Role of nuclear redox control, intra-population heterogeneity and oxygen tension in human amniotic fluid stem cells aging

Amniotic fluid stem cells (hAFSC) are emerging as a potential therapeutic approach for various disorders. The low number of available hAFSC requires their ex vivo expansion prior to clinical use, however, during their in vitro culture, hAFSC quickly reach replicative senescence. The principal aim of this study was to investigate the aging process occurring during in vitro expansion of hAFSC, focusing on the redox control that has been reported to be affected in premature and physiological aging. My results show that a strong heterogeneity is present among samples that reflects their different behaviour in culture. I identified three proteins, namely Nox4, prelamin A and PML, which expression increases during hAFSC aging process and could be used as new biomarkers to screen the samples. Furthermore, I found that Nox4 degradation is regulated by sumoylation via proteasome and involves interactions with PML bodies and prelamin A. Since various studies revealed that donor-dependent differences could be explained by cell-to-cell variation within each patient, I studied in deep this phenomenon. I showed that the heterogeneity among samples is also accompanied by a strong intra-population heterogeneity. Separation of hAFSC subpopulations from the same donor, using Celector® technology, showed that an enrichment in the last eluted fraction could improve hAFSC application in regenerative medicine. One of the other problems is that nowadays hAFSC are expanded under atmospheric O2 concentration, which is higher than the O2 tension in their natural niches. This higher O2 concentration might cause environmental stress to the in vitro cultured hAFSCs and accelerate their aging process. Here, I showed that prolonged low oxygen tension exposure preserves different hAFSC stemness properties. In conclusion, my study pointed different approaches to improve in vitro hAFSC expansion and manipulation with the purpose to land at stem cell therapy.

Impiego di cellule staminali in terapia veterinaria

Over the past few years, in veterinary medicine there has been an increased interest in understanding the biology of mesenchymal stem cells (MSCs). This interest comes from their potential clinical use especially in wound repair, tissue engineering and application in therapeutics fields, including regenerative surgery. MSCs can be isolated directly from bone marrow aspirates, adipose tissue, umbilical cord and various foetal tissues. In this study, mesenchymal stem cells were isolated from equine bone marrow, adipose tissue, cord blood, Wharton’s Jelly and, for the first time, amniotic fluid. All these cell lines underwent in vitro differentiation in chondrocytes, osteocytes and adipocytes. After molecular characterization, cells resulted positive for mesenchymal markers such as CD90, CD105, CD44 and negative for CD45, CD14, CD34 and CD73. Adipose tissue and bone marrow mesenchymal stem cells were successfully applied in the treatment of tendinitis in race horses. Furthermore, for the first time in the horse, skin wounds of septicemic foal, were treated applying amniotic stem cells. Finally, results never reported have been obtained in the present study, isolating mesenchymal stem cells from domestic cat foetal fluid and membranes. All cell lines underwent in vitro differentiation and expressed mesenchymal molecular markers.

Isufficienza Placentare nella Specie Equina

Lo sviluppo e la funzionalità della placenta influenzano direttamente la crescita ed il benessere del feto all'interno dell'utero, quindi qualsiasi problema strutturale o funzionale della placenta influenzerà lo sviluppo del feto. Lo scopo di questa tesi è stato quello di approfondire diversi aspetti clinici e clinico-patologici dell’insufficienza placentare nella specie equina, con l’intento di individuare dei parametri che possano essere di ausilio per l’identificazione precoce del puledro a rischio e della necessità di interventi terapeutici. La valutazione della concentrazione di lattato nel sangue e nel liquido amniotico potrebbe essere un utile strumento diagnostico per la diagnosi di acidosi metabolica associata ad ipossia/ischemia nel puledro e per identificare la necessità di un intervento precoce alla nascita. La risposta all’ipossia sembra essere mediata dall’HIF-1 e dall’HSF-1 anche nel puledro neonato, e se questi dati venissero confermati su un numero maggiore di animali, i due marcatori proteici e la MDA potrebbero essere utilizzati per la diagnosi di PAS nel puledro. L’esame di tutta l’unità placentare riveste un ruolo di fondamentale importanza per l’acquisizione di informazioni riguardo all’ambiente di vita intrauterino del puledro, ed è quindi auspicabile nella pratica ostetrica routinaria una maggiore attenzione all’esame della placenta, soprattutto in caso di patologie materno-fetali. Tra i parametri biochimici valutati al momento della nascita, la creatininemia e la glicemia possono fornire informazioni sull’efficienza dello scambio placentare ed essere quindi utilizzati per individuare puledri a rischio. Infine, lo sviluppo di una macro per il software ImageJ porta alla luce uno strumento nuovo, semplice da usare ed economico, per la valutazione morfometrica dell’arborizzazione dei villi placentari; tuttavia la ricerca necessità ulteriori indagini su un numero maggiore di animali per valutare le differenze morfometriche tra placente normali e patologiche.

