Pleiotrophin mRNA is highly expressed in neural stem (progenitor) cells of mouse ventral mesencephalon and the product promotes production of dopaminergic neurons from embryonic stem cell-derived nestin-positive cells

The Role of Various Factors in Neural Differentiation of Human Umbilical Cord Mesenchymal Stem Cells with a Special Focus on the Physical Stimulants

Human umbilical cord matrix-derived mesenchymal stem cells (hUCMs) are considered as ideal tools for cell therapy procedures and regenerative medicine. The capacity of these cells to differentiate into neural lineage cells make them potentially important in the treatment of various neurodegenerative diseases. An electronic search was performed in Web of Science, PubMed/MEDLINE, Scopus and Google Scholar databases for articles published from January 1990 to March 2022. This review discusses the current knowledge on the effect of various factors, including physical, chemical and biological stimuli which play a key role in the differentiation of hUCMs into neural and glial cells. Moreover, the currently understood molecular mechanisms involved in the neural differentiation of hUCMs under various environmental stimuli are reviewed. Various stimuli, especially physical stimuli and specifically different light sources, have revealed effects on neural differentiation of mesenchymal stem cells, including hUCMs; however, due to the lack of information about the exact mechanisms, there is still a need to find optimal conditions to promote the differentiation capacity of these cells which in turn can lead to significant progress in the clinical application of hUCMs for the treatment of neurological disorders.

Single-cell analysis reveals specific neuronal transition during mouse corticogenesis

Background: Currently, the mechanism(s) underlying corticogenesis is still under characterization. Methods: We curated the most comprehensive single-cell RNA-seq (scRNA-seq) datasets from mouse and human fetal cortexes for data analysis and confirmed the findings with co-immunostaining experiments. Results: By analyzing the developmental trajectories with scRNA-seq datasets in mice, we identified a specific developmental sub-path contributed by a cell-population expressing both deep- and upper-layer neurons (DLNs and ULNs) specific markers, which occurred on E13.5 but was absent in adults. In this cell-population, the percentages of cells expressing DLN and ULN markers decreased and increased, respectively, during the development suggesting direct neuronal transition (namely D-T-U). Whilst genes significantly highly/uniquely expressed in D-T-U cell population were significantly enriched in PTN/MDK signaling pathways related to cell migration. Both findings were further confirmed by co-immunostaining with DLNs, ULNs and D-T-U specific markers across different timepoints. Furthermore, six genes (co-expressed with D-T-U specific markers in mice) showing a potential opposite temporal expression between human and mouse during fetal cortical development were associated with neuronal migration and cognitive functions. In adult prefrontal cortexes (PFC), D-T-U specific genes were expressed in neurons from different layers between humans and mice. Conclusion: Our study characterizes a specific cell population D-T-U showing direct DLNs to ULNs neuronal transition and migration during fetal cortical development in mice. It is potentially associated with the difference of cortical development in humans and mice.

Cross-sectional proteomic expression in Parkinson's disease-related proteins in drug-naïve patients vs healthy controls with longitudinal clinical follow-up

There is an urgent need to find reliable and accessible blood-based biomarkers for early diagnosis of Parkinson's disease (PD) correlating with clinical symptoms and displaying predictive potential to improve future clinical trials. This led us to a conduct large-scale proteomics approach using an advanced high-throughput proteomics technology to create a proteomic profile for PD. Over 1300 proteins were measured in serum samples from a de novo Parkinson's (DeNoPa) cohort made up of 85 deep clinically phenotyped drug-naïve de novo PD patients and 93 matched healthy controls (HC) with longitudinal clinical follow-up available of up to 8 years. The analysis identified 73 differentially expressed proteins (DEPs) of which 14 proteins were confirmed as stable potential diagnostic markers using machine learning tools. Among the DEPs identified, eight proteins-ALCAM, contactin 1, CD36, DUS3, NEGR1, Notch1, TrkB, and BTK- significantly correlated with longitudinal clinical scores including motor and non-motor symptom scores, cognitive function and depression scales, indicating potential predictive values for progression in PD among various phenotypes. Known functions of these proteins and their possible relation to the pathophysiology or symptomatology of PD were discussed and presented with a particular emphasis on the potential biological mechanisms involved, such as cell adhesion, axonal guidance and neuroinflammation, and T-cell activation. In conclusion, with the use of advance multiplex proteomic technology, a blood-based protein signature profile was identified from serum samples of a well-characterized PD cohort capable of potentially differentiating PD from HC and predicting clinical disease progression of related motor and non-motor PD symptoms. We thereby highlight the need to validate and further investigate these markers in future prospective cohorts and assess their possible PD-related mechanisms.

Metabolomics and biochemical alterations caused by pleiotrophin in the 6-hydroxydopamine mouse model of Parkinson's disease

Pleiotrophin (PTN) is a cytokine involved in nerve tissue repair processes, neuroinflammation and neuronal survival. PTN expression levels are upregulated in the nigrostriatal pathway of Parkinson's Disease (PD) patients. We aimed to characterize the dopaminergic injury and glial responses in the nigrostriatal pathway of mice with transgenic Ptn overexpression in the brain (Ptn-Tg) after intrastriatal injection of the catecholaminergic toxic 6-hydroxydopamine (6-OHDA) at a low dose (5 µg). Ten days after surgery, the injection of 6-OHDA induced a significant decrease of the number of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra and of the striatal TH contents in Wild type (Wt) mice. In contrast, these effects of 6-OHDA were absent in Ptn-Tg mice. When the striatal Iba1 and GFAP immunoreactivity was studied, no statistical differences were found between vehicle-injected Wt and Ptn-Tg mice. Furthermore, 6-OHDA did not cause robust glial responses neither on Wt or Ptn-Tg mice 10 days after injections. In metabolomics studies, we detected interesting metabolites that significantly discriminate the more injured 6-OHDA-injected Wt striatum and the more protected 6-OHDA-injected Ptn-Tg striatum. Particularly, we detected groups of metabolites, mostly corresponding to phospholipids, whose trends were opposite in both groups. In summary, the data confirm lower 6-OHDA-induced decreases of TH contents in the nigrostriatal pathway of Ptn-Tg mice, suggesting a neuroprotective effect of brain PTN overexpression in this mouse model of PD. New lipid-related PD drug candidates emerge from this study and the data presented here support the increasingly recognized "lipid cascade" in PD.

