Use of the MLPA Assay in the Molecular Diagnosis of Gene Copy Number Alterations in Human Genetic Diseases

Multiplex Ligation-dependent Probe Amplification (MLPA) assay is a recently developed technique able to evidence variations in the copy number of several human genes. Due to this ability, MLPA can be used in the molecular diagnosis of several genetic diseases whose pathogenesis is related to the presence of deletions or duplications of specific genes. Moreover, MLPA assay can also be used in the molecular diagnosis of genetic diseases characterized by the presence of abnormal DNA methylation. Due to the large number of genes that can be analyzed by a single technique, MLPA assay represents the gold standard for molecular analysis of all pathologies derived from the presence of gene copy number variation. In this review, the main applications of the MLPA technique for the molecular diagnosis of human diseases are described

Sequence-specific modification of a β-thalassemia locus by small DNA fragments in human erythroid progenitor cells

Gene therapy has been proposed as a definitive cure of beta-thalassemia. We applied a gene targeting approach, based on the introduction of small DNA fragments (SDF) into erythroid progenitor cells, to specifically modify the beta-globin gene sequence at codon 39. The strategy was first tested in normal individuals by delivering mutant SDF that were able to produce the beta-39 (C-T) mutation. Secondly, wild-type SDF were electroporated into target cells of beta-3i9/beta-39 b-thalassemic patients to correct the endogenous mutation. In both cases, gene modification was assayed by allele-specific polymerase chain reaction of DNA and mRNA, by restriction fragment length polymorphism analysis and by direct sequencing

Testis transcriptome analysis in male infertility: new insight on the pathogenesis of oligo-azoospermia in cases with and without AZFc microdeletion

<p>Abstract</p> <p>Background</p> <p>About 10% of cases of male infertility are due to the presence of microdeletions within the long arm of the Y chromosome (Yq). Despite the large literature covering this critical issue, very little is known about the pathogenic mechanism leading to spermatogenesis disruption in patients carrying these microdeletions. In order to identify the presence of specific molecular pathways leading to spermatogenic damage, testicular gene expression profiling was carried out by employing a microarray assay in 16 patients carrying an AZFc microdeletion or affected by idiopathic infertility. Hierarchical clustering was performed pooling the data set from 26 experiments (16 patients, 10 replicates).</p> <p>Results</p> <p>An intriguing and unexpected finding is that all the samples showing the AZFc deletion cluster together irrespectively of their testicular phenotypes. This cluster, including also four patients affected by idiopathic infertility, showed a downregulation of several genes related to spermatogenesis that are mainly involved in testicular mRNA storage. Interestingly, the four idiopathic patients present in the cluster showed no testicular expression of <it>DAZ </it>despite the absence of AZFc deletion in the peripheral blood.</p> <p>Conclusions</p> <p>Our expression profiles analysis indicates that several forms of infertility can be triggered by a common pathogenic mechanism that is likely related to alterations in testicular mRNA storage. Our data suggest that a lack of testicular DAZ gene expression may be the trigger of such mechanism. Furthermore, the presence of AZFc deletions in mosaic or the loss of function of AZFc genes in absence of Yq deletion can perhaps explain these findings. Finally, based on our data, it is intriguing to hypothesize that <it>DAZ </it>gene dysfunctions can account for a larger number of previously thought "idiopathic" infertility cases and investigation of such testicular gene dysfunction can be important to reveal the molecular determinant of infertility than are undetected when only testing Yq deletions in peripheral blood.</p

Embryoid body in vitro formation from human amniotic fluid stem cells (AFSCs): an ultrastructural study

Amniotic fluid stem cells (AFSCs) harbour the potential to differentiate into cells of any of the three germ layers and to form embryoid bodies (EBs) without inducing teratoma formation (De Coppi et al., 2007; Antonucci et al., 2012). However, no previous findings have been reported regarding embryoid body in vitro development and ultrastructural organization. Thus, this was the aim of our study. Amniotic fluid samples were obtained from women undergoing amniocentesis for prenatal diagnosis at 16-19 weeks of pregnancy after written informed consent and the local ethical committee approval. Human AFSCs were cultured up to the 8th passage and analysed with RT-PCR for the expression of pluripotency markers. Some cellular pools were cultured in suspension in uncoated Petri dishes (hanging drop method) to obtain EB formation. After 5 days of culture, the appearance of EBs of different size was observed with phase contrast microscopy and monitored up to 10-15 days of culture. In parallel, EB standard embedding in paraffin for light microscopy or in epoxy resin for transmission electron microscopy was performed. RT-PCR analysis revealed the presence of classical markers of pluripotency (OCT4, NANOG, SOX2) in AFSCs at the 2th-8th passage, whereas specific markers of the three embryonic germ layers were detected in EB specimens. Morphological assays of three-dimensional aggregates demonstrated the presence of solid structures only at the beginning of the culture whereas signs of apoptotic cell death accompanied by the secretion of an amorphous substance were soon detected. These features were preliminary to the development, at later culture time intervals, of an inner hollow cavity surrounded by a crown of flat cells displaying a number of electron dense granules and highly resembling trophoblastic cells

