCs and investigated the neural differentiation potential of these cells.

Results

Human ADSCs from earlobe fat maintained self-renewing capacity and differentiated into adipocytes, osteoblasts, or chondrocytes under specific culture conditions. Following neural induction with bFGF and forskolin, hADSCs were differentiated into various types of neural cells including neurons and glia in vitro. In neural differentiated-hADSCs (NI-hADSCs), the immunoreactivities for neural stem cell marker (nestin), neuronal markers (Tuj1, MAP2, NFL, NFM, NFH, NSE, and NeuN), astrocyte marker (GFAP), and oligodendrocyte marker (CNPase) were significantly increased than in the primary hADSCs. RT-PCR analysis demonstrated that the mRNA levels encoding for ABCG2, nestin, Tuj1, MAP2, NFL, NFM, NSE, GAP43, SNAP25, GFAP, and CNPase were also highly increased in NI-hADSCs. Moreover, NI-hADSCs acquired neuron-like functions characterized by the display of voltage-dependent tetrodotoxin (TTX)-sensitive sodium currents, outward potassium currents, and prominent negative resting membrane potentials under whole-cell patch clamp recordings. Further examination by RT-PCR showed that NI-hADSCs expressed high level of ionic channel genes for sodium (SCN5A), potassium (MaxiK, Kv4.2, and EAG2), and calcium channels (CACNA1C and CACNA1G), which were expressed constitutively in the primary hADSCs. In addition, we demonstrated that Kv4.3 and Eag1, potassium channel genes, and NE-Na, a TTX-sensitive sodium channel gene, were highly induced following neural differentiation.

Conclusions

These combined results indicate that hADSCs have the same self-renewing capacity and multipotency as stem cells, and can be differentiated into functional neurons using bFGF and forskolin.

Platelet-derived growth factor BB mediates the tropism of human mesenchymal stem cells for malignant gliomas

OBJECTIVE

Bone marrow-derived human mesenchymal stem cells (hMSCs) are capable of localizing to gliomas after systemic delivery and can be used in glioma therapy. However, the mechanism underlying the tropism of hMSCs for gliomas remains unclear. In vitro studies suggest that platelet-derived growth factor BB (PDGF-BB) may mediate this tropism. However, a causal role of PDGF-BB has not been demonstrated in vivo. Therefore, we tested the hypothesis that PDGF-BB mediates the attraction of hMSCs to gliomas in vitro and in vivo.

METHODS

U87 or LN229 glioma cells were transfected with plasmids encoding human PDGF-B. Stable transfected clones that secreted large amounts of PDFG-BB and clones that produced low levels of PDGF were chosen. In vitro migration of hMSCs toward PDGF-B or conditioned media from high- and low-secreting PDGF-B tumor cells was assessed using Matrigel invasion assays. For in vivo localization studies, hMSCs were tracked by bioluminescence imaging (BLI) after transduction with an adenovirus containing luciferase cDNA. In other studies, hMSCs were labeled with green fluorescent protein (gfp) and analyzed for intratumoral localization by immunohistochemistry.

RESULTS

In vitro invasion assays showed that significantly more hMSCs migrated toward glioma cells engineered to secrete high levels of PDGF-BB compared with low-secreting gliomas. Anti-PDGF-BB-neutralizing antibody abrogated this increase in migration. Pretreatment of hMSCs with inhibitory antibodies against PDGF receptor-beta also reduced hMSC migration. To demonstrate that PDGF-BB mediates the localization of hMSCs in vivo, hMSCs-Ad-Luc were injected into the carotid artery of mice harboring orthotopic 7-day-old U87-PDGF-BB-high secreting or U87-PDGF-BB-low secreting xenografts and analyzed by BLI. Statistically significant increases in hMSCs were seen within PDGF-BB-high xenografts compared with PDGF-BB-low xenografts. To control for PDGF-BB-induced differences in tumor size and vascularity, gfp-labeled hMSCs were injected into the carotid arteries of animals harboring 4-day old PDGF-BB-high secreting xenografts or 7-day old PDGF-BB-low secreting xenografts. At these times tumors had similar size and vessel density. Statistically significant more hMSCs localized to PDGF-BB-high secreting xenografts compared with PDGF-BB-low secreting xenografts. Pretreatment of hMSCs with anti-PDGFR-beta-inhibitory antibodies decreased the localization of hMSCs in this intracranial model.

