Biomedical subjects

Silvia Brunelli

Publications and source records attributed to Silvia Brunelli.

13 recordsLinked to original sources

PubMed2007

Nitric oxide: emerging concepts about its use in cell-based therapies.

Regenerative medicine is an emerging clinical discipline in which cell-based therapies are used to restore the functions of damaged or defective tissues and organs. Along with the well-established use of cells derived from bone marrow or pancreatic islets, novel approaches of cell therapy have recently emerged that appear particularly promising; that is, those using cell-based vaccines and stem cells. This review focuses on the recent developments of these experimental therapeutic approaches and their drawbacks, with specific focus on dendritic cell vaccines in tumours and mesoangioblasts in muscular dystrophies. The authors discuss how the unique properties of a gaseous messenger, NO, may be exploited to overcome some of the drawbacks of these cell-based approaches in combined therapies based on NO-releasing drugs and cell delivery.

Animals↗

PubMed2006

Nitric oxide release combined with nonsteroidal antiinflammatory activity prevents muscular dystrophy pathology and enhances stem cell therapy.

Duchenne muscular dystrophy is a relatively common disease that affects skeletal muscle, leading to progressive paralysis and death. There is currently no resolutive therapy. We have developed a treatment in which we combined the effects of nitric oxide with nonsteroidal antiinflammatory activity by using HCT 1026, a nitric oxide-releasing derivative of flurbiprofen. Here, we report the results of long-term (1-year) oral treatment with HCT 1026 of two murine models for limb girdle and Duchenne muscular dystrophies (alpha-sarcoglycan-null and mdx mice). In both models, HCT 1026 significantly ameliorated the morphological, biochemical, and functional phenotype in the absence of secondary effects, efficiently slowing down disease progression. HCT 1026 acted by reducing inflammation, preventing muscle damage, and preserving the number and function of satellite cells. HCT 1026 was significantly more effective than the corticosteroid prednisolone, which was analyzed in parallel. As an additional beneficial effect, HCT 1026 enhanced the therapeutic efficacy of arterially delivered donor stem cells, by increasing 4-fold their ability to migrate and reconstitute muscle fibers. The therapeutic strategy we propose is not selective for a subset of mutations; it provides ground for immediate clinical experimentation with HCT 1026 alone, which is approved for use in humans; and it sets the stage for combined therapies with donor or autologous, genetically corrected stem cells.

Animals↗

PubMed2006

Ex vivo treatment with nitric oxide increases mesoangioblast therapeutic efficacy in muscular dystrophy.

Muscular dystrophies are characterized by primary wasting of skeletal muscle for which no satisfactory therapy is available. Studies in animal models have shown that stem cell-based therapies may improve the outcome of the disease, and that mesoangioblasts are promising stem cells in this respect. The efficacy of mesoangioblasts in yielding extensive muscle repair is, however, still limited. We found that mesoangioblasts treated with nitric oxide (NO) donors and injected intra-arterially in alpha-sarcoglycan-null dystrophic mice have a significantly enhanced ability to migrate to dystrophic muscles, to resist their apoptogenic environment and engraft into them, yielding a significant recovery of alpha-sarcolgycan expression. In vitro NO-treated mesoangioblasts displayed an enhanced chemotactic response to myotubes, cytokines and growth factors generated by the dystrophic muscle. In addition, they displayed an increased ability to fuse with myotubes and differentiating myoblasts and to survive when exposed to cytotoxic stimuli similar to those present in the dystrophic muscle. All the effects of NO were cyclic GMP-dependent since they were mimicked by treatment with the membrane permeant cyclic-GMP analogue 8-bromo-cGMP and prevented by inhibiting guanylate cyclase. We conclude that NO donors exert multiple beneficial effects on mesoangioblasts that may be used to increase their efficacy in cell therapy of muscular dystrophies.

Animals↗

PubMed2006

Complete repair of dystrophic skeletal muscle by mesoangioblasts with enhanced migration ability.

