Generation of five induced pluripotent stem cells lines from four members of the same family carrying a C9orf72 repeat expansion and one wild-type member

The most common genetic cause of Amyotrophic Lateral Sclerosis (ALS) is the expansion of a G4C2 hexanucleotide repeat in the C9orf72 gene. The size of the repeat expansion is highly variable and a cut-off of 30 repeats has been suggested as the lower pathological limit. Repeat size variability has been observed intergenerationally and intraindividually in tissues from different organs and within the same tissue, suggesting instability of the pathological repeat expansion. In order to study this genomic instability, we established iPSCs from five members of the same family of which four carried a C9orf72 repeat expansion and one was wild-type.

Exosome microRNAs in Amyotrophic Lateral Sclerosis: A Pilot Study

The pathogenesis of amyotrophic lateral sclerosis (ALS), a lethal neurodegenerative disease, remains undisclosed. Mutations in ALS related genes have been identified, albeit the majority of cases are unmutated. Clinical pathology of ALS suggests a prion-like cell-to-cell diffusion of the disease possibly mediated by exosomes, small endocytic vesicles involved in the propagation of RNA molecules and proteins. In this pilot study, we focused on exosomal microRNAs (miRNAs), key regulators of many signaling pathways. We analyzed serum-derived exosomes from ALS patients in comparison with healthy donors. Exosomes were obtained by a commercial kit. Purification of miRNAs was performed using spin column chromatography and RNA was reverse transcribed into cDNA. All samples were run on the miRCURY LNA^TM Universal RT miRNA PCR Serum/Plasma Focus panel. An average of 29 miRNAs were detectable per sample. The supervised analysis did not identify any statistically significant difference among the groups indicating that none of the miRNA of our panel has a strong pathological role in ALS. However, selecting samples with the highest miRNA content, six biological processes shared across miRNAs through the intersection of the GO categories were identified. Our results, combined to those reported in the literature, indicated that further investigation is needed to elucidate the role of exosome-derived miRNA in ALS.

Reprogramming fibroblasts and peripheral blood cells from a C9ORF72 patient: A proof-of-principle study

As for the majority of neurodegenerative diseases, pathological mechanisms of amyotrophic lateral sclerosis (ALS) have been challenging to study due to the difficult access to alive patients' cells. Induced pluripotent stem cells (iPSCs) offer a useful in vitro system for modelling human diseases. iPSCs can be theoretically obtained by reprogramming any somatic tissue although fibroblasts (FB) remain the most used cells. However, reprogramming peripheral blood cells (PB) may offer significant advantages. In order to investigate whether the choice of starting cells may affect reprogramming and motor neuron (MNs) differentiation potential, we used both FB and PB from a same C9ORF72-mutated ALS patient to obtain iPSCs and compared several hallmarks of the pathology. We found that both iPSCs and MNs derived from the two tissues showed identical properties and features and can therefore be used interchangeably, giving the opportunity to easily obtain iPSCs from a more manageable source of cells, such as PB.

TDP-43 and NOVA-1 RNA-binding proteins as competitive splicing regulators of the schizophrenia-associated TNIK gene

The RNA-binding protein TDP-43, associated to amyotrophic lateral sclerosis and frontotemporal dementia, regulates the alternative splicing of several genes, including the skipping of TNIK exon 15. TNIK, a genetic risk factor for schizophrenia and causative for intellectual disability, encodes for a Ser/Thr kinase regulating negatively F-actin dynamics. Here we show that in the human adult nervous system TNIK exon 15 is mostly included compared to the other tissues and that, during neuronal differentiation of human induced pluripotent stem cells and of human neuroblastoma cells, TNIK exon 15 inclusion increases independently of TDP-43 protein content. By studying the possible molecular interplay of TDP-43 with brain-specific splicing factors, we found that the neuronal NOVA-1 protein competitively inhibits both TDP-43 and hnRNPA2/B1 skipping activity on TNIK by means of a RNA-dependent interaction and that this competitive mechanism is common to other TDP-43 RNA targets. We also show that the TNIK protein isoforms including/excluding exon 15 differently regulate cell spreading in non-neuronal cells and neuritogenesis in primary cortical neurons. Our data suggest a complex regulation between the ubiquitous TDP-43 and the neuron-specific NOVA-1 splicing factors in the brain that may help better understand the pathobiology of both neurodegenerative diseases and schizophrenia.