CONCLUSION

PDGF-BB increases the attraction of hMSCs for gliomas in vitro and in vivo, and this tropism is mediated via PDGF-beta receptors on hMSCs. These findings can be exploited for advancing hMSC treatment.

Purification of Mouse Bone Marrow-Derived Stem Cells Promotes Ex Vivo Neuronal Differentiation

The main objective of this study is to test the potential of specific populations of mouse bone marrow-derived stem cells (BMSCs) to differentiate into the neuronal cell lineage. Bone marrow of 33 mice was aspirated under general anesthesia. The collected marrows were analyzed for cell counts, compositions, and percentages of different stem cell types. We used the Midi MACS magnetic separator to purify specific populations of stem cells from the aspirated bone marrow. Cells were analyzed using flow cytometry. We assessed the presence of stem cell antigen-1 (Sca-1+) and prominin-1+ cells in the cellular fraction that was depleted of lineage-committed cells (lineage-). Both purified and nonpurified cells were cultured ex vivo using specific growth media with factors that drive the cells to differentiate into the neuroglial cell types. Cells were then analyzed by flow cytometry for expression of specific neuronal markers. Our results showed that there was an increase of Sca-1+ and prominin-1+ cells in the lineage- fraction over the unpurified BM. After lineage depletion, the percentages of Sca-1+ and prominin-1+ cells increased from 4.9% and 2.6%, up to 76.1% and 59%, respectively. Unpurified mouse BM differentiated into fibroblasts, whereas Sca-1+ cells were able to generate astrocytes. Interestingly, purified prominin-1+ cells were able to generate neuronal cells. Purification of adult bone marrow-derived stem cells enhances their potentiality for differentiating into specific neuronal cell lineages.

CD34+ and CD133+ Primitive Stem Cell Expression in Peripheral Blood: Considering Gender, Age, and Smoking

BACKGROUND: The number of primitive progenitor cells (pPC) in healthy individuals, in correlation to age, gender, and smoking status, has not yet been thoroughly elucidated. MATERIAL AND METHODS: The pPC from a collective of 168 healthy blood donors aged 18-61 years was investigated using flow cytometric analysis. In addition, the pPC of 20 subjects were studied once a month for half a year to determine the extent of physiological variation of pPC within a single individual. RESULTS: We demonstrated a statistically significant difference (p = 0.005) in the numbers of pPC in men (836,100/l) versus women (583,850/l). No statistical difference was found between younger and older donors or between smokers and non-smokers, both overall and within a single gender. The extent of physiological variation in pPC was lower than 20% in 2 individuals, 18 individuals exhibited amplitudes greater than 20%. CONCLUSION: We conclude that the number of pPC in healthy individuals was primarily determined by gender as an operative factor. It seems that age and smoking status are of minor importance. Furthermore, our data demonstrate strong variability in the expression of pPC within a single individual. This may be influenced by varying physiological and environmental factors.

In vitro and in vivo characterization of neurally modified mesenchymal stem cells induced by epigenetic modifiers and neural stem cell environment

Mesenchymal stem cell (MSC)-mediated tissue regeneration is a promising strategy to treat several neurodegenerative diseases and traumatic injuries of the central nervous system. Bone marrow MSCs have great potential as therapeutic agents, since they are easy to isolate and expand and are capable of producing various cell types, including neural cells. Recently we developed a highly efficient methodology to produce neural stem-like and neural precursor-like cells from mice bone marrow-derived MSCs that eventually differentiate into neuronal- and glial-like cells in vitro. The aim of this study is to further elucidate neural expression profile of neurally induced mesenchymal stem cells (NI-MSCs) and their ability to retain neural differentiation potential when grafted into the intact spinal cord of rats. To this end, we further characterized in vitro and in vivo properties of NI-MSCs by immunocytochemistry, Western blot, ELISA, and immunohistochemistry. Immunocytochemical data demonstrated that NI-MSCs express several mature neural markers such as B3T, GFAP MAP-2, NF-200, and NeuN, which were confirmed through Western blot. ELISA data showed that NI-MSCs release nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF). In vivo studies demonstrated that grafted NI-MSCs survived after transplantation into intact spinal cord and produced cells that expressed neural markers. All these data suggest that neurally modified MSCs, induced by recently developed methodology, could be a potential source of cells to replace damaged neurons and glia in injured spinal cord, and/or to promote cell survival and axonal growth of host tissue.