Calcitonin-Induced Effects on Amniotic Fluid-Derived Mesenchymal Stem Cells

Background/Aims: Mesenchymal stem cells from human amniotic fluid (huAFMSCs) can differentiate into multiple lineages and are not tumorigenic after transplantation, making them good candidates for therapeutic purposes. The aim was to determine the effects of calcitonin on these huAFMSCs during osteogenic differentiation, in terms of the physiological role of calcitonin in bone homeostasis. Methods: For huAFMSCs cultured under different conditions, we assayed: expression of the calcitonin receptor, using immunolabelling techniques; proliferation and osteogenesis, using colorimetric and enzymatic assays; intracellular Ca2+ and cAMP levels, using videomicroscopy and spectrophotometry. Results: The calcitonin receptor was expressed in proliferating and osteo-differentiated huAFMSCs. Calcitonin triggered intracellular Ca2+ increases and cAMP production. Its presence in cell medium also induced dose-dependent inhibitory effects on proliferation and increased osteogenic differentiation of huAFMSCs, as also indicated by enhancement of specific markers and alkaline phosphatase activity. Conclusions: These data show that huAFMSCs represent a potential osteogenic model to study in-vitro cell responses to calcitonin (and other members of the calcitonin family). This leads the way to the opening of new lines of research that will add new insight both in cell therapies and in the pharmacological use of these molecules

Calcitonin-Induced Effects on Amniotic Fluid-Derived Mesenchymal Stem Cells

Background/Aims: Mesenchymal stem cells from human amniotic fluid (huAFMSCs) can differentiate into multiple lineages and are not tumorigenic after transplantation, making them good candidates for therapeutic purposes. The aim was to determine the effects of calcitonin on these huAFMSCs during osteogenic differentiation, in terms of the physiological role of calcitonin in bone homeostasis. Methods: For huAFMSCs cultured under different conditions, we assayed: expression of the calcitonin receptor, using immunolabelling techniques; proliferation and osteogenesis, using colorimetric and enzymatic assays; intracellular Ca2+ and cAMP levels, using videomicroscopy and spectrophotometry. Results: The calcitonin receptor was expressed in proliferating and osteo-differentiated huAFMSCs. Calcitonin triggered intracellular Ca2+ increases and cAMP production. Its presence in cell medium also induced dose-dependent inhibitory effects on proliferation and increased osteogenic differentiation of huAFMSCs, as also indicated by enhancement of specific markers and alkaline phosphatase activity. Conclusions: These data show that huAFMSCs represent a potential osteogenic model to study in-vitro cell responses to calcitonin (and other members of the calcitonin family). This leads the way to the opening of new lines of research that will add new insight both in cell therapies and in the pharmacological use of these molecules

Isolation of osteogenic progenitors from human amniotic fluid using a single step culture protocol

<p>Abstract</p> <p>Background</p> <p>Stem cells isolated from amniotic fluid are known to be able to differentiate into different cells types, being thus considered as a potential tool for cellular therapy of different human diseases. In the present study, we report a novel single step protocol for the osteoblastic differentiation of human amniotic fluid cells.</p> <p>Results</p> <p>The described protocol is able to provide osteoblastic cells producing nodules of calcium mineralization within 18 days from withdrawal of amniotic fluid samples. These cells display a complete expression of osteogenic markers (COL1, ONC, OPN, OCN, OPG, BSP, Runx2) within 30 days from withdrawal. In order to test the ability of these cells to proliferate on surfaces commonly used in oral osteointegrated implantology, we carried out cultures onto different test disks, namely smooth copper, machined titanium and Sandblasted and Acid Etching titanium (SLA titanium). Electron microscopy analysis evidenced the best cell growth on this latter surface.</p> <p>Conclusion</p> <p>The described protocol provides an efficient and time-saving tool for the production of osteogenic cells from amniotic fluid that in the future could be used in oral osteointegrated implantology.</p

A morpho-functional analysis of embryoid body-like structures from human amniotic fluid-derived stem cells (AFSCs) unselected for c-kit

Human AFSCs, a novel class of stem cells sharing characteristics of both embryonic and adult stem cells, harbour high proliferative capacity and high differentiation potential and do not raise the ethical concerns associated with human embryonic stem cells (ESCs). The formation of three-dimensional aggregates known as embryoid bodies (EBs) is the main step in the differentiation of pluripotent embryonic stem cells. The purpose of this study was to investigate whether human AFSCs, unselected for c-kit, have features of pluripotency. With this aim, we evaluated both AFSC ability to form in vitro EB structures and transcriptional profiles of genes typically expressed in human ESCs. Total AFSCs were cultured in suspension in uncoated Petri dishes for EB formation, whose incidence was assessed in 5 independent experiments. EB-like structures were observed and morphometrically analysed under a LEICA phase contrast microscope equipped with a CoolSnap videocamera. A number of samples were processed for alkaline phosphatase (AP) or haematoxylin-eosin staining, immunofluorescence and transmission electron microscopy to follow-up morphology and markers of pluripotency. As to the expression studies, RNA was extracted from AFSCs at the 3th, 4th, 5th and 8th passage in culture and the presence of ESC and primordial germ cell (PGC) specific markers was assessed with RT-PCR. As early as after 5 days of culture we were able to observe the formation of EB-like solid structures of different size progressively increasing at later time intervals of incubation in cell culture medium (10-15 days). At these later time points EB aggregates showed the presence of an internal cavity and were surrounded by a wide cohort of bigger cells detaching from them. Both early and late time EBs were positive for alkaline phosphatase (AP) staining and specific markers of pluripotency (OCT4 and SOX2). The parallel analysis of AFSCs with RT-PCR demonstrated the presence of ESC and PGC specific gene transcripts and, moreover, the expression of alternatively spliced genes also detectable in EB cells. These findings demonstrate that AFSCs are a new and powerful biological system to recapitulate the three-dimensional and tissue level contexts of in vivo development