Enriched Environment and Exercise Enhance Stem Cell Therapy for Stroke, Parkinson’s Disease, and Huntington’s Disease

Stem cells, specifically embryonic stem cells (ESCs), mesenchymal stem cells (MSCs), induced pluripotent stem cells (IPSCs), and neural progenitor stem cells (NSCs), are a possible treatment for stroke, Parkinson’s disease (PD), and Huntington’s disease (HD). Current preclinical data suggest stem cell transplantation is a potential treatment for these chronic conditions that lack effective long-term treatment options. Finding treatments with a wider therapeutic window and harnessing a disease-modifying approach will likely improve clinical outcomes. The overarching concept of stem cell therapy entails the use of immature cells, while key in recapitulating brain development and presents the challenge of young grafted cells forming neural circuitry with the mature host brain cells. To this end, exploring strategies designed to nurture graft-host integration will likely enhance the reconstruction of the elusive neural circuitry. Enriched environment (EE) and exercise facilitate stem cell graft-host reconstruction of neural circuitry. It may involve at least a two-pronged mechanism whereby EE and exercise create a conducive microenvironment in the host brain, allowing the newly transplanted cells to survive, proliferate, and differentiate into neural cells; vice versa, EE and exercise may also train the transplanted immature cells to learn the neurochemical, physiological, and anatomical signals in the brain towards better functional graft-host connectivity.

Schizophrenia is defined by cell-specific neuropathology and multiple neurodevelopmental mechanisms in patient-derived cerebral organoids

Due to an inability to ethically access developing human brain tissue as well as identify prospective cases, early-arising neurodevelopmental and cell-specific signatures of Schizophrenia (Scz) have remained unknown and thus undefined. To overcome these challenges, we utilized patient-derived induced pluripotent stem cells (iPSCs) to generate 3D cerebral organoids to model neuropathology of Scz during this critical period. We discovered that Scz organoids exhibited ventricular neuropathology resulting in altered progenitor survival and disrupted neurogenesis. This ultimately yielded fewer neurons within developing cortical fields of Scz organoids. Single-cell sequencing revealed that Scz progenitors were specifically depleted of neuronal programming factors leading to a remodeling of cell-lineages, altered differentiation trajectories, and distorted cortical cell-type diversity. While Scz organoids were similar in their macromolecular diversity to organoids generated from healthy controls (Ctrls), four GWAS factors (PTN, COMT, PLCL1, and PODXL) and peptide fragments belonging to the POU-domain transcription factor family (e.g., POU3F2/BRN2) were altered. This revealed that Scz organoids principally differed not in their proteomic diversity, but specifically in their total quantity of disease and neurodevelopmental factors at the molecular level. Single-cell sequencing subsequently identified cell-type specific alterations in neuronal programming factors as well as a developmental switch in neurotrophic growth factor expression, indicating that Scz neuropathology can be encoded on a cell-type-by-cell-type basis. Furthermore, single-cell sequencing also specifically replicated the depletion of BRN2 (POU3F2) and PTN in both Scz progenitors and neurons. Subsequently, in two mechanistic rescue experiments we identified that the transcription factor BRN2 and growth factor PTN operate as mechanistic substrates of neurogenesis and cellular survival, respectively, in Scz organoids. Collectively, our work suggests that multiple mechanisms of Scz exist in patient-derived organoids, and that these disparate mechanisms converge upon primordial brain developmental pathways such as neuronal differentiation, survival, and growth factor support, which may amalgamate to elevate intrinsic risk of Scz.

Midkine is neuroprotective and influences glial reactivity and the formation of Müller glia-derived progenitor cells in chick and mouse retinas

Recent studies suggest midkine (MDK) is involved in the development and regeneration of the zebrafish retina. We investigate the expression patterns of MDK and related factors, roles in neuronal survival, and influence upon the formation of Müller glia-derived progenitor cells (MGPCs) in chick and mouse model systems. By using single-cell RNA-sequencing, we find that MDK and pleiotrophin (PTN), a MDK-related cytokine, are upregulated by Müller glia (MG) during later stages of development in chick. While PTN is downregulated, MDK is dramatically upregulated in mature MG after retinal damage or FGF2 and insulin treatment. By comparison, MDK and PTN are downregulated by MG in damaged mouse retinas. In both chick and mouse retinas, exogenous MDK induces expression of cFos and pS6 in MG. In the chick, MDK significantly decreases numbers dying neurons, reactive microglia, and proliferating MGPCs, whereas PTN has no effect. Inhibition of MDK-signaling with Na₃ VO₄ blocks neuroprotective effects with an increase in the number of dying cells and negates the pro-proliferative effects on MGPCs in damaged retinas. Inhibitors of PP2A and Pak1, which are associated with MDK-signaling through integrin β1, suppressed the formation of MGPCs in damaged chick retinas. In mice, MDK promotes a small but significant increase in proliferating MGPCs in damaged retinas and potently decreases the number of dying cells. We conclude that MDK expression is dynamically regulated in Müller glia during embryonic maturation, following retinal injury, and during reprogramming into MGPCs. MDK mediates glial activity, neuronal survival, and the re-programming of Müller glia into proliferating MGPCs.

Age-Related Macular Degeneration (AMD) Transmitochondrial Cybrids Protected from Cellular Damage and Death by Human Retinal Progenitor Cells (hRPCs)

Purpose

One of the leading causes of irreversible blindness worldwide, age-related macular degeneration (AMD) is a progressive disorder leading to retinal degeneration. While several treatment options exist for the exudative form of AMD, there are currently no FDA-approved treatments for the more common nonexudative (atrophic) form. Mounting evidence suggests that mitochondrial damage and retinal pigment epithelium (RPE) cell death are linked to the pathogenesis of AMD. Human retinal progenitor cells (hRPCs) have been studied as a potential restorative therapy for degenerative conditions of the retina; however, the effects of hRPC treatment on retinal cell survival in AMD have not been elucidated.

Methods

In this study, we used a cell coculture system consisting of hRPCs and AMD or age-matched normal cybrid cells to characterize the effects of hRPCs in protecting AMD cybrids from cellular and mitochondrial damage and death.

Results

AMD cybrids cocultured with hRPCs showed (1) increased cell viability; (2) decreased gene expression related to apoptosis, autophagy, endoplasmic reticulum (ER) stress, and antioxidant pathways; and (3) downregulation of mitochondrial replication genes compared to AMD cybrids without hRPC treatment. Furthermore, hRPCs cocultured with AMD cybrids showed upregulation of (1) neuronal and glial markers, as well as (2) putative neuroprotective factors, responses not found when hRPCs were cocultured with age-matched normal cybrids.

Conclusion

The current study provides the first evidence that therapeutic benefits may be obtainable using a progenitor cell-based approach for atrophic AMD. Our results suggest that bidirectional interactions exist between hRPCs and AMD cybrids such that hRPCs release trophic factors that protect the cybrids against the cellular and mitochondrial changes involved in AMD pathogenesis while, conversely, AMD cybrids upregulate the release of these neuroprotective factors by hRPCs while promoting hRPC differentiation. These in vitro data provide evidence that hRPCs may have therapeutic potential in atrophic AMD.