Differentiation of human adipose-derived adult stem cells into neuronal tissue: does it work?

Adipose tissue contains many cells and proteins that are of value not only for their potential therapeutic applications, but also for the low cost of their harvest and delivery. Mesenchymal stem cells (MSC) were originally isolated from the bone marrow, although similar populations have been isolated from adipose and other tissues. At one time, neural tissues were not regarded as regenerative populations of cells. Therefore, the identification of cell populations capable of neuronal differentiation has generated immense interest. Adipose tissue may represent an alternative source of cells that are capable of neuronal differentiation, potentially enhancing its use in the treatment of neurological disease. The aim of this review is to cover the current state of knowledge of the differentiation potential of human adipose-derived stem (ADAS) cells, specifically their ability to give rise to neuronal cells in vitro. This review presents and discusses different protocols used for inducing human ADAS cells to differentiate in vitro, and the neuronal markers utilized in each system.

Transplantation of human bone marrow-derived stromal cells into the contused spinal cord of nude rats

OBJECT

Human bone marrow stromal cells (hMSCs) constitute a potential source of pluripotent stem cells. In the present study, hMSCs were transplanted into an area of spinal cord contusion in nude rats to determine their survival, differentiation, potential for neuroprotection, and influence on axonal growth and functional recovery.

METHODS

Twenty-nine animals received 6 x 10(5) hMSCs in 6 microl medium 1 week after a contusion, while 14 control animals received an injection of 6 microl medium alone. Basso-Beattie-Bresnahan (BBB) tests were performed weekly. The spinal cords were collected at 6 weeks posttransplantation for histological analysis and assessment of tissue injury.

RESULTS

Immunostaining with anti-human mitochondria antibody and pretransplantation labeling with green fluorescent protein demonstrated that the grafted hMSCs survived and were capable of achieving a flattened appearance in the grafted area; however, none of the transplanted cells stained positively for human-specific neuronal, anti-neurofilament H or glial fibrillary acidic protein within the sites of engraftment. While neuronal or astrocytic differentiation was not seen, cells lining blood vessels in the vicinity of the transplant stained positively for anti-human endothelium CD105 antibody. Staining for anti-neurofilament H antibody demonstrated abundant axonlike structures around the transplanted area in the hMSC group. Tissue sparing analysis showed that animals with grafted hMSCs had a smaller area of contusion cyst compared with controls, but there was no significant difference between the two groups in BBB scores.

CONCLUSIONS

The grafted hMSCs survived for > or = 6 weeks posttransplantation, although they did not differentiate into neural or glial cells. Cells with human endothelial characteristics were observed. Spinal cord-injured rats grafted with hMSCs had smaller contusion cavities, which did not have a significant influence on functional recovery.

Identification of surface markers for prospective isolation of human endometrial stromal colony-forming cells

BACKGROUND

Human endometrium is a highly regenerative tissue. We hypothesized that the source of endometrial stromal and vascular regeneration is a resident stromal stem/progenitor cell population. Putative human endometrial stromal stem/progenitor cells have been identified using clonal assays, a retrospective functional stem cell assay. Therefore, the aim of this study was to screen potential stem cell markers for the prospective isolation of human endometrial stromal stem/progenitor cells and to determine their capacity to identify colony-forming stromal cells.

METHODS

Single-cell suspensions of human endometrial stromal cells were sorted using fluorescence-activated cell sorting into positive and negative populations based on STRO-1, CD133, CD90 or CD146 expression for clonal assays. All markers were immunolocalized in human endometrium.

RESULTS

Small populations (2-9%) of human endometrial stromal cells expressed each of the markers. Only CD146(+) cells were enriched for colony-forming cells, and CD90(hi) cells showed a trend for greater enrichment compared with CD90(lo) cells. STRO-1 and CD146 were localized to perivascular cells of the endometrium. CD90 was strongly expressed by functionalis stroma and perivascular cells, but only weakly expressed in the basalis stroma. CD133 was expressed by epithelial cells of the endometrium, rather than by stroma or perivascular cells.

