Efficient generation of neural stem cell-like cells from adult human bone marrow stromal cells

Generation of inner ear sensory cells from bone marrow-derived human mesenchymal stem cells

AIM

Hearing loss is the most common sensory disorder in humans, its main cause being the loss of cochlear hair cells. We studied the potential of human mesenchymal stem cells (hMSCs) to differentiate towards hair cells and auditory neurons.

MATERIALS & METHODS

hMSCs were first differentiated to neural progenitors and subsequently to hair cell- or auditory neuron-like cells using in vitro culture methods.

RESULTS

Differentiation of hMSCs to an intermediate neural progenitor stage was critical for obtaining inner ear sensory lineages. hMSCs generated hair cell-like cells only when neural progenitors derived from nonadherent hMSC cultures grown in serum-free medium were exposed to EGF and retinoic acid. Auditory neuron-like cells were obtained when treated with retinoic acid, and in the presence of defined growth factor combinations containing Sonic Hedgehog.

CONCLUSION

The results show the potential of hMSCs to give rise to inner ear sensory cells.

Electrophysiological properties and synaptic function of mesenchymal stem cells during neurogenic differentiation - a mini-review

INTRODUCTION

Mesenchymal stem cells (MSCs) have gained considerable interest due to their potential use in cell therapies and tissue engineering. They have been reported to differentiate into various anchorage-dependent cell types, including bone, cartilage, and tendon. Our focus is on the differentiation of MSCs into neuron-like cells through the use of soluble chemical stimuli or specific growth factor supplements. The resulting cells appear to adopt neural phenotypes and express some typical neuronal markers, however, their electrophysiological properties and synaptic function remains unclear.

RESULTS

This mini-review illustrates how particular characteristics, electrophysiological properties, and synaptic functions of MSCs change during their neuronal differentiation. In particular we focus on changes in ion currents, ion channels, synaptic communication, and neurotransmitter release. We also highlight conflicting results, caused by inconsistencies in the experimental conditions used and in the methodologies adopted.

CONCLUSIONS

We conclude that there is insufficient data and that further, carefully controlled investigations are required in order to ascertain whether MSC-derived neuron-like cells can exhibit the necessary neuronal functions to become clinically relevant for use in neural repairs.

Stem cell-based therapy for spinal cord injury

Stem cells (SCs) represent a new therapeutic approach for spinal cord injury (SCI) by enabling improved sensory and motor functions in animal models. The main goal of SC-based therapy for SCI is the replacement of neurons and glial cells that undergo cell death soon after injury. Stem cells are able to promote remyelination via oligodendroglia cell replacement to produce trophic factors enhancing neurite outgrowth, axonal elongation, and fiber density and to activate resident or transplanted progenitor cells across the lesion cavity. While several SC transplantation strategies have shown promising yet partial efficacy, mechanistic proof is generally lacking and is arguably the largest impediment toward faster progress and clinical application. The main challenge ahead is to spur on cooperation between clinicians, researchers, and patients in order to define and optimize the mechanisms of SC function and to establish the ideal source/s of SCs that produce efficient and also safe therapeutic approaches.

Cellular replacement and regenerative medicine therapies in ischemic stroke

Worldwide, tissue engineering and cellular replacement therapies are at the forefront of the regenerative medicine agenda, and researchers are addressing key diseases, including diabetes, stroke and neurological disorders. It is becoming evident that neurological cell therapy is a necessarily complex endeavor. The brain as a cellular environment is complex, with diverse cell populations, including specialized neurons (e.g., dopaminergic, motor and glutamatergic neurons), each with specific functions. The population also contains glial cells (astrocytes and oligodendrocytes) that offer the supportive network for neuronal function. Neurological disorders have wide and varied pathologies; they can affect predominantly one cell type or a multitude of cell types, which is the case for ischemic stroke. Both neuronal and glial cells are affected by stroke and, depending on the region of the brain affected, different specialized cells are influenced. This review will address currently available therapies and focus on the application and potential of cell replacement, including stem cells and immortalized cell line-derived neurons as regenerative therapies for ischemic stroke, addressing current advances and challenges ahead.

Generation of neural stem cell-like cells from bone marrow-derived human mesenchymal stem cells

Under appropriate culture conditions, bone marrow (BM)-derived mesenchymal stem cells are capable of differentiating into diverse cell types unrelated to their phenotypical embryonic origin, including neural cells. Here, we report the successful generation of neural stem cell (NSC)-like cells from BM-derived human mesenchymal stem cells (hMSCs). Initially, hMSCs were cultivated in a conditioned medium of human neural stem cells. In this culture system, hMSCs were induced to become NSC-like cells, which proliferate in neurosphere-like structures and express early NSC markers. Like central nervous system-derived NSCs, these BM-derived NSC-like cells were able to differentiate into cells expressing neural markers for neurons, astrocytes, and oligodendrocytes. Whole-cell patch clamp recording revealed that neuron-like cells, differentiated from NSC-like cells, exhibited electrophysiological properties of neurons, including action potentials. Transplantation of NSC-like cells into mouse brain confirmed that these NSC-like cells retained their capability to differentiate into neuronal and glial cells in vivo. Our data show that multipotent NSC-like cells can be efficiently produced from BM-derived hMSCs in culture and that these cells may serve as a useful alternative to human neural stem cells for potential clinical applications such as autologous neuroreplacement therapies.

Neural differentiation ability of mesenchymal stromal cells from bone marrow and adipose tissue: a comparative study

BACKGROUND AIMS

The characteristics, such as morphologic and phenotypic characteristics and neural transdifferentiation ability, of mesenchymal stromal cells (MSC) derived from different origins have yet to be reported for cases isolated from the same individual.

METHODS

The proliferation capacity, secretion ability of neurotrophins (NT) and neural differentiation ability in rat MSC isolated from bone marrow (BMSC) and adipose tissue (ADSC) were compared from the same animal.

RESULTS

The ADSC had a significantly higher proliferation capacity than BMSC according to cell cycle and cumulative population doubling analyses. The proportion of cells expressing neural markers was greater in differentiated ADSC than in differentiated BMSC. Furthermore, the single neurosphere derived from ADSC showed stronger expansion and differentiation abilities than that derived from BMSC. The findings from Western blot lent further support to the immunocytochemical data. The mRNA and protein levels of nerve growth factor (NGF) and brain-derived growth factor (BDNF) expressed in ADSC were significantly higher than those in BMSC at different stages before and following induction.

CONCLUSIONS

Our study suggests that the proliferation ability of ADSC is superior to that of BMSC. Furthermore, differentiated ADSC expressed higher percentages of neural markers. As one possible alternative source of BMSC, ADSC may have wide potential for treating central nervous system (CNS) diseases.