Efficient delivery of cells to target tissues is a major problem in cell therapy. We report that enhancing delivery of mesoangioblasts leads to a complete reconstitution of downstream skeletal muscles in a mouse model of severe muscular dystrophy (alpha-sarcoglycan ko). Mesoangioblasts, vessel-associated stem cells, were exposed to several cytokines, among which stromal- derived factor (SDF) 1 or tumor necrosis factor (TNF) alpha were the most potent in enhancing transmigration in vitro and migration into dystrophic muscle in vivo. Transient expression of alpha4 integrins or L-selectin also increased several fold migration both in vitro and in vivo. Therefore, combined pretreatment with SDF-1 or TNF-alpha and expression of alpha4 integrin leads to massive colonization (>50%) followed by reconstitution of >80% of alpha-sarcoglycan-expressing fibers, with a fivefold increase in efficiency in comparison with control cells. This study defines the requirements for efficient engraftment of mesoangioblasts and offers a new potent tool to optimize future cell therapy protocols for muscular dystrophies.

3T3 Cells↗

PubMed2006

Follistatin induction by nitric oxide through cyclic GMP: a tightly regulated signaling pathway that controls myoblast fusion.

The mechanism of skeletal myoblast fusion is not well understood. We show that endogenous nitric oxide (NO) generation is required for myoblast fusion both in embryonic myoblasts and in satellite cells. The effect of NO is concentration and time dependent, being evident only at the onset of differentiation, and direct on the fusion process itself. The action of NO is mediated through a tightly regulated activation of guanylate cyclase and generation of cyclic guanosine monophosphate (cGMP), so much so that deregulation of cGMP signaling leads to a fusion-induced hypertrophy of satellite-derived myotubes and embryonic muscles, and to the acquisition of fusion competence by myogenic precursors in the presomitic mesoderm. NO and cGMP induce expression of follistatin, and this secreted protein mediates their action in myogenesis. These results establish a hitherto unappreciated role of NO and cGMP in regulating myoblast fusion and elucidate their mechanism of action, providing a direct link with follistatin, which is a key player in myogenesis.

Animals↗

PubMed2005

A role for MSX2 and necdin in smooth muscle differentiation of mesoangioblasts and other mesoderm progenitor cells.

The molecular regulation of smooth muscle differentiation is currently far less well understood than that of striated muscle, in part because in this cell type, the differentiated state is plastic and reversible. In recent years, however, several molecules, the best characterized of which is myocardin, have been shown to be necessary and sufficient to promote at least partial smooth muscle differentiation. Indeed, mice deficient in myocardin have a severe reduction of smooth muscle tissue. However, possibly because of multiple embryological origins, which include mesenchyme, neural crest, and even endothelium, different types of smooth muscle cells differ in their expression of myocardin and of other potential regulatory molecules. Here, we will review recent work on the topic, focusing on the mesoangioblast, a recently described vessel-associated stem cell, whose differentiation into smooth muscle is dependent upon expression of msx2 and necdin, but not of myocardin.

Animals↗

PubMed2005

Accuracy of ultrasound in the detection of liver fibrosis in chronic viral hepatitis.

PURPOSE: To assess the accuracy of ultrasonography (US) in the identification and grading of hepatic fibrosis in patients afflicted with chronic viral liver disease, compared to histological examination as a gold standard. MATERIALS AND METHODS: We prospectively studied 105 patients (32 F, 73 M) affected by chronic viral liver disease in 36 months. Patients were studied with B-mode US and then underwent US-guided liver biopsy. All the patients were studied with conventional US with a Sequoia 512, 6.0 (Acuson, Mountain View CA, USA). We evaluated the following US parameters: liver margins, parenchymal echotexture, portal vein caliber and spleen diameter. The four B-mode US parameters were used for the US grading (from 0 to 4). Scheuer's grading (from 0 to 4) was used for the histological score. Grades 3 and 4 were considered as positive for fibrosis. Sensitivity, specificity, positive and negative predictive values and accuracy were calculated in the case of absence, positivity of one or all the US parameters. The correlation between US and histological scores was evaluated with Spearman's test. RESULTS: At histology seventy-seven patients (73%) had absent grade 0 (1 patient; 1%), low-moderate grade 1 (35 patients; 33%) or grade 2 (41 patients; 39%) liver fibrosis. Twenty-eight patients (27%) had severe grade 3 (16 patients; 15%) or grade 4 (12 patients; 11%) fibrosis. In the case of absence of US parameters sensitivity was 32%, specificity 32%, positive predictive value 15%, negative predictive value 57% and accuracy 32%. In the case of positivity of at least one of the US parameters the values were 68%, 68%, 43%, 84% and 69%. In the case of presence of all the US signs the results were 25%, 100%, 100%, 79% and 80%. None of the 77 patients with a healthy liver or with low-grade fibrosis was positive for all the US parameters. All the patients positive for all of the ultrasonographic parameters had high-grade fibrosis or cirrhosis at liver biopsy. Correlation between B-mode and histological scores was not statistically significant (Rs=0.45; p=0.0001). CONCLUSIONS: US identification of liver fibrosis in chronic liver disease is possible with 25% sensitivity, 100% specificity, 100% positive predictive value and 79% negative predictive value, with an 80% diagnostic accuracy.