CONCLUSIONS

This study identified CD146 as a marker of colony-forming human endometrial stromal cells supporting the concept that human endometrium contains a population of candidate stromal stem/progenitor cells.

New insights into the cell biology of hematopoietic progenitors by studying prominin-1 (CD133)

Prominin-1 (alias CD133) has received considerable interest because of its expression by several stem and progenitor cells originating from various sources, including the neural and hematopoietic systems. As a cell surface marker, prominin-1 is now used for somatic stem cell isolation. Its expression in cancer stem cells has broadened its clinical value, as it might be useful to outline new prospects for more effective cancer therapies by targeting tumor-initiating cells. Cell biological studies of this molecule have demonstrated that it is specifically concentrated in various membrane structures that protrude from the planar areas of the plasmalemma. Prominin-1 binds to the plasma membrane cholesterol and is associated with a particular membrane microdomain in a cholesterol-dependent manner. Although its physiological function is not yet determined, it is becoming clear that this cell surface protein, as a unique marker of both plasma membrane protrusions and membrane microdomains, might reveal new aspects of the cell biology of rare stem and cancer stem cells. The aim of this review is to outline the recent discoveries regarding the dynamic reorganization of the plasma membrane of rare CD133+ hematopoietic progenitor cells during cell migration and division.

Formation of neurons by non-neural adult stem cells: potential mechanism implicates an artifact of growth in culture

Trans-differentiation is a mechanism proposed to explain how tissue-specific stem cells could generate cells of other organs, thus supporting the emerging concept of enhanced adult stem cell plasticity. Although spontaneous cell fusion rather than trans-differentiation may explain some unexpected cell fate changes in vivo, such a mechanism does not explain potential trans-differentiation events in vitro, including the generation of neural cell types from cultured bone marrow-derived stem cells. Here we present evidence that shows that cultured bone marrow-derived stem cells express neural proteins and form structures resembling neurons under defined growth conditions. We demonstrate that these changes in cell structure and neural protein expression are not consistent with typical neural development. Furthermore, the ability of bone marrow-derived stem cells to adopt a neural phenotype in vitro may occur as a result of cellular stress in response to removing cells from their niche and their growth in alternative environmental conditions. These findings suggest a potential explanation for the growth behavior of cultured bone marrow-derived stem cells and highlight the need to carefully validate the plasticity of stem cell differentiation.

Viable CD34+/CD133+ blood progenitor cell dose as a predictor of haematopoietic engraftment in multiple myeloma patients undergoing autologous peripheral blood stem cell transplantation

Both CD34 (cluster of differentiation 34) and the more recently described CD133 are markers of primitive stem cells with haematopoietic repopulating ability. Most transplanting centres use a minimum number of CD34+ cells as the requirement for a transplant and consider this a predictor of haematopoietic engraftment. However, transplanted CD34+ cell dose does not always give a close correlation with time to engraftment nor explain delayed engraftment in some patients. We have retrospectively evaluated the potential of measuring viable CD133+ cell numbers in the autograft as an alternative predictor of haematological engraftment after autologous stem-cell transplantation in a cohort of patients with multiple myeloma (MM). We found an average 32% loss of viability of CD34+ cells in the post-thaw sample compared with the fresh sample. Of the original estimated CD34+ cell numbers transplanted per kg, 43% of the thawed samples were double positive for CD34+/CD133+. In this patient group, the CD34+/CD133+ subset gave the closest statistical correlation with time to neutrophil engraftment (p < 0.05), particularly for patients given above median (1.8 x 10(6)/kg) dose of the double-positive cells. The CD34+/CD133+ population was the only parameter to give a significant correlation with white cell engraftment in this patient cohort (p < 0.05). There was no significant correlation between CD34+, viable CD34+ or viable CD34+/CD133+ cells/kilogram with platelet engraftment. Determination of viable CD34+/CD133+ progenitor cell dose in the autograft may be a useful tool to predict neutrophil recovery after autologous transplantation than conventional assessment of CD34+ numbers. These results warrant further investigation of the role of CD133 in haematopoietic engraftment.