Characterization of autologous mesenchymal stem cell-derived neural progenitors as a feasible source of stem cells for central nervous system applications in multiple sclerosis

Bone marrow mesenchymal stem cell-derived neural progenitors (MSC-NPs) are a potential therapeutic source of cells that have been shown to be efficacious in a preclinical model of multiple sclerosis (MS). To examine the feasibility of using MSC-NPs as an autologous source of cells to promote central nervous system (CNS) repair in MS, this study characterized human MSC-NPs from a panel of both MS and non-MS donors. Expanded MSCs showed similar characteristics in terms of growth and cell surface phenotype, regardless of the donor disease status. MSC-NPs derived from all MSCs showed a consistent pattern of gene expression changes that correlated with neural commitment and increased homogeneity. Furthermore, the reduced expression of mesodermal markers and reduced capacity for adipogenic or osteogenic differentiation in MSC-NPs compared with MSCs suggested that MSC-NPs have reduced potential of unwanted mesodermal differentiation upon CNS transplantation. The immunoregulatory function of MSC-NPs was similar to that of MSCs in their ability to suppress T-cell proliferation and to promote expansion of FoxP3-positive T regulatory cells in vitro. In addition, MSC-NPs promoted oligodendroglial differentiation from brain-derived neural stem cells that correlated with the secretion of bioactive factors. Our results provide a set of identity characteristics for autologous MSC-NPs and suggest that the in vitro immunoregulatory and trophic properties of these cells may have therapeutic value in the treatment of MS.

Stem/progenitor cells in non-lactating versus lactating equine mammary gland

The mammary gland is a highly regenerative organ that can undergo multiple cycles of proliferation, lactation, and involution. Based on the facts that (i) mammary stem/progenitor cells (MaSC) are proposed to be the driving forces behind mammary growth and function and (ii) variation exists between mammalian species with regard to physiological and pathological functioning of this organ, we believe that studying MaSC from different mammals is of great comparative interest. Over the years, important data has been gathered on MaSC of men and mice, although knowledge on MaSC in other mammals remains limited. Therefore, the aim of this work was to isolate and characterize MaSC from the mammary gland of horses. Hereby, our salient findings were that the isolated equine cells met the 2 in vitro hallmark properties of stem cells, namely the ability to self-renew and to differentiate into multiple cell lineages. Moreover, the cells were immunophenotyped using markers for CD29, CD44, CD49f, and Ki67. Finally, we propose the mammosphere assay as a valuable in vitro assay to study MaSC during different physiological phases since it was observed that equine lactating mammary gland contains significantly more mammosphere-initiating cells than the inactive, nonlactating gland (a reflection of MaSC self-renewal) and, moreover, that these spheres were significantly larger in size upon initial cultivation (a reflection of progenitor cell proliferation). Taken together, this study not only extends the current knowledge of mammary gland biology, but also benefits the comparative approach to study and compare MaSC in different mammalian species.

Autologous bone marrow mononuclear cell implantation for intracerebral hemorrhage-a prospective clinical observation

BACKGROUND

This study was designed to assess the clinical effect of bone marrow mononuclear cells including mesenchymal stem cell (MSCs) in patients with intracerebral hemorrhage (ICH).

METHODS

One hundred patients were divided into a study (n=60) or a control group (n=40). Bone marrow mononuclear cells from the same patient were injected to the perihemorrhage area in the base ganglia through an intracranial drainage tube 5.9 days after ICH. National Institute Stroke Scale (NIHSSS) and Barthel index was used to assess neurologic impairment and daily activities, respectively, before and 6 months after intervention.

RESULTS

Six months after implantation, the NIHSS score in the study group was lower than in the control group (10.09 ± 8.86 vs 14.35 ± 10.14, P<0.01), whereas the Barthel scores were higher (57.39 ± 23.51 vs 46.90 ± 20.29, P<0.01). Neurological and functional improvement was observed in 52 (86.7%) of the study group patients, and in 17 (42.5%) of the control group patients (P=0.001). No allergic or other adverse effects were observed in the study group.

CONCLUSION

Autologous bone marrow mononuclear cell implantation reduced neurological impairment and improved activities of daily living in a selected group of ICH patients. Further studies are required to ascertain the long-term safety and efficacy of this treatment.

Efficient transdifferentiation of human adipose-derived stem cells into Schwann-like cells: A promise for treatment of demyelinating diseases

BACKGROUND

Schwann cells (SCs) can provide a suitable option for treatment not only diseases of peripheral nervous system (PNS), but also diseases of central nervous system (CNS). It is difficult to obtain sufficient large number of SCs for clinical purpose because of their restricted mitotic activity, and by sacrificing one or more functioning nerves with the consequence of loss of sensation. So, providing an alternative source for transplantation is desired. The aim of this study was isolation, characterization of human adipose derived stem cells (ADSCs), and transdifferentiation into Schwann-cells.

MATERIALS AND METHODS

After isolation of ADSCs by mechanical and enzymatic digestion of adipose samples, characterization human ADSCs using flow cytometry was carried out. Human ADSCs were sequentially treated with various factors for neurosphere formation and terminal differentiation into Schwann-like cells. We used Schwann cell markers, GFAP and S100 to confirm the effectiveness of the differentiation of human ADSCs using Immunostaining and real time RT-PCR techniques.

RESULTS

Flow cytometry analysis of ADSC showed isolated stem cells were positive for CD90 and CD44 markers of mesenchymal stem cells, but for CD45 and CD34 markers were negative. Dual immunofluorescence staining and real time RT-PCR analysis for GFAP and S100 markers were revealed that approximately 90% of differentiated cells expressed co-markers.

CONCLUSION

We indicated that human ADSCs have a suitable option to induce Schwann-like cells for autologous transplantation, offer promise for treatment in demyelinating diseases.

Human dedifferentiated adipocytes show similar properties to bone marrow-derived mesenchymal stem cells

Mature adipocytes are generally considered terminally differentiated because they have lost their proliferative abilities. Here, we studied the gene expression and functional properties of mature adipocytes isolated from human omental and subcutaneous fat tissues. We also focused on dedifferentiated adipocytes in culture and their morphologies and functional changes with respect to mature adipocytes, stromal-vascular fraction (SVF)-derived mesenchymal stem cells (MSCs) and bone marrow (BM)-derived MSCs. Isolated mature adipocytes expressed stem cell and reprogramming genes. They replicated in culture after assuming a fibroblast-like shape and expanded similarly to SVF- and BM-derived MSCs. During the dedifferentiation process, mature adipocytes lost their lineage gene expression profile, assumed the typical mesenchymal morphology and immunophenotype, expressed stem cell genes and differentiated into multilineage cells. Moreover, during the dedifferentiation process, we showed changes in the epigenetic status of mature adipocytes, which led dedifferentiated adipocytes to display a similar DNA methylation condition to BM-derived MSCs. Like SVF- and BM-derived MSCs, dedifferentiated adipocytes were able to inhibit the proliferation of stimulated lymphocytes in coculture while mature adipocytes stimulated their growth. Furthermore, dedifferentiated adipocytes maintained the survival and complete differentiation characteristic of hematopoietic stem cells. This is the first study that in addition to characterizing isolated and dedifferentiated adipocytes also reports on the immunoregulatory and hematopoietic supporting functions of these cells. This structural and functional characterization might have clinical applications of both mature and dedifferentiated adipocytes in such fields, as regenerative medicine.

