Peripheral nervous system progenitors can be reprogrammed to produce myelinating oligodendrocytes and repair brain lesions

Negative regulation by proBDNF signaling of peripheral neurogenesis in the sensory ganglia of adult rats

Neurogenesis in the adult brain is well recognized and plays a critical role in the maintenance of brain function and homeostasis. However, whether neurogenesis also occurs in the adult peripheral nervous system remains unknown. Here, using sensory ganglia (dorsal root ganglia, DRGs) as a model, we show that neurogenesis also occurs in the peripheral nervous system, but in a manner different from that in the central nervous system. Satellite glial cells (SGCs) express the neuronal precursor markers Nestin, POU domain, class 4, transcription factor 1, and p75 pan-neurotrophin receptor. Following sciatic nerve injury, the suppression of endogenous proBDNF by proBDNF antibodies resulted in the transformation of proliferating SGCs into doublecortin-positive cells in the DRGs. Using purified SGCs migrating out from the DRGs, the inhibition of endogenous proBDNF promoted the conversion of SGCs into neuronal phenotypes in vitro. Our findings suggest that SGCs are neuronal precursors, and that proBDNF maintains the SGC phenotype. Furthermore, the suppression of proBDNF signaling is necessary for neuronal phenotype acquisition by SGCs. Thus, we propose that peripheral neurogenesis may occur via the direct conversion of SGCs into neurons, and that this process is negatively regulated by proBDNF.

EXPERIMENTAL RATIONALE OF THE USE OF CELL THERAPY FOR THE TREATMENT OF GLAUCOMA OPTICAL NEUROPATHY

Development of new effective treatments for glaucomatous optic neuropathy is one of the most acute aspects of modern ophthalmology. The aim of the work is to investigate the effectiveness of cell therapy with postnatal multipotent neural crest stem cells (NCSCs) using different cell delivery methods in a model of adrenaline-induced glaucoma. Materials and methods. Glaucoma was induced in Wistar rats by intraperitoneal injections of 10 μg to 15 μg/100 g body weight of 0.18 % adrenaline hydrotartrate. NCSCs were delivered intravenously (5 million cells), retrobulbarly (0.5 million cells) or parabulbarly (0.5 million cells). Histomorphometric analysis of the retina was performed on stained haematoxylin-eosin sections with a thickness of 5 μm one month after the delivery of NCSCs. Results. NCSCs transplantation by all modes of delivery caused positive morphological changes to varying degrees. Intravenous administration induced a decrease in edema in all retinal layers and a slight restoration of the cytoarchitectonics of the retinal layers. The parabulbar administration of NCSCs led to a decrease in edema and the restoration of the cytoarchitectonics of the layers, most pronouncedly the ganglion cell layer and the inner retinal layer. After the retrobulbar administration of NCSCs, the reduction in edema and restoration of the cytoarchitectonics of the layers were the most pronounced. Conclusions. According to the results of the study, the positive effect of NCSCs transplantation in an experimental model of glaucoma was the most pronounced following the retrobulbar injection of cells. Further investigations of the mechanisms of the effect of transplanted NCSCs on retinal structure restoration are needed.

Astrocytic endothelin-1 overexpression promotes neural progenitor cells proliferation and differentiation into astrocytes via the Jak2/Stat3 pathway after stroke

Background

Endothelin-1 (ET-1) is synthesized and upregulated in astrocytes under stroke. We previously demonstrated that transgenic mice over-expressing astrocytic ET-1 (GET-1) displayed more severe neurological deficits characterized by a larger infarct after transient middle cerebral artery occlusion (tMCAO). ET-1 is a known vasoconstrictor, mitogenic, and a survival factor. However, it is unclear whether the observed severe brain damage in GET-1 mice post stroke is due to ET-1 dysregulation of neurogenesis by altering the stem cell niche.