Malignant gliomas actively recruit bone marrow stromal cells by secreting angiogenic cytokines

The transplantation of progenitor cells is a promising new approach for the treatment of gliomas. Marrow stromal cells (MSC) are possible candidates for such a cell-based therapy, since they are readily and autologously available and show an extensive tropism to gliomas in vitro and in vivo. However, the signals that guide the MSC are still poorly understood. In this study, we show that gliomas have the capacity to actively attract MSC by secreting a multitude of angiogenic cytokines. We demonstrate that interleukin-8 (IL-8), transforming growth factor-ss1 (TGF-ss1) and neurotrophin-3 (NT-3) contribute to this glioma-directed tropism of human MSC. Together with the finding that vascular endothelial growth factor (VEGF) is another MSC-attracting factor secreted by glioma cells, these data support the hypothesis that gliomas use their angiogenic pathways to recruit mesenchymal progenitor cells.

Detection of Bone Marrow-Derived Cells Expressing a Neural Phenotype in the Human Brain

Animal studies suggest that adult bone marrow cells have the potential to migrate into the brain and generate new neural cells. Because data on this physiologic repair mechanism in humans are lacking, we investigated bone marrow engraftment into the brain of bone marrow recipients after sex-mismatched transplantation. Brain sections of seven allogeneic female bone marrow recipients were examined. The Y-chromosome, which served as a natural marker of donor bone marrow-derived cells after male-to-female transplantation, was identified by in situ hybridization. The neural phenotype of Y-chromosome-positive cells was determined using neural nuclear protein (NeuN) immunohistochemistry. Y-chromosome-positive cells expressing NeuN were found within the first 3 months after transplantation in both the cerebrum and the cerebellum at a frequency of 0.003% to 0.013% of all neurons. These cells were observed only in patients with cerebral lymphocytic infiltration and graft-versus-host disease. Our data suggest that adult bone marrow cells are capable of generating cells that express the neural marker NeuN early after transplantation. Cells with this specific phenotype may contribute to tissue repair in brain regions remote from neurogenic zones.

Human bone marrow mesenchymal stromal cells express the neural ganglioside GD2: a novel surface marker for the identification of MSCs

Mesenchymal stromal cells (MSCs) have enormous potential for the regeneration of bone, cartilage, and other tissues derived from primitive mesoderm. Despite extensive research, there is still no single marker that reliably identifies MSCs within the bone marrow. Using immunocytochemistry and flow cytometry, we demonstrate here that the neural ganglioside GD2 is expressed by MSCs either newly isolated from bone marrow or expanded in tissue culture; this finding was supported by reverse transcriptase-polymerase chain reaction (RT-PCR) analysis showing expression of the mRNA for GD2 synthase, an essential enzyme for GD2 biosynthesis. GD2 was also expressed on MSCs isolated from adipose tissue, but not on foreskin fibroblasts. Importantly, MSCs were the only cells within normal marrow that expressed this marker. Thus, GD2 appears to be the first reported single surface marker that uniquely distinguishes MSCs from other marrow elements. GD2 may prove valuable to study MSC biology and for the preparation of MSCs for clinical applications.

Differentiation assays of bone marrow-derived Multipotent Adult Progenitor Cell (MAPC)-like cells towards neural cells cannot depend on morphology and a limited set of neural markers

There are accumulating studies that report a neurogenic potential of bone marrow-derived cells both in vitro as well as in vivo. Most claims of neural "transdifferentiation" have based their conclusions on morphology and neural gene expression. Recently, doubts have been raised about the validity of both outcome parameters since non-neural cells can extend neurites and show aberrant neural gene expression as a response to stress inducing factors. In this study, we compared bone marrow-derived Multipotent Adult Progenitor Cell (MAPC)-like cells and neural stem cells (NSC) in their morphology and neural gene expression profile after neural differentiation using three differentiation protocols. We evaluated the expression of five neuroglial antigens [neurofilament 200 (NF200); beta III tubulin (beta3 tub); tau; Glial Fibrillary Acidic Protein (GFAP); Myelin Basic Protein (MBP) and RIP antigen] using real-time PCR (RT-PCR) and immunocytochemistry (ICC). MAPC-like cells adopted a neural-like morphology in one protocol but a fibroblast-like morphology in the two other protocols. RT-PCR and ICC show that MAPC-like cells already express the neural antigens beta III tubulin and NF200 at baseline, but no upregulation of these genes after exposure to three distinct differentiation protocols was seen. In contrast, NSC adopt neural and glial morphologies with a clear increase in expression of all neuroglial genes in all differentiation protocols used. In conclusion, our data demonstrate that neural-like morphology and expression of a limited set of neural marker genes by MAPC-like cells after differentiation are not absolute proof of neural transdifferentiation because MAPC-like cells only partially meet the criteria which are fulfilled by NSC after neural differentiation.