Biopsy, Needle↗

PubMed2004

Mitochondrial biogenesis by NO yields functionally active mitochondria in mammals.

We recently found that long-term exposure to nitric oxide (NO) triggers mitochondrial biogenesis in mammalian cells and tissues by activation of guanylate cyclase and generation of cGMP. Here, we report that the NO/cGMP-dependent mitochondrial biogenesis is associated with enhanced coupled respiration and content of ATP in U937, L6, and PC12 cells. The observed increase in ATP content depended entirely on oxidative phosphorylation, because ATP formation by glycolysis was unchanged. Brain, kidney, liver, heart, and gastrocnemius muscle from endothelial NO synthase null mutant mice displayed markedly reduced mitochondrial content associated with significantly lower oxygen consumption and ATP content. In these tissues, ultrastructural analyses revealed significantly smaller mitochondria. Furthermore, a significant reduction in the number of mitochondria was observed in the subsarcolemmal region of the gastrocnemius muscle. We conclude that NO/cGMP stimulates mitochondrial biogenesis, both in vitro and in vivo, and that this stimulation is associated with increased mitochondrial function, resulting in enhanced formation of ATP.

Adenosine Triphosphate↗

PubMed2004

TGFbeta/BMP activate the smooth muscle/bone differentiation programs in mesoangioblasts.

Mesoangioblasts are vessel-derived stem cells that can be induced to differentiate into different cell types of the mesoderm such as muscle and bone. The gene expression profile of four clonal derived lines of mesoangioblasts was determined by DNA micro-array analysis: it was similar in the four lines but different from 10T1/2 embryonic fibroblasts, used as comparison. Many known genes expressed by mesoangioblasts belong to response pathways to developmental signalling molecules, such as Wnt or TGFbeta/BMP. Interestingly, mesoangioblasts express receptors of the TGFbeta/BMP family and several Smads and, accordingly, differentiate very efficiently into smooth muscle cells in response to TGFbeta and into osteoblasts in response to BMP. In addition, insulin signalling promotes adipogenic differentiation, possibly through the activation of IGF-R. Several Wnts and Frizzled, Dishevelled and Tcfs are expressed, suggesting the existence of an autocrine loop for proliferation and indeed, forced expression of Frzb-1 inhibits cell division. Mesoangioblasts also express many neuro-ectodermal genes and yet undergo only abortive neurogenesis, even after forced expression of neurogenin 1 or 2, MASH or NeuroD. Finally, mesoangioblasts express several pro-inflammatory genes, cytokines and cytokine receptors, which may explain their ability to be recruited by tissue inflammation. Our data define a unique phenotype for mesoangioblasts, explain several of their biological features and set the basis for future functional studies on the role of these cells in tissue histogenesis and repair.

Animals↗

PubMed2004

Msx2 and necdin combined activities are required for smooth muscle differentiation in mesoangioblast stem cells.