Motor neuron differentiation of iPSCs obtained from peripheral blood of a mutant TARDBP ALS patient

Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative disease, mainly affecting the motor neurons (MNs) and without effective therapy. Drug screening is hampered by the lack of satisfactory experimental and pre-clinical models. Induced pluripotent stem cells (iPSCs) could help to define disease mechanisms and therapeutic strategies as they could be differentiated into MNs, otherwise inaccessible from living humans. In this study, given the seminal role of TDP-43 in ALS pathophysiology, MNs were obtained from peripheral blood mononuclear cells-derived iPSCs of an ALS patient carrying a p.A382T TARDBP mutation and a healthy donor. Venous samples were preferred to fibroblasts for their ease of collection and no requirement for time consuming extended cultures before experimentation. iPSCs were characterized for expression of specific markers, spontaneously differentiated into primary germ layers and, finally, into MNs. No differences were observed between the mutated ALS patient and the control MNs with most of the cells displaying a nuclear localization of the TDP-43 protein. In conclusion, we here demonstrated for the first time that human TARDBP mutated MNs can be successfully obtained exploiting the reprogramming and differentiation ability of peripheral blood cells, an easily accessible source from any patient.

Phenotypic Modulation and Neuroprotective Effects of Olfactory Ensheathing Cells: a Promising Tool for Cell Therapy

Olfactory Ensheathing Cells (OECs), exhibiting phenotypic characteristics of both astrocytes and Schwann Cells, show peculiar plasticity. In vitro, OECs promote axonal growth, while in vivo they promote remyelination of damaged axons. We decided to further investigate OEC potential for regeneration and functional recovery of the damaged Central Nervous System (CNS). To study OEC antigen modulation, OECs prepared from postnatal mouse olfactory bulbs were grown in different culture conditions: standard or serum-free media with/without Growth Factors (GFs) and analyzed for different neural specific markers. OEC functional characterizations were also achieved. Resistance of OECs to the neurotoxin 6-hydroxydopamine (6-OHDA) was analyzed by evaluating apoptosis and death. OEC neuroprotective properties were investigated by in vitro co-cultures or by addition of OEC conditioned medium to the neuroblastoma SH-SY5Y cells exposed to 6-OHDA. We observed: 1) modification of OEC morphology, reduced cell survival and marker expression in serum-free medium; 2) GF addition to serum-free medium condition influenced positively survival and restored basal marker expression; 3) no OEC apoptosis after a prolonged exposition to 6-OHDA; 4) a clear OEC neuroprotective tendency, albeit non statistically significant, on 6-OHDA treated SH-SY5Y cells. These peculiar properties of OECs might render them potential clinical agents able to support injured CNS.

Adiponectin levels in the serum and cerebrospinal fluid of amyotrophic lateral sclerosis patients: possible influence on neuroinflammation?

BACKGROUND

Adiponectin (APN) is a key player in energy homeostasis strictly associated with cerebrovascular and neurodegenerative diseases. Since APN also belongs to anti-inflammatory-acting adipokines and may influence both neuroinflammation and neurodegenerative processes, we decided to study the APN levels in amyotrophic lateral sclerosis (ALS) and other neurodegenerative diseases.

METHODS

We assessed APN levels by ELISA immunoassay in both the serum and cerebrospinal fluid of a cohort of familial and sporadic ALS patients, characterized by normal body mass index and absence of dysautonomic symptoms. The screening of serum APN levels was also performed in patients affected by other neurological disorders, including fronto-temporal dementia (FTD) patients. Means were compared using the non-parametric Wilcoxon test, and Pearson's or Spearman's rho was used to assess correlations between variables.

RESULTS

In the whole ALS group, serum APN levels were not different when compared to the age- and sex-matched control group (CTR), but a gender-specific analysis enlightened a significant opposite APN trend between ALS males, characterized by lower values (ALS 9.8 ± 5.2 vs. CTR 15 ± 9.7 μg/ml), and ALS females, showing higher amounts (ALS 26.5 ± 11.6 vs. CTR 14.6 ± 5.2 μg/ml). This sex-linked difference was significantly enhanced in familial ALS cases (p ≤ 0.01). The APN levels in ALS cerebrospinal fluids were unrelated to serum values and not linked to sex and/or familiarity of the disease. Finally, the screening of serum APN levels in patients affected by other neurological disorders revealed the highest serum values in FTD patients.

CONCLUSIONS

Opposite serum APN levels are gender-related in ALS and altered in several neurological disorders, with the highest values in FTD, which shares with ALS several overlapping and neuropathological features. Further investigations are needed to clarify the possible involvement of APN in neuroinflammation and neurodegeneration. Possible involvement of APN in neuroinflammatory neurodegenerative diseases.

Improvement of Combined FISH and Immunofluorescence to Trace the Fate of Somatic Stem Cells after Transplantation

Fluorescence in situ hybridization (FISH) combined with immunohistochemistry of tissue-specific markers provides a reliable method for characterizing the fate of somatic stem cells in transplantation experiments. Furthermore, the association between FISH and fluorescent gene reporter detection can unravel cell fusion phenomena, which could account for apparent transdifferentiation events. However, despite the widespread use of these techniques, they still require labor-extensive protocol adjustments to achieve correct and satisfactory simultaneous signal detection. In the present paper, we describe an improvement of simultaneous FISH and immunofluorescence detection. We applied this protocol to the identification of transplanted human and mouse hematopoietic stem cells in murine brain and muscle. This technique provides unique opportunities for following the path taken by transplanted cells and their differentiation into mature cell types.