Expression of the heparin-binding growth factors Midkine and pleiotrophin during ocular development

Midkine (MDK) and Pleiotrophin (PTN) belong to a group of heparin-binding growth factors that has been shown to have pleiotropic functions in various biological processes during development and disease. Development of the vertebrate eye is a multistep process that involves coordinated interactions between neuronal and non-neuronal cells, but very little is known about the potential function of MDK and PTN in these processes. In this study, we demonstrate by section in situ hybridization, the spatiotemporal expression of MDK and PTN during ocular development in chick and mouse. We show that MDK and PTN are expressed in dynamic patterns that overlap in a few non-neuronal tissues in the anterior eye and in neuronal cell layers of the posterior eye. We show that the expression patterns of MDK and PTN are only conserved in a few tissues in chick and mouse but they overlap with the expression of some of their receptors LRP1, RPTPZ, ALK, NOTCH2, ITGβ1, SDC1, and SDC3. The dynamic expression patterns of MDK, PTN and their receptors suggest that they function together during the multistep process of ocular development and they may play important roles in cell proliferation, adhesion, and migration of neuronal and non-neuronal cells.

Serum pleiotrophin as a diagnostic and prognostic marker for small cell lung cancer

Pleiotrophin (PTN) is involved in tumour progression, angiogenesis and metastasis. The purpose of this study was to investigate the expression level of PTN in the serum of patients with small cell lung cancer (SCLC) and to explore the clinical significance of PTN. Serum samples from 128 patients with SCLC, 120 healthy volunteers (HV) and 60 patients with benign lung disease (BLD) were collected. The levels of serum PTN were determined with ELISA and its correlation with the clinical data was examined. The serum PTN levels in SCLC patients were significantly higher than that in BLD patients (P < 0.05) or HV (P < 0.05). With a cutoff value of 258.18 ng/mL, the sensitivity and specificity of PTN to SCLC patients and BLD patients, SCLC patients and HV were 79.2% and 91.7%, 86.7% and 95.8% respectively. An area under the curve for all stages of SCLC resulting from PTN, which was significantly better than the other tumour markers tested including progastrin‐releasing peptide and neuron‐specific enolase. High serum PTN levels appear to correlate with poor survival in patients with SCLC. These results suggest that PTN levels in the serum could be a new effective biomarker for the diagnosis and prognosis of SCLC.

Zika virus E protein alters the properties of human fetal neural stem cells by modulating microRNA circuitry

Zika virus (ZV) infects neural stem cells (NSCs) and causes quiescence in NSCs, reducing the pool of brain cells, leading to microcephaly. Despite conscientious efforts, the molecular mechanisms for ZV-mediated effects on NSCs lack clarity. This study aimed to explore the underlying mechanisms for ZV-mediated induction of quiescence in the primary cultures of human fetal neural stem cells (fNSCs). We demonstrate that expression of ZV envelope (E) protein displays maximum quiescence in human fNSCs by accumulating cells in the G0/G1 phase of the cell cycle as compared to other non-structural proteins, viz. NS2A, NS4A and NS4B. E protein induces immature differentiation by induction of pro-neuronal genes in proliferating fNSCs, induces apoptosis in differentiating fNSCs 3 days post differentiation, and disrupts migration of cells from differentiating neurospheres. In utero electroporation of mouse brain with E protein shows drastic downregulation of proliferating cells in ventricular and subventricular zone regions. Global microRNA sequencing suggests that E protein modulates miRNA circuitry. Among differentially expressed miRNAs, we found 14 upregulated and 11 downregulated miRNAs. Mir-204-3p and mir-1273g-3p directly regulate NOTCH2 and PAX3 expression, respectively, by binding to their 3'UTR. Bioinformatic analysis using GO analysis for the targets of differentially expressed miRNAs revealed enrichment of cell cycle and developmental processes. Furthermore, WNT, CCKR, PDGF, EGF, p53, and NOTCH signaling pathways were among the top enriched pathways. Thus, our study provides evidence for the involvement of ZV E protein and novel insights into the molecular mechanism through identification of miRNA circuitry. Art work depicting the effect of Zika virus E protein on human fetal neural stem cells.

The absence of pleiotrophin modulates gene expression in the hippocampus in vivo and in cerebellar granule cells in vitro

Pleiotrophin (PTN) is a secreted growth factor recently proposed to act as a neuromodulatory peptide in the Central Nervous System. PTN appears to be involved in neurodegenerative diseases and neural disorders, and it has also been implicated in learning and memory. Specifically, PTN-deficient mice exhibit a lower threshold for LTP induction in the hippocampus, which is attenuated in mice overexpressing PTN. However, there is little information about the signaling systems recruited by PTN to modulate neural activity. To address this issue, the gene expression profile in hippocampus of mice lacking PTN was analyzed using microarrays of 22,000 genes. In addition, we corroborated the effect of the absence of PTN on the expression of these genes by silencing this growth factor in primary neuronal cultures in vitro. The microarray analysis identified 102 genes that are differentially expressed (z-score>3.0) in PTN null mice, and the expression of eight of those modified in the hippocampus of KO mice was also modified in vitro after silencing PTN in cultured neurons with siRNAs. The data obtained indicate that the absence of PTN affects AKT pathway response and modulates the expression of genes related with neuroprotection (Mgst3 and Estrogen receptor 1, Ers 1) and cell differentiation (Caspase 6, Nestin, and Odz4), both in vivo and in vitro.

Treating non-motor symptoms of Parkinson's disease with transplantation of stem cells

Parkinson's disease (PD) treatment-based research has focused on developing therapies for the management of motor symptoms. Non-motor symptoms do not respond to treatments targeting motor deficits, thus necessitating an urgent need to develop new modalities that cater to both motor and non-motor deficits. Stem cell transplantation is potentially therapeutic for PD, but the disease non-motor symptoms have been primarily neglected in such cell therapy regimens. Many types of stem cells are currently available for transplantation therapy, including adult tissue (e.g., bone marrow, placenta)-derived mesenchymal stem cells. The fact that mesenchymal stem cells can replace and rescue degenerated dopaminergic and non-dopaminergic cells suggests their potential for the treatment of motor as well as non-motor symptoms of PD, which is discussed in this article.

Pleiotrophin as a central nervous system neuromodulator, evidences from the hippocampus

Pleiotrophin (PTN) is a secreted growth factor, and also a cytokine, associated with the extracellular matrix, which has recently starting to attract attention as a significant neuromodulator with multiple neuronal functions during development. PTN is expressed in several tissues, where its signals are generally related with cell proliferation, growth, and differentiation by acting through different receptors. In Central Nervous System (CNS), PTN exerts post-developmental neurotrophic and -protective effects, and additionally has been involved in neurodegenerative diseases and neural disorders. Studies in Drosophila shed light on some aspects of the different levels of regulatory control of PTN invertebrate homologs. Specifically in hippocampus, recent evidence from PTN Knock-out (KO) mice involves PTN functioning in learning and memory. In this paper, we summarize, discuss, and contrast the most recent advances and results that lead to proposing a PTN as a neuromodulatory molecule in the CNS, particularly in hippocampus.