The adult human brain harbors multipotent perivascular mesenchymal stem cells

Blood vessels and adjacent cells form perivascular stem cell niches in adult tissues. In this perivascular niche, a stem cell with mesenchymal characteristics was recently identified in some adult somatic tissues. These cells are pericytes that line the microvasculature, express mesenchymal markers and differentiate into mesodermal lineages but might even have the capacity to generate tissue-specific cell types. Here, we isolated, purified and characterized a previously unrecognized progenitor population from two different regions in the adult human brain, the ventricular wall and the neocortex. We show that these cells co-express markers for mesenchymal stem cells and pericytes in vivo and in vitro, but do not express glial, neuronal progenitor, hematopoietic, endothelial or microglial markers in their native state. Furthermore, we demonstrate at a clonal level that these progenitors have true multilineage potential towards both, the mesodermal and neuroectodermal phenotype. They can be epigenetically induced in vitro into adipocytes, chondroblasts and osteoblasts but also into glial cells and immature neurons. This progenitor population exhibits long-term proliferation, karyotype stability and retention of phenotype and multipotency following extensive propagation. Thus, we provide evidence that the vascular niche in the adult human brain harbors a novel progenitor with multilineage capacity that appears to represent mesenchymal stem cells and is different from any previously described human neural stem cell. Future studies will elucidate whether these cells may play a role for disease or may represent a reservoir that can be exploited in efforts to repair the diseased human brain.

Differentiation of chromaffin progenitor cells to dopaminergic neurons

The differentiation of dopamine-producing neurons from chromaffin progenitors might represent a new valuable source for replacement therapies in Parkinson's disease. However, characterization of their differentiation potential is an important prerequisite for efficient engraftment. Based on our previous studies on isolation and characterization of chromaffin progenitors from adult adrenals, this study investigates their potential to produce dopaminergic neurons and means to enhance their dopaminergic differentiation. Chromaffin progenitors grown in sphere culture showed an increased expression of nestin and Mash1, indicating an increase of the progenitor subset. Proneurogenic culture conditions induced the differentiation into neurons positive for neural markers β-III-tubulin, MAP2, and TH accompanied by a decrease of Mash1 and nestin. Furthermore, Notch2 expression decreased concomitantly with a downregulation of downstream effectors Hes1 and Hes5 responsible for self-renewal and proliferation maintenance of progenitor cells. Chromaffin progenitor-derived neurons secreted dopamine upon stimulation by potassium. Strikingly, treatment of differentiating cells with retinoic and ascorbic acid resulted in a twofold increase of dopamine secretion while norepinephrine and epinephrine were decreased. Initiation of dopamine synthesis and neural maturation is controlled by Pitx3 and Nurr1. Both Pitx3 and Nurr1 were identified in differentiating chromaffin progenitors. Along with the gained dopaminergic function, electrophysiology revealed features of mature neurons, such as sodium channels and the capability to fire multiple action potentials. In summary, this study elucidates the capacity of chromaffin progenitor cells to generate functional dopaminergic neurons, indicating their potential use in cell replacement therapies.

Gene expression profile of adult human olfactory bulb and embryonic neural stem cell suggests distinct signaling pathways and epigenetic control

Global gene expression profiling was performed using RNA from human embryonic neural stem cells (hENSC), and adult human olfactory bulb-derived neural stem cells (OBNSCs), to define a gene expression pattern and signaling pathways that are specific for each cell lineage. We have demonstrated large differences in the gene expression profile of human embryonic NSC, and adult human OBNSCs, but less variability between parallel cultures. Transcripts of genes involved in neural tube development and patterning (ALDH1A2, FOXA2), progenitor marker genes (LMX1a, ALDH1A1, SOX10), proliferation of neural progenitors (WNT1 and WNT3a), neuroplastin (NPTN), POU3F1 (OCT6), neuroligin (NLGN4X), MEIS2, and NPAS1 were up-regulated in both cell populations. By Gene Ontology, 325 out of 3875 investigated gene sets were scientifically different. 41 out of the 307 investigated Cellular Component (CC) categories, 45 out of the 620 investigated Molecular Function (MF) categories, and 239 out of the 2948 investigated Biological Process (BP) categories were significant. KEGG Pathway Class Comparison had revealed that 75 out of 171 investigated gene sets passed the 0.005 significance threshold. Levels of gene expression were explored in three signaling pathways, Notch, Wnt, and mTOR that are known to be involved in NS cell fates determination. The transcriptional signature also deciphers the role of genes involved in epigenetic modifications. SWI/SNF DNA chromatin remodeling complex family, including SMARCC1 and SMARCE1, were found specifically up-regulated in our OBNSC but not in hENSC. Differences in gene expression profile of transcripts controlling epigenetic modifications, and signaling pathways might indicate differences in the therapeutic potential of our examined two cell populations in relation to in cell survival, proliferation, migration, and differentiation following engraftments in different CNS insults.

Conditionally immortalized mouse embryonic fibroblasts retain proliferative activity without compromising multipotent differentiation potential

Mesenchymal stem cells (MSCs) are multipotent cells which reside in many tissues and can give rise to multiple lineages including bone, cartilage and adipose. Although MSCs have attracted significant attention for basic and translational research, primary MSCs have limited life span in culture which hampers MSCs' broader applications. Here, we investigate if mouse mesenchymal progenitors can be conditionally immortalized with SV40 large T antigen and maintain long-term cell proliferation without compromising their multipotency. Using the system which expresses SV40 large T antigen flanked with Cre/loxP sites, we demonstrate that mouse embryonic fibroblasts (MEFs) can be efficiently immortalized by SV40 large T antigen. The conditionally immortalized MEFs (iMEFs) exhibit an enhanced proliferative activity and maintain long-term cell proliferation, which can be reversed by Cre recombinase. The iMEFs express most MSC markers and retain multipotency as they can differentiate into osteogenic, chondrogenic and adipogenic lineages under appropriate differentiation conditions in vitro and in vivo. The removal of SV40 large T reduces the differentiation potential of iMEFs possibly due to the decreased progenitor expansion. Furthermore, the iMEFs are apparently not tumorigenic when they are subcutaneously injected into athymic nude mice. Thus, the conditionally immortalized iMEFs not only maintain long-term cell proliferation but also retain the ability to differentiate into multiple lineages. Our results suggest that the reversible immortalization strategy using SV40 large T antigen may be an efficient and safe approach to establishing long-term cell culture of primary mesenchymal progenitors for basic and translational research, as well as for potential clinical applications.