Candidate genes, pathways and mechanisms for alcoholism: an expanded convergent functional genomics approach

We describe a comprehensive translational approach for identifying candidate genes for alcoholism. The approach relies on the cross-matching of animal model brain gene expression data with human genetic linkage data, as well as human tissue data and biological roles data, an approach termed convergent functional genomics. An analysis of three animal model paradigms, based on inbred alcohol-preferring (iP) and alcohol-non-preferring (iNP) rats, and their response to treatments with alcohol, was used. A comprehensive analysis of microarray gene expression data from five key brain regions (frontal cortex, amygdala, caudate-putamen, nucleus accumbens and hippocampus) was carried out. The Bayesian-like integration of multiple independent lines of evidence, each by itself lacking sufficient discriminatory power, led to the identification of high probability candidate genes, pathways and mechanisms for alcoholism. These data reveal that alcohol has pleiotropic effects on multiple systems, which may explain the diverse neuropsychiatric and medical pathology in alcoholism. Some of the pathways identified suggest avenues for pharmacotherapy of alcoholism with existing agents, such as angiotensin-converting enzyme (ACE) inhibitors. Experiments we carried out in alcohol-preferring rats with an ACE inhibitor show a marked modulation of alcohol intake. Other pathways are new potential targets for drug development. The emergent overall picture is that physical and physiological robustness may permit alcohol-preferring individuals to withstand the aversive effects of alcohol. In conjunction with a higher reactivity to its rewarding effects, they may able to ingest enough of this nonspecific drug for a strong hedonic and addictive effect to occur.

Epigenetic conversion of human adult bone mesodermal stromal cells into neuroectodermal cell types for replacement therapy of neurodegenerative disorders

Tissue-specific stem cells, such as bone marrow-derived mesodermal stromal cells (MSCs), are thought to be lineage restricted and, therefore, could only be differentiated into cell types of the tissue of origin. Several recent studies, however, suggest that these types of stem cells might be able to break barriers of germ layer commitment and differentiate in vitro and/or in vivo into cells of different tissues, such as neuroectodermal cell types. Recently, protocols for high-yield generation of undifferentiated neural stem cell (NSC)-like cells from MSCs of primate and human origin were reported. Undifferentiated NSCs are commonly used and are more suitable for neurotransplantation compared with fully differentiated neural cells, as differentiated neural cells are well known to poorly survive detachment and subsequent transplantation procedures. These human MSC-derived NSC-like cells (MSC-NSCs) grow in neurosphere-like structures and express high levels of early neuroectodermal markers, but lose characteristics of MSCs. In the presence of selected growth factors, human MSC-NSCs can be differentiated into the three main neural phenotypes: astroglia, oligodendroglia and neurons. Compared with direct differentiation of human MSCs into mature neural cells, the conversion step seems to be essential to generate mature functional neuroectodermal cells. This review describes the techniques for the conversion of human MSCs into NSCs and summarises the data on epigenetic conversion of human MSCs into immature neuroectodermal cells. These cells provide a powerful tool for investigating the molecular mechanisms of neural differentiation, and might serve as an autologous cell source to treat acute and chronic neurodegenerative diseases.