Glial activation and midkine and pleiotrophin transcription in the ventral tegmental area are modulated by morphine administration

Opiates cause persistent restructuring in the mesolimbic reward system. Although a possible role for midkine and pleiotrophin cytokines in the field of synaptic plasticity has been proposed, it has not been assessed whether morphine administration regulates astrogliosis and midkine and pleiotrophin transcription. We observed that single morphine injection and chronic morphine increased glial fibrillary acidic protein expression in the ventral tegmental area (VTA). Interestingly, single morphine injection and chronic morphine increased VTA midkine and pleiotrophin mRNA expression. Given these results, we hypothesize a role for these cytokines in mediating, at least in part, acute neuroprotective effects and chronic neurotrophic adaptations that contribute to drug dependence.

Regenerative therapy in experimental parkinsonism: mixed population of differentiated mouse embryonic stem cells, rather than magnetically sorted and enriched dopaminergic cells provide neuroprotection

AIM

The objective of the study was to develop regenerative therapy by transplanting varied populations of dopaminergic neurons, differentiated from mouse embryonic stem cells (mES) in the striatum for correcting experimental parkinsonism in rats.

METHODS

mES differentiated by default for 7 days in serum-free media (7D), or by enhanced differentiation of 7D in retinoic acid (7R), or dopaminergic neurons enriched by manual magnetic sorting from 7D (SSEA-) were characterized and transplanted in the ipsilateral striatum of 6-hydroxydopamine-induced hemiparkinsonian rats. Neurochemical, neuronal, glial and neurobehavioral recoveries were examined.

RESULTS

7R and SSEA- contained significantly reduced NANOG and high MAP2 mRNA and protein levels as revealed, respectively, by reverse transcriptase-PCR and immunocytochemistry, compared with 7D. Striatal engraftment of 7D resulted in a significantly better behavioral and neurochemical recovery, as compared to the animals that received either 7R or SSEA-. The 7R transplanted animals showed improvement neither in behavior nor in striatal dopamine level. The grafted striatum revealed increased GFAP staining intensity in 7D and SSEA-, but not in 7R cells transplanted group, suggesting a vital role played by glial cells in the recovery. Substantia nigra ipsilateral to the side of the striatum, which received transplants showed more tyrosine hydroxylase immunostained neurons, as compared to 6-hydroxydopamine-infused animals.

CONCLUSION

These results demonstrate that default differentiated mixed population of cells are better than sorted, enriched dopaminergic cells, or cells containing more mature neurons for transplantation recovery in hemiparkinsonian rats.

Targeting midkine and pleiotrophin signalling pathways in addiction and neurodegenerative disorders: recent progress and perspectives

Midkine (MK) and pleiotrophin (PTN) are two neurotrophic factors that are highly up-regulated in different brain regions after the administration of various drugs of abuse and in degenerative areas of the brain. A deficiency in both MK and PTN has been suggested to be an important genetic factor, which confers vulnerability to the development of the neurodegenerative disorders associated with drugs of abuse in humans. In this review, evidence demonstrating that MK and PTN limit the rewarding effects of drugs of abuse and, potentially, prevent drug relapse is compiled. There is also convincing evidence that MK and PTN have neuroprotective effects against the neurotoxicity and development of neurodegenerative disorders induced by drugs of abuse. Exogenous administration of MK and/or PTN into the CNS by means of non-invasive methods is proposed as a novel therapeutic strategy for addictive and neurodegenerative diseases. Identification of new molecular targets downstream of the MK and PTN signalling pathways or pharmacological modulation of those already known may also provide a more traditional, but probably effective, therapeutic strategy for treating addictive and neurodegenerative disorders.

LINKED ARTICLES

This article is part of a themed section on Midkine. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-4.

Pleiotrophin (PTN) expression and function and in the mouse mammary gland and mammary epithelial cells

Expression of the heparin-binding growth factor, pleiotrophin (PTN) in the mammary gland has been reported but its function during mammary gland development is not known. We examined the expression of PTN and its receptor ALK (Anaplastic Lymphoma Kinase) at various stages of mouse mammary gland development and found that their expression in epithelial cells is regulated in parallel during pregnancy. A 30-fold downregulation of PTN mRNA expression was observed during mid-pregnancy when the mammary gland undergoes lobular-alveolar differentiation. After weaning of pups, PTN expression was restored although baseline expression of PTN was reduced significantly in mammary glands of mice that had undergone multiple pregnancies. We found PTN expressed in epithelial cells of the mammary gland and thus used a monoclonal anti-PTN blocking antibody to elucidate its function in cultured mammary epithelial cells (MECs) as well as during gland development. Real-time impedance monitoring of MECs growth, migration and invasion during anti-PTN blocking antibody treatment showed that MECs motility and invasion but not proliferation depend on the activity of endogenous PTN. Increased number of mammospheres with laminin deposition after anti-PTN blocking antibody treatment of MECs in 3D culture and expression of progenitor markers suggest that the endogenously expressed PTN inhibits the expansion and differentiation of epithelial progenitor cells by disrupting cell-matrix adhesion. In vivo, PTN activity was found to inhibit ductal outgrowth and branching via the inhibition of phospho ERK1/2 signaling in the mammary epithelial cells. We conclude that PTN delays the maturation of the mammary gland by maintaining mammary epithelial cells in a progenitor phenotype and by inhibiting their differentiation during mammary gland development.

Receptor type protein tyrosine phosphatases (RPTPs) - roles in signal transduction and human disease

Protein tyrosine phosphorylation is a fundamental regulatory mechanism controlling cell proliferation, differentiation, communication, and adhesion. Disruption of this key regulatory mechanism contributes to a variety of human diseases including cancer, diabetes, and auto-immune diseases. Net protein tyrosine phosphorylation is determined by the dynamic balance of the activity of protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). Mammals express many distinct PTKs and PTPs. Both of these families can be sub-divided into non-receptor and receptor subtypes. Receptor protein tyrosine kinases (RPTKs) comprise a large family of cell surface proteins that initiate intracellular tyrosine phosphorylation-dependent signal transduction in response to binding of extracellular ligands, such as growth factors and cytokines. Receptor-type protein tyrosine phosphatases (RPTPs) are enzymatic and functional counterparts of RPTKs. RPTPs are a family of integral cell surface proteins that possess intracellular PTP activity, and extracellular domains that have sequence homology to cell adhesion molecules. In comparison to extensively studied RPTKs, much less is known about RPTPs, especially regarding their substrate specificities, regulatory mechanisms, biological functions, and their roles in human diseases. Based on the structure of their extracellular domains, the RPTP family can be grouped into eight sub-families. This article will review one representative member from each RPTP sub-family.