In vitro differentiation of bone marrow stromal cells into oligodendrocyte-like cells using triiodothyronine as inducer

An in vitro technique was devised to induced autologous adult stem cells into oligodendrocyte-like cells. In this study, a protocol was developed for the induction of bone marrow stromal cells (BMSCs) into oligodendrocyte-like cells. BMSCs were incubated in one of these three pre-inducers: dimethyl sulfoxide (DMSO), β-mercaptoethanol (βME) or biotylated hydroxyanisol (BHA), each followed by retinoic acid (RA) treatment. The percentage of viable cells in BHA-RA preinduced cells was significantly lower than the others. The results showed that the preinduced cells were immunoreactive for nestin and NF-68; among the mentioned protocols, the immunoreactivity yielded by following the DMSO-RA protocol was significantly higher than the others. Moreover, no significant immunoreactivity was observed for preinduced cells to O4, O1, MBP (myelin basic protein), S100, and GFAP (glial fibrillary acidic protein). The cells were immunoreactive to oligo-2. Two phases of induction were done: the first was a combination of basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF) and heregulin (HRG), followed by either triiodothyronine (T3) or Forskolin (FSK) as the second phase. The conclusion is that the trans-differentiation of BMSCs by DMSO followed by RA (preinduction stage) then bFGF-PDGF-HRG followed by T3 (10 ng/ml) (induction stage) can be a potential source for oligodendrocyte-like cells preparation.

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.

Comparison of neurosphere-like cell clusters derived from dental follicle precursor cells and retinal Müller cells

Unrelated cells such as dental follicle precursor cells (DFPCs) and retinal Müller cells (MCs) make spheres after cultivation in serum-replacement medium (SRM). Until today, the relation and molecular processes of sphere formation from different cell types remain undescribed. Thus in this study we compared proteomes of spheres derived from MCs and DFPCs. 73% of 676 identified proteins were similar expressed in both cell types and many of them are expressed in the brain (55%). Moreover proteins are overrepresented that are associated with pathways for neural diseases such as Huntington disease or Alzheimer disease. Interestingly up-regulated proteins in DFPCs are involved in the biosynthesis of glycosphingolipids. These lipids are components of gangliosides such as GD3, which is a novel neural stem cell marker. In conclusion spheres from different types of cells have highly similar proteomes. These proteomes probably show essential cellular processes in neurosphere-like cell clusters.

Biomaterial implants mediate autologous stem cell recruitment in mice

Autologous stem cells, recognized as the best cells for stem cell therapy, are associated with difficult extraction procedures which often lead to more traumas for the patients and time-consuming laboratory work, which delays their subsequent application. To combat such challenges, it was recently uncovered that, shortly after biomaterial implantation, following the recruitment of inflammatory cells, substantial numbers of mesenchymal stem cells (MSC) and hematopoietic stem cells (HSC) were recruited to the implantation sites. These multipotent MSC could be differentiated into various lineages in vitro. Inflammatory signals may be responsible for the gathering of stem cells, since there is a good relationship between biomaterial-mediated inflammatory responses and stem cell accumulation in vivo. In addition, the treatment with the anti-inflammatory drug dexamethasone substantially reduced the recruitment of both MSC and HSC. The results from this work support that such strategies could be further developed towards localized recruitment and differentiation of progenitor cells. This may permit the future development of autologous stem cell therapies without the need for tedious cell isolation, culture and transplantation.

Clinical and pathological effects of intrathecal injection of mesenchymal stem cell-derived neural progenitors in an experimental model of multiple sclerosis

Multiple sclerosis (MS) is associated with irreversible disability in a significant proportion of patients. At present, there is no treatment to halt or reverse the progression of established disability. In an effort to develop cell therapy-based strategies for progressive MS, we investigated the pre-clinical efficacy of bone marrow mesenchymal stem cell-derived neural progenitors (MSC-NPs) as an autologous source of stem cells. MSC-NPs consist of a subpopulation of bone marrow MSCs with neural progenitor and immunoregulatory properties, and a reduced capacity for mesodermal differentiation, suggesting that this cell population may be appropriate for clinical application in the CNS. We investigated whether MSC-NPs could promote repair and recovery after intrathecal injection into mice with EAE. Multiple injections of MSC-NPs starting at the onset of the chronic phase of disease improved neurological function compared to controls, whereas a single injection had no effect on disease scores. Intrathecal injection of MSC-NPs correlated with reduced immune cell infiltration, reduced area of demyelination, and increased number of endogenous nestin-positive progenitor cells in EAE mice. These observations suggest that MSC-NPs may influence the rate of repair through effects on endogenous progenitors in the spinal cord. This study supports the use of autologous MSC-NPs in MS patients as a means of promoting CNS repair.

Comparison of transdifferentiated and untransdifferentiated human umbilical mesenchymal stem cells in rats after traumatic brain injury

Transdifferentiated and untransdifferentiated mesenchymal stem cells (MSCs) have shown therapeutic benefits in central nervous system (CNS) injury. However, it is unclear which would be more appropriate for transplantation. To address this question, we transplanted untransdifferentiated human umbilical mesenchymal stem cells (HUMSCs) and transdifferentiated HUMSCs (HUMSC-derived neurospheres, HUMSC-NSs) into a rat model of traumatic brain injury. Cognitive function, cell survival and differentiation, brain tissue morphology and neurotrophin expression were compared between groups. Significant improvements in cognitive function and brain tissue morphology were seen in the HUMSCs group compared with HUMSC-NSs group, which was accompanied by increased neurotrophin expression. Moreover, only few grafted cells survived in both the HUMSCs and HUMSC-NSs groups, with very few of the cells differentiating into neural-like cells. These findings indicate that HUMSCs are more appropriate for transplantation and their therapeutic benefits may be associated with neuroprotection rather than cell replacement.

Transplanted neurally modified bone marrow-derived mesenchymal stem cells promote tissue protection and locomotor recovery in spinal cord injured rats

BACKGROUND

Stem cell-based therapy for repair and replacement of lost neural cells is a promising treatment for central nervous system (CNS) diseases. Bone marrow (BM)-derived mesenchymal stem cells (MSCs) can differentiate into neural phenotypes and be isolated and expanded for autotransplantation with no risk of rejection.

OBJECTIVE

The authors examined whether transplanted neurally induced human MSCs (NI hMSCs), developed by a new procedure, can survive, differentiate, and promote tissue protection and functional recovery in injured spinal cord (ISC) rats.

METHODS

Neural induction was achieved by exposing cells simultaneously to inhibitors of DNA methylation, histone deacetylation, and pharmacological agents that increased cAMP levels. Three groups of adult female Sprague-Dawley rats were injected immediately rostral and caudal to the midline lesion with phosphate-buffered saline, MSCs, or NI hMSCs, 1 week after a spinal cord impact injury at T-8. Functional outcome was measured using the Basso Beattie Bresnahan (BBB) locomotor rating scale and thermal sensitivity test on a weekly basis up to 12 weeks postinjury. Graft integration and anatomy of spinal cord was assessed by stereological, histochemical, and immunohistochemical techniques.

RESULTS

The transplanted NI hMSCs survived, differentiated, and significantly improved locomotor recovery of ISC rats. Transplantation also reduced the volume of lesion cavity and white matter loss.