Dose dependent side effect of superparamagnetic iron oxide nanoparticle labeling on cell motility in two fetal stem cell populations

Multipotent stem cells (SCs) could substitute damaged cells and also rescue degeneration through the secretion of trophic factors able to activate the endogenous SC compartment. Therefore, fetal SCs, characterized by high proliferation rate and devoid of ethical concern, appear promising candidate, particularly for the treatment of neurodegenerative diseases. Super Paramagnetic Iron Oxide nanoparticles (SPIOn), routinely used for pre-clinical cell imaging and already approved for clinical practice, allow tracking of transplanted SCs and characterization of their fate within the host tissue, when combined with Magnetic Resonance Imaging (MRI). In this work we investigated how SPIOn could influence cell migration after internalization in two fetal SC populations: human amniotic fluid and chorial villi SCs were labeled with SPIOn and their motility was evaluated. We found that SPIOn loading significantly reduced SC movements without increasing production of Reactive Oxygen Species (ROS). Moreover, motility impairment was directly proportional to the amount of loaded SPIOn while a chemoattractant-induced recovery was obtained by increasing serum levels. Interestingly, the migration rate of SPIOn labeled cells was also significantly influenced by a degenerative surrounding. In conclusion, this work highlights how SPIOn labeling affects SC motility in vitro in a dose-dependent manner, shedding the light on an important parameter for the creation of clinical protocols. Establishment of an optimal SPIOn dose that enables both a good visualization of grafted cells by MRI and the physiological migration rate is a main step in order to maximize the effects of SC therapy in both animal models of neurodegeneration and clinical studies.

Biocompatible fluorescent nanoparticles for in vivo stem cell tracking

Efficient application of stem cells to the treatment of neurodegenerative diseases requires safe cell tracking to follow stem cell fate over time in the host environment after transplantation. In this work, for the first time, fluorescent and biocompatible methyl methacrylate (MMA)-based nanoparticles (fluoNPs) were synthesized through a free-radical co-polymerization process with a fluorescent macromonomer obtained by linking Rhodamine B and hydroxyethyl methacrylate. We demonstrate that the fluoNPs produced by polymerization of MMA-Rhodamine complexes (1) were efficient for the labeling and tracking of multipotent human amniotic fluid cells (hAFCs); (2) did not alter the main biological features of hAFCs (such as viability, cell growth and metabolic activity); (3) enabled us to determine the longitudinal bio-distribution of hAFCs in different brain areas after graft in the brain ventricles of healthy mice by a direct fluorescence-based technique. The reliability of our approach was furthermore confirmed by magnetic resonance imaging analyses, carried out by incubating hAFCs with both superparamagnetic iron oxide nanoparticles and fluoNPs. Our data suggest that these finely tunable and biocompatible fluoNPs can be exploited for the longitudinal tracking of stem cells.

Labeling and tracking of human mesenchymal stem cells using near-infrared technology

The recently developed near-infrared (NIR) light imaging technology combines low background noise with deep tissue penetration and readily allows imaging and tracking of NIR-labeled cells, following transplantation in small animal model of diseases. The real-time and longitudinal detection of grafted cells in vivo, as well as their rapid ex vivo localization, may further clarify graft interactions with the surrounding, in target and nontarget organs throughout the body, over time. The present chapter describes a protocol for (1) the efficient labeling of human mesenchymal stem cells (hMSCs) using a membrane intercalating dye, emitting in the NIR 815 nm spectrum; (2) the stereotaxic transplantation of NIR 815-hMSCs in rodent model of Parkinson's disease; and (3) the longitudinal in vivo detection of the grafted cells and the subsequent ex vivo imaging in selected tissues.

Noninvasive near-infrared live imaging of human adult mesenchymal stem cells transplanted in a rodent model of Parkinson's disease

BACKGROUND

We have previously shown that human mesenchymal stem cells (hMSCs) can reduce toxin-induced neurodegeneration in a well characterized rodent model of Parkinson's disease. However, the precise mechanisms, optimal cell concentration required for neuroprotection, and detailed cell tracking need to be defined. We exploited a near-infrared imaging platform to perform noninvasive tracing following transplantation of tagged hMSCs in live parkinsonian rats.

METHODS

hMSCs were labeled both with a membrane intercalating dye, emitting in the near- infrared 815 nm spectrum, and the nuclear counterstain, Hoechst 33258. Effects of near-infrared dye on cell metabolism and proliferation were extensively evaluated in vitro. Tagged hMSCs were then administered to parkinsonian rats bearing a 6-hydroxydopamine-induced lesion of the nigrostriatal pathway, via two alternative routes, ie, intrastriatal or intranasal, and the cells were tracked in vivo and ex vivo using near-infrared technology.