Musculoskeletal tissue regeneration by human non-embryonic stem cells

The aim of this thesis was to investigate the regenerative potential of alternative sources of stem cells, derived from human dental pulp (hDPSCs) and amniotic fluid (hAFSCs) and, specifically, to evaluate their capability to be committed towards osteogenic and myogenic lineages, for the eventual applicability of these stem cells to translational strategies in regenerative medicine of bone and skeletal muscle tissues. The in vitro bone production by stem cells may represent a radical breakthrough in the treatment of pathologies and traumas characterized by critical bone mass defects, with no medical or surgical solution. Human DPSCs and AFSCs were seeded and pre-differentiated on different scaffolds to test their capability to subsequently reach the osteogenic differentiation in vivo, in order to recover critical size bone defects. Fibroin scaffold resulted to be the best scaffold promoting mature bone formation and defect correction when combined to both hDPSCs and hAFSCs. This study also described a culture condition that might allow human DPSCs to be used for human cell therapy in compliance with good manufacturing practices (GMPs): the use of human serum (HS) promoted the expansion and the osteogenic differentiation of hDPSCs in vitro and, furthermore, allowed pre-differentiated hDPSCs to regenerate critical size bone defects in vivo. This thesis also showed that hDPSCs and hAFSCs can be differentiated towards the myogenic lineage in vitro, either when co-cultured with murine myoblasts and when differentiated alone after DNA demethylation treatment. Interestingly, when injected into dystrophic muscles of SCID/mdx mice - animal model of Duchenne Muscular Dystrophy (DMD) - hDPSCs and hAFSCs pre-differentiated after demethylating treatment were able to regenerate the skeletal muscle tissue and, particularly, to restore dystrophin expression. These observations suggest that human DPSCs and AFSCs might be eventually applied to translational strategies, in order to enhance the repair of injured skeletal muscles in DMD patients.

Mesenchymal Stromal Cells (MSCs) and induced Plutipotent Stem Cells (iPSCs) in Domestic Animals: Characterization and Differentiation Potential

Derivation of stem cell lines from domesticated animals has been of great interest as it benefits translational medicine, clinical applications to improve human and animal health and biotechnology. The main types of stem cells studied are Embryonic Stem Cells (ESCs), induced Pluripotent Stem Cells (iPSCs) and Mesenchymal Stem/Stromal Cells (MSCs). This thesis had two main aims: (I) The isolation of bovine MSCs from amniotic fluid (AF) at different trimesters of pregnancy and their characterization to study pluripotency markers expression. Stemness markers were studied also in MSCs isolated from equine AF, Wharton’s jelly (WJ) and umbilical cord blood (UCB) as continuation of the characterization of these cells previously performed by our research group; (II) The establishment and characterization of iPSCs lines in two attractive large animal models for biomedical and biotechnology research such as the bovine and the swine, and the differentiation into the myogenic lineage of porcine iPSCs. It was observed that foetal tissues in domestic animals such as the bovine and the horse represent a source of MSCs able to differentiate into the mesodermal lineage but they do not proliferate indefinitely and they lack the expression of many pluripotency markers, making them an interesting source of cells for regenerative medicine, but not the best candidate to elucidate pluripotency networks. The protocol used to induce pluripotency in bovine fibroblasts did not work, as well as the chemical induction of pluripotency in porcine fibroblasts, while the reprogramming protocol used for porcine iPSCs was successful and the line generated was amenable to being differentiated into the myogenic lineage, demonstrating that they could be addressed into a desired lineage by genetic modification and appropriated culture conditions. Only a few cell types have been differentiated from domestic animal iPSCs to date, so the development of a reliable directed-differentiation protocol represents a very important result.