Study of cardiomyogenic potential of human Amniotic Fluid Stem Cells

It has been shown that Amniotic fluid stem cells (AFSCs) have characteristics intermediate between pluripotent embryonic and lineage-restricted adult stem cells, and are non-tumorigenic and low immunogenic. Moreover, they are obtained without destroying human embryos, so that preventing most of the ethical and social controversy. Human AFSCs express some genes specific of both embryonic (OCT3/4, NANOG, c-MYC) and primordial germ stem cells (Fragilis, Stella, c-KIT). We have demonstrated that hAFSCs form in vitro embryoid bodies (EBs) and express markers of three germ layers. Studies reported the ability of hAFSCs to differentiate in vitro into adipocytes and osteocytes, but only few data are available on their cardiomyogenic potential. Aim of this study is to analyze hAFSCs differentiation through the cardiac pathway. Embryonic Bodies (EBs) were obtained from hAFSCs cultured in presence of ascorbic acid and 5-aza-2’-deoxycytidine. Cardiomyogenic potential of hAFSCs and EBs was explored by WB and immunoflorescent analyses of specific markers. Simultaneous quantitative detection and cellular localization analysis of cardiomyogenic markers were conducted with an ImageStream multispectral imaging flow cytometer (Amnis-Seattle, WA) equipped with IDEAS statistical software. We evidenced that both AFSCs and EBs at early stage express Nkx2.5, a transcription factor expressed by cardiomyocytes precursor cells. Moreover, ImageStream imaging cytometer analysis evidenced that EBs formation was accompanied by an up-regulation of Nkx2.5 expression (36.54±1.83% and 64.68±3.23% positive cells in hAFSC and EBs respectively, p&lt;.005) and by a significant nuclear translocation (12.98±0.64% and 37.98±1.9% nuclear positive cells in hAFSC and EBs respectively, p&lt;.005). Microscopical analysis evidenced inside the EBs cells positive for the presence of cardiac α-Myosin heavy chain protein structurally organized in oriented filaments. Moreover, we detected cells expressing Connexin43. These results evidenced that EBs obtained from hAFSCs cultured in permissive conditions terminally differentiate into cardiomyocytes and suggest them as possible model to study the cardiac differentiation

Human Cardiopoietic Amniotic Fluid cell population: characterization and terminal differentiation

Rationale. Human amniotic fluid-derived (hAF) stem cells are considered a novel class of multipotent stem cells, sharing characteristics of both embryonic and adult stem cells. In fact, they proliferate rapidly, are able to differentiate into cells of all the embryonic germ layers, but do not form teratoma. It has been already reported that the embryoid bodies (EBs) obtained from hAFs have a cardiac potential, but it has not been described a functional terminal differentiation in cardiomyocytes (CMs) yet. Objective. Aim of this study was to foster the cardiomyogenic potential of hAFs in order to obtain a cellular population with morphological and functional features of CMs. Methods and Results. AFCs were exposed sequentially to inducing factors (Ascorbic Acid, 5-Azacytidine, BMP4, ActivinA, VEGF) up to 15 days and differentiation was monitored. Only the hAF samples expressing the multipotency markers SSEA4, OCT4 and CD90 (CardiopoieticAF) responded to the differentiation process loosing their stemness and increasing the cardiac nuclear factors NKX2.5 and GATA4. After the differentiation cells expressed high levels of the sarcomeric proteins (cTnT, αMHC and αSA), the gap junction marker Connexin43 and both atrial and ventricular markers; moreover, up to 90% of the cells was positive for CACNA1C and SERCA2a, cardiac calcium pumps involved in the excitation/contraction coupling, and about 30% of the CardiopoieticAF-derived cells presented spontaneous intracellular Ca2+ waves and Ca2+ fluctuation in response to caffeine or adrenergic stimulation. Some spontaneous beating foci were also observed. Conclusion. Our results demonstrate that CardiopoietichAFs can fully differentiate into a homogenous population of CM-like cells, characterized by cardiac-specific molecular, structural, and functional properties. Thus, CardiopoietichAFs can hold great promise for the development of in vitro models of cardiac genetic disorders, for drug discovery and testing, and for the emerging field of cardiovascular regenerative medicine