Methods

Non-transgenic (Ntg) and GET-1 mice were subjected to tMCAO with 1 h occlusion followed by long-term reperfusion (from day 1 to day 28). Neurological function was assessed using a four-point scale method. Infarct area and volume were determined by 2,3,5-triphenyltetra-zolium chloride staining. Neural stem cell (NSC) proliferation and migration in subventricular zone (SVZ) were evaluated by immunofluorescence double labeling of bromodeoxyuridine (BrdU), Ki67 and Sox2, Nestin, and Doublecortin (DCX). NSC differentiation in SVZ was evaluated using the following immunofluorescence double immunostaining: BrdU and neuron-specific nuclear protein (NeuN), BrdU and glial fibrillary acidic protein (GFAP). Phospho-Stat3 (p-Stat3) expression detected by Western-blot and immunofluorescence staining.

Results

GET-1 mice displayed a more severe neurological deficit and larger infarct area after tMCAO injury. There was a significant increase of BrdU-labeled progenitor cell proliferation, which co-expressed with GFAP, at SVZ in the ipsilateral side of the GET-1 brain at 28 days after tMCAO. p-Stat3 expression was increased in both Ntg and GET-1 mice in the ischemia brain at 7 days after tMCAO. p-Stat3 expression was significantly upregulated in the ipsilateral side in the GET-1 brain than that in the Ntg brain at 7 days after tMCAO. Furthermore, GET-1 mice treated with AG490 (a JAK2/Stat3 inhibitor) sh owed a significant reduction in neurological deficit along with reduced infarct area and dwarfed astrocytic differentiation in the ipsilateral brain after tMCAO.

Conclusions

The data indicate that astrocytic endothelin-1 overexpression promotes progenitor stem cell proliferation and astr ocytic differentiation via the Jak2/Stat3 pathway.

Comparative Analysis of Biological Properties of Large-Scale Expanded Adult Neural Crest-Derived Stem Cells Isolated from Human Hair Follicle and Skin Dermis

Introduction

The adult neural crest-derived stem cells (NCSCs) have significant perspectives for use in regenerative medicine. The most attractive sources for adult NCSC isolation are the hair follicles (HF) and skin dermis (SD) because of easy access and minimally invasive biopsy. The aim of this study was to compare the biological properties of HF- and SD-derived NCSCs after their large-scale expansion.

Methods

The conventional explant method was used to obtain HF NCSCs. For the isolation of SD NCSCs, a new combined technique consisting of preplating and subsequent culturing in 3D blood plasma-derived fibrin hydrogel was applied. The studied cells were characterized by flow cytometry, ICC, qPCR, Bio-Plex multiplex assay, and directed multilineage differentiation assays.

Results

We have obtained both adult SD and HF NCSCs from each skin sample (n = 5). Adult SD and HF NCSCs were positive for key neural crest markers: SOX10, P75 (CD271), NESTIN, SOX2, and CD349. SD NCSCs showed a higher growth rate during the large-scale expansion compared to HF NCSCs (p < 0.01). Final population of SD NCSCs also contained more clonogenic cells (p < 0.01) and SOX10⁺, CD271⁺, CD105⁺, CD140a⁺, CD146⁺, CD349⁺ cells (p < 0.01). Both HF and SD NCSCs had similar gene expression profiling and produced growth factors, but some quantitative differences were detected. Adult HF and SD NCSCs were able to undergo directed differentiation into neurons, Schwann cells, adipocytes, and osteoblasts.

Conclusion

The HF and SD are suitable sources for large-scale manufacturing of adult NCSCs with similar biological properties. We demonstrated that the NCSC population from SD was homogenous and displayed significantly higher growth rate than HF NCSCs. Moreover, SD NCSC isolation is cheaper, easier, and minimally time-consuming method.

Quantitative Multimodal Evaluation of Passaging Human Neural Crest Stem Cells for Peripheral Nerve Regeneration