Synergistic effects of CoCl(2) and ROCK inhibition on mesenchymal stem cell differentiation into neuron-like cells

Bone-marrow-derived mesenchymal stem cells (MSCs) constitute an interesting cellular source to promote brain regeneration after neurodegenerative diseases. Recently, several studies suggested that oxygen-dependent gene expression is of crucial importance in governing the essential steps of neurogenesis such as cell proliferation, survival and differentiation. In this context, we analysed the effect of the HIF-1 (hypoxia inducible factor-1) activation-mimicking agent CoCl(2) on MSCs. CoCl(2) treatment increased the expression of the anti-proliferative gene BTG2/PC3 and decreased cyclin D1 expression. Expression of HIF-1alpha and its target genes EPO, VEGF and p21 was also upregulated. These changes were followed by inhibition of cell proliferation and morphological changes resulting in neuron-like cells, which had increased neuronal marker expression and responded to neurotransmitters. Echinomycin, a molecule inhibiting HIF-1 DNA-binding activity, blocked the CoCl(2) effect on MSCs. Additionally, by using Y-27632, we demonstrated that Rho kinase (ROCK) inhibition potentiated CoCl(2)-induced MSC differentiation in particular into dopaminergic neuron-like cells as attested by its effect on tyrosine hydroxylase expression. Altogether, these results support the ability of MSCs to differentiate into neuron-like cells in response to CoCl(2), an effect that might act, in part, through HIF-1 activation and cell-cycle arrest, and which is potentiated by inhibition of ROCK.

Comparative analysis of neuroectodermal differentiation capacity of human bone marrow stromal cells using various conversion protocols

Human adult bone marrow-derived mesodermal stromal cells (hMSCs) are able to differentiate into multiple mesodermal tissues, including bone and cartilage. There is evidence that these cells are able to break germ layer commitment and differentiate into cells expressing neuroectodermal properties. There is still debate about whether this results from cell fusion, aberrant marker gene expression or real neuroectodermal differentiation. Here we extend our work on neuroectodermal conversion of adult hMSCs in vitro by evaluating various epigenetic conversion protocols using quantitative RT-PCR and immunocytochemistry. Undifferentiated hMSCs expressed high levels of fibronectin as well as several neuroectodermal genes commonly used to characterize neural cell types, such as nestin, beta-tubulin III, and GFAP, suggesting that hMSCs retain the ability to differentiate into neuroectodermal cell types. Protocols using a direct differentiation of hMSCs into a neural phenotype failed to induce significant changes in morphology and/or expression of markers of early and mature glial/neuronal cells types. In contrast, a multistep protocol with conversion of hMSCs into a neural stem cell-like population and subsequent terminal differentiation in mature glia and neurons generated relevant morphological changes as well as significant increase of expression levels of marker genes for early and late neural cell types, such as nestin, neurogenin2, MBP, and MAP2ab, accompanied by a loss of their mesenchymal properties. Our data provide an impetus for differentiating hMSCs in vitro into mature neuroectodermal cells. Neuroectodermally converted hMSCs may therefore ultimately help in treating acute and chronic neurodegenerative diseases. Analysis of marker gene expression for characterization of neural cells derived from MSCs has to take into account that several early and late neuroectodermal genes are already expressed in undifferentiated MSCs.

Human Mesenchymal Stem Cells Express Neural Genes, Suggesting a Neural Predisposition

Because of their unique attributes of plasticity and accessibility, bone marrow-derived mesenchymal stem cells (MSCs) may find use for therapy of neurodegenerative disorders. Our previous studies of adult human MSCs demonstrated that these cells express an extensive assortment of neural genes at a low but clearly detectable level. Here, we report expression of 12 neural genes, 8 genes related to the neuro-dopaminergic system, and 11 transcription factors with neural significance by human MSCs. Our results suggest that, as opposed to cells that do not express neural genes, human MSCs are predisposed to differentiate to neuronal and glial lineages, given the proper conditions. Our findings add a new dimension in which to view adult stem cell plasticity, and may explain the relative ease with which MSCs, transplanted into the central nervous system (CNS) differentiate to a variety of functional neural cell types. Our results further promote the possibility that adult human MSCs are promising candidates for cell-based therapy of neurodegenerative diseases.

Vascular endothelial growth factor A contributes to glioma-induced migration of human marrow stromal cells (hMSC)

OBJECTIVE

It has been demonstrated that murine neural stem cells (mNSCs) and human mesenchymal stroma cells migrate toward experimental gliomas, making stem cells a candidate for cellular carrier systems of anti-glioma therapy. However, few data are available on the factors involved in regulating stem cell migration. The aim of our study was to characterize the migratory and invasive behavior of adult human marrow stromal cells (hMSC) that interact with glioma cells, especially focusing on vascular endothelial growth factor A (VEGF-A)-mediated effects.