CONCLUSION

This method of hMSC modification may provide an alternative source of autologous adult stem cells for CNS repair.

Role of mesenchymal stem cells in neurogenesis and nervous system repair

Bone marrow-derived mesenchymal stem cells (MSCs) are attractive candidates for use in regenerative medicine since they are easily accessible and can be readily expanded in vivo, and possess unique immunogenic properties. Moreover, these multipotent cells display intriguing environmental adaptability and secretory capacity. The ability of MSCs to migrate and engraft in a range of tissues has received significant attention. Evidence indicating that MSC transplantation results in functional improvement in animal models of neurological disorders has highlighted exciting potential for their use in neurological cell-based therapies. The manner in which MSCs elicit positive effects in the damaged nervous system remains unclear. Cell fusion and/or 'transdifferentiation' phenomena, by which MSCs have been proposed to adopt neural cell phenotypes, occur at very low frequency and are unlikely to fully account for observed neurological improvement. Alternatively, MSC-mediated neural recovery may result from the release of soluble molecules, with MSC-derived growth factors and extracellular matrix components influencing the activity of endogenous neural cells. This review discusses the potential of MSCs as candidates for use in therapies to treat neurological disorders and the molecular and cellular mechanisms by which they are understood to act.

Multilineage-differentiating stress-enduring (Muse) cells are a primary source of induced pluripotent stem cells in human fibroblasts

The stochastic and elite models have been proposed for the mechanism of induced pluripotent stem (iPS) cell generation. In this study we report a system that supports the elite model. We previously identified multilineage-differentiating stress-enduring (Muse) cells in human dermal fibroblasts that are characterized by stress tolerance, expression of pluripotency markers, self-renewal, and the ability to differentiate into endodermal-, mesodermal-, and ectodermal-lineage cells from a single cell. They can be isolated as stage-specific embryonic antigen-3/CD105 double-positive cells. When human fibroblasts were separated into Muse and non-Muse cells and transduced with Oct3/4, Sox2, Klf4, and c-Myc, iPS cells were generated exclusively from Muse cells but not from non-Muse cells. Although some colonies were formed from non-Muse cells, they were unlike iPS cells. Furthermore, epigenetic alterations were not seen, and some of the major pluripotency markers were not expressed for the entire period during iPS cell generation. These findings were confirmed further using cells transduced with a single polycistronic virus vector encoding all four factors. The results demonstrate that in adult human fibroblasts a subset of preexisting adult stem cells whose properties are similar in some respects to those of iPS cells selectively become iPS cells, but the remaining cells make no contribution to the generation of iPS cells. Therefore this system seems to fit the elite model rather than the stochastic model.

Transplantation of neuronal-primed human bone marrow mesenchymal stem cells in hemiparkinsonian rodents

Bone marrow-derived human mesenchymal stem cells (hMSCs) have shown promise in in vitro neuronal differentiation and in cellular therapy for neurodegenerative disorders, including Parkinson' disease. However, the effects of intracerebral transplantation are not well defined, and studies do not agreed on the optimal neuronal differentiation method. Here, we investigated three growth factor-based neuronal differentiation procedures (using FGF-2/EGF/PDGF/SHH/FGF-8/GDNF), and found all to be capable of eliciting an immature neural phenotype, in terms of cell morphology and gene/protein expression. The neuronal-priming (FGF-2/EGF) method induced neurosphere-like formation and the highest NES and NR4A2 expression by hMSCs. Transplantation of undifferentiated and neuronal-primed hMSCs into the striatum and substantia nigra of 6-OHDA-lesioned hemiparkinsonian rats revealed transient graft survival of 7 days, despite the reported immunosuppressive properties of MSCs and cyclosporine-immunosuppression of rats. Neither differentiation of hMSCs nor induction of host neurogenesis was observed at injection sites, and hMSCs continued producing mesodermal fibronectin. Strategies for improving engraftment and differentiation post-transplantation, such as prior in vitro neuronal-priming, nigral and striatal grafting, and co-transplantation of olfactory ensheathing cells that promote neural regeneration, were unable to provide advantages. Innate inflammatory responses (Iba-1-positive microglia/macrophage and GFAP-positive astrocyte activation and accumulation) were detected around grafts within 7 days. Our findings indicate that growth factor-based methods allow hMSC differentiation toward immature neuronal-like cells, and contrary to previous reports, only transient survival and engraftment of hMSCs occurs following transplantation in immunosuppressed hemiparkinsonian rats. In addition, suppression of host innate inflammatory responses may be a key factor for improving hMSC survival and engraftment.

In vitro and in vivo magnetic resonance tracking of Sinerem-labeled human umbilical mesenchymal stromal cell-derived Schwann cells

Tracking of ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles-labeled embryonic stem cells, neural stem cells, or adult mesenchymal stem cells in vitro and in vivo by using magnetic resonance (MR) imaging have been reported. However, whether the transdifferentiated cells can be effectively labeled by USPIO has not yet been investigated. The requirement for nerve donor material evokes additional morbidity and inability to generate a sufficiently large number of cells in a short time to hamper the clinic application of Schwann cells (SCs) transplantation. These limitations may be avoided if SCs can be generated from clinically accessible sources, such as bone marrow and umbilical cord. However, a reliable means of inducing the selective differentiation of human mesenchymal stromal cells isolated from the umbilical cord (HUMSCs) into SCs in vitro has not yet been established. In this study, we induce HUMSCs into Schwann-like cells in terms of morphology, phenotype, and function by an improved protocol basing on our previous studies. Furthermore, HUMSCs-derived SCs are labeled efficiently in vitro with ultrasmall superparamagnetic iron oxide contrast agent (USPIO) Sinerem and poly-L-lysine (PLL) without affecting morphology, cell cycle, proliferation, and differentiation ability of the labeled cells between the concentration of 200 to 800 μg/ml. Importantly, when grafted into the intact cerebral cortex and striatum, the survival and migration of these Sinerem-labeled cells were observed using MRI. Our study suggest the effective concentration field for Sinerem use in tracking transdifferentiated HUMSCs, and Sinerem labeling transdifferentiated HUMSCs is feasible, efficient, and safe for MRI tracing following grafting into nervous system.

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.