Recent preclinical evidence advancing cell therapy for Alzheimer's disease

Alzheimer's disease (AD) causes brain degeneration, primarily depleting cholinergic cells, and leading to cognitive and learning dysfunction. Logically, to augment the cholinergic cell loss, a viable treatment for AD has been via drugs boosting brain acetylcholine production. However, this is not a curative measure. To this end, nerve growth factor (NGF) has been examined as a possible preventative treatment against cholinergic neuronal death while enhancing memory capabilities; however, NGF brain bioavailability is challenging as it does not cross the blood-brain barrier. Investigations into stem cell- and gene-based therapy have been explored in order to enhance NGF potency in the brain. Along this line of research, a genetically modified cell line, called HB1.F3 transfected with the cholinergic acetyltransferase or HB1.F3.ChAT cells, has shown safety and efficacy profiles in AD models. This stem cell transplant therapy for AD is an extension of the neural stem cells' use in other neurological treatments, such as Parkinson's disease and stroke, and recently extended to cancer. The HB1 parent cell and its associated cell lines have been used as a vehicle to deliver genes of interest in various neurological models, and are highly effective as they can differentiate into neurons and glial cells. A focus of this mini-review is the recent demonstration that the transplantation of HB1.F3.ChAT cells in an AD animal model increases cognitive function coinciding with upregulation of acetylcholine levels in the cerebrospinal fluid. In addition, there is a large dispersion throughout the brain of the transplanted stem cells which is important to repair the widespread cholinergic cell loss in AD. Some translational caveats that need to be satisfied prior to initiating clinical trials of HB1.F3.ChAT cells in AD include regulating the host immune response and the possible tumorigenesis arising from the transplantation of this genetically modified cell line. Further studies are warranted to test the safety and effectiveness of these cells in AD transgenic animal models. This review highlights the recent progress of stem cell therapy in AD, not only emphasizing the significant basic science strides made in this field, but also providing caution on remaining translational issues necessary to advance this novel treatment to the clinic.

Chicken pleiotrophin: regulation of tissue specific expression by estrogen in the oviduct and distinct expression pattern in the ovarian carcinomas

Pleiotrophin (PTN) is a developmentally-regulated growth factor which is widely distributed in various tissues and also detected in many kinds of carcinomas. However, little is known about the PTN gene in chickens. In the present study, we found chicken PTN to be highly conserved with respect to mammalian PTN genes (91–92.6%) and its mRNA was most abundant in brain, heart and oviduct. This study focused on the PTN gene in the oviduct where it was detected in the glandular (GE) and luminal (LE) epithelial cells. Treatment of young chicks with diethylstilbesterol induced PTN mRNA and protein in GE and LE, but not in other cell types of the oviduct. Further, several microRNAs, specifically miR-499 and miR-1709 were discovered to influence PTN expression via its 3′-UTR which suggests that post-transcriptional regulation influences PTN expression in chickens. We also compared expression patterns and CpG methylation status of the PTN gene in normal and cancerous ovaries from chickens. Our results indicated that PTN is most abundant in the GE of adenocarcinoma of cancerous, but not normal ovaries of hens. Bisulfite sequencing revealed that 30- and 40% of −1311 and −1339 CpG sites are demethylated in ovarian cancer cells, respectively. Collectively, these results indicate that chicken PTN is a novel estrogen-induced gene expressed mainly in the oviductal epithelia implicating PTN regulation of oviduct development and egg formation, and also suggest that PTN is a biomarker for epithelial ovarian carcinoma that could be used for diagnosis and monitoring effects of therapies for the disease.

The heparin binding growth factors midkine and pleiotrophin regulate the antinociceptive effects of morphine through α(2)-adrenergic independent mechanisms

Genetic deletion of pleiotrophin (PTN) impairs spinal nociceptive transmission suggesting that this heparin binding growth factor could play roles in acute pain processing. Despite the high functional redundancy between PTN and midkine (MK), the only other member of this family of growth factors, we now demonstrate that genetic inactivation of MK does not alter acute nociceptive transmission since pain responses of female MK genetically deficient (MK-/-) and wild type (WT+/+) mice were found to be similar in the hot-plate and tail-immersion tests. It has also been shown that morphine administration significantly regulates MK levels within the brain, suggesting that MK could play a role in morphine-induced antinociceptive effects. To test this hypothesis, we have now studied morphine-induced antinociceptive effects in female MK-/- and WT+/+ mice. We did not find differences among genotypes using different doses of morphine (2.5, 5 and 10 mg/kg) in the hot-plate test. In contrast, we found that morphine significantly delayed pain responses in MK-/- mice compared to WT+/+ mice in the tail-immersion test. In confirmation of previous results from our group, we also found significantly enhanced morphine-induced antinociceptive effects in PTN-/- mice in the tail-immersion test. In addition, we now demonstrate that enhanced morphine analgesic effects in PTN-/- and MK-/- mice are not caused by a different contribution of descending noradrenergic inhibitory pathways since the α(2)-adrenergic antagonist yohimbine failed to alter morphine-induced analgesia in all genotypes. The data demonstrate that MK is an endogenous modulator of morphine antinociceptive effects, identify significant differences between PTN and MK in the control of pain processing at the spinal level, and support the hypothesis that inhibitors of the PTN/MK signaling pathway could potentiate opioid analgesia which may be relevant in opioid-refractory pain cases.

Pleiotrophin over-expression provides trophic support to dopaminergic neurons in parkinsonian rats

Background

Pleiotrophin is known to promote the survival and differentiation of dopaminergic neurons in vitro and is up-regulated in the substantia nigra of Parkinson's disease patients. To establish whether pleiotrophin has a trophic effect on nigrostriatal dopaminergic neurons in vivo, we injected a recombinant adenovirus expressing pleiotrophin in the substantia nigra of 6-hydroxydopamine lesioned rats.

Results

The viral vector induced pleiotrophin over-expression by astrocytes in the substantia nigra pars compacta, without modifying endogenous neuronal expression. The percentage of tyrosine hydroxylase-immunoreactive cells as well as the area of their projections in the lesioned striatum was higher in pleiotrophin-treated animals than in controls.

Conclusions

These results indicate that pleiotrophin over-expression partially rescues tyrosine hydroxylase-immunoreactive cell bodies and terminals of dopaminergic neurons undergoing 6-hydroxydopamine-induced degeneration.

Selection of housekeeping genes for normalization of RT-PCR in hypoxic neural stem cells of rat in vitro

Gene expression analysis under various conditions using real-time reverse transcription polymerase chain reaction (RT-PCR) needs reliable control genes. Housekeeping genes are commonly used as the control. However, no validated housekeeping gene is available for study of hypoxic neural stem cell culture. To choose appropriate internal control genes, the expression of eight commonly used housekeeping genes was examined in rat neural stem cell model to find one or more stably expressed genes under hypoxic/ischemic conditions. Two genes, HPRT and RPL13A were identified as the most confidential housekeeping genes in this research by geNorm and NormFinder softwares. As a groundwork, the most stable housekeeping genes for neural stem cells under hypoxic/ischemic conditions are initially investigated and validated in this experiment, which might provide a better understanding for the gene expression study in ischemic and necrotic neural stem cell cultures or in ischemic diseases of the central nervous system (CNS).