Study on NGF and VEGF during the equine perinatal period

Part 1 of the study aims to: evaluate NGF and VEGF levels obtained at parturition from mare, foal and umbilical cord vein plasma, as well as in amniotic fluid; evaluate NGF and VEGF content in plasma of healthy foals during the first 72 h of life; evaluate NGF and VEGF levels at parturition in relation to selected mares’ and foals’ clinical parameters; evaluate the relationship between the two trophic factors and thyroid hormone levels in the first 72 h of life; assess mRNA expression of NGF, VEGF and BDNF and their cell surface receptors in the placenta. Part 2 aims to clinically characterize a population of foals spontaneously affected by Neonatal Encephalopathy (NE), and then to: evaluate NGF and VEGF levels in plasma samples obtained in the affected population at parturition from mare’s jugular vein, umbilical cord vein and foal’s jugular vein, as well as in amniotic fluid; evaluate NGF and VEGF content in plasma of foals affected by NE during the first 72 h of life/hospitalization; evaluate NGF and VEGF levels at birth/admission in relation to selected mares’ and foals’ clinical parameters; evaluate the relationship between the two trophic factors and thyroid hormone levels in the first 72 h of life/hospitalization; assess the mRNA expression of NGF, VEGF and BDNF, and their cell surface receptors, in the placenta of mares that delivered affected foals. The close relationship between the two trophic factors in foal plasma over time and their fine expression in placental tissues under physiological conditions appear to be key regulators of fetal development and adaptation. Their less pronounced decrease in compromised foals compared to healthy ones, their relationship with thyroid hormones over time, and the reduced expression of NGF and BDNF in placental tissues, could be key regulators in the mechanisms of NE.

Predizione degli outcome del rivolgimento per manovre esterne nelle gravidanze con presentazione podalica del feto con l'utilizzo dell'angolo di progressione della parte presentata

Introduzione: La presentazione podalica complica il 3-4% delle gravidanze singole a termine. Sebbene il parto vaginale sia possibile, gli studi in letteratura hanno riportato un aumento del rischio di mortalità e morbilità fetale. Di conseguenza nel mondo il numero di tagli cesarei eseguiti per presentazione podalica è alto. Il rivolgimento per manovre esterne (RME) è una procedura ostetrica sicura che permette il passaggio del feto dalla presentazione podalica a quella cefalica, riducendo il numero dei tagli cesarei. L’angolo di progressione della parte presentata (AoP) è un parametro ecografico descritto in letteratura per la valutazione della progressione della parte presentata attraverso il canale del parto ed è stato recentemente studiato nelle gravidanze con presentazione podalica del feto. Obiettivi: L’obiettivo primario è valutare la correlazione tra l’AoP e il successo del RME. L’obiettivo secondario è verificare se esiste correlazione tra parametri anamnestici ed ecografici e la riuscita del RME. Materiali e metodi: È stato condotto uno studio osservazione prospettico monocentrico, sono state reclutate previo consenso informato 54 pazienti afferenti presso l’Ospedale Maggiore di Bologna con gravidanza singola dopo le 36 settimane e feto in presentazione podalica tra gennaio 2020 e giugno 2023. Risultati: La percentuale di RME riusciti è stata del 48,2%, il 53,7% delle donne ha partorito mediante taglio cesareo. Non abbiamo trovato una correlazione tra AoP e successo del rivolgimento. Tra le altre variabili analizzate l’unica correlata al successo del RME è la quantità di liquido amniotico Conclusioni: Non abbiamo trovato una correlazione tra AOP e successo del RME. Come descritto in letteratura l’unico parametro ecografico che è risultato associato al successo del RME è la quantità di liquido amniotico. Dato il disegno dello studio e la scarsa numerosità del campione sono necessari ulteriori studi per confermare i risultati.