Peripheral nerve injury is a major burden to societies worldwide, however, current therapy options (e.g. autologous nerve grafts) are unable to produce satisfactory outcomes. Many studies have shown that stem cell transplantation holds great potential for peripheral nerve repair, and human neural crest stem cells (hNCSCs), which give rise to a variety of tissues in the peripheral nervous system, are particularly promising. NCSCs are one of the best candidates for clinical translation, however, to ensure the viability and quality of NCSCs for research and clinical use, the effect of in vitro cell passaging on therapeutic effects needs be evaluated given that passaging is required to expand NCSCs to meet the demands of transplantation in preclinical research and clinical trials. To date, no study has investigated the quality of NCSCs past the 5th passage in vivo. In this study, we employed a multimodal evaluation system to investigate changes in outcomes between transplantation with 5th (p5) and 6th passage (p6) NCSCs in a 15 mm rat sciatic nerve injury and repair model. Using CatWalk gait analysis, gastrocnemius muscle index, electrophysiology, immunohistochemistry, and histomorphometric analysis, we showed that p6 NCSCs demonstrated decreased cell survival, Schwann-cell differentiation, axonal growth, and functional outcomes compared to p5 NCSCs (all p < 0.05). In conclusion, p6 NCSCs showed significantly reduced therapeutic efficacy compared to p5 NCSCs for peripheral nerve regeneration.

Reclassification of 21 Presumptive Canine Peripheral Nerve Sheath Tumors (PNST) Using a Literature-Based Immunohistochemical Panel

The aim of this study was to re-evaluate archived samples of canine soft tissue sarcomas (STSs) morphologically consistent with peripheral nerve sheath tumors (PNSTs). In each case, an immunohistochemical panel was applied, including α-SMA, calponin, desmin, S-100, GFAP, NSE and Olig2, in order to assess whether the phenotype was consistent with the tumor histological appearance. Additionally, the expression of EGFR, a marker with potential therapeutic implications in malignant PNSTs, was evaluated. Twenty-one tumors were included. Fourteen cases (66.7%) were positive for one or more muscular markers and were reclassified as perivascular tumors (PWTs). A positive labeling for S-100 was observed in one tumor (4.8%), thus classifi ed as PNST. The other 6 tumors were generically classified as poorly differentiated STSs. No unique histopathological feature was observed within the three groups. NSE and Olig2 labeling was aspecific and not useful for diagnostic purposes. GFAP was negative in all cases. Six cases (28.6%) were positive for EGFR, including the PNST. Even after the application of a wide immunohistochemical panel, distinguishing between PNSTs and PWTs remains a challenge. Finally, a subgroup of cases cannot be classified based on light microscopy alone.

Distinct capacity for differentiation to inner ear cell types by progenitor cells of the cochlea and vestibular organs

Disorders of hearing and balance are most commonly associated with damage to cochlear and vestibular hair cells or neurons. Although these cells are not capable of spontaneous regeneration, progenitor cells in the hearing and balance organs of the neonatal mammalian inner ear have the capacity to generate new hair cells after damage. To investigate whether these cells are restricted in their differentiation capacity, we assessed the phenotypes of differentiated progenitor cells isolated from three compartments of the mouse inner ear - the vestibular and cochlear sensory epithelia and the spiral ganglion - by measuring electrophysiological properties and gene expression. Lgr5⁺ progenitor cells from the sensory epithelia gave rise to hair cell-like cells, but not neurons or glial cells. Newly created hair cell-like cells had hair bundle proteins, synaptic proteins and membrane proteins characteristic of the compartment of origin. PLP1⁺ glial cells from the spiral ganglion were identified as neural progenitors, which gave rise to neurons, astrocytes and oligodendrocytes, but not hair cells. Thus, distinct progenitor populations from the neonatal inner ear differentiate to cell types associated with their organ of origin.

Familial Dysautonomia (FD) Human Embryonic Stem Cell Derived PNS Neurons Reveal that Synaptic Vesicular and Neuronal Transport Genes Are Directly or Indirectly Affected by IKBKAP Downregulation

A splicing mutation in the IKBKAP gene causes Familial Dysautonomia (FD), affecting the IKAP protein expression levels and proper development and function of the peripheral nervous system (PNS). Here we found new molecular insights for the IKAP role and the impact of the FD mutation in the human PNS lineage by using a novel and unique human embryonic stem cell (hESC) line homozygous to the FD mutation originated by pre implantation genetic diagnosis (PGD) analysis. We found that IKBKAP downregulation during PNS differentiation affects normal migration in FD-hESC derived neural crest cells (NCC) while at later stages the PNS neurons show reduced intracellular colocalization between vesicular proteins and IKAP. Comparative wide transcriptome analysis of FD and WT hESC-derived neurons together with the analysis of human brains from FD and WT 12 weeks old embryos and experimental validation of the results confirmed that synaptic vesicular and neuronal transport genes are directly or indirectly affected by IKBKAP downregulation in FD neurons. Moreover we show that kinetin (a drug that corrects IKBKAP alternative splicing) promotes the recovery of IKAP expression and these IKAP functional associated genes identified in the study. Altogether, these results support the view that IKAP might be a vesicular like protein that might be involved in neuronal transport in hESC derived PNS neurons. This function seems to be mostly affected in FD-hESC derived PNS neurons probably reflecting some PNS neuronal dysfunction observed in FD.