Bone marrow stromal cells as replacement cells for Parkinson's disease: generation of an anatomical but not functional neuronal phenotype

The focus of cell replacement therapies (CRTs) for Parkinson's disease has been on delivering dopamine-producing cells to the striatum. Fetal grafts have proven the feasibility of this approach, but an appropriate source of replacement cells has restricted the clinical translation. Bone marrow stromal cells (BMSCs) have been heralded as an ideal source of dopaminergic (DAergic) replacement cells, as they are viewed as ethically acceptable, easily procured, and readily expanded. It is known that they confer functional benefits, particularly in stroke models, through the release of neurotrophic factors, but their transdifferentiation into neurons is still under contention. We sought to evaluate the neuronal phenotype and functional capacity of adult rat BMSCs after exposure to a novel multistep in vitro differentiation protocol compared with cells exposed to other reported neuronal differentiation conditions. We employed a systematic, comprehensive method of assessment to determine the neuronal differentiation capacity of BMSCs. Our fluorescence-activated cell sorting, immunofluorescent and semiquantitative polymerase chain reaction results confirmed that undifferentiated BMSCs isolated based on their adherence to plastic are of mesenchymal origin and express a range of lineage markers. After exposure to preinduction and neuronal induction steps, BMSCs down-regulate markers of other lineages but fail, as assessed by patch clamp, to differentiate into functional neurons. Thus, for BMSCs to be considered a source of DAergic neuronal replacement cells, their ability to transdifferentiate terminally along a neuronal lineage first must be clarified before attempting to direct more complex specification process required for them to be used in Parkinson's-disease-focused CRTs.

The antidiabetic effect of MSCs is not impaired by insulin prophylaxis and is not improved by a second dose of cells

Type 1 diabetes mellitus (T1D) is due to autoimmune destruction of pancreatic beta-cells. Previously, we have shown that intravenously administered bone marrow-derived multipotent mesenchymal stromal cells (MSCs) allows pancreatic islet recovery, improves insulin secretion and reverts hyperglycemia in low doses streptozotocin (STZ)-induced diabetic mice. Here we evaluate whether insulin prophylaxis and the administration of a second dose of cells affect the antidiabetic therapeutic effect of MSC transplantation. Insulitis and subsequent elimination of pancreatic beta-cells was promoted in C57BL/6 mice by the injection of 40 mg/kg/day STZ for five days. Twenty-four days later, diabetic mice were distributed into experimental groups according to if they received or not insulin and/or one or two doses of healthy donor-derived MSCs. Three and half months later: glycemia, pancreatic islets number, insulinemia, glycated hemoglobin level and glucose tolerance were determined in animals that did not received exogenous insulin for the last 1.5 months. Also, we characterized MSCs isolated from mice healthy or diabetic. The therapeutic effect of MSC transplantation was observed in diabetic mice that received or not insulin prophylaxis. Improvements were similar irrespective if they received one or two doses of cells. Compared to MSCs from healthy mice, MSCs from diabetic mice had the same proliferation and adipogenic potentials, but were less abundant, with altered immunophenotype and no osteogenic potential.

Our preclinical results should be taken into account when designing phase II clinical trials aimed to evaluate MSC transplantation in patients with T1D. Cells should be isolated form healthy donor, insulin prophylaxis could be maintained and a second dose, after an elapse of two months, appears unnecessary in the medium-term.

Cellular environment directs differentiation of human umbilical cord blood-derived neural stem cells in vitro

Cord blood-derived neural stem cells (NSCs) are proposed as an alternative cell source to repair brain damage upon transplantation. However, there is a lack of data showing how these cells are driven to generate desired phenotypes by recipient nervous tissue. Previous research indicates that local environment provides signals driving the fate of stem cells. To investigate the impact of these local cues interaction, the authors used a model of cord blood-derived NSCs co-cultured with different rat brain-specific primary cultures, creating the neural-like microenvironment conditions in vitro. Neuronal and astro-, oligo-, and microglia cell cultures were obtained by the previously described methods. The CMFDA-labeled neural stem cells originated from, non-transformed human umbilical cord blood cell line (HUCB-NSCs) established in a laboratory. The authors show that the close vicinity of astrocytes and oligodendrocytes promotes neuronal differentiation of HUCB-NSCs, whereas postmitotic neurons induce oligodendrogliogenesis of these cells. In turn, microglia or endothelial cells do not favor any phenotypes of their neural commitment. Studies have confirmed that HUCB-NSCs can read cues from the neurogenic microenvironment, attaining features of neurons, astrocytes, or oligodendrocytes. The specific responses of neurally committed cord blood-derived cells, reported in this work, are very much similar to those described previously for NSCs derived from other "more typical" sources. This further proves their genuine neural nature. Apart from having a better insight into the neurogenesis in the adult brain, these findings might be important when predicting cord blood cell derivative behavior after their transplantation for neurological disorders.

The potential of stem cells in adult tissues representative of the three germ layers

Mature adult tissues contain stem cells that express many genes normally associated with the early stage of embryonic development, when maintained in appropriate environments. Cells procured from adult tissues representative of the three germ layers (spinal cord, muscle, and lung), each exhibiting the potential to mature into cells representative of all three germ layers. Cells isolated from adult tissues of different germ layer origin were propagated as nonadherent clusters or spheres that were composed of heterogeneous populations of cells. When the clusters or spheres were dissociated, the cells had the ability to reform new, nonadherent spheres for several generations. When implanted in vivo, in association with biodegradable scaffolds, into immunodeficient mice, tissue containing cells characteristic of the three germ layers was generated. These findings suggest the existence of a population of stem cells in adult tissues that is quite different and distinct from embryonic stem cells that demonstrate a greater potency for differentiation across germ lines than previously believed. Such cells could potentially be as useful as embryonic stem cells in tissue engineering and regenerative medicine.

Late transplantation of allogeneic bone marrow stromal cells improves neurologic deficits subsequent to intracerebral hemorrhage

BACKGROUND AIMS

Stem cell therapy seems to be a promising therapeutic tool for treating central nervous system (CNS) injuries. Bone marrow stromal cell (BMSC) transplantation influences functional outcome subsequent to intracerebral hemorrhage (ICH), and enhances endogenous neurogenesis in acute condition studies. We investigated whether late administration of BMSC improves functional deficits subsequent to ICH.

METHODS

Experimental ICH was induced by stereotactic injection of 0.5 IU collagenase type IV in the striatum of adult female Wistar rats, and 2 months later intralesional administration of 5 × 10(6) allogeneic BMSC from male donors rats in saline (n = 10), or saline only (n = 10), was performed. In the following 6 months, functional outcome was evaluated in each animal by rotarod, modified neurologic severity score (mNSS) and video-tracking box (VTB) tests. To study the behavior of BMSC after transplantation, in situ hybridization studies were performed, with double labeling of the chromosome Y-linked SrY-gene, and neuronal nuclei (NeuN) protein or gliofibrillary acidic protein (GFAP).

RESULTS

The assessment test revealed significant improvements in functional outcome for the BMSC-treated animals after 2 months of follow-up. Histologic results showed that functional outcome was associated with strong reactivation of endogenous neurogenesis. Furthermore, intralesional BMSC not only integrated in the injured tissue but also showed phenotypic expression of GFAP and NeuN.

CONCLUSIONS

Late intracerebral transplantation of allogeneic BMSC induces functional recovery after ICH. The possibility of using this type of cell therapy to reverse the consequences of hemorrhagic stroke in humans should be considered.

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.