Network-like impact of MicroRNAs on neuronal lineage differentiation of unrestricted somatic stem cells from human cord blood

Unrestricted somatic stem cells (USSCs) represent an intrinsically multipotent CD45-negative fetal population from human cord blood. They show differentiation into neuronal cells of a dopaminergic phenotype, which express neuronal markers such as synaptophysin, neuronal-specific nuclear protein, and neurofilament and release the neurotransmitter dopamine accompanied by expression of dopaminergic key factors tyrosine hydroxylase and Nurr1 (NR4A2). MicroRNA expression analysis highlighted their importance in neural development but their specific functions remain poorly understood. Here, downregulation of a set of 18 microRNAs during neuronal lineage differentiation of unrestricted somatic stem cells, including members of the miR-17-92 family and additional microRNAs such as miR-130a, -138, -218, and -335 as well as their target genes, is described. In silico target gene predictions for this microRNA group uncovered a large set of proteins involved in neuronal differentiation and having a strong impact on differentiation-related pathways such as axon guidance and TGFβ, WNT, and MAPK signaling. Experimental target validations confirmed approximately 35% of predictions tested and revealed a group of proteins with specific impact on neuronal differentiation and function including neurobeachin, neurogenic differentiation 1, cysteine-rich motor neuron protein 1, neuropentraxin 1, and others. These proteins are combined targets for several subgroups from the set of 18 downregulated microRNAs. This finding was further supported by the observed upregulation of a significant amount of predicted and validated target genes based on Illumina Beadstudio microarray data. Confirming the functional relationship of a limited panel of microRNAs and predicted target proteins reveals a clear network-like impact of the group of 18 downregulated microRNAs on proteins involved in neuronal development and function.

The neurotrophic factor pleiotrophin modulates amphetamine-seeking behaviour and amphetamine-induced neurotoxic effects: evidence from pleiotrophin knockout mice

Pleiotrophin (PTN), a neurotrophic factor with important roles in survival and differentiation of dopaminergic neurons, is up-regulated in the nucleus accumbens after amphetamine administration suggesting that PTN could modulate amphetamine-induced pharmacological or neuroadaptative effects. To test this hypothesis, we have studied the effects of amphetamine administration in PTN genetically deficient (PTN -/-) and wild type (WT, +/+) mice. In conditioning studies, we found that amphetamine induces conditioned place preference in both PTN -/- and WT (+/+) mice. When these mice were re-evaluated after a 5-day period without amphetamine administration, we found that WT (+/+) mice did not exhibit amphetamine-seeking behaviour, whereas, PTN -/- mice still showed a robust drug-seeking behaviour. In immunohystochemistry studies, we found that amphetamine (10 mg/kg, four times, every 2 hours) causes a significant increase of glial fibrillary acidic protein positive cells in the striatum of amphetamine-treated PTN -/- mice compared with WT mice 4 days after last administration of the drug, suggesting an enhanced amphetamine-induced astrocytosis in the absence of endogenous PTN. Interestingly, we found in concomitant in vitro studies that PTN (3 µM) limits amphetamine (1 mM)-induced loss of viability of PC12 cell cultures, effect that could be related to the ability of PTN to induce the phosphorylation of Akt and ERK1/2. To test this possibility, we used specific Akt and ERK1/2 inhibitors uncovering for the first time that PTN-induced protective effects against amphetamine-induced toxicity in PC12 cells are mediated by the ERK1/2 signalling pathway. The data suggest an important role of PTN to limit amphetamine-induced neurotoxic and rewarding effects.

Neural stem cell regulation, fibroblast growth factors, and the developmental origins of neuropsychiatric disorders

There is increasing appreciation for the neurodevelopmental underpinnings of many psychiatric disorders. Disorders that begin in childhood such as autism, language disorders or mental retardation as well as adult-onset mental disorders may have origins early in neurodevelopment. Neural stem cells (NSCs) can be defined as self-renewing, multipotent cells that are present in both the embryonic and adult brain. Several recent research findings demonstrate that psychiatric illness may begin with abnormal specification, growth, expansion and differentiation of embryonic NSCs. For example, candidate susceptibility genes for schizophrenia, autism and major depression include the signaling molecule Disrupted In Schizophrenia-1 (DISC-1), the homeodomain gene engrailed-2 (EN-2), and several receptor tyrosine kinases, including brain-derived growth factor and fibroblast growth factors, all of which have been shown to play important roles in NSCs or neuronal precursors. We will discuss here stem cell biology, signaling factors that affect these cells, and the potential contribution of these processes to the etiology of neuropsychiatric disorders. Hypotheses about how some of these factors relate to psychiatric disorders will be reviewed.

Genetic inactivation of pleiotrophin triggers amphetamine-induced cell loss in the substantia nigra and enhances amphetamine neurotoxicity in the striatum

Pleiotrophin (PTN) is a neurotrophic factor with important effects in survival and differentiation of dopaminergic neurons that has been suggested to play important roles in drug of abuse-induced neurotoxicity. To test this hypothesis, we have studied the effects of amphetamine (10 mg/kg, four times, every 2 h) on the nigrostriatal pathway of PTN genetically deficient (PTN-/-) mice. We found that amphetamine causes a significantly enhanced loss of dopaminergic terminals in the striatum of PTN-/- mice compared to wild type (WT+/+) mice. In addition, we found a significant decrease ( approximately 20%) of tyrosine hydroxylase (TH)-positive neurons only in the substantia nigra of amphetamine-treated PTN-/- mice, whereas this area of WT+/+ animals remained unaffected after amphetamine treatment. This effect was accompanied by enhanced amphetamine-induced astrocytosis in the substantia nigra of PTN-/- mice. Interestingly, we found a significant decrease in the phosphorylation levels of p42 extracellular-signal regulated kinase (ERK2) in both saline- and amphetamine-treated PTN-/- mice, whereas phosphorylation of p44 ERK (ERK1) was almost abolished in the striatum of PTN-/- mice compared to WT+/+ mice, suggesting that basal deficiencies in the phosphorylation levels of ERK1/2 could underlie the higher vulnerability of PTN-/- mice to amphetamine-induced neurotoxic effects. The data suggest an important role of PTN in the protection of nigrostriatal pathways against amphetamine insult.

A novel combination of factors, termed SPIE, which promotes dopaminergic neuron differentiation from human embryonic stem cells

Background

Stromal-Derived Inducing Activity (SDIA) is one of the most efficient methods of generating dopaminergic (DA) neurons from embryonic stem cells (ESC). DA neuron induction can be achieved by co-culturing ESC with the mouse stromal cell lines PA6 or MS5. The molecular nature of this effect, which has been termed “SDIA” is so far unknown. Recently, we found that factors secreted by PA6 cells provided lineage-specific instructions to induce DA differentiation of human ESC (hESC).

Methodology/Principal Findings

In the present study, we compared PA6 cells to various cell lines lacking the SDIA effect, and employed genome expression analysis to identify differentially-expressed signaling molecules. Among the factors highly expressed by PA6 cells, and known to be associated with CNS development, were stromal cell-derived factor 1 (SDF-1/CXCL12), pleiotrophin (PTN), insulin-like growth factor 2 (IGF2), and ephrin B1 (EFNB1). When these four factors, the combination of which was termed SPIE, were applied to hESC, they induced differentiation to TH-positive neurons in vitro. RT-PCR and western blot analysis confirmed the expression of midbrain specific markers, including engrailed 1, Nurr1, Pitx3, and dopamine transporter (DAT) in cultures influenced by these four molecules. Electrophysiological recordings showed that treatment of hESC with SPIE induced differentiation of neurons that were capable of generating action potentials and forming functional synaptic connections.