Design of wireless sensor networks for fluid dynamic applications

In fluid dynamics research, pressure measurements are of great importance to define the flow field acting on aerodynamic surfaces. In fact the experimental approach is fundamental to avoid the complexity of the mathematical models for predicting the fluid phenomena. It’s important to note that, using in-situ sensor to monitor pressure on large domains with highly unsteady flows, several problems are encountered working with the classical techniques due to the transducer cost, the intrusiveness, the time response and the operating range. An interesting approach for satisfying the previously reported sensor requirements is to implement a sensor network capable of acquiring pressure data on aerodynamic surface using a wireless communication system able to collect the pressure data with the lowest environmental–invasion level possible. In this thesis a wireless sensor network for fluid fields pressure has been designed, built and tested. To develop the system, a capacitive pressure sensor, based on polymeric membrane, and read out circuitry, based on microcontroller, have been designed, built and tested. The wireless communication has been performed using the Zensys Z-WAVE platform, and network and data management have been implemented. Finally, the full embedded system with antenna has been created. As a proof of concept, the monitoring of pressure on the top of the mainsail in a sailboat has been chosen as working example.

Two fluid numerical model for coastal applications

Wave breaking is an important coastal process, influencing hydro-morphodynamic processes such as turbulence generation and wave energy dissipation, run-up on the beach and overtopping of coastal defence structures. During breaking, waves are complex mixtures of air and water (“white water”) whose properties affect velocity and pressure fields in the vicinity of the free surface and, depending on the breaker characteristics, different mechanisms for air entrainment are usually observed. Several laboratory experiments have been performed to investigate the role of air bubbles in the wave breaking process (Chanson & Cummings, 1994, among others) and in wave loading on vertical wall (Oumeraci et al., 2001; Peregrine et al., 2006, among others), showing that the air phase is not negligible since the turbulent energy dissipation involves air-water mixture. The recent advancement of numerical models has given valuable insights in the knowledge of wave transformation and interaction with coastal structures. Among these models, some solve the RANS equations coupled with a free-surface tracking algorithm and describe velocity, pressure, turbulence and vorticity fields (Lara et al. 2006 a-b, Clementi et al., 2007). The single-phase numerical model, in which the constitutive equations are solved only for the liquid phase, neglects effects induced by air movement and trapped air bubbles in water. Numerical approximations at the free surface may induce errors in predicting breaking point and wave height and moreover, entrapped air bubbles and water splash in air are not properly represented. The aim of the present thesis is to develop a new two-phase model called COBRAS2 (stands for Cornell Breaking waves And Structures 2 phases), that is the enhancement of the single-phase code COBRAS0, originally developed at Cornell University (Lin & Liu, 1998). In the first part of the work, both fluids are considered as incompressible, while the second part will treat air compressibility modelling. The mathematical formulation and the numerical resolution of the governing equations of COBRAS2 are derived and some model-experiment comparisons are shown. In particular, validation tests are performed in order to prove model stability and accuracy. The simulation of the rising of a large air bubble in an otherwise quiescent water pool reveals the model capability to reproduce the process physics in a realistic way. Analytical solutions for stationary and internal waves are compared with corresponding numerical results, in order to test processes involving wide range of density difference. Waves induced by dam-break in different scenarios (on dry and wet beds, as well as on a ramp) are studied, focusing on the role of air as the medium in which the water wave propagates and on the numerical representation of bubble dynamics. Simulations of solitary and regular waves, characterized by both spilling and plunging breakers, are analyzed with comparisons with experimental data and other numerical model in order to investigate air influence on wave breaking mechanisms and underline model capability and accuracy. Finally, modelling of air compressibility is included in the new developed model and is validated, revealing an accurate reproduction of processes. Some preliminary tests on wave impact on vertical walls are performed: since air flow modelling allows to have a more realistic reproduction of breaking wave propagation, the dependence of wave breaker shapes and aeration characteristics on impact pressure values is studied and, on the basis of a qualitative comparison with experimental observations, the numerical simulations achieve good results.