RESULTS

In vitro, NIR815 staining was stable in long-term hMSC cultures and did not interfere with cell metabolism or proliferation. A significant near-infrared signal was detectable in vivo, confined around the injection site for up to 14 days after intrastriatal transplantation. Conversely, following intranasal delivery, a strong near-infrared signal was immediately visible, but rapidly faded and was completely lost within 1 hour. After sacrifice, imaging data were confirmed by presence/absence of the Hoechst signal ex vivo in coronal brain sections. Semiquantitative analysis and precise localization of transplanted hMSCs were further performed ex vivo using near-infrared imaging.

CONCLUSION

Near-infrared technology allowed longitudinal detection of fluorescent-tagged cells in living animals giving immediate information on how different delivery routes affect cell distribution in the brain. Near-infrared imaging represents a valuable tool to evaluate multiple outcomes of transplanted cells, including their survival, localization, and migration over time within the host brain. This procedure considerably reduces the number of animal experiments needed, as well as interindividual variability, and may favor the development of efficient therapeutic strategies promptly applicable to patients.

Metalloproteinase alterations in the bone marrow of ALS patients

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease, nowadays considered as suitable candidate for autologous stem therapy with bone marrow (BM). A careful characterization of BM stem cell (SC) compartment is mandatory before its extensive application to clinic. Indeed, widespread systemic involvement has been recently advocated given that non-neuronal neighboring cells actively influence the pathological neuronal loss. We therefore investigated BM samples from 21 ALS patients and reported normal hematopoietic biological properties while an atypical behavior and impaired SC capabilities affected only the mesenchymal compartment. Moreover, by quantitative real-time approach, we observed altered Collagen IV and Metalloproteinase-9 levels in patients' derived mesenchymal stem cells (MSCs). Widespread metalloproteinase (MMPs) and their tissue inhibitor (TIMPs) alterations were established by multiplex ELISA analysis, demonstrating diffuse enzymatic variations in MSC compartment. Since MMPs act as fundamental effectors of extra-cellular matrix remodeling and stem cell mobilization, their modifications in ALS may influence reparative mechanisms effective in counteracting the pathology. In conclusion, ALS is further confirmed to be a systemic disease, not restricted to the nervous system, but affecting also the BM stromal compartment, even in sporadic cases. Therefore, therapeutic implantation of autologous BM derived SC in ALS patients needs to be carefully reevaluated.

Induction of neurotrophin expression via human adult mesenchymal stem cells: implication for cell therapy in neurodegenerative diseases

In animal models of neurological disorders for cerebral ischemia, Parkinson's disease, and spinal cord lesions, transplantation of mesenchymal stem cells (MSCs) has been reported to improve functional outcome. Three mechanisms have been suggested for the effects of the MSCs: transdifferentiation of the grafted cells with replacement of degenerating neural cells, cell fusion, and neuroprotection of the dying cells. Here we demonstrate that a restricted number of cells with differentiated astroglial features can be obtained from human adult MSCs (hMSCs) both in vitro using different induction protocols and in vivo after transplantation into the developing mouse brain. We then examined the in vitro differentiation capacity of the hMSCs in coculture with slices of neonatal brain cortex. In this condition the hMSCs did not show any neuronal transdifferentiation but expressed neurotrophin low-affinity (NGFR(p75)) and high-affinity (trkC) receptors and released nerve growth factor (NGF) and neurotrophin-3 (NT-3). The same neurotrophin's expression was demonstrated 45 days after the intracerebral transplantation of hMSCs into nude mice with surviving astroglial cells. These data further confirm the limited capability of adult hMSC to differentiate into neurons whereas they differentiated in astroglial cells. Moreover, the secretion of neurotrophic factors combined with activation of the specific receptors of transplanted hMSCs demonstrated an alternative mechanism for neuroprotection of degenerating neurons. hMSCs are further defined in their transplantation potential for treating neurological disorders.

Molecular and phenotypic characterization of human amniotic fluid cells and their differentiation potential

The main goal of the study was to identify a novel source of human multipotent cells, overcoming ethical issues involved in embryonic stem cell research and the limited availability of most adult stem cells. Amniotic fluid cells (AFCs) are routinely obtained for prenatal diagnosis and can be expanded in vitro; nevertheless current knowledge about their origin and properties is limited. Twenty samples of AFCs were exposed in culture to adipogenic, osteogenic, neurogenic and myogenic media. Differentiation was evaluated using immunocytochemistry, RT-PCR and Western blotting. Before treatments, AFCs showed heterogeneous morphologies. They were negative for MyoD, Myf-5, MRF4, Myogenin and Desmin but positive for osteocalcin, PPARgamma2, GAP43, NSE, Nestin, MAP2, GFAP and beta tubulin III by RT-PCR. The cells expressed Oct-4, Rex-1 and Runx-1, which characterize the undifferentiated stem cell state. By immunocytochemistry they expressed neural-glial proteins, mesenchymal and epithelial markers. After culture, AFCs differentiated into adipocytes and osteoblasts when the predominant cellular component was fibroblastic. Early and late neuronal antigens were still present after 2 week culture in neural specific media even if no neuronal morphologies were detectable. Our results provide evidence that human amniotic fluid contains progenitor cells with multi-lineage potential showing stem and tissue-specific gene/protein presence for several lineages.

