Autocrine TGF-β induces epithelial to mesenchymal transition in human amniotic epithelial cells

Pretreatment with Inflammatory Factors Altered the Secretome of Human Amniotic Epithelial Cells

Human amniotic epithelial cells (hAECs) are novel and promising therapeutic agents for patients suffering from degenerative diseases. Studies have demonstrated that the therapeutic effects of hAECs mainly depend on their paracrine components. Currently, appropriate pretreatment is a widely confirmed strategy for enhancing the repair potential of stem cells; however, the effect of proinflammatory factor pretreatment on hAECs and their secretome is still unclear. In this study, we used the well-characterized proinflammatory factors tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ) to stimulate hAECs and analyzed the effect of TNF-α and IFN-γ on hAECs, including gene expression profile, paracrine proteins, and microRNAs (miRNAs) in exosomes. Results showed that TNF-α and IFN-γ pretreatment improved the viability of hAECs but inhibited the proliferation of hAECs. TNF-α and IFN-γ pretreatment altered the gene expression profile of hAECs, and upregulated differentially expressed genes were predominantly enriched in biological adhesion, antioxidant activity, and response to IFN-beta. In addition, TNF-α and IFN-γ pretreatment enhanced the paracrine secretion of cytokines by hAECs. The upregulated differentially expressed proteins were mainly enriched in tissue remodeling proteins and cytokine-cytokine receptor. Notably, the expression of miRNAs in exosomes from hAECs was also changed by TNF-α and IFN-γ pretreatment. The target genes of upregulated exosomal miRNAs substantially contributed to the response to stimulus, metabolic pathways, and PI3K-Akt signaling pathway. Our findings improve our understanding of the biological characteristics of hAECs after proinflammatory factor pretreatment and provide novel insights to strengthen and optimize the therapeutic potential of hAECs and their secretome in regenerative medicine.

Histologic Evidence of Epithelial-Mesenchymal Transition and Autophagy in Human Fetal Membranes

Preterm, prelabor rupture of the human fetal membranes (pPROM) is involved in 40% of spontaneous preterm births worldwide. Cellular-level disturbances and inflammation are effectors of membrane degradation, weakening, and rupture. Maternal risk factors induce oxidative stress (OS), senescence, and senescence-associated inflammation of the fetal membranes as reported mechanisms related to pPROM. Inflammation can also arise in fetal membrane cells (amnion/chorion) due to OS-induced autophagy and epithelial-mesenchymal transition (EMT). Autophagy, EMT, and their correlation in pPROM, along with OS-induced autophagy-related changes in amnion and chorion cells in vitro, were investigated. Immunocytochemistry staining of cytokeratin-18 (epithelial marker)/vimentin (mesenchymal marker) and proautophagy-inducing factor LC3B were performed in fetal membranes from pPROM, term not in labor, and term labor. Ultrastructural changes associated with autophagy were verified by transmission electron microscopy of the fetal membranes and in cells exposed to cigarette smoke extract (an OS inducer). EMT and LC3B staining was compared in the chorion from pPROM versus term not in labor. Transmission electron microscopy confirmed autophagosome formation in pPROM amnion and chorion. In cell culture, autophagosomes were formed in the amnion with OS treatment, while autophagosomes were accumulated in both cell types with autophagy inhibition. This study documents the association between pPROMs and amniochorion autophagy and EMT, and supports a role for OS in inducing dysfunctional cells that increase inflammation, predisposing membranes to rupture.

Amniotic Membrane and Amniotic Epithelial Cell Culture

Amniotic membrane (AM) is considered an important medical device for applications in regenerative medicine. The therapeutic properties of AM are due to its resistant extracellular matrix and to the large number of bioactive molecules released by its cells. To this regard, ovine amniotic epithelial cells (AECs) are a subset of placental stem cells with great regenerative and immunomodulatory properties. Indeed, either oAEC or AM have been object of intense study for regenerative medicine, thanks to several advantages in developing preclinical studies on a high value translational animal model, such as sheep. For this reason, a critical standardization of cultural practices is fundamental in order to maintain, on one hand, AM integrity and structure and, on the other hand, oAEC native properties, thus improving their in vivo therapeutic potential and clinical outcomes.In addition, freshly isolated AECs or AM can be exploited to produce enriched immunomodulatory secretomes that had been used with success into cell-free regenerative medicine procedures.To this aim, here is described an improved oAEC cultural protocol able to preserve their native epithelial phenotype also after the in vitro amplification and an innovative AM in vitro cultural protocol design to prolong the integrity and the biological properties of this tissue in order to collect stable conditioned media enriched with immunomodulatory factors.

Hyaluronan delays human amniotic epithelial stem cell senescence by regulating CD44 isoform switch to activate AKT/mTOR signals

The replicative senescence of human amniotic epithelial stem cells (hAECs) is a major concern towards its clinical application. This study found that a 300-kDa hyaluronic acid (HA) could effectively delay the replicative senescence of hAECs, as indicated by the downregulation of cellular senescence markers and alteration of the cell cycle, and substantially improve the differentiation capacities of hAECs. HA was confirmed to regulate the CD44 isoform switch by upregulating the CD44s and downregulating the CD44v, thus exerting an anti-aging effect. We further found that HA induced the upregulation of hyaluronan synthase (HAS) 2, resulting in the activation of epithelial splicing regulatory protein 1 (ESRP1) and alternative splicing of CD44 mRNA, thereby promoting CD44s expression and inhibiting CD44v expression. Knockdown of HAS2 blocked ESRP1 expression and attenuated the anti-aging effects of HA. Hermes-1, a specific blocker of CD44, caused partial loss of the anti-aging effect of HA, upregulated senescence markers, and downregulated stemness markers. Furthermore, CD44s receptor activation was shown to initiate the AKT/mTOR downstream signaling. Conclusively, the study suggested that HA delayed hAEC senescence by regulating CD44 isoform switch to activate the AKT/mTOR signaling pathway, and there is potential for the clinical application of hAECs in combination with HA.

Graphene oxide accelerates TGFβ-mediated epithelial-mesenchymal transition and stimulates pro-inflammatory immune response in amniotic epithelial cells

The application of biomaterials on immune regenerative strategies to deal with unsolved pathologies is getting attention in the field of tissue engineering. In this context, graphene oxide (GO) has been proposed as an immune-mimetic material largely used for developing stem cell-based regenerative therapies, since it has shown to influence stem cell behavior and modulate their immune response. Similarly, amniotic epithelial stem cells (AECs) are getting an increasing clinical interest as source of stem cells due to their great plasticity and immunomodulatory paracrine activities, even though GO bio-mimetic effects still remain unknown. To this aim, GO-functionalized glass coverslips have been used for AECs culture. The results demonstrated how GO-coating is able to induce and accelerate the Epithelial-Mesenchymal Transition (EMT), in a process mediated by the intracellular activation of TGFβ1-SMAD2/3 signaling pathway. The trans-differentiation towards mesenchymal phenotype provides AECs of migratory ability and substantially changes the pattern of cytokines secretion upon inflammatory stimulus. Indeed, GO-exposed AECs enhance their pro-inflammatory interleukins production thus inducing a more efficient activation of macrophages and, at the same time, by slightly reducing their inhibitory action on peripheral blood mononuclear cells proliferation. Therefore, the adhesion of AECs on GO-functionalized surfaces might contribute to the generation of a tailored microenvironment useful to face both the phases of the inflammation, thereby fostering the regenerative process.

Fetal macrophages assist in the repair of ruptured amnion through the induction of epithelial-mesenchymal transition

The premature rupture of the amniotic sