In vitro clonal analysis of murine pluripotent stem cells isolated from skeletal muscle and adipose stromal cells

Phenotypical Characterization and Neurogenic Differentiation of Rabbit Adipose Tissue-Derived Mesenchymal Stem Cells

Although the rabbit is a frequently used biological model, the phenotype of rabbit adipose-derived mesenchymal stem cells (rAT-MSCs) is not well characterized. One of the reasons is the absence of specific anti-rabbit antibodies. The study aimed to characterize rAT-MSCs using flow cytometry and PCR methods, especially digital droplet PCR, which confirmed the expression of selected markers at the mRNA level. A combination of these methods validated the expression of MSCs markers (CD29, CD44, CD73, CD90 and CD105). In addition, cells were also positive for CD49f, vimentin, desmin, α-SMA, ALDH and also for the pluripotent markers: NANOG, OCT4 and SOX2. Moreover, the present study proved the ability of rAT-MSCs to differentiate into a neurogenic lineage based on the confirmed expression of neuronal markers ENO2 and MAP2. Obtained results suggest that rAT-MSCs have, despite the slight differences in marker expression, the similar phenotype as human AT-MSCs and possess the neurodifferentiation ability. Accordingly, rAT-MSCs should be subjected to further studies with potential application in veterinary medicine but also, in case of their cryopreservation, as a source of genetic information of endangered species stored in the gene bank.

IL-4 and SDF-1 Increase Adipose Tissue-Derived Stromal Cell Ability to Improve Rat Skeletal Muscle Regeneration

Skeletal muscle regeneration depends on the satellite cells, which, in response to injury, activate, proliferate, and reconstruct damaged tissue. However, under certain conditions, such as large injuries or myopathies, these cells might not sufficiently support repair. Thus, other cell populations, among them adipose tissue-derived stromal cells (ADSCs), are tested as a tool to improve regeneration. Importantly, the pro-regenerative action of such cells could be improved by various factors. In the current study, we tested whether IL-4 and SDF-1 could improve the ability of ADSCs to support the regeneration of rat skeletal muscles. We compared their effect at properly regenerating fast-twitch EDL and poorly regenerating slow-twitch soleus. To this end, ADSCs subjected to IL-4 and SDF-1 were analyzed in vitro and also in vivo after their transplantation into injured muscles. We tested their proliferation rate, migration, expression of stem cell markers and myogenic factors, their ability to fuse with myoblasts, as well as their impact on the mass, structure and function of regenerating muscles. As a result, we showed that cytokine-pretreated ADSCs had a beneficial effect in the regeneration process. Their presence resulted in improved muscle structure and function, as well as decreased fibrosis development and a modulated immune response.

Current Perspectives regarding Stem Cell-Based Therapy for Alzheimer's Disease

Alzheimer's disease (AD), a progressive neurodegenerative disorder featuring memory loss and cognitive impairment, is caused by synaptic failure and the excessive accumulation of misfolded proteins. Many unsuccessful attempts have been made to develop new small molecules or antibodies to intervene in the disease's pathogenesis. Stem cell-based therapies cast a new hope for AD treatment as a replacement or regeneration strategy. The results from recent preclinical studies regarding stem cell-based therapies are promising. Human clinical trials are now underway. However, a number of questions remain to be answered prior to safe and effective clinical translation. This review explores the pathophysiology of AD and summarizes the relevant stem cell research according to cell type. We also briefly summarize related clinical trials. Finally, future perspectives are discussed with regard to their clinical applications.

Therapeutic potential of human adipose-derived stem cells in neurological disorders

Stem cell therapy has been noted as a novel strategy to various diseases including neurological disorders such as Alzheimer's disease, Parkinson's disease, stroke, amyotrophic lateral sclerosis, and Huntington's disease that have no effective treatment available to date. The adipose-derived stem cells (ASCs), mesenchymal stem cells (MSCs) isolated from adipose tissue, are well known for their pluripotency with the ability to differentiate into various types of cells and immuno-modulatory property. These biological features make ASCs a promising source for regenerative cell therapy in neurological disorders. Here we discuss the recent progress of regenerative therapies in various neurological disorders utilizing ASCs.

Upregulation of pluripotency markers in adipose tissue-derived stem cells by miR-302 and leukemia inhibitory factor

The expression pattern of pluripotency markers in adipose tissue-derived stem cells (ADSCs) is a subject of controversy. Moreover, there is no data about the signaling molecules that regulate these markers in ADSCs. In the present study, we studied the roles of leukemia inhibitory factor (LIF) and miR-302 in this regard. Freshly isolated mouse ADSCs expressed hematopoietic, mesenchymal, and pluripotency markers. One day after plating, ADSCs expressed OCT4 and Sox2 proteins. After three passages, the expression of hematopoietic and pluripotency markers decreased, while the expression of mesenchymal stem cell markers exhibited a striking rise. Both supplementation of culture media with LIF and transfection of the ADSCs with miR-302 family upregulated the expression levels of OCT4, Nanog, and Sox2 mRNAs. These findings showed that mouse adipose tissue contains a population of cells with molecular resemblance to embryonic stem cells, and LIF and miR-302 family positively affect the expression of pluripotency markers.

A human neuronal model of Niemann Pick C disease developed from stem cells isolated from patient's skin

Background

Niemann Pick C (NPC) disease is a neurovisceral lysosomal storage disorder due to mutations in NPC1 or NPC2 genes, characterized by the accumulation of endocytosed unesterified cholesterol, gangliosides and other lipids within the lysosomes/late endosomes. Even if the neurodegeneration is the main feature of the disease, the analysis of the molecular pathways linking the lipid accumulation and cellular damage in the brain has been challenging due to the limited availability of human neuronal models.

Objective

The aim of this study was to develop a human neuronal model of NPC disease by inducing neuronal differentiation of multipotent adult stem cells (MASC) isolated from NPC patients.

Methods

Stem cells were isolated from 3 NPC patients and 3 controls both from skin biopsies and previously established skin fibroblast cultures. Cells were induced to differentiate along a neuronal fate adapting methods previously described by Beltrami et al, 2007. The surface immunophenotype of stem cells was analyzed by FACS. Stem cell and neuronal markers expression were evaluated by immunofluorescence. Intracellular accumulation of cholesterol and gangliosides were assessed by filipin staining and immunofluorescence, respectively. A morphometric analysis was performed using a Neurite outgrowth image program.

Results

After 3 passages in selective medium, MASC isolated either from skin biopsies or previously established skin fibroblast cultures displayed an antigenic pattern characteristic of mesenchymal stem cells and expressed the stem cell markers Oct-4, Nanog, Sox-2 and nestin. A massive lysosomal accumulation of cholesterol was observed only in cells isolated from NPC patients. After the induction of neural differentiation, remarkable morphologic changes were observed and cells became positive to markers of the neuronal lineage NeuN and MAP2. Differentiated cells from NPC patients displayed characteristic features of NPC disease, they showed intracellular accumulation of unesterified cholesterol and GM2 ganglioside and presented morphological differences with respect to cells derived from healthy donors.

In conclusion, we generated a human neuronal model of NPC disease through the induction of differentiation of stem cells obtained from patient’s easily accessible sources. The strategy described here may be applied to easily generate human neuronal models of other neurodegenerative diseases.

Comparative analysis of mesenchymal stem cells from adult mouse adipose, muscle, and fetal muscle

Recently, increasing evidence supports that adult stem cells are the part of a natural system for tissue growth and repair. This study focused on the differences of mesenchymal stem cells from adult adipose (ADSCs), skeletal muscle (MDSCs) and fetal muscle (FMSCs) in biological characteristics, which is the key to cell therapy success. Stem cell antigen 1 (Sca-1) expression of MDSCs and FMSCs at passage 3 was two times more than that at passage 1 (P < 0.0001). After 28-day myogenic induction, higher expression levels of skeletal muscle-specific genes were observed in MDSCs than FMSCs (P < 0.01), and the lowest expression levels were demonstrated in ADSCs among three cells (P < 0.01). Besides, M-Cad and MyHC expressions in ADSCs were not detected by immunofluorescence or real-time quantitative PCR. Furthermore, after 14 days adipogenic induction, PPARγ2, LPL and aP2 mRNA expressions were higher in ADSCs vs. MDSCs (P < 0.01). Besides, MSCs from adult or fetal muscle expressed higher OCN and OPN than ADSCs after 28 days osteogenic induction (P < 0.01). Taken together, our results suggested that cell source and developmental stage had great impacts on biological properties of mesenchymal stem cells, and proper consideration of all the issues is necessary.

Inhibition of adipogenic differentiation by myostatin is alleviated by arginine supplementation in porcine-muscle-derived mesenchymal stem cells

Porcine mesenchymal stem cells in postnatal muscle have been demonstrated to differentiate into adipocytes. This increases adipocyte number and lipid accumulation, and is thought to be the origin of intramuscular fat. In this study, the effects of myostatin and arginine on adipogenic differentiation in mesenchymal stem cells derived from porcine muscle (pMDSCs) were investigated in vitro. Intracellular triglyceride levels were reduced by exogenous myostatin and increased by arginine supplementation or myostatin antibody (P<0.01). The inhibition of lipid accumulation by myostatin in pMDSCs was alleviated by arginine supplementation (P<0.01). Expression patterns of adipogenic transcription factors showed that exogenous myostatin suppressed PPARγ2 and aP2 expression (P<0.01), while supplemental arginine or myostatin antibody promoted ADD1 expression (P<0.01). Furthermore, compared with the addition of either myostatin protein or antibody alone, ADD1 and PPARδ expression were promoted by the combination of arginine and myostatin (P<0.01), and arginine combined with myostatin antibody promoted the expression of ADD1, PPARδ, C/EBPα, PPARγ2 and LPL in pMDSCs (P<0.05). These results suggest that myostatin inhibits adipogenesis in pMDSCs, and that this can be alleviated by arginine supplementation, at least in part, through promoting ADD1 and PPARδ expression.

Defining the heterogeneity of skeletal muscle-derived side and main population cells isolated immediately ex vivo

Myoblast transfer therapy for Duchenne muscular dystrophy (DMD) largely fails due to cell death and inability of transplanted cells to engraft in diseased muscles. One method attempting to enrich for cell subpopulations is the Hoechst 33342 dye exclusion assay, yielding a side population (SP) thought to be progenitor enriched and a main population (MP). However, in vitro and transplant studies yielded inconsistent results relative to downstream progeny. Cell surface markers expressed by skeletal muscle-derived MP and SP cells have not been fully characterized directly ex vivo. Using flow cytometry, MP and SP cells were characterized based on their expression of several well-accepted progenitor cell antigens. Both the MP and SP populations are heterogeneous and overlapping in the cells they contain. The percentages of cells in each population vary with species and specific muscle examined. MP and SP populations contain both satellite and multipotent progenitor cells, based on expression of CD34, Sca-1, Pax7, and M-cadherin. Thus, isolation using this procedure cannot be used to predict downstream differentiation outcomes, and explains the conflicting literature on these cells. Hoechst dye also results in significant mortality of sorted cells. As defined subpopulations are easily obtained using flow cytometry, sorting immediately ex vivo based on accepted myogenic precursor cell markers will yield superior results in terms of cell homogeneity for transplantation therapy.

Adipocytes as immune cells: differential expression of TWEAK, BAFF, and APRIL and their receptors (Fn14, BAFF-R, TACI, and BCMA) at different stages of normal and pathological adipose tissue development

Adipose tissue represents a rich source of multipotent stem cells. Mesenchymal cells, isolated from this source, can differentiate to other cell types in vitro and therefore can be used for a number of regenerative therapies. Our view of adipose tissue has recently changed, establishing adipocytes as new members of the immune system, as they produce a number of proinflammatory cytokines (such as IL-6 and TNFalpha and chemokines, in addition to adipokines (leptin, adiponectin, resistin) and molecules associated with the innate immune system. In this paper, we report the differential expression of TNF-superfamily members B cell activating factor of the TNF Family (BAFF), a proliferation inducing ligand (APRIL), and TNF-like weak inducer of apoptosis (TWEAK) in immature-appearing and mature adipocytes and in benign and malignant adipose tissue-derived tumors. These ligands act through their cognitive receptors, BAFF receptor, transmembrane activator and calcium signal-modulating cyclophilic ligand (TACI), B cell maturation Ag (BCMA), and fibroblast growth factor-inducible 14 (Fn14), which are also expressed in these cells. We further report the existence of functional BCMA, TACI, and Fn14 receptors and their ligands BAFF, APRIL, and TWEAK on adipose tissue-derived mesenchymal cells, their interaction modifying the rate of adipogenesis. Our data integrate BAFF, APRIL, and TWEAK and their receptors BCMA, TACI, and Fn14 as novel potential mediators of adipogenesis, in addition to their specific role in immunity, and define immature and mature adipocytes as source of immune mediators.

Interphase FISH demonstrates that human adipose stromal cells maintain a high level of genomic stability in long-term culture

Human adipose stromal cells (ASCs) reside within the stromal-vascular fraction (SVF) in fat tissue, can be readily isolated, and include stem-like cells that may be useful for therapy. An important consideration for clinical application and functional studies of stem/progenitor cells is their capacity to maintain chromosome stability in culture. In this study, cultured ASC populations and ASC clones were evaluated at intervals for maintenance of chromosome stability. Uncultured SVF (uSVF) cells were included for comparison. G-banded chromosome analysis demonstrated that ASCs are diploid and have a normal karyotype. However since only approximately 20 cells are examined, low levels of chromosome instability would not be detected. To increase detection sensitivity, fluorescence in situ hybridization was employed, to permit chromosome enumeration in larger numbers of interphase cells. Seven cultured ASC populations, two ASC clones and four uSVF samples were examined. Chromosome X and 17 probes identified diploid, tetraploid, and aneuploid interphase cells. Both cultured ASC populations [up to approximately 35 Population Doublings (PDs)] and uSVF cells exhibited a similar level of diploidy (97.8% n = 6,355 and 98.83% n = 1,197, respectively) and numerical abnormalities, suggesting that cultured ASCs are genomically stable and supporting their suitability for transplantation applications. In comparison, cultured primary human chorionic villus cells exhibited marked genomic instability resulting in an 11.6% tetraploidy rate after 8-10 PD. Thus effects of culture on genomic stability may be cell type dependent and should be tested by appropriately scaled interphase fluorescence in situ hybridization analysis in any ex vivo expanded cell population destined for transplantation.

Pluripotency rush! Molecular cues for pluripotency, genetic reprogramming of adult stem cells, and widely multipotent adult cells

In the last few years, pluripotent stem cells have been the objective of intense investigation efforts. These cells are of paramount therapeutic interest, since they could be utilized: as in vitro models of disease, for pharmaceutical screening purposes, and for the regeneration of damaged organs. Over the years, pluripotent cells have been cultured from teratomas, the inner cell mass, and primordial germ cells. Accumulating informations have partially decrypted the molecular machinery responsible for the maintenance of a very primitive state, permitting the reprogramming of differentiated cells. Although the debate is still open, an extreme excitement is arising from two strictly related possibilities: pluripotent cells could be obtained from adult tissues with minimal manipulations or very rare pluripotent cells could be identified in adult tissues. This intriguing option will trigger new researches aimed both at identifying the possible biological role of pluripotent adult stem cells and at exploiting their potential clinical use. The present review article will summarize current knowledge of the molecular cues for pluripotency but also discusses whether pluripotent stem cells could be obtained from adult tissues.

A neural network model for cell classification based on single-cell biomechanical properties

The potential success of tissue engineering or other cell-based therapies is dependent on factors such as the purity and homogeneity of the source cell populations. The ability to enrich cell harvests for specific phenotypes can have significant effects on the overall success of such therapies. While most techniques for cell sorting or enrichment have relied on cell surface markers, recent studies have shown that single-cell mechanical properties can serve as identifying markers of phenotype. In this study, a neural network modeling approach was developed to classify mesenchymal-derived primary and stem cells based on their biomechanical properties. Cell sorting was simulated using previously published data characterizing the mechanical properties of several different cell types as measured by atomic force microscopy. Neural networks were trained using combined data sets, with the resultant groupings analyzed for their purity, efficiency, and enrichment. Heterogeneous populations of zonal chondrocytes, chondrosarcoma cells, and mesenchymal-lineage cells, respectively, could all be classified into enriched subpopulations. Additionally, adult stem cells (adipose-derived or bone marrow-derived) separated disproportionately into nodes associated with the three primary mesenchymal lineages examined. These findings suggest that mathematical approaches such as neural network modeling, in combination with novel measures of cell properties, may provide a means of classifying and eventually sorting mixed populations of cells that are otherwise difficult to identify using more established techniques. In this respect, the identification of biomechanically based cell properties that increase the percentage of stem cells capable of differentiating into predictable lineages may improve the overall success of cell-based therapies.

Glandular stem cells are a promising source for much more than beta-cell replacement

Glandular stem cells (GSCs) can be obtained from exocrine glands such as pancreas or salivary glands using well-established cell culturing methods. The resulting cell populations are characterized by a high proliferative capacity and an unusually high plasticity. Cells from pancreas have been demonstrated to differentiate into a multitude of cell types and even into oocyte-like cells. It has been found that the preparation method for GSCs can be applied to many vertebrates, including fishes and birds. Since the cells are excellently cryopreservable, this finding has been utilized to establish a new stem cell bank for preserving living cells of rare and wild animals. Apart from these advances, this mini-review also points out that GSCs from pancreas must not be confused with beta-cell progenitors but constitute a distinct cell type.