Neuro-glial differentiation of human bone marrow stem cells in vitro

Bone marrow (BM) is a rich source of stem cells and may represent a valid alternative to neural or embryonic cells in replacing autologous damaged tissues for neurodegenerative diseases. The purpose of the present study is to identify human adult BM progenitor cells capable of neuro-glial differentiation and to develop effective protocols of trans-differentiation to surmount the hematopoietic commitment in vitro. Heterogeneous cell populations such as whole BM, low-density mononuclear and mesenchymal stem (MSCs), and several immunomagnetically separated cell populations were investigated. Among them, MSCs and CD90+ cells were demonstrated to express neuro-glial transcripts before any treatment. Several culture conditions with the addition of stem cell or astroblast conditioned media, different concentrations of serum, growth factors, and supplements, used alone or in combinations, were demonstrated to alter the cellular morphology in some cell subpopulations. In particular, MSCs and CD90+ cells acquired astrocytic and neuron-like morphologies in specific culture conditions. They expressed several neuro-glial specific markers by RT-PCR and glial fibrillary acid protein by immunocytochemistry after co-culture with astroblasts, both in the absence or presence of cell contact. In addition, floating neurosphere-like clones have been observed when CD90+ cells were grown in neural specific media. In conclusion, among the large variety of human adult BM cell populations analyzed, we demonstrated the in vitro neuro-glial potential of both the MSC and CD90+ subset of cells. Moreover, unidentified soluble factors provided by the conditioned media and cellular contacts in co-culture systems were effective in inducing the neuro-glial phenotype, further supporting the adult BM neural differentiative capability.

Developmental and tissue-specific regulation of a novel dysferlin isoform

Dysferlin plays an essential role in the muscle repair machinery, and its deficiency is associated with limb-girdle muscular dystrophy type 2B and with two different distal myopathies (Miyoshi myopathy and distal anterior compartment myopathy). Our aims were to characterize the pattern of dysferlin expression during myogenic cell differentiation and to assess possible differentially spliced isoforms of the DYSF gene. Human primary myogenic cells express a splice variant of dysferlin mRNA lacking exon 17 (Delta17), together with full-length dysferlin mRNA. Real-time polymerase chain reaction analysis of human myoblasts, myotubes, and normal skeletal muscle showed that Delta17 expression inversely correlates with muscle differentiation. Indeed, Delta17 is progressively replaced by the wild type as myoblast fusion proceeds, and it disappears in adult skeletal muscle. Conversely, Delta17 is the predominant dysferlin variant in mature peripheral nerve. Our findings suggest that the two proteins play different roles in myogenic cell differentiation and that dysferlin function in peripheral nerve might be accomplished by this novel isoform.

Skeletal muscle differentiation potential of human adult bone marrow cells

Murine bone marrow (BM) cells have been shown to undergo myogenic differentiation and participate in muscle repair in different muscle regeneration models. In the present paper, we report on a subset of cells (CD45+/desmin+) with myogenic potential being present at very low frequencies in human adult BM. By a simple culture method, we were able to obtain in vitro multinucleated myotubes in up to 20% of the cultures. Myotubes were generated using both BM flushed from rib fragments obtained during thoracotomy and BM derived from iliac crest aspirates. Cells of the different adherent and non-adherent fractions expressed numerous muscle specific markers by immunocytochemistry, real-time RT-PCR, flow cytometry, and Western blot analyses. Moreover, direct injection of whole BM into the right tibialis anterior muscle of immunodeficient mice (NOD/RAG) that had previously been treated with cardiotoxin to induce muscle degeneration, showed a variable but significant level of human cell engraftment (from 0.06 to 0.26% Dys+/FISH+ fibers). These data suggest that cells with skeletal muscle differentiation potential are present in adult human BM can differentiate in vitro and give rise to myogenic cells in vivo in immunodeficient mice after muscle damage. Further improvements might allow new approaches to cell-mediated therapies for muscular diseases.

Detection of micrometastatic cells in breast cancer by RT-pCR for the mammaglobin gene

The detection of circulating cancer cells in the bone marrow (BM) and peripheral blood (PB) of patients with solid tumors may be useful for disease staging. To this aim, we evaluated the expression of the mammaglobin gene by reverse transcriptase polymerase chain reaction (RT-PCR) in 60 patients with breast cancer. Moreover, several controls were examined to test the specificity of this marker. The positive cases included 23.6% of the patients with and 9% of those without metastasis. Only 4/60 negative controls analyzed were positive by PCR. Our results show high specificity and a good correlation with disease status.