Evaluation of fluid transport processes in dental enamel. Methods to assess the relevance of enamel permeability in caries prevention and etching treatments.

This thesis evaluated in vivo and in vitro enamel permeability in different physiological and clinical conditions by means of SEM inspection of replicas of enamel surface obtained from polyvinyl siloxane impressions subsequently later cast in polyether impression ma-terial. This technique, not invasive and risk-free, allows the evaluation of fluid outflow from enamel surface and is able to detect the presence of small quantities of fluid, visu-alized as droplets. Fluid outflow on enamel surface represents enamel permeability. This property has a paramount importance in enamel physiolgy and pathology although its ef-fective role in adhesion, caries pathogenesis and prevention today is still not fully under-stood. The aim of the studies proposed was to evaluate enamel permeability changes in differ-ent conditions and to correlate the findings with the actual knowledge about enamel physiology, caries pathogenesis, fluoride and etchinhg treatments. To obtain confirmed data the replica technique has been supported by others specific techniques such as Ra-man and IR spectroscopy and EDX analysis. The first study carried out visualized fluid movement through dental enamel in vivo con-firmed that enamel is a permeable substrate and demonstrated that age and enamel per-meability are closely related. Examined samples from subjects of different ages showed a decreasing number and size of droplets with increasing age: freshly erupted permanent teeth showed many droplets covering the entire enamel surface. Droplets in permanent teeth were prominent along enamel perikymata. These results obtained through SEM inspection of replicas allowed innovative remarks in enamel physiology. An analogous testing has been developed for evaluation of enamel permeability in primary enamel. The results of this second study showed that primary enamel revealed a substantive permeability with droplets covering the entire enamel sur-face without any specific localization accordingly with histological features, without changes during aging signs of post-eruptive maturation. These results confirmed clinical data that showed a higher caries susceptibility for primary enamel and suggested a strong relationship between this one and enamel permeability. Topical fluoride application represents the gold standard for caries prevention although the mechanism of cariostatic effect of fluoride still needs to be clarified. The effects of topical fluoride application on enamel permeability were evaluated. Particularly two dif-ferent treatments (NaF and APF), with different pH, were examined. The major product of topical fluoride application was the deposition of CaF2-like globules. Replicas inspec-tion before and after both treatments at different times intervals and after specific addi-tional clinical interventions showed that such globule formed in vivo could be removed by professional toothbrushing, sonically and chemically by KOH. The results obtained in relation to enamel permeability showed that fluoride treatments temporarily reduced enamel water permeability when CaF2-like globules were removed. The in vivo perma-nence of decreased enamel permeability after CaF2 globules removal has been demon-strated for 1 h for NaF treated teeth and for at least 7 days for APF treated teeth. Important clinical consideration moved from these results. In fact the caries-preventing action of fluoride application may be due, in part, to its ability to decrease enamel water permeability and CaF2 like-globules seem to be indirectly involved in enamel protection over time maintaining low permeability. Others results obtained by metallographic microscope and SEM/EDX analyses of or-thodontic resins fluoride releasing and not demonstrated the relevance of topical fluo-ride application in decreasing the demineralization marks and modifying the chemical composition of the enamel in the treated area. These data obtained in both the experiments confirmed the efficacy of fluoride in caries prevention and contribute to clarify its mechanism of action. Adhesive dentistry is the gold standard for caries treatment and tooth rehabilitation and is founded on important chemical and physical principles involving both enamel and dentine substrates. Particularly acid etching of dental enamel enamel has usually employed in bonding pro-cedures increasing microscopic roughness. Different acids have been tested in the litera-ture suggesting several etching procedures. The acid-induced structural transformations in enamel after different etching treatments by means of Raman and IR spectroscopy analysis were evaluated and these findings were correlated with enamel permeability. Conventional etching with 37% phosphoric acid gel (H3PO4) for 30 s and etching with 15 % HCl for 120 s were investigated. Raman and IR spectroscopy showed that the treatment with both hydrochloric and phosphoric acids induced a decrease in the carbonate content of the enamel apatite. At the same time, both acids induced the formation of HPO42- ions. After H3PO4 treatment the bands due to the organic component of enamel decreased in intensity, while in-creased after HCl treatment. Replicas of H3PO4 treated enamel showed a strongly reduced permeability while replicas of HCl 15% treated samples showed a maintained permeability. A decrease of the enamel organic component, as resulted after H3PO4 treatment, involves a decrease in enamel permeability, while the increase of the organic matter (achieved by HCl treat-ment) still maintains enamel permeability. These results suggested a correlation between the amount of the organic matter, enamel permeability and caries. The results of the different studies carried out in this thesis contributed to clarify and improve the knowledge about enamel properties with important rebounds in theoretical and clinical aspects of Dentistry.