In vitro culture of bone marrow mesenchymal stem cells in rats and differentiation into retinal neural-like cells

In order to study the in vitro culture and expansion of bone marrow mesenchymal stem cells in rats (rMSCs) and the possibility of rMSCs differentiation into retinal neural cells, the bone marrow-derived cells in SD rats were isolated and cultured in vitro. The retinal neural cells in SD rats were cultured and the supernatants were collected to prepare conditioned medium. The cultured rMSCs were induced to differentiate by two steps. Immunofluorescence method and anti-nestin, anti-NeuN, anti-GFAP and anti-Thy1.1 antibodies were used to identify the cells derived from the rMSCs. The results showed that the in vitro cultured rMSCs grew well and expanded quickly. After induction with two conditioned media, rMSCs was induced to differentiate into neural progenitor cells, then into retinal neural-like cells which were positive for nestin, NeuN, GFAP and Thy1.1 detected by fluorescence method. The findings suggested that rMSCs could be culture and expanded in vitro, and induced to differentiate into retinal neural-like cells.

In vitro interactions between bone marrow stromal cells and hippocampal slice cultures

Bone marrow stromal cells (BMSCs) are capable of differentiating into various cell types including brain cells. Several groups have also demonstrated trophic effects of MSC grafts in experimental ischemia models. However, the underlying molecular mechanisms of these effects are not fully understood. We developed an "in vitro graft model" which consisted in a coculture of GFP-expressing BMSCs and hippocampal organotypic slice cultures. Total marrow cells (MCs) or BMSCs after one (BMSC(1P)) or five passages (BMSC(5P)) were transplanted on hippocampal slices. During the 10 days of our experiments, MCs and BMSC(1P) migrated toward the tissue, but their total number remained constant. Conversely, the number of BMSC(5P) decreased over the 10 days of the experiment, and no migration could be detected. Using immunohistochemistry, we observed that the hippocampal slices induced the expression of neural antigens in very few grafted cells, but MCs and BMSC(1P) improved the conservation of the hippocampal slice culture. Similar experiments using BMSC(5P) did not produce any significant change. We conclude that the number of passages greatly influence BMSCs survival rate, migration and neuroprotective capacities.

Membrane properties of neuron-like cells generated from adult human bone-marrow-derived mesenchymal stem cells

Adult mesenchymal stem cells (MeSCs) isolated from human bone marrow are capable of generating neural stem cell (NSC)-like cells that can be subsequently differentiated into cells expressing molecular markers for neurons. Here we report that these neuron-like cells had functional properties similar to those of brain-derived neurons. Whole-cell patch-clamp recordings and calcium imaging experiments were performed on neuron-like cells differentiated from bone-marrow-derived NSC-like cells. The neuron-like cells were subjected to current pulses to determine if they were capable of generating depolarization-induced action potentials. We found that nearly all of the cells with neuron-like morphology exhibited active membrane properties in response to the depolarizing pulses. The most common response was a single spike-like event with an overshoot and brief afterhyperpolarization. Cells that did not generate overshooting spike-like events usually displayed rectifying current-voltage relationships. The prevalence of these active membrane properties in response to the depolarizing current pulses suggested that the human MeSCs (hMeSCs) were capable of converting to a neural lineage under defined culture conditions. The spike-like events were blocked by the voltage-gated sodium channel inhibitor lidocaine, but unaffected by another sodium channel inhibitor tetrodotoxin (TTX). In calcium imaging experiments, the neuron-like cells responded to potassium chloride depolarization and l-glutamate application with increases in the cytoplasmic calcium levels. Thus, the neuron-like cells appeared to express TTX-resistant voltage-gated sodium channels, voltage-gated calcium channels, and functional l-glutamate receptors. These results demonstrate that hMeSCs were capable of generating cells with characteristics typical of functional neurons that may prove useful for neuroreplacement therapies.

In vitro differentiation of human amniotic fluid-derived cells: augmentation towards a neuronal dopaminergic phenotype

Amniotic fluid is known to yield a number of cell types which are multipotent, ethically derived, genetically stable, easily grown, expanded and possess favourable immunogenicity, which has resulted in an increasing interest for use in various neuronal disorders such as Parkinson's disease. The neuronal potential of cells derived from the adherent fraction of amniotic fluid, routinely taken by amniocentesis, are least explored. The aim of the present study was to investigate the capacity of these cells for neuronal and dopaminergic differentiation using in vitro differentiation protocols with canonical inductive factors not previously tested. To do this, samples derived from multiple donors were grown under four conditions: standard serum-containing media, NB (neurobasal) media designed specifically for propagation and maintenance of neuronal cells, NB media with addition of retinoic acid and BDNF (brain-derived neurotrophic factor) for NI (neuronal induction), and NB media with addition of FGF8 (fibroblast growth factor-8) and Shh (sonic hedgehog) after NI. Our results showed the presence of multiple neuronal markers after growth in serum-containing medium [TUJ1, MAP2, NF-M, TH (tyrosine hydroxylase)], which was significantly up-regulated after serum withdrawal in NB medium alone with induction of NeuN (neuronal nuclei) and NSE (neuron-specific enolase). NI and DA.I (dopaminergic induction) was accompanied by further increases in expression and a distinct transition to a sustained neuronal morphology. Western blot analysis confirmed increasing TH expression and NURR1, expressed in base serum-containing media, found to be down-regulated after induction. In conclusion, these cells possess a highly favourable base neuronal and dopaminergic prepotential, which may easily be accentuated by standard induction protocols.

Neurogenic transdifferentiation of human adipose-derived stem cells? A critical protocol reevaluation with special emphasis on cell proliferation and cell cycle alterations

Adipose-derived stem cells (ASCs) are reported to display multilineage differentiation potential, including neuroectodermal pathways. The aim of the present study was to critically re-evaluate the potential neurogenic (trans-)differentiation capacity of ASCs using a neurogenic induction protocol based on the combination of isobutylmethylxanthine (IBMX), indomethacin and insulin. ASCs isolated from lipo-aspirate samples of five healthy female donors were characterized and potential neurogenic (trans-)differentiation was assessed by means of immunohistochemistry and gene expression analyses. Cell proliferation and cell cycle alterations were studied, and the expression of CREB/ATF transcription factors was analyzed. ASCs expressed CD59, CD90 and CD105, and were tested negative for CD34 and CD45. Under neurogenic induction, ASCs adopted a characteristic morphology comparable to neur(on)al progenitors and expressed musashi1, β-III-tubulin and nestin. Gene expression analyses revealed an increased expression of β-III-tubulin, GFAP, vimentin and BDNF, as well as SOX4 in induced ASCs. Cell proliferation was significantly reduced under neurogenic induction; cell cycle analyses showed a G2-cell cycle arrest accompanied by differential expression of key regulators of cell cycle progression. Differential expression of CREB/ATF transcription factors could be observed on neurogenic induction, pointing to a decisive role of the cAMP-CREB/ATF system. Our findings may point to a potential neurogenic (trans-)differentiation of ASCs into early neur(on)al progenitors, but do not present definite evidence for it. Especially, the adoption of a neural progenitor cell-like morphology must not automatically be misinterpreted as a specific characteristic of a respective (trans-)differentiation process, as this may as well be caused by alterations of cell cycle progression.