Modulated generation of neuronal cells from bone marrow by expansion and mobilization of circulating stem cells with in vivo cytokine treatment

The aim of the present study is to determine whether the expansion and mobilization of circulating bone marrow (BM) stem cells by in vivo treatment with granulocyte-colony stimulating factor (G-CSF) and stem cell factor (SCF) increase the amount of BM-derived neuronal cells in mouse brain. The presence of BM-derived cells in the brain was traced by transplanting into lethally irradiated adults and newborns adult BM from transgenic mice that ubiquitously expressed enhanced green fluorescent protein (GFP). GFP+ and Y-chromosome+ donor-derived cells were present in several brain areas of all treated mice (cortical and subcortical areas, cerebellum, olfactory bulb). The presence of GFP+ cells expressing nuclear neural specific antigen (NeuN), neurofilament, and beta-III tubulin in cortical forebrain and olfactory bulb (OB) was higher in G-CSF-SCF treated groups (P < 0.05, analysis of variance, Fisher post hoc). We observed that overall the amount of double positive cells was higher in animals treated at birth than in adults and in OB than in forebrain areas (P < 0.05). Temporal cortical areas of cytokine-treated adult animals revealed a mean threefold increase in the number of GFP+ cells expressing the nuclear neural specific antigen (211 +/- 86 GFP+NeuN+/mm(3) in G-CSF + SCF treated mice and 66 +/- 33 GFP+NeuN+/mm(3) in control animals). GFP+ cells coexpressing neuronal markers contain only one nucleus and have a DNA index (a measure of DNA ploidy) identical to that of surrounding neurons, thus excluding donor cell fusion with endogenous cells as a relevant phenomenon under these experimental conditions. Our results indicate that G-CSF and SCF administration modulates the availability of GFP+ cells in the brain and enhances their capacity to acquire neuronal characteristics. Cytokine stimulation of autologous stem cells might be seen as a new strategy for neuronal repair in neurodegenerative diseases.

Isolation of bone marrow mesenchymal stem cells by anti-nerve growth factor receptor antibodies

OBJECTIVE

Mesenchymal stem cells (MSCs) are a population of multipotent cells that can proliferate and differentiate into multiple mesodermal tissues. We previously reported that monoclonal antibodies to the low-affinity nerve growth factor receptor (alpha-LNGFR) stain bone marrow (BM) mesenchymal cells. We now show that LNGFR antibodies label primitive MSCs with high specificity and purity in adult BM, and compare these cells to those isolated by plastic adherence (PA) and CD45(-)anti-glycophorin A(-) selection.

MATERIALS AND METHODS

Low-density mononuclear cells (LD-MNCs) from normal BM were separated by PA or immunomagnetic selection for NGFR(+) or CD45(-)alpha-glycophorin A(-) cells. The three fractions were grown in Iscove's modified Dulbecco medium + 20% fetal bovine serum +/- basic fibroblast growth factor (bFGF) in order to assess their proliferative capacity and evaluate their phenotype during culture. The clonogenic potential of the MSCs was assessed using a colony-forming unit fibroblast (CFU-F) assay, whereas multipotential differentiation was determined after culture in adipocytic and osteoblastic conditioned media.

RESULTS

The NGFR(+) mesenchymal cells grown without growth factors showed persistent NGFR expression (rapidly down-regulated after the addition of bFGF) and persistent CFU-F activity. The NGFR(+) fractions were rich in clonogenic precursors: CFU-F median frequency was 1584/1 x 10(6) cells (range 325-13,793) in the NGFR(+) cells and 35/1 x 10(6) cells (range 27-112) in the LD-MNCs. The NGFR(-) fraction never showed any residual CFU-F activity. Compared with the other two fractions, the NGFR(+) cells (+/- bFGF) showed a 1 to 3 log greater expansion in the number of fibroblastic cells and a greater capacity to give rise to adipocyte colonies and induce osteoblastic differentiation, and they had similar effects in supporting the growth of hematopoietic precursors.

CONCLUSION

The data suggest that positive selection using low-affinity NGFR antibodies makes it possible to obtain homogeneous multipotent MSCs.

A subpopulation of murine bone marrow cells fully differentiates along the myogenic pathway and participates in muscle repair in the mdx dystrophic mouse

Bone marrow (BM) transplantation in mice suggests the existence of pluripotent cells able to differentiate into skeletal muscle tissue, although sustained myofiber reconstitution has not yet been achieved. We investigated the myogenic potential of mouse BM cells and evaluated whether a BM fraction enriched for cells expressing skeletal muscle markers would ameliorate muscle repair, when compared to whole BM, into the dystrophic mdx mouse. We demonstrate that cells expressing striated-muscle-specific proteins are already present in the BM independently from experimentally forced myogenic conversion. We observed the presence of both markers of early myogenic program such as Pax3, Myf5, MyoD, desmin, and late myogenesis such as myosin heavy chain and alpha-sarcomeric actin. These myogenic cells are more represented in the early nonadherent BM fraction, which generates clones able to fully differentiate into myotubes. Transplantation in mdx mice by intravenous injection of whole BM and a tenfold BM myogenic enriched fraction resulted in BM reconstitution and limited dystrophin restoration. Taken together, these data show that a fraction of BM cells have a definite potential for differentiation along the skeletal muscle pathway and can be recruited by muscle repair mechanisms. They also indicate that factors limiting the degree of muscle recruitment and the host stem cell competition should be assessed in order to evaluate the usefulness of BM-derived myogenic cells into the context of cell-mediated gene therapy of inherited muscle diseases.

