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HLA-G-mediated Immune Tolerance: Past and New Outlooks

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889451197 Year: Pages: 92 DOI: 10.3389/978-2-88945-119-7 Language: English
Publisher: Frontiers Media SA
Subject: Allergy and Immunology --- Medicine (General)
Added to DOAB on : 2017-07-06 13:27:36
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Abstract

The non-classical HLA class I molecule HLA-G is different from classical HLA class I molecules because of the low polymorphism in the coding region, the fact that HLA-G primary transcript is alternatively spliced in seven isoforms, and the inhibitory action on immune cells. Although HLA-G is low polymorphic, variants in both promoter and 3’ un-translated region (UTR) of HLA-G locus regulate its expression. In healthy conditions, a basal level of HLA-G gene transcription is observed in most cells and tissues; however, translation into HLA-G protein is restricted to trophoblasts in the placenta, where it participates in promoting tolerance at the fetal-maternal interface. HLA-G is also expressed by thymic epitelial, cornea, mesenchymal stem cells, nail matrix, pancreatic beta cells, erythroid, and endothelial precursors. HLA-G can be neo-expressed in adult tissues in pathological conditions, and its expression has been documented autoimmune disorders, viral infections, and cancer. In the latter setting de novo HLA-G expression is associated with the capability of tumor cells to evade the immune control. In the last decade it has become evident that HLA-G expression on T cells and antigenpresenting cells confers to these cells tolerogenic properties. This Research Topic focused on i) summarizing updated clinical and immunological evidences that HLA-G expression is associate with beneficial or detrimental tolerance, ii) gathering new insights into the mechanisms governing the expression of HLA-G in healthy and pathological conditions, such as pre-eclampsia, and iii) examining the mechanisms underlying HLA-G mediated tolerance.

Stem Cell and Biologic Scaffold Engineering

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ISBN: 9783039214976 / 9783039214983 Year: Pages: 110 DOI: 10.3390/books978-3-03921-498-3 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Science (General) --- Biology
Added to DOAB on : 2019-12-09 11:49:15
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Tissue engineering and regenerative medicine is a rapidly evolving research field which effectively combines stem cells and biologic scaffolds in order to replace damaged tissues. Biologic scaffolds can be produced through the removal of resident cellular populations using several tissue engineering approaches, such as the decellularization method. Indeed, the decellularization method aims to develop a cell-free biologic scaffold while keeping the extracellular matrix (ECM) intact. Furthermore, biologic scaffolds have been investigated for their in vitro potential for whole organ development. Currently, clinical products composed of decellularized matrices, such as pericardium, urinary bladder, small intestine, heart valves, nerve conduits, trachea, and vessels, are being evaluated for use in human clinical trials. Tissue engineering strategies require the interaction of biologic scaffolds with cellular populations. Among them, stem cells are characterized by unlimited cell division, self-renewal, and differentiation potential, distinguishing themselves as a frontline source for the repopulation of decellularized matrices and scaffolds. Under this scheme, stem cells can be isolated from patients, expanded under good manufacturing practices (GMPs), used for the repopulation of biologic scaffolds and, finally, returned to the patient. The interaction between scaffolds and stem cells is thought to be crucial for their infiltration, adhesion, and differentiation into specific cell types. In addition, biomedical devices such as bioreactors contribute to the uniform repopulation of scaffolds. Until now, remarkable efforts have been made by the scientific society in order to establish the proper repopulation conditions of decellularized matrices and scaffolds. However, parameters such as stem cell number, in vitro cultivation conditions, and specific growth media composition need further evaluation. The ultimate goal is the development of “artificial” tissues similar to native ones, which is achieved by properly combining stem cells and biologic scaffolds and thus bringing them one step closer to personalized medicine. The original research articles and comprehensive reviews in this Special Issue deal with the use of stem cells and biologic scaffolds that utilize state-of-the-art tissue engineering and regenerative medicine approaches.

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