Keratinocyte proximity and contact can play a significant role in determining mesenchymal stem cell fate in human tissue

Bone marrow-derived human mesenchymal stem cells (hMSCs) possess multipotent differentiation capabilities and are a potent source of paracrine factors. We show how the epidermal keratinocyte can direct hMSC differentiation selectively. Keratinocytes and hMSCs were either cocultured in physical contact (contact cocultures), or separated without physical contact using a transwell insert (noncontact cocultures). We also delivered hMSCs into an ex vivo human excisional wound where subpopulations of the hMSCs were either in contact or were physically separated from the epidermal keratinocytes. In comparison to control hMSCs that were not cocultured, contact cocultured hMSCs adopted an epithelial morphology and expressed keratinocyte markers while noncontact cocultured hMSCs, surprisingly, adopted phenotypes that resembled myofibroblast and early neural lineage, both of which are of dermal origin. Cell fusion was not a requirement in in vitro contact cocultures, as determined by fluorescence-activated cell sorting (FACS) and fluorescence in situ hybridization analysis (FISH). To the best of our knowledge, this work provides the first example of hMSC differentiation into different lineages depending on their proximity to a single cell type.

Translation of stem cell therapy for neurological diseases

"Regenerative medicine" hopefully will provide novel therapies for diseases that remain without effective therapy. This development is also true for most neurodegenerative disorders including Alzheimer's disease, Huntington's disease, or Parkinson's disease. Transplantation of new neurons to the brain has been performed in Parkinson's disease and in Huntington's disease. The restoration of dopaminergic neurons in patients with Parkinson's disease via implantation of embryonic midbrain tissue was taken from animal experiments to clinical applications, showing a limited efficacy. Clinical trials in patients with Huntington's disease using fetal striatal tissue currently are underway. Today, it seems possible to generate functional dopaminergic or striatal neurons form a variety of stem cells including embryonic or neural stem cells as well as induced pluripotent stem cells. First clinical trials using neural stem cell or embryonic-stem-cell-derived tissue are approved or already underway. Such cells allow for extensive in vitro and in vivo testing as well as "good manufacturing production," reducing the risks in clinical application.

EGF and bFGF pre-treatment enhances neural specification and the response to neuronal commitment of MIAMI cells

AIMS

Multipotent mesenchymal stromal cells raise great interest for regenerative medicine studies. Some MSC subpopulations have the potential to undergo neural differentiation, including marrow isolated adult multilineage inducible (MIAMI) cells, which differentiate into neuron-like cells in a multi-step neurotrophin 3-dependent manner. Epidermal and basic fibroblast growth factors are often used in neuronal differentiation protocols for MSCs, but with a limited understanding of their role. In this study, we thoroughly assessed for the first time the capacity of these factors to enhance the neuronal differentiation of MSCs.

MATERIALS AND METHODS

We have characterized MIAMI cell neuronal differentiation program in terms of stem cell molecule expression, cell cycle modifications, acquisition of a neuronal morphology and expression of neural and neuronal molecules in the absence and presence of an EGF-bFGF pre-treatment.

RESULTS

EGF-bFGF pre-treatment down-regulated the expression of stemness markers Oct4A, Notch1 and Hes5, whereas neural/neuronal molecules Nestin, Pax6, Ngn2 and the neurotrophin receptor tyrosine kinase 1 and 3 were up-regulated. During differentiation, a sustained Erk phosphorylation in response to NT3 was observed, cells began to exit from the cell cycle and exhibit increased neurite-like extensions. In addition, neuronal β3-tubulin and neurofilament expression was increased; an effect mediated via the Erk pathway. A slight pre-oligodendrocyte engagement was noted, and no default neurotransmitter phenotype was observed. Overall, mesodermal markers were unaffected or decreased, while neurogenic/adipogenic PPARγ2 was increased.

CONCLUSION

EGF and bFGF pre-treatment enhances neural specification and the response to neuronal commitment of MIAMI cells, further increasing their potential use in adult cell therapy of the nervous system.

Evaluation of bone marrow- and brain-derived neural stem cells in therapy of central nervous system autoimmunity

Adult subventricular zone (SVZ)-derived neural stem cells (NSCs) have therapeutic effects in experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis. However, SVZ precursor cells as a source of NSCs are not readily accessible for clinical application. In the present study, we demonstrate that NSCs derived from bone marrow (BM) cells exhibit comparable morphological properties as those derived from SVZ cells and possess a similar ability to differentiate into neurons, astrocytes, and oligodendrocytes both in vitro and in vivo. Importantly, both types of NSCs suppressed chronic experimental autoimmune encephalomyelitis to a comparable extent on transplantation. Mechanisms underlying the therapeutic effects of NSCs include immunomodulation in the periphery and the central nervous system (CNS), neuron/oligodendrocyte repopulation by transplanted cells, and enhanced endogenous remyelination and axonal recovery. Furthermore, we provide evidence for the trans-differentiation of transplanted BM-NSCs into neural cells in the CNS, while no fusion of these cells with host neural cells was detected. This is the first study that directly compares SVZ- versus BM-NSCs with regard to in vivo neural differentiation and anti-inflammatory and therapeutic effects on CNS inflammatory demyelination. Their virtually identical therapeutic potential, greater accessibility, and autologous properties make BM-NSCs a novel and highly applicable substitute for SVZ-NSCs in cell-based multiple sclerosis therapies.

Comparison of human dental follicle cells (DFCs) and stem cells from human exfoliated deciduous teeth (SHED) after neural differentiation in vitro

Dental stem cells from human exfoliated deciduous teeth (SHED) and dental follicle cells (DFCs) are neural crest-derived stem cells from human dental tissues. Interestingly, SHED and DFCs can successfully differentiate into neuron-like cells. We hypothesized that SHED and DFCs have the same neural cell differentiation potentials. To evaluate neural cell differentiation, we cultivated SHED and DFCs in four different serum-replacement media (SRMs) and analyzed cell morphology, cell proliferation, and gene expression patterns before and after differentiation. In a standard cell culture medium, SHED and DFCs have not only similar cell morphologies, but they also have similar gene expression patterns for known stem cell markers. However, only SHED expressed the neural stem cell marker Pax6. After cultivation in SRMs, cell proliferations of DFCs and SHED were reduced and the cell morphology was spindle-like with long processes. However, differentiated DFCs and SHED had different neural cell marker expression patterns. For example, gene expression of the late neural cell marker microtubule-associated protein 2 was upregulated in DFCs and downregulated in SHED in SRM with the B27 supplement. In contrast, SHED formed neurosphere-like cell clusters in SRM with the B27 supplement, epidermal growth factor, and fibroblast growth factor-2. Moreover, SHED differentially expressed the glial cell marker glial fibrillary acidic protein, which in contrast was weakly or not expressed in DFCs. In conclusion, SHED and DFCs have different neural differentiation potentials under the same cell culture conditions.