Differentiation and expansion of endothelial cells from human bone marrow CD133(+) cells

We report a method of purifying, characterizing and expanding endothelial cells (ECs) derived from CD133(+) bone marrow cells, a subset of CD34(+) haematopoietic progenitors. Isolated using immunomagnetic sorting (mean purity 90 +/- 5%), the CD133(+) bone marrow cells were grown on fibronectin-coated flasks in M199 medium supplemented with fetal bovine serum (FBS), vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and insulin growth factor (IGF-1). The CD133(+) fraction contained 95 +/- 4% CD34(+) cells, 3 +/- 2% cells expressing VEGF receptor (VEGFR-2/KDR), but did not express von Willebrand factor (VWF), VE-cadherin, P1H12 or TE-7. After 3 weeks of culture, the cells formed a monolayer with a typical EC morphology and expanded 11 +/- 5 times. The cells were further purified using Ulex europaeus agglutinin-1 (UEA-1)-fluorescein isothiocyanate (FITC) and anti-FITC microbeads, and expanded with VEGF for a further 3 weeks. All of the cells were CD45(-) and CD14(-), and expressed several endothelial markers (UEA-1, VWF, P1H12, CD105, E-selectin, VCAM-1 and VE-cadherin) and typical Weibel-Palade bodies. They had a high proliferative potential (up to a 2400-fold increase in cell number after 3 weeks of culture) and the capacity to modulate cell surface antigens upon stimulation with inflammatory cytokines. Purified ECs were also co-cultivated with CD34(+) cells, in parallel with a purified fibroblastic cell monolayer. CD34(+) cells (10 x 10(5)) gave rise to 17,951 +/- 2422 CFU-GM colonies when grown on endothelial cells, and to 12,928 +/- 4415 CFU-GM colonies on fibroblast monolayers. The ECs also supported erythroid blast-forming unit (BFU-E) colonies better. These results suggest that bone marrow CD133(+) progenitor cells can give rise to highly purified ECs, which have a high proliferative capacity, can be activated by inflammatory cytokines and are superior to fibroblasts in supporting haematopoiesis. Our data support the hypothesis that endothelial cell progenitors are present in adult bone marrow and may contribute to neo-angiogenesis.

Efficient retrovirus-mediated transduction of primitive human peripheral blood progenitor cells in stroma-free suspension culture

Retroviral transduction of hematopoietic cells has resulted in unsatisfactory gene marking in clinical studies. Since cytokine-stimulated stem cells have engrafted poorly in animal models, we investigated phenotypic changes during culture of peripheral blood progenitor cells (PBPC). Human CD34(+) HLA-DR(low) cells, immunomagnetically separated from PBPC collections, were found to extrude rhodamine-123, which is characteristic for primitive hematopoietic cells. Cells were grown in suspension cultures supplemented with cytokines. While interleukin-3-containing factor combinations promoted cell proliferation they caused loss of rhodamine-123 extrusion and reduced the frequencies of cobblestone area-forming cells (CAFC). Several other cytokines failed to stimulate cell divisions, which are required for retroviral transduction. A combination including Flt-3 ligand (FL), interleukin-6 and stem cell factor (SCF) preserved an immature phenotype for 5 to 6 days and stimulated cell divisions, which was improved upon addition of leukemia inhibitory factor and interleukin-11. Furthermore, the CAFC frequency among cells treated with these cytokines was increased as compared with widely used cocktails containing interleukin-3, interleukin-6 and SCF. Rhodamine-123 appeared to be a particularly sensitive indicator for differentiation of PBPC. For analysis of gene transfer, amphotropic retroviruses conferring an MDR1 cDNA were added repeatedly for 6 days to cytokine-treated PBPC stroma-free cultures. Proviral cDNA was detected by polymerase chain reaction in 68% of cobblestone areas derived from CD34(+)HLA-DR(low) cells that had been exposed to Flt-3 ligand, interleukin-6 and SCF. In summary, conditions were identified that facilitate efficient transduction of early PBPC with amphotropic retroviruses while preserving a primitive phenotype for extended periods.

Bone marrow-disseminated tumor cells in patients with carcinoma of the esophagus or cardia

BACKGROUND

The long-term prognosis after surgical therapy for esophageal carcinoma depends on tumor stage and completeness of resection. Similarly to other epithelial tumors, the presence of micro deposits of neoplastic cells in the bone marrow may indicate residual disease and the potential for recurrence. This study assesses the prevalence of bone marrow-disseminated tumor cells in patients undergoing surgical resection for esophageal carcinoma. In addition, we investigated the agreement between immunohistochemical and molecular techniques for the detection of micrometastases in a subgroup of patients.

