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"Regeneration medicine applications on age-related macular degeneration"
Abstract
Despite recent advances in diagnosis and treatment, age-related macular degeneration (AMD) remains the commonest cause of blindness in the developed world. Anti-VEGF agents are the mainstay of treatment of the neovascular form of the disease but they cannot reverse visual loss and they have a short time of action, so repeated injections are needed.
There has been a significant research interest in the use of cell replacement therapies in AMD in order to reverse loss of vision. The outer retina is ideal for applying cellular therapies since it is surgically accessible, easily observable and has a relatively simple architecture. A broad range of cells have been tested but predominantly pluripotent stem cells have been used. These have been differentiated into retinal pigment epithelium (RPE) cells and transplanted as cell suspensions or cell sheets under the retina. The first clinical trials of RPE cell replacement have demonstrated the safety of the method and hinted on possible efficacy. Further research is needed in order to tackle issues such as immune rejection and ensure long-term graft survival and maximal efficacy.
Gene therapy could also provide therapeutic options for patients with AMD. Gene transfer via viral vectors may enable the potential for continuous production of antiangiogenetic proteins thus avoiding the need for repeated anti-VEGF injections. Gene silencing with RNA interference has been tested in various clinical trials and could act synergistically with current anti-VEGF treatments. Even though the use of gene editing tools such as CRISPR-Cas is currently limited to preclinical studies, it has been shown to be effective in treating neovascularization in animal models.
GORGOLI Konstantina
"Autism spectrum and genetics"
Abstract
The genetic etiology of spectrum disorders was first proposed by studies in the 1970s. More recently, genome-wide copy number variant and sequence analyses across the individual gene have revealed a list of rare and highly invasive variations of the copy number variants (CNVs) or single nucleotide variants (SNVs) associated with the autism spectrum, which is claimed. for genetic etiology of the disorder. Findings from research studies in the field of genetic factors associated with autism spectrum disorders lead to the emergence of their important role in their diagnosis and genetic evaluation.
Various molecular diagnostic tests, including single gene tests, targeted multiple gene frames, and copy number analyzes to be considered in the clinical genetic evaluation of autism spectrum disorders. The whole exome sequencing could also be considered in specific clinical cases. However, the challenge that remains is not determining the causal role of genetic variants identified through molecular testing. The variable expression, pleiotropic effects, and incomplete penetration associated with CNVs and SNVs also present significant challenges for counseling and prenatal diagnosis. Based on the above, the value of the genetic diagnosis of autism spectrum disorders becomes clear and so does the important contribution of the scientific community to the process of examining and highlighting the factors that lead to their manifestation. In this way, it is possible to highlight the nature of the disorder and to clarify aspects of it that to this day, many decades after its first observation, are not fully understood. The aspects of this development will be important for science, but also for society, people on the autism spectrum and their caregivers, education systems, health and welfare systems.
Therefore, it would be necessary to further examine the genetic aspects of autism spectrum disorders and to develop more accurate diagnosis methods, ideally methods that can lead to early diagnosis, that is more beneficial for the children that are diagnosed to be in the spectrum.
AGGELI Ioanna
"Liquid Biopsy: exosomes. Their role in the confrontation of cancer"
Abstract
Nowadays, the majority of the biomarkers that are being used, help into monitoring and coming into decision for cancer treatment, based on the analysis of primary region or metastasis. Although, cancer is continiously evolving in molecular level, leading to difficulties as for monitoring of its progression. The solution of this problem is given by the method of liquid biopsy.
Despite of the isolation of circulating tumour cells, the capture of circulating tumour DNA and exosomes, comes to the surface dynamically. During the next decade the use of the previously reported biomarkers will lead to the application of the real time precision medicine. The application of liquid biopsy and more specifically the analysis of exosomes is based on the analysis of subcellular vesicles and their ingredients. Compared with other vesicles, such as apoptotic bodies and microvesicles, exosomes are more homogenic as their size and appearance, thus they are easily detected by electronic microscope. Another advantage of exosomes is that are tend to be found in almost every biological fluids and are steady in the circulation. So that with the right methods they can be isolated and used as diagnostic tools. The expression of their surface markers takes place in that, as they make the exosomes stand out of other vesicles. Last but not least, the content of nucleid acids is important as they show the condition of mutations in the primary cell.
Exosomes seems to be extremely important biomarkers, because of their contents and especially mRNA that induces angiogenesis and metastases. Isolating exosomes from biological fluids provides the possibility of analysis of these exact vesicles and thus the detection of mutations, splice variants and gene fusions, as well as gene expression profiling. In comparison with ctDNA f ragments, of which only two copies are actually present in cancer cell, mRNA that originates from the overexpressed gene could have thousands of copies per cell and be present into circulation in high concentrations. In conclusion, analysis of exosomal mRNA might have advantages, especially in patients with limited amounts of detectable ctDNA. One of the most important advantages of the analysis of exosomes, against the analysis of CTCs or ctDNA, is that inside those small vesicles are being hidden all the important informations that are needed for a study. According to recent studies inside of exosomes are being detected high amounts of ctDNA.
