Cells derived from the amniotic membrane of human placenta have been receiving particular attention because of their stem cell potentiality and immunomodulatory properties, which make them an attractive candidate source for cell therapy approaches. In this study, we isolated cells from the mesenchymal region of amnion and identified two subpopulations discordant for expression of the HLA-DR, CD45, CD14, and CD86 cellular markers. We therefore refer to the unfractionated cell population derived from this region as amniotic mesenchymal tissue cells (AMTC). We studied the suppressive and stimulatory characteristics of the unfrac-

Malignant gliomas, the most frequent primary brain tumors, are characterized by a dismal prognosis. Reliable biomarkers complementary to neuroradiology in the differential diagnosis of gliomas and monitoring for post-surgical progression are unmet needs. Altered expression of several microRNAs in tumour tissues from patients with gliomas compared to normal brain tissue have been described, thus supporting the rationale of using microRNA-based biomarkers. Although different circulating microRNAs were proposed in association with gliomas, they have not been introduced into clinical practice so far. Blood samples were collected from patients with high and low grade gliomas, both before and after surgical resection, and the expression of miR-21, miR-222 and miR-124-3p was measured in exosomes isolated from serum. The expression levels of miR-21, miR-222 and miR-124-3p in serum exosomes of patients with high grade gliomas were significantly higher than those of low grade gliomas and healthy controls and were sharply decreased in samples obtained after surgery. The analysis of miR-21, miR-222 and miR-124-3p in serum exosomes of patients affected by gliomas can provide a minimally invasive and innovative tool to help the differential diagnosis of gliomas at their onset in the brain and predict glioma grading and non glial metastases before surgery.

Cells derived from the amniotic membranes of human term placenta have drawn much interest for their characteristics of multipotency and low immunogenicity, supporting a variety of possible clinical applications in the field of cell transplantation and regenerative medicine. We have previously shown that cells derived from the mesenchymal region of human amnion (AMTC) can strongly inhibit T-lymphocyte proliferation. In this study, we demonstrate that AMTC can block differentiation and maturation of monocytes into dendritic cells (DC), preventing the expression of the DC marker CD1a and reducing the expression of HLA-DR, CD80, and CD83. The monocyte maturation block resulted in impaired allostimulatory ability of these cells on allogeneic T cells. In attempting to define the mechanisms responsible for these findings, we have observed that the presence of AMTC in differentiating DC cultures results in the arrest of the cells to the G 0 phase and abolishes the production of inflammatory cytokines such as TNF-α, CXCL10, CXCL9, and CCL5. Finally, we also demonstrate that the monocytic cells present in the amniotic mesenchymal region fail to differentiate toward the DC lineage. Taken together, our data suggest that the mechanisms by which AMTC exert immumodulatory effects do not only relate directly to T cells, but also include inhibition of the generation and maturation of antigen-presenting cells. In this context, AMTC represent a very attractive source of multipotent allogeneic cells that promise to be remarkably valuable for cell transplantation approaches, not only due to their low immunogenicity, but also because of the added potential of modulating immune responses, which could be fundamental both for controlling graft rejection after transplantation and also for controlling diseases characterized by inflammatory processes.

We previously demonstrated that mesenchymal cells from human amniotic membrane (hAMTCs) inhibit the generation and maturation of monocyte-derived dendritic cells (DCs) in vitro. Considering the crucial role of DCs in the immune response and that epithelial cells of the human amniotic membrane (hAECs) share some of the immunoregulatory properties of hAMTCs, we investigated whether hAECs also modulate monocytederived DCs. We compared hAECs with hAMTCs in a cell-to-cell contact setting and their secreted factors in modulating DC differentiation and function. First, we demonstrated that primary and expanded hAMTCs strongly inhibited the differentiation of DCs and induced a shift toward M2-like macrophages. This was observed when hAMTCs were cultured in contact (hAMTC-DC cont ) or in Transwells (hAMTC-DC tw ) with monocytes and even when medium conditioned by hAMTCs was used instead of hAMTCs. hAECs also prevented DC development, but to a lesser extent than hAMTCs. hAECs were more effective when cultured in contact with monocytes (hAEC-DC cont ) rather than in Transwells (hAEC-DC tw ). The modulatory capacity of hAECs changed during passaging unlike the hAMSCs. The ability to stimulate CD4 + and CD8 + T-cell proliferation was almost completely abolished by hAMTC-DC cont , whereas hAMTC-DC tw and hAEC-DC cont displayed only a reduced ability to stimulate CD8 + T cells. Furthermore, monocytes cocultured with hAMTCs and hAECs showed some similarities, but also differences in cytokine/chemokine secretion. Similarities were observed in the inhibition of IL-12p70 and TNF-a and the increase in IL-10 in supernatants taken from monocyteDCs cocultured with hAMTCs and hAECs in contact and Transwell settings. The inflammatory factors IL-8, CXCL9, and MIP-1a were significantly lower in hAMTC-DC cont , hAMTC-DC tw , and hAEC-DC cont conditions. In contrast, only hAMTCs (in both contact and Transwell conditions) were able to significantly increase IL-1b and CCL2. Altogether, we demonstrated that hAMTCs and hAECs affect DC differentiation, but that hAMTCs exerted a stronger inhibitory effect, abolished T-cell proliferation, and also induced more changes in cytokine/ chemokine production.

Human amniotic mesenchymal cells (hAMTCs) possess interesting immunomodulatory properties, making them attractive candidates for regenerative medicine applications. Recent in vivo reports argue in favour of an important role for macrophages as targets of hAMTC‐mediated suppression of inflammation and the enhancement of tissue repair. However, a comprehensive study of the effects of hAMTCs and their conditioned medium (CM) on human macrophage differentiation and function is unavailable. In the present study we found that hAMTCs and CM induce the differentiation of myeloid cells (U937 and monocytes) towards macrophages. We then investigated their effects on monocytes differentiated toward pro‐inflammatory M1 and anti‐inflammatory M2 macrophages. Monocytes treated under M1 conditions in the presence of hAMTCs or CMs shifted towards M2‐like macrophages, which expressed CD14, CD209, CD23, CD163 and PM‐2 K, possessed higher phagocytic activity and produced higher IL‐10 and lower pro‐inflammatory cytokines. They were also poor T cell stimulators and Th1 inducers, while they were able to increase activated and naïve suppressive Treg subsets. We show that prostaglandins, and not IL‐6, play a role in determining the M2 activation status. Instead, monocytes treated under M2 conditions in the presence of hAMTCs or CM retained M2‐like features, but with an enhanced anti‐inflammatory profile, having a reduced expression of the co‐stimulatory molecule CD80, reduced phagocytosis activity and decreased the secretion of inflammatory chemokines. Importantly, we provide evidence that macrophages re‐educated by CM improve tissue regeneration/repair in wound‐healing models. In conclusion, we identified new cell targets of hAMTCs and their bioactive factors and here provide insight into the beneficial effects observed when these cells are used in therapeutic approaches in vivo. © 2016 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons Ltd.