A study on the fluid dynamics of domestic Gas burners

Domestic gas burners are investigated experimentally and numerically in order to further understand the fluid dynamics processes that drive the cooking appliance performances. In particular, a numerical simulation tool has been developed in order to predict the onset of two flame instabilities which may deteriorate the performances of the burner: the flame back and flame lift. The numerical model has been firstly validated by comparing the simulated flow field with a data set of experimental measurements. A prediction criterion for the flame back instability has been formulated based on isothermal simulations without involving the combustion modelization. This analysis has been verified by a Design Of Experiments investigation performed on different burner prototype geometries. On the contrary, the formulation of a prediction criterion regarding the flame lift instability has required the use of a combustion model in the numerical code. In this analysis, the structure and aerodynamics of the flame generated by a cooking appliance has thus been characterized by experimental and numerical investigations, in which, by varying the flow inlet conditions, the flame behaviour was studied from a stable reference case toward a complete blow-out.

Stability, viscous dissipation and local thermal non-equilibrium in fluid saturated porous media

In this thesis, the field of study related to the stability analysis of fluid saturated porous media is investigated. In particular the contribution of the viscous heating to the onset of convective instability in the flow through ducts is analysed. In order to evaluate the contribution of the viscous dissipation, different geometries, different models describing the balance equations and different boundary conditions are used. Moreover, the local thermal non-equilibrium model is used to study the evolution of the temperature differences between the fluid and the solid matrix in a thermal boundary layer problem. On studying the onset of instability, different techniques for eigenvalue problems has been used. Analytical solutions, asymptotic analyses and numerical solutions by means of original and commercial codes are carried out.

Fluid dynamic analysis and modelling of industrial chemical equipment

The research is aimed at contributing to the identification of reliable fully predictive Computational Fluid Dynamics (CFD) methods for the numerical simulation of equipment typically adopted in the chemical and process industries. The apparatuses selected for the investigation, specifically membrane modules, stirred vessels and fluidized beds, were characterized by a different and often complex fluid dynamic behaviour and in some cases the momentum transfer phenomena were coupled with mass transfer or multiphase interactions. Firs of all, a novel modelling approach based on CFD for the prediction of the gas separation process in membrane modules for hydrogen purification is developed. The reliability of the gas velocity field calculated numerically is assessed by comparison of the predictions with experimental velocity data collected by Particle Image Velocimetry, while the applicability of the model to properly predict the separation process under a wide range of operating conditions is assessed through a strict comparison with permeation experimental data. Then, the effect of numerical issues on the RANS-based predictions of single phase stirred tanks is analysed. The homogenisation process of a scalar tracer is also investigated and simulation results are compared to original passive tracer homogenisation curves determined with Planar Laser Induced Fluorescence. The capability of a CFD approach based on the solution of RANS equations is also investigated for describing the fluid dynamic characteristics of the dispersion of organics in water. Finally, an Eulerian-Eulerian fluid-dynamic model is used to simulate mono-disperse suspensions of Geldart A Group particles fluidized by a Newtonian incompressible fluid as well as binary segregating fluidized beds of particles differing in size and density. The results obtained under a number of different operating conditions are compared with literature experimental data and the effect of numerical uncertainties on axial segregation is also discussed.