Human amniotic fluid stem cells are able to form embryoid body-like aggregates which performs specific functions: morphological evidences

Human second trimester Amniotic Fluid Stem Cells (hAFSCs) harbour the potential to differentiate into cells of each of the three germ layers and to form Embryoid Body (EB)-like aggregates, without inducing teratoma formation and with no ethical concerns. However, in spite of the number of reports on hAFSCs-EBs and their characterization, a thorough evaluation in light and electron microscopy of morphological and morphometric features of hAFSCs-EBs development in vitro has not been reported yet. Apart from a superficial layer of epithelial-like flat cells, displaying rare microvilli on the free surface, hAFSCs-EBs enclose inner material, abundant in vesicles and secretory granules, showing early characteristics of connective extracellular matrix dispersed among different types of inner cells. The observation of a number of microvesicles mainly represented by microparticles and, to a lower extent, by exosomes indicates the presence of a complex cellular communication system within this structure. According to morphological analysis, after 7 days of in vitro culture hAFSCs-EB appears as a well-organized corpuscle, sufficiently young to be a carrier of stemness and at the same time, when appropriately stimulated, able to differentiate. In fact, 7-day hAFSCs-EB represents itself an initial cellular transformation towards a specialized structure both in recording and in providing different stimuli from the surrounding environment, organizing structures and cells towards a differentiation fate.

Differential response to hepatic differentiation stimuli of amniotic epithelial cells isolated from four regions of the amniotic membrane

Human Amniotic Epithelial Cells (hAEC) isolated from term placenta are a promising source for regenerative medicine. However, it has long been debated whether the hAEC population consists of heterogeneous or homogeneous cells. In a previous study, we investigated the characteristics of hAEC isolated from four different regions of the amniotic membrane finding significant heterogeneity. The aim of this study was to evaluate the hepatic differentiation capability of hAEC isolated from these four regions. Human term placentae were collected after caesarean section and hAEC were isolated from four regions of the amniotic membrane (R1-R4, according to their relative distance from the umbilical cord) and treated in hepatic differentiation conditions for 14 days. hAEC-derived hepatocyte-like cells showed marked differences in the expression of hepatic markers: R4 showed higher levels of Albumin and Hepatocyte Nuclear Factor (HNF) 4α whereas R1 expressed higher Cytochrome P450 enzymes, both at the gene and protein level. These preliminary results suggest that hAEC isolated from R1 and R4 of the amniotic membrane are more prone to hepatic differentiation. Therefore, the use of hAEC from a specific region of the amniotic membrane should be taken into consideration as it could have an impact on the outcome of therapeutic applications.

Mapping of the Human Placenta: Experimental Evidence of Amniotic Epithelial Cell Heterogeneity

The human placenta is an important source of stem cells that can be easily collected without ethical concerns since it is usually discarded after childbirth. In this study, we analyzed the amniotic membrane (AM) from the human placenta with the aim of mapping different regions with respect to their morpho-functional features and regenerative potential. AMs were obtained from 24 healthy women, undergoing a caesarean section, and mapped into 4 different regions according to their position in relation to the umbilical cord: the central, intermediate, peripheral, and reflected areas. We carried out a multiparametric analysis focusing our attention on amniotic epithelial cells (AECs). Our results revealed that AECs, isolated from the different areas, are a heterogeneous cell population with different pluripotency and proliferation marker expression (octamer-binding transcription factor 4 [OCT-4], tyrosine-protein kinase KIT [c-KIT], sex determining region Y-box 2 [SOX-2], α-fetoprotein, cyclic AMP response element binding [CREB] protein, and phosphorylated active form of CREB [p-CREB]), proliferative ability, and osteogenic potential. Our investigation discloses interesting findings that could be useful for increasing the efficiency of AM isolation and application for therapeutic purposes.

Regulation of Cancer Cell Responsiveness to Ionizing Radiation Treatment by Cyclic AMP Response Element Binding Nuclear Transcription Factor

Cyclic AMP response element binding (CREB) protein is a member of the CREB/activating transcription factor (ATF) family of transcription factors that play an important role in the cell response to different environmental stimuli leading to proliferation, differentiation, apoptosis, and survival. A number of studies highlight the involvement of CREB in the resistance to ionizing radiation (IR) therapy, demonstrating a relationship between IR-induced CREB family members' activation and cell survival. Consistent with these observations, we have recently demonstrated that CREB and ATF-1 are expressed in leukemia cell lines and that low-dose radiation treatment can trigger CREB activation, leading to survival of erythro-leukemia cells (K562). On the other hand, a number of evidences highlight a proapoptotic role of CREB following IR treatment of cancer cells. Since the development of multiple mechanisms of resistance is one key problem of most malignancies, including those of hematological origin, it is highly desirable to identify biological markers of responsiveness/unresponsiveness useful to follow-up the individual response and to adjust anticancer treatments. Taking into account all these considerations, this mini-review will be focused on the involvement of CREB/ATF family members in response to IR therapy, to deepen our knowledge of this topic, and to pave the way to translation into a therapeutic context.

Predictive value of microparticle-associated tissue factor activity for permeability glycoprotein-mediated multidrug resistance in cancer

Multidrug resistance (MDR) protein 1, which is also known as permeability glycoprotein (Pgp), and tissue factor (TF) are recurrently overexpressed on the surface of cancer cells, likely in response to stimuli such as chemotherapy. Microparticles (MPs) released from cancer cells into the bloodstream express tumour markers on their surface that may be useful as predictive biomarkers for evaluating disease progression. The present study measured the level of TF/factor VII (FVII)-dependent coagulation of MPs isolated from the plasma of cancer patients with various tumours, who were undergoing chemotherapy. Furthermore, Pgp expression on the surface of MPs was evaluated by immunohistochemistry. A total of 50 cancer patients, as well as 10 healthy volunteers, were enrolled in the present study. MP-associated TF/FVII-dependent coagulation pathways were evaluated as the effect of an anti-FVII antibody on the time to thrombin generation, as compared with controls treated with saline. The significantly lengthened times of coagulation [obtained in 20/50 samples (36.5 ± 16%) after treatment with anti-FVIIa when compared with controls] suggest the presence of TF activity is associated with circulating MPs. Furthermore, the 20 MP/TF-positive samples were associated with Pgp overexpression on their surface. Conversely, in the remaining samples (n=30), treatment with the anti-FVIIa antibody did not significantly lengthen the time to clotting (<10%), and Pgp overexpression was not detected. In addition, in the control samples from healthy individuals, Pgp expression at the plasma membrane and clotting in the presence of the anti-FVII antibody were not observed, indicating the absence of MPs. The present study demonstrated that MPs in the blood of cancer patients promoted fibrin generation via TF/FVII-dependent pathways, thus suggesting that the evaluation of MP-TF activity may have a predictive value for Pgp-mediated MDR in various cancer types. Although further studies are required, the measurement of plasma MP-associated TF activity as a predictive biomarker may provide novel therapeutic perspectives to improve the prognosis and effectiveness of anti-cancer drugs in patients who are at a high-risk of Pgp-mediated MDR.

Ultrastructural regenerating features of nasal mucosa following microdebrider-assisted turbinoplasty are related to clinical recovery

BACKGROUND

The nasal mucosa plays a key role in conditioning the inhaled air and in regulating the immune response. These functions led many authors to recommend mucosal sparing techniques for the surgical management of inferior turbinate hypertrophy. However, the histological modifications of chronic diseases retain the inflammatory activity and prevent the nasal physiology restoration. It has been proved that the basal cells of the nasal mucosa are able to proliferate and to repair after cold-knife incision. The aim of this study was to demonstrate that the healing process after removal of the inferior turbinate mucosa with cold techniques results in a complete structural restoration.

METHODS

A prospective study was performed in 18 patients who underwent Microdebrider inferior turbinoplasty (cold technique). Subjective and objective improvement of nasal patency was evaluated with visual analogue scale, rhinomanometry, videoendoscopy and mucociliary transport test. Pre- and post-operative biopsy specimens were taken from 7 patients to evaluate the healing process. Two samples were taken from two healthy patients as control. The specimens were processed for transmission electron microscopy analysis.

RESULTS

Videoendoscopy showed reduction of lower turbinate after surgery. Nasal patency augmented and no adverse consequences were observed. After 4 months the nasal mucosa showed normal appearance, with restoration of the pseudostratified ciliated pattern, intercellular connections and normal cellular morphology. Fibrosis and submucosal edema disappeared. At longer time after operation (4 years) clinical improvement was confirmed.

CONCLUSIONS

The total removal of the nasal mucosa with cold techniques results in a complete restoration of the normal structure and permanent resolution of the chronic inflammation typical of hypertrophic rhinopathy.

Tumor Necrosis Factor Related Apoptosis Inducing Ligand (Trail) in endothelial response to biomechanical and biochemical stresses in arteries

Shear stress is determined by three physical components described in a famous triad: blood flow, blood viscosity and vessel geometry. Through the direct action on endothelium, shear stress is able to radically interfere with endothelial properties and the physiology of the vascular wall. Endothelial cells (ECs) have also to sustain biochemical stresses represented by chemokines, growth factors, cytokines, complement, hormones, nitric oxide (NO), oxygen and reactive oxygen species (ROS). Many growth factors, cytokines, chemokines, hormones, and chemical substances, like NO, act and regulate endothelium functions and homeostasis. Among these cytokines Tumor Necrosis Factor Related Apoptosis Inducing Ligand (TRAIL) has been assigned a regulatory role in ECs physiology and physiopathology. Thus, the aim of this review is to provide a general overview of the endothelial response pathways after different types of biomechanical and biochemical stress in in vitro models and to analyze the crucial role of TRAIL under pathological conditions of the cardiocirculatory system like atherosclerosis, coronary artery disease, and diabetes.

Human second trimester amniotic fluid cells are able to create embryoid body-like structures in vitro and to show typical expression profiles of embryonic and primordial germ cells

Human amniotic fluid-derived stem cells (AFSCs) represent a novel class of broadly multipotent stem cells sharing characteristics of both embryonic and adult stem cells. However, both the origin of these cells and their actual properties in terms of pluripotent differentiation potential are still debated. In order to verify the presence of features of pluripotency in human second trimester AFSCs, we have investigated the ability of these cells to form in vitro three-dimensional aggregates, known as embryoid bodies (EBs), and to express specific genes of embryonic stem cells (ESCs) and primordial germ cells (PGCs). EBs were obtained after 5 days of AFSC culture in suspension and showed positivity for alkaline phosphatase (AP) staining and for specific markers of pluripotency (OCT4 and SOX2). Moreover, EB-derived cells showed the expression of specific transcripts of the three germ layers. RT-PCR analysis, carried out at different culture times (second, third, fourth, fifth, and eighth passages), revealed the presence of specific markers of ESCs (such as FGF4 and DAPPA4), as well as of markers typical of PGCs and, in particular, genes involved in early stages of germ cell development (Fragilis, Stella, Vasa, c-Kit, Rnf17). Finally, the expression of genes related to the control of DNA methylation (DNMT3A, DNMT3b1, DNMT1, DNMT3L, MBD1, MBD2, MBD3, MDB4, MeCP2), as well as the lack of inactivation of the X-chromosome in female samples, was also demonstrated. Taken together, these data provide further evidence for the presence of common features among human AFSCs, PGCs, and ESCs.

A flow cytometry procedure for simultaneous characterization of cell DNA content and expression of intracellular protein kinase C-zeta

A selective involvement of protein kinase C-zeta (PKC-zeta) in the events regulating cell proliferation has been recently proposed. Here we report a flow cytometric method allowing the simultaneous association of intracellular PKC-zeta expression or phosphorylation with each cell cycle phase. Current methods for flow cytometry analysis were applied to several cell lines and compared to the method developed in our laboratory. The latter includes 2% paraformaldehyde (PFA), as fixing agent, a permeabilization/saturation step by means of a solution containing 150 mM NaCl, 5 mM EDTA, 50 mM Tris-HCl pH 7.4, 0.05% NP-40, 0.25% lambda-carrageenan and 0.02% NaN3, followed by labelling with a primary antibody (PKC-zeta or P-PKC-zeta) and with the appropriate FITC-conjugated secondary antibody. Cells processed by such a method disclosed no substantial modification of light scattering features with respect to live cells. In addition, stainability with anti-PKC-zeta or anti-P-PKC-zeta antibodies was well preserved while stoichiometric staining of DNA with PI enabled accurate cell cycle analysis. Results show that a distinct up-regulation of P-PKC-zeta in G2/M phase occurs. The method here described, therefore, represents a simple, reproducible and conservative assay for a simultaneous assessment of intracellular PKC or P-PKC modulations within each cell cycle phase.

Dimethylsulfoxide-induced cell death of murine erythroleukemia cells exposed to ionising radiation

The present investigation was aimed at studying the effects of dimethylsulfoxide (DMSO) in combination with high dose (15 and 60 Gy) ionising radiation on the growth and differentiation of murine erythroleukemia cells (MEL). The incubation with DMSO was performed for 96 h starting immediately after exposure to radiation and resulted only in a slight inhibition of cell growth and in a high increase in cell death with the induction of both necrosis and apoptosis. The enhancement of radiation cytotoxicity was directly related to dose, time in culture and degree of differentiation as demonstrated by the severe and multiple aberrations observed in light and electron microscopy. Of interest was the observation in induced cells of a marked rearrangement of the plasma membrane architecture as well as that of the nuclear envelope, with a massive translocation and/or decrease in the nuclear pore complexes.

Immunocytochemical discrimination between early and late S phase: a new approach to the study of gingival epithelium proliferation in rats

The renewal of the free gingival margin epithelium in rats was studied evaluating 5-bromodeoxyuridine (BrdU) incorporation in proliferating cells by means of an immunocytochemical method. We found a close correspondence between light and electron microscopy patterns of BrdU incorporation at a nuclear level. BrdU was localized in the inner interchromatin regions in cells starting DNA synthesis, while it was localized in the peripheral heterochromatin domains in cells terminating the S phase. This possibility of discriminating cells in early S phase from cells in late S is able to provide far more information as to the time at which a labeled cell starts proliferation than that obtainable with 3H-thymidine autoradiography. This, in turn, permits detection of cells that start proliferation in a wide period of time by means of a single BrdU administration. Rats treated at 7 a.m. demonstrated higher proliferation than rats treated at 7 p.m., supporting the existence of circadian variations in the epithelial renewal. Proliferative events take place by consecutive activation of at least three replication waves, producing clusters of labeled cells which could be observed in rats sacrificed at 10 a.m. In rats treated once with BrdU at 7 a.m., the clusters were localized in both the basal and suprabasal layer of the epithelium; in rats further injected with BrdU at the same time, the clusters increased in size, progressively extending throughout the epithelium. In this way, the renewal of the free gingival margin epithelium does not proceed randomly, but by consecutive activation of discrete units or clusters of basal cells, which then extend to the upper layers. This can be followed at a morphological level as a progression of labeled cells, which move from the basal layer to the epithelium surface in approximately 82-85 hours.

TNF-alpha-induced apoptosis in Daudi cells: multiparametric analysis

Tumour necrosis factor alpha (TNF-alpha) is a cytokine that induces physiological and pathophysiological effects in the immune system. In this study we analyzed its action on a human lymphoma cell line (Daudi cells) after 1 h, 6 h and 24 h of incubation. Using vital DNA stains, DNA gel electrophoresis, in situ nick translation, transmission electron microscopy and flow cytometry we showed that as early as after 6 h of treatment, target cells were able to undergo death by apoptosis. This was associated with cell shrinkage, chromatin condensation, apoptotic bodies in the cytoplasm without the typical DNA fragmentation into low molecular weight nucleosomes. Of interest was the observation of a significant number (60%) of cells positive to the nick translation in specimens treated for 6 h, decreasing to 40% in samples treated for 24 h, when most of the cells were in late apoptosis. In addition, no subdiploid peak was evident in flow cytometry regardless of the time of incubation with TNF. Our study on Daudi cells clearly supports the existence of alternative forms of apoptosis in which DNA degradation does not result only in oligonucleosomal fragmentation.

Age- and training-related events in active T subpopulation. Changes in polyphosphoinositide metabolism during mitogenic stimulation

To examine the effects of age and training on the active T subpopulation we considered elderly amateur cyclists over 65 in comparison with young amateur cyclists and young and aged sedentary healthy controls. Significant differences were observed between trained and sedentary elderly subjects consisting of an increase in the percentage of active E rosettes after 4 and 24 h of in vitro PHA stimulation, and of a decrease in the in vitro phosphorylation of phosphatydylinositol 4,5-bisphosphate (PtdInsP2) and a corresponding increase in phosphatydylinositol 4-phosphate (PtdInsP) in the early steps of the mitotic response. Our findings support the hypothesis of the involvement of inositol lipids in controlling the expression of lymphocyte surface receptors.

Synergistic regulatory effects of TNF alpha, IL-1 alpha and IFN alpha on the growth and differentiation of Daudi lymphoma cells

The regulatory effects of the combined treatment of tumour necrosis factor alpha (TNF alpha), interleukin-1 alpha (IL-1 alpha) and interferon alpha (IFN alpha) on the growth and differentiation of Daudi lymphoma cells were investigated. By means of anti-BrdU monoclonal antibodies and [3H-thymidine] incorporation a reduced proliferation rate was shown both through a combination of TNF alpha with either IL-1 alpha or IFN alpha and, above all, through simultaneous treatment with the three cytokines. In parallel, the degree of differentiation was evaluated via morphological criteria and detection of Fc receptors (FcR) and appeared higher after treatment with the three cytokines. Our results provide evidence of the increased sensitivity of this cell line to this combined treatment supporting the existence of a synergistic interaction in inducing the antiproliferative and differentiative effects.

Ionizing radiation-induced apoptosis and DNA repair in murine erythroleukemia cells

A morphological study of DNA repair and apoptotic patterns in relationship with cell cycle events was performed on murine erythroleukemia cells. The presence and distribution of DNA replicon sites were evaluated through the BrdU-anti BrdU immunofluorescence and immunogold techniques in light and electron microscopy. Different patterns of labelling and percentages of BrdU positive cells were observed depending on irradiation dose (up to 60 Gy) and time in post-irradiation culture (up to 24 hours). An enlargement of the S phase of the cell cycle was evidenced 18 hours post-irradiation as determined by flow cytometry analysis. The high resolution approach showed that, in spite of several morphological alterations, BrdU labelling was present even in cells displaying early and late apoptotic features.

IL-1 alpha antiproliferative and differentiative effects on Daudi lymphoma cells: multiparametric analysis

Interleukin I alpha (IL-1) is a potent agent that induces a wide range of biological effects. In this study we analysed its effects on cell cycle progression and differentiation of Daudi lymphoma cells. The parallel analysis in light microscopy and cytofluorimetry by means of anti-BrdU monoclonal antibodies showed a reduced rate of proliferation (S phase) with a G1 arrest. These features were confirmed by the lower incorporation of [3H]-thymidine supporting the decrease in the rate of DNA synthesis. In addition this cytokine was able to induce differentiation after 24 hrs of treatment as assessed by the increased expression of Fc receptors (FcR) and morphological criteria. This multiparametric analysis gives evidence to the sensitivity to this cytokine of this peculiar cell line.

Ultrastructural patterns of cell damage and death following gamma radiation exposure of murine erythroleukemia cells

Radiation causes damage to cell surface membranes, cytoplasmic organelles, and the nuclear process of DNA synthesis and repair, and this eventually results in different modes of cell death. In this study we examined murine erythroleukemia (MEL) cells, exposed to 15 and 60 Gy of 10 MeV photonic energy, and left in culture for up to 96 hours. Electron microscopical analysis was performed on conventionally embedded samples and freeze-fracture replicas, in order to detect ultrastructural patterns of cell damage and death. Of interest was the observation of chromatin condensates, nuclear membrane associations and nuclear pore redistribution during early apoptosis. Pronounced rearrangements of transmembrane particles during late stages of cellular necrosis were also found. The morphological damage induced by both doses of radiation as a function of time after exposure was only quantitatively but not qualitatively different.