METHODS

Between January 1998 and November 1999, forty-eight patients with adenocarcinoma of the esophagogastric junction (n = 29) or squamous cell carcinoma of the thoracic esophagus (n = 19) and no evidence of overt metastatic disease entered the study. An immunohistochemical assay (capable of detecting 1 carcinoma cell in 7 x 10(5) bone marrow cells) was used to test bone marrow obtained by flushing a resected rib or by needle aspiration either of the iliac crest or of a rib. A polymerase chain reaction (PCR) molecular technique was also used to identify bone marrow and peripheral blood epithelial cells.

RESULTS

Cytokeratin-positive cells were found in 79.1% of the bone marrow samples obtained from the rib, and in only 8% of the needle aspirates either from the iliac crest or from a contiguous rib: This difference is probably explained by the improved removal of metastatic cells with the flushing of the rib. Comparable results were obtained at a qualitative level by the PCR technique on bone marrow. In addition, PCR-positive results were found in 3 of 18 peripheral blood samples. There was no association with tumor type, neoadjuvant therapy, or lymph node status. Patients with a pT3 or pT4 tumor showed, at a borderline statistical level, a higher proportion of cytokeratin-positive cells in the flushed rib.

CONCLUSIONS

Bone marrow-disseminated tumor cells are present in the resected rib of a high proportion of patients undergoing esophagectomy for carcinoma, and immunohistochemistry seems to be the method of choice for their quantitative assessment. However, the prognostic and therapeutic implications of this finding need further investigation.

Response of myelodysplastic syndrome bone marrow cells to multiple cytokine stimulation in liquid cultures: an in situ hybridization study

BACKGROUND AND OBJECTIVE

Myelodysplastic syndrome progenitor cells can be grown and expanded in long term bone marrow liquid cultures in the presence of multiple cytokines. In this study we investigated the pattern of differentiation and response to growth factors in six cases of myelodysplastic syndrome (MDS) with well-defined cytogenetic abnormalities by means of conventional cytogenetics and fluorescence in situ hybridization (FISH).

METHODS

Bone marrow cells were grown in stroma-free liquid cultures in the presence of SCF, IL-3, IL-6 and GM-CSF.

RESULTS

IN three cases a CFU-GM expansion comparable to normal controls was observed, together with a decrease or increase of cells with abnormal karyotype. Two cases showed no response to growth factor stimulation, morphological signs of terminal myeloid differentiation and increase (one case) or decrease (one case) in the percentage of abnormal FISH signals along the cultures. In one additional case, while CFU-C expansion was present, clearcut leukemic transformation was observed in the culture, together with a sharp decrease in the percentage of abnormal FISH signals, indicating a leukemic transformation of MDS progenitor cells with a normal karyotype.

INTERPRETATION AND CONCLUSIONS

Our data indicate that FISH analysis is generally a poor indicator of clonality in MDS; nevertheless, determining the kinetics of cytogenetically abnormal clones in liquid bone marrow cultures may provide insight as to the growth abnormalities of MDS progenitor cells and may be useful prior to in vivo growth factor administration.

Response of myelodysplastic syndrome marrow progenitor cells to stimualtion with cytokine combinations in a stroma-free long-term culture system

The effect of an ex vivo expansion culture system using multiple cytokine combinations was evaluated in 38 cases of myelodysplastic syndrome (MDS) with the aim of overcoming the defective in vitro growth of haemopoietic progenitor cells. A combination of four growth factors (GF) including SCF, IL-3, IL-6 and GM-CSF was identified as the optimal combination for expanding clonogenic progenitor cells in MDS bone marrow liquid cultures. The cultures of 50% of the patients (19/38) responded to GF stimulation (mean CFU-GM fold increase 15.65+/-48 at week 4) and showed morphological features of normal and/or dysplastic myeloid differentiation. In 12/38 cases (31%), complete unresponsiveness to multiple cytokine stimulation was observed; a small number of patients (7/38) showed progressive leukaemic growth along the cultures with the presence of 100% immature blasts at week 4. GM-CSF and c-kit receptors, analysed by immuno-histochemistry in 10 patients, were over-expressed in responding patients and either lacking or down-regulated in non-responders. Fluorescence in situ hybridization (FISH) analysis of cultured interphase cells of nine patients (trisomy 8 in eight patients) showed a clear-cut increase in the percentage of cells with three signals in the two responding patients, thus indicating the expansion of a MDS clone. Multiple cytokine liquid cultures seem to be able to override the refractoriness of MDS progenitor cells to GF stimulation in many cases, revealing a heterogeneity which may have prognostic implications and should be considered in ex-vivo and in vivo clinical trials with cytokine combinations.