Although, there are many limitations concerning the transportation of the results in vivo. Most of the studies use cell cultures and the exosomes result from the elaboration of them. This cell culture is homogenic in comparison with exosomes that are being heterogenous, as a consequence of their production from different cell types inside the organism, leading to the misunderstanding of the results. Studies that analyse patients’ serum are extremely rare, because there are not markers that allow the safe identification of tumour-originate exosomes, except melanoma. Nevertheless, are being reported as ideal biomarkers of cancer diagnosis. Also, they could be useful as potential vaccines against cancer or drug transfer system in cancer therapy. Targeting tumour-originate exosomes or inhibiting their release, might lead to an important therapeutic approach.
Many of the newly candidate drugs, such as proteins and nucleid acids, are extremely unstable inside of the organism, thus a challenge is created for a succesful approach. Although, exosomes are imitating psysiological drug transfer systems, allowing the transfer of these biological molecules. Due to their small size and composition, they could avoid phagocytosis or their disruption by macrophages and also they could circulate for a long period. Unlike other nanovesicles systems, such as liposomes, exosomes are capable of the avoidance of lysosomes and tranfer substances into the cytoplasm. One of their most important advantage is their capability to penetrate the blood brain barrier. Their localization and detection in vivo are urgent for their understanding, concerning their impact on target organs. Until now there is not an isolation technique with high clearance. The isolation methods are giving low amount of exosomes and their large production scale for trials and drug approval is too expensive. Its possible in the future exosomes use into practice to demand the creation of hybrid vesicles with possible side effects. For the design of such systems, clinical effectiveness has to be studied in detail, as well safety parameters. Also, methods and combinatorial substances for the active target of molecules must be studied for the exosomes to be operational.
Even if the biology of exosomes is known, they are full of heterogeneous components that could create immunogenic results, based on the nature of donor cell. The role of exosomes in tumour evolution is a challenge. One of many approaches is the design of exosomes imitators, that could avoid any disadvantage, such as adverse immune reactions.
NASTOULI Anastasia
"Liquid Biopsy: exosomes. Their role in the confrontation of cancer"
Abstract
The present study constitutes an extensive literature review of the prognostic and diagnostic biomarkers, as well as the “mixed” biomarkers (that may be used for both the diagnosis and the prognosis of patients) that can be used for the assessment of patients with heart failure.
In total, the study consists of 6 chapters. The first chapter presents the syndrome of heart failure (causes, symptoms etc.), as well as the defense mechanisms that are activated by the human organism for the maintenance of homeostasis, while the second chapter refers to sudden cardiac death and its association with heart failure. A noteworthy part of this chapter is the reference to the prevention of sudden cardiac death in both primary and secondary stages. Both the third and fourth chapters are dedicated to biomarkers that are associated to the syndrome of heart failure. More specifically, in the third chapter, purely diagnostic biomarkers (electrocardiogram, chest x-ray, natriuretic peptides etc.) are presented, while in the fourth chapter, the prognostic biomarkers of heart failure are presented, as well as those biomarkers that may be considered as “mixed”, such as interleukin-1β, osteopontin and cystatin-C. It appears that all of these biomarkers have been studied to a great extent, both by the research and medical communities, for the global and more effective assessment of the syndrome. The fifth chapter, introduces readers to an innovative laboratory investigation, the “metabolomics” that can offer significant help towards the pathophysiological assessment of the syndrome, through the analysis of the metabolism of the human organism. Finally, the sixth chapter includes the conclusions reached by the literature review, while at the end of the dissertation, the large number of references studied for the purpose of this review, are indicated.
KAZAKOS Vasilios
"Flow-cytometric approch to the diagnosis of T-lymphomas"
Abstract
Due to the rapid development of flow cytometry technology in various medical disciplines and fields, the following postgraduate thesis was completed. In particular, the main topic of lymphomas and especially of T-lymphomas, which their heterogeneity and their cytochemistry are complex and unknown in many cases, will be analyzed in 6 chapters independently and explicitly related to each other.
The first chapters will present the general data of the cells and the forms of pathological cells in the various subgroups of lymphomas. It will then describe how the machine of flow cytometer works and its principle of method . The order in which the topics will be presented is the function of normal blood cells and how they behave in pathological conditions. Also, to understand how flow cytometer works in these fields and its valuable help in prognosis, early diagnosis and effective treatment of lymphomas and more specifically of T-lymphomas. In the last two chapters, there are 10 incidents of different types of T-lymphomas, in full picture when diagnosed by flow cytometry, histological examination and further molecular techniques for additional diagnostic value. Also, the latest literature data on therapies and the further development of flow cytometry will be presented.
Finally, the work will conclude with the conclusions from the author and the scientists who have dealt with the clarification of the major issue of T-lymphocytes and recorded at work under the rules governing patients' personal rights
FLOROU Athina