The effects of tumor location on diagnostic criteria for canine malignant peripheral nerve sheath tumors (MPNSTs) and the markers for distinction between canine MPNSTs and canine perivascular wall tumors

Canine malignant peripheral nerve sheath tumors (MPNSTs) occur not only in the peripheral nervous system (PNS) but also in soft tissue and various organs (non-PNS). The most important diagnostic criterion is proof of peripheral nerve sheath origin. This is difficult in non-PNS MPNSTs, and its differential diagnosis is challenging. Canine perivascular wall tumors (PWTs) also commonly arise in soft tissue. Their histopathological features are quite similar to those of canine MPNSTs, making their differential diagnosis challenging. To elucidate whether the morphological features are applicable to diagnose non-PNS MPNSTs and to demonstrate useful markers for distinction between canine MPNSTs and PWTs, the authors examined 30 canine MPNSTs and 31 PWTs immunohistochemically for S100, nestin, NGFR, Olig2, claudin-1, CD57, PRX, α-SMA, desmin, and calponin. Among canine MPNSTs, the PNS tumors displayed significantly higher S100 and Olig2 expression than the non-PNS tumors. The expression levels of the other markers did not differ significantly, suggesting that the same morphological diagnostic criteria are applicable regardless of their location. The PWT cells displayed significantly weaker immunoreactivity than MPNSTs to markers used except α-SMA and desmin. Cluster analysis sorted most canine MPNSTs and PWTs into 2 distinctly different clusters, whereas 3 MPNSTs and 6 PWTs were assigned to the opposing cluster. These 3 MPNSTs were negative for almost all markers, while these 6 PWTs were positive for only neuronal markers. In particular, NGFR and Olig2 were almost negative in the rest of PWT cases. These findings suggest that NGFR and Olig2 are useful to distinguish these 2 tumors.

Sonic hedgehog and neurotrophin-3 increase oligodendrocyte numbers and myelination after spinal cord injury

Spinal cord injury (SCI) results in loss of sensory and motor function below the level of injury and has limited available therapies. Multiple channel bridges have been investigated as a means to create a permissive environment for regeneration, with channels supporting axonal growth through the injury. Bridges support robust axon growth and myelination. Here, we investigated the cell types that myelinate axons in the bridges and whether over-expression of trophic factors can enhance myelination. Lentivirus encoding for neurotrophin-3 (NT3), sonic hedgehog (SHH) and the combination of these factors was delivered from bridges implanted into a lateral hemisection defect at T9/T10 in mice, and the response of endogenous progenitor cells within the spinal cord was investigated. Relative to control, the localized, sustained expression of these factors significantly increased growth of regenerating axons into the bridge and enhanced axon myelination 8 weeks after injury. SHH decreased the number of Sox2(+) cells and increased the number of Olig2(+) cells, whereas NT3 alone or in combination with SHH enhanced the numbers of GFAP(+) and Olig2(+) cells relative to control. For delivery of lentivirus encoding for either factor, we identified cells at various stages of differentiation along the oligodendrocyte lineage (e.g., O4(+), GalC(+)). Expression of NT3 enhanced myelination primarily by infiltrating Schwann cells, whereas SHH over-expression substantially increased myelination by oligodendrocytes. These studies further establish biomaterial-mediated gene delivery as a promising tool to direct activation and differentiation of endogenous progenitor cells for applications in regenerative medicine.