METHODS

Human MSC were isolated from bone marrow biopsies carried out for hematological indications. The chemokinetic activity of hMSC in response to glioma-conditioned medium as well as VEGF-A was analyzed using a modified Boyden chamber assay. Invasion of hMSC and glioma spheroids was investigated using confrontational cultures. To provide analogous data from a well-described system, invasion of murine C17.2 neural stem cells was assessed. VEGF-A secretion by gliomas and the expression of VEGF-receptor 2 in hMSC were evaluated.

RESULTS

Human MSC showed an extensive invasion into glioma spheroids. Glioma-conditioned medium significantly increased hMSC migration and also invasion, driven by chemotaxis. VEGF-A also showed significant pro-migratory and pro-invasive effects on hMSC, but in a reduced fashion compared to glioma-conditioned medium.

CONCLUSIONS

Human MSC show intensive migratory and invasive behavior in the presence of glioma cells and glioma-conditioned medium. Among others, VEGF-A seems to be one important factor in enhancing and directing stem cell motility.

Autoreactive T cells induce in vitro BM mesenchymal stem cell transdifferentiation to neural stem cells

BACKGROUND

The degree of post-injury inflammation of the damaged area of a spinal cord is the main difference between the natural successful repair in inferior vertebrates and failure in superior vertebrates. The treatment of rats with anti-myelin lymphocytes after experimental spinal cord injury induces their functional recovery. On the other hand, mesenchymal stem cells (MSC) from adult BM implanted in injured areas recover the morphology and function of spinal cord in mammals. The purpose of this study was to determine whether there is a direct relationship between anti-nervous tissue T cells and MSC reparatory properties.

METHODS

Circulating autoreactive lymphocytes of patients with spinal cord injuries and amyotrophic lateral sclerosis were isolated and activated in vitro. These cells were cocultured with autologous MSC for 2-15 days. Cocultures of non-selected lymphocytes were used as controls.

RESULTS

After 48 h of coculture, MSC adopted a spindle shape with polarization of the cytoplasm that resembled bipolar neurons. Their nuclei diminished the nucleolus number and the chromatin lost its granular appearance. After 15 days of culture the cells developed the typical structure of a neural network. No morphologic changes were observed in control cultures. The differentiated cells reacted positively to tubuline III, GFAP and nestin. No differences were observed between the different patient cell sources.

DISCUSSION

We observed that autoreactive cells may induce the transdifferentiation of MSC to neural stem cells. This T-cell-MSC interaction may be a common phenomenon during physiologic nerve tissue repair.

Undifferentiated mouse mesenchymal stem cells spontaneously express neural and stem cell markers Oct-4 and Rex-1

BACKGROUND

Previous adult stem cells studies have provided evidence that BM mesenchymal stem cells (MSC) exhibit multilineage differentiation capacity. These properties of MSC prompted us to explore the neural potential of MSC with a view to their use for the treatment of demyelinating disorders, such as multiple sclerosis. Indeed, issues such as the identification of a subset of stem cells that is neurally fated, methods of expansion and optimal stage of differentiation for transplantation remain poorly understood.

METHODS

In order to isolate mouse (m) MSC from BM, we used and compared the classic plastic-adhesion method and one depleting technique, the magnetic-activated cell sorting technique.

RESULTS

We established and optimized culture conditions so that mMSC could be expanded for more than 360 days and 50 passages. We also demonstrated that undifferentiated mMSC express the neural markers nestin, MAP2, A2B5, GFAP, MBP, CNPase, GalC, O1 under standard culture conditions before transplantation. The pluripotent stem cell marker Oct-4 and the embryonic stem cell marker Rex-1 are spontaneously expressed by untreated mMSC. The lineage-negative mMSC (CD5- CD11b- Ly-6G- Ter119- CD45R- c-kit/CD117-) overexpressed Oct-4, O1 and A2B5 in the first days of culture compared with the non-sorted MSC. Finally, we identified a distinct subpopulation of mMSC that is primed towards a neural fate, namely Sca-1+/nestin+ mMSC.

DISCUSSION

These results should facilitate the optimal timing of harvesting a neurally fated subpopulation of mMSC for transplantation into animal models of human brain diseases.