Little is known about the molecular mechanism underlying specification and differentiation of smooth muscle (SM), and this is, at least in part, because of the few cellular systems available to study the acquisition of a SM phenotype in vitro. Mesoangioblasts are vessel-derived stem cells that can be induced to differentiate into different cell types of the mesoderm, including SM. We performed a DNA microarray analysis of a mesoangioblast clone that spontaneously expresses an immature SM phenotype and compared it with a sister clone mainly composed of undifferentiated progenitor cells. This study allowed us to define a gene expression profile for "stem" cells versus smooth muscle cells (SMCs) in the absence of differentiation inducers such as transforming growth factor beta. Two transcription factors, msx2 and necdin, are expressed at least 100 times more in SMCs than in stem cells, are coexpressed in all SMCs and tissues, are induced by transforming growth factor beta, and, when coexpressed, induce a number of SM markers in mesoangioblast, fibroblast, and endothelial cell lines. Conversely, their downregulation through RNA interference results in a decreased expression of SM markers. These data support the hypothesis that Msx2 and necdin act as master genes regulating SM differentiation in at least a subset of SMCs.

Animals↗

PubMed2004

SOX3 is required during the formation of the hypothalamo-pituitary axis.

The pituitary develops from the interaction of the infundibulum, a region of the ventral diencephalon, and Rathke's pouch, a derivative of oral ectoderm. Postnatally, its secretory functions are controlled by hypothalamic neurons, which also derive from the ventral diencephalon. In humans, mutations affecting the X-linked transcription factor SOX3 are associated with hypopituitarism and mental retardation, but nothing is known of their etiology. We find that deletion of Sox3 in mice leads to defects of pituitary function and of specific central nervous system (CNS) midline structures. Cells in the ventral diencephalon, where Sox3 is usually highly expressed, have altered properties in mutant embryos, leading to abnormal development of Rathke's pouch, which does not express the gene. Pituitary and hypothalamic defects persist postnatally, and SOX3 may also function in a subset of hypothalamic neurons. This study shows how sensitive the pituitary is to subtle developmental defects and how one gene can act at several levels in the hypothalamic-pituitary axis.

Animals↗

PubMed2003

Expression of Sox3 throughout the developing central nervous system is dependent on the combined action of discrete, evolutionarily conserved regulatory elements.

SOX3 is one of the earliest neural markers in vertebrates and is thought to play a role in specifying neuronal fate. To investigate the regulation of Sox3 expression we identified cis-regulatory regions in the Sox3 promoter that direct tissue-specific heterologous marker gene expression in transgenic mice. Our results show that an 8.3 kb fragment, comprising 3 kb upstream and 3 kb downstream of the Sox3 transcriptional unit, is sufficient in a lacZ reporter construct to reproduce most aspects of Sox3 expression during CNS development from headfold to midgestation stages. The apparently uniform expression of Sox3 in the neural tube depends, however, on the combined action of distinct regulatory modules within this 8.3 kb region. Each of these gives expression in a subdomain of the complete expression pattern. These are restricted along both the rostral-caudal and dorso-ventral axes and can be quite specific, one element giving expression largely confined to V2 interneuron precursors. We also find that at least some of the regulatory sequences are able to drive expression of the transgene in the CNS Xenopus laevis embryos in a manner that reflects the endogenous Sox3 expression pattern. These results imply that the underlying mechanism regulating early CNS patterning is conserved, despite several substantial differences in neurogenesis between mammals and amphibians.

Animals↗

PubMed2003

Bhlhb5 is expressed in the CNS and sensory organs during mouse embryonic development.

Basic loop helix transcription factors have been shown to be implicated in the specification of various cell types, and many are involved in different aspects of neural development. Here we describe the expression of Bhlhb5, belonging to the beta3 subfamily, in mouse embryos ranging from 9 to 16.5dpc. Bhlhb5 is initially detected at 9.5dpc in the neural tube, restricted to longitudinal ventral columns of neurons, extending from the hindbrain to the caudal spinal cord. At later stages the expression is maintained in the central nervous system, in particular in the brain, where it is detected in the outer and more mature layer of the forming cerebral cortex and in the spinal cord. In addition Bhlhb5 is expressed in the developing eye and hair follicles, in the epithelial layer of the cochlea in the developing inner, and in the nasal epithelium.

Animals↗