Boundary cap neural crest stem cells homotopically implanted to the injured dorsal root transitional zone give rise to different types of neurons and glia in adult rodents

Background

The boundary cap is a transient group of neural crest-derived cells located at the presumptive dorsal root transitional zone (DRTZ) when sensory axons enter the spinal cord during development. Later, these cells migrate to dorsal root ganglia and differentiate into subtypes of sensory neurons and glia. After birth when the DRTZ is established, sensory axons are no longer able to enter the spinal cord. Here we explored the fate of mouse boundary cap neural crest stem cells (bNCSCs) implanted to the injured DRTZ after dorsal root avulsion for their potential to assist sensory axon regeneration.

Results

Grafted cells showed extensive survival and differentiation after transplantation to the avulsed DRTZ. Transplanted cells located outside the spinal cord organized elongated tubes of Sox2/GFAP expressing cells closely associated with regenerating sensory axons or appeared as small clusters on the surface of the spinal cord. Other cells, migrating into the host spinal cord as single cells, differentiated to spinal cord neurons with different neurotransmitter characteristics, extensive fiber organization, and in some cases surrounded by glutamatergic terminal-like profiles.

Conclusions

These findings demonstrate that bNCSCs implanted at the site of dorsal root avulsion injury display remarkable differentiation plasticity inside the spinal cord and in the peripheral compartment where they organize tubes associated with regenerating sensory fibers. These properties offer a basis for exploring the ability of bNCSCs to assist regeneration of sensory axons into the spinal cord and replace lost neurons in the injured spinal cord.

Adult olfactory sphere cells are a source of oligodendrocyte and Schwann cell progenitors

The olfactory epithelial layer contains multipotent horizontal basal cells (HBCs) that differentiate into olfactory sensory neurons. Here, we show that rat HBCs express oligodendrocyte progenitor cell (OPC) and astrocyte markers. We generated olfactory sphere (OS) cells in cultures that were derived from adult rat olfactory mucosa. Fluorescence-activated cell sorting and immunofluorescence analyses showed that OS cells also express OPC and astrocyte markers. Interestingly, OS cells underwent oligodendrocyte differentiation in vitro. To study oligodendrocyte differentiation in vivo, OS cells were transplanted into injured rat spinal cords. The transplanted cells integrated into host tissue and differentiated into oligodendrocytes. When transected saphenous nerve ends were encased in collagen-containing silicone tubes with or without OS cells, the transplanted OS cells differentiated into Schwann cells. Our data provide new insights into of the stemness of OS cells.

Neural crest and olfactory system: new prospective

Sensory neurons in vertebrates are derived from two embryonic transient cell sources: neural crest (NC) and ectodermal placodes. The placodes are thickenings of ectodermal tissue that are responsible for the formation of cranial ganglia as well as complex sensory organs that include the lens, inner ear, and olfactory epithelium. The NC cells have been indicated to arise at the edges of the neural plate/dorsal neural tube, from both the neural plate and the epidermis in response to reciprocal interactions Moury and Jacobson (Dev Biol 141:243-253, 1990). NC cells migrate throughout the organism and give rise to a multitude of cell types that include melanocytes, cartilage and connective tissue of the head, components of the cranial nerves, the dorsal root ganglia, and Schwann cells. The embryonic definition of these two transient populations and their relative contribution to the formation of sensory organs has been investigated and debated for several decades (Basch and Bronner-Fraser, Adv Exp Med Biol 589:24-31, 2006; Basch et al., Nature 441:218-222, 2006) review (Baker and Bronner-Fraser, Dev Biol 232:1-61, 2001). Historically, all placodes have been described as exclusively derived from non-neural ectodermal progenitors. Recent genetic fate-mapping studies suggested a NC contribution to the olfactory placodes (OP) as well as the otic (auditory) placodes in rodents (Murdoch and Roskams, J Neurosci Off J Soc Neurosci 28:4271-4282, 2008; Murdoch et al., J Neurosci 30:9523-9532, 2010; Forni et al., J Neurosci Off J Soc Neurosci 31:6915-6927, 2011b; Freyer et al., Development 138:5403-5414, 2011; Katoh et al., Mol Brain 4:34, 2011). This review analyzes and discusses some recent developmental studies on the OP, placodal derivatives, and olfactory system.

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.