Conclusions/Significance

The combination of SDF-1, PTN, IGF2, and EFNB1 mimics the DA phenotype-inducing property of SDIA and was sufficient to promote differentiation of hESC to functional midbrain DA neurons. These findings provide a method for differentiating hESC to form DA neurons, without a requirement for the use of animal-derived cell lines or products.

Enhanced neurogenesis from neural progenitor cells with G1/S-phase cell cycle arrest is mediated by transforming growth factor beta1

We have previously demonstrated that a G1/S-phase cell cycle blocker, deferoxamine (DFO), increased the number of new neurons from rat neurosphere cultures, which correlated with prolonged expression of cyclin-dependent kinase (cdk) inhibitor p27(kip1) [H. J. Kim et al. (2006)Brain Research, 1092, 1-15]. The present study focuses on neuronal differentiation mechanisms following treatment of neural stem/progenitor cells (NPCs) with a G1/S-phase cell cycle blocker. The addition of DFO (0.5 mm) or aphidicolin (Aph) (1.5 microm) to neurospheres for 8 h, followed by 3 days of differentiation, resulted in an increased number of neurons and neurite outgrowth. DFO induced enhanced expression of transforming growth factor (TGF)-beta1 and cdk5 at 24 h after differentiation, whereas Aph only increased TGF-beta1 expression. DFO-induced neurogenesis and neurite outgrowth were attenuated by administration of a cdk5 inhibitor, roscovitine, suggesting that the neurogenic mechanisms differ between DFO and Aph. TGF-beta1 (10 ng/mL) did not increase neurite outgrowth but rather the number of beta-tubulin III-positive cells, which was accompanied by enhanced p27(kip1) mRNA expression. In addition, TGF-beta receptor type II expression was observed in nestin-positive NPCs. Results indicated that DFO-induced TGF-beta1 signaling activated smad3 translocation from the cytoplasm to the nucleus. In contrast, TGF-beta1 signaling inhibition, via a TGF-beta receptor type I inhibitor (SB-505124), resulted in decreased DFO-induced neurogenesis, in conjunction with decreased p27(kip1) protein expression and smad3 translocation to the nucleus. These results suggest that cell cycle arrest during G1/S-phase induces TGF-beta1 expression. This, in turn, prompts enhanced neuronal differentiation via smad3 translocation to the nucleus and subsequent p27(kip1) activation in NPCs.

Pleiotrophin prevents cocaine-induced toxicity in vitro

Pleiotrophin is a cytokine involved in differentiation, survival and repair processes in the central nervous system. Pleiotrophin is upregulated in the brain after administration of different drugs of abuse, thus suggesting a protective role of this cytokine on drug-induced toxicity. We have tested this hypothesis in vitro using NG108-15 cells, a line widely used for neurotoxicity studies. It was found that pleiotrophin (3 and 6 microM) significantly prevents cocaine (5 mM)-induced cytotoxicity as measured by the neutral red test. Similar results were obtained in PC12 cells, which were found to endogenously express both pleiotrophin and its main target, receptor protein tyrosine phosphatase (RPTP) beta/zeta. Blockade of pleiotrophin signaling using anti-pleiotrophin antibodies (2 microg/ml) did not potentiate cocaine-induced toxicity; interestingly, incubation of PC12 cells only with anti-pleiotrophin antibodies significantly reduced cellular viability, thus suggesting an important role of endogenous pleiotrophin signaling in cell survival. The data suggest that pleiotrophin overexpression in response to drugs of abuse may be relevant to prevent drug-induced toxicity.

Assessment of stromal-derived inducing activity in the generation of dopaminergic neurons from human embryonic stem cells

Producing dopaminergic (DA) neurons is a major goal of human embryonic stem cell (hESC) research. DA neurons can be differentiated from hESC by coculture with the mouse PA6 stromal cell line; this differentiation-inducing effect is termed stromal-derived inducing activity (SDIA). The molecular and biochemical nature of SDIA is, however, unknown. Various studies have suggested that SDIA involves either a fixation-resistant component located on the PA6 cell surface or factors secreted into the medium by PA6 cells. To address this question, hESC were cocultured with PA6 cells for 12 days and then further differentiated with sonic hedgehog homolog, fibroblast growth factor-8, and glial cell line-derived neurotrophic factor. After 18 days, 34% of cells were tyrosine hydroxylase (TH)+. When PA6 cells were fixed or irradiated, the number of TH+ cells was decreased by threefold, whereas mitomycin-c treatment of feeder cells decreased the number of TH+ cells by 32%. The neural-inducing effect of PA6 cells, as monitored by beta-III-tubulin expression, was minimally affected by mitomycin-c treatment or fixation but was decreased 50% by irradiation. Medium conditioned by PA6 cells was ineffective in differentiating TH+ cells when used alone. Conditioned medium combined with heparin and/or fixed PA6 cells produced TH+ cell differentiation, although less effectively than PA6 cell coculture. Thus, PA6 cell surface activity is required for neural differentiation of hESC, but secreted factors are required for the specific DA neuron-inducing effect. Disclosure of potential conflicts of interest is found at the end of this article.

Expression profiling of circulating non-red blood cells in embryonic blood

Background

In addition to erythrocytes, embryonic blood contains other differentiated cell lineages and potential progenitor or stem cells homed to changing niches as the embryo develops. Using chicken as a model system, we have isolated an enriched pool of circulating non red blood cells (nRBCs) from E4 and E6 embryos; a transition period when definitive hematopoietic lineages are being specified in the peri-aortic region.

Results

Transcriptome analysis of both nRBC and RBC enriched populations was performed using chicken Affymetrix gene expression arrays. Comparison of transcript profiles of these two populations, with verification by RT-PCR, reveals in nRBCs an expression signature indicative of hematopoietic stem cells (HSCs) and progenitor cells of myeloid and lymphoid lineages, as well as a number of previously undescribed genes possibly involved in progenitor and stem cell maintenance.

Conclusion

This data indicates that early circulating embryonic blood contains a full array of hematopoietic progenitors and stem cells. Future studies on their heterogeneity and differentiation potentials may provide a useful alternative to ES cells and perinatal blood.

Behavioral and neurochemical alterations in mice deficient in anaplastic lymphoma kinase suggest therapeutic potential for psychiatric indications

The receptor tyrosine kinase product of the anaplastic lymphoma kinase (ALK) gene has been implicated in oncogenesis as a product of several chromosomal translocations, although its endogeneous role in the hematopoietic and neural systems has remained poorly understood. We describe that the generation of animals homozygous for a deletion of the ALK tyrosine kinase domain leads to alterations in adult brain function. Evaluation of adult ALK homozygotes (HOs) revealed an age-dependent increase in basal hippocampal progenitor proliferation and alterations in behavioral tests consistent with a role for this receptor in the adult brain. ALK HO animals displayed an increased struggle time in the tail suspension test and the Porsolt swim test and enhanced performance in a novel object-recognition test. Neurochemical analysis demonstrates an increase in basal dopaminergic signalling selectively within the frontal cortex. Altogether, these results suggest that ALK functions in the adult brain to regulate the function of the frontal cortex and hippocampus and identifies ALK as a new target for psychiatric indications, such as schizophrenia and depression, with an underlying deregulated monoaminergic signalling.

FGFR-1 regulates angiogenesis through cytokines interleukin-4 and pleiotrophin

The role of fibroblast growth factors (FGFs) in blood vessel formation has remained unclear. We used differentiating stem-cell cultures (embryoid bodies) and teratomas to show that FGF receptor-1 (FGFR-1) exerts a negative regulatory effect on endothelial cell function in these models. Embryoid bodies lacking expression of FGFR-1 as a result of gene targeting (Fgfr-1−/−) displayed increased vascularization and a distinct, elongated vessel morphology. Teratomas derived from FGFR-1–deficient stem cells were characterized by an increased growth rate and abundant, morphologically distinct vessels. Transmission electron microscopy of the Fgfr-1−/− teratomas showed a compact and voluminous but functional endothelium, which anastomosed with the host circulation. The increased vascularization and altered endothelial cell morphology was dependent on secreted factor(s), based on the transfer of the Fgfr-1−/− vascular phenotype by conditioned medium to Fgfr-1+/− embryoid bodies. Antibody and transcript arrays showed down-regulation of interleukin-4 (IL-4) and up-regulation of pleiotrophin in Fgfr-1−/− embryoid bodies, compared with the heterozygous cultures. We used neutralizing antibodies to show that IL-4 and pleiotrophin act as negative and positive angiogenic regulators, respectively. We conclude that FGFR-1 negatively regulates endothelial cell function by altering the balance of modulatory cytokines.

Pleiotrophin expression in astrocytic and oligodendroglial tumors and it’s correlation with histological diagnosis, microvascular density, cellular proliferation and overall survival

BACKGROUND

Pleiotrophin (PTN) is a secreted cytokine with several properties related with tumor development, including differentiation, angiogenesis, invasion, apoptosis and metastasis. There is evidence that PTN has also a relevant role in primary brain neoplasms and its inactivation could be important to treatment response. Astrocytic and oligodendroglial tumors are the most frequent primary brain neoplasms. Astrocytic tumors are classified as pilocytic astrocytoma (PA), diffuse astrocytoma (DA), anaplastic astrocytoma (AA) and glioblastoma (GBM). Oligodendroglial tumors are classified as oligodendroglioma (O) and anaplastic oligodendroglioma (AO). The aim of the present study was to compare PTN expression, in astrocytomas and oligodendrogliomas and its association with the histological diagnosis, microvascular density, proliferate potential and clinical outcome.

METHODS

Seventy-eight central nervous system tumors were analyzed. The histological diagnosis in accordance with WHO classification was: 13PA, 18DA, 8AA, 15GBM, 16O and 8AO. Immunohistochemistry was realized with these specific antibodies: pleiotrophin, CD31 to microvascular density and Ki-67 to cell proliferation.

RESULTS

PTN expression was significantly higher in GBM and AA when compared to PA and higher in GBM compared to DA. PTN expression did not differ between O and AO. Proliferate index and microvascular density were evaluated only in high grade tumors (AA, GBM and AO) divided in three groups according to PTN expression (low, intermediate and high). These results showed no statistical difference between PTN expression and index of cellular proliferation and neither to PTN expression and microvascular density. Overall survival (OS) analysis (months) showed similar results in high grade gliomas with different levels of PTN expression.

CONCLUSIONS

Our results suggest that PTN expression is associated with histopathological grade of astrocytomas. Proliferation rate, microvascular density and overall survival do not seem to be associated with PTN expression.

Pleiotrophin promotes functional recovery after neural transplantation in rats

Pleiotrophin promotes survival of dopaminergic neurons in vitro. To investigate whether pleiotrophin promotes survival of grafted dopaminergic neurons in vivo, donor cells from ventral mesencephalon were treated with pleiotrophin (100 ng/ml) during cell preparation and grafted into striatum of hemi-Parkinson model rats. Functional recovery in methamphetamine-induced rotations was improved, and more tyrosine hydroxylase-positive cells survived in the striatum in the pleiotrophin-treated group. Pleiotrophin addition to cells just before transplantation also resulted in better functional recovery; however, no caspase-3 activation was seen during cell preparation. Interestingly, the effect of pleiotrophin on the survival was additive to that of glial-cell line-derived neutropic factor. These results revealed that pleiotrophin had effects on donor cells in neural transplantation in vivo.

Role of heparin binding growth factors in nigrostriatal dopamine system development and Parkinson's disease

The developmental biology of the dopamine (DA) system may hold important clues to its reconstruction. We hypothesized that factors highly expressed during nigrostriatal development and re-expressed after injury and disease may play a role in protection and reconstruction of the nigrostriatal system. Examination of gene expression in the developing striatum suggested an important role for the heparin binding growth factor family at time points relevant to establishment of dopaminergic innervation. Midkine, pleiotrophin (PTN), and their receptors syndecan-3 and receptor protein tyrosine phosphatase beta/zeta, were highly expressed in the striatum during development. Furthermore, PTN was up-regulated in the degenerating substantia nigra of Parkinson's patients. The addition of PTN to ventral mesencephalic cultures augmented DA neuron survival and neurite outgrowth. Thus, PTN was identified as a factor that plays a role in the nigrostriatal system during development and in response to disease, and may therefore be useful for neuroprotection or reconstruction of the DA system.

Female infertility in mice deficient in midkine and pleiotrophin, which form a distinct family of growth factors

Midkine and pleiotrophin form a family of growth factors. Mice deficient in one of the genes show few abnormalities on reproduction and development. To understand their roles in these processes, we produced mice deficient in both genes; the double deficient mice were born in only one third the number expected by Mendelian segregation and 4 weeks after birth weighed about half as much as wild-type mice. Most of the female double deficient mice were infertile. In these mice, the numbers of mature follicles and of ova at ovulation were reduced compared to numbers in wild-type mice. Both midkine and pleiotrophin were expressed in the follicular epithelium and granulosa cells of the ovary. The expression of these factors in the uterus was dramatically altered during the estrous cycle. The diestrus and proestrus periods were long and the estrus period was short in the double deficient mice, indicating the role of the factors in the estrous cycle. Furthermore, vaginal abnormality was found in about half of the double deficient mice. These abnormalities in combination resulted in female infertility. Therefore, midkine and pleiotrophin, together with their signaling receptors, play important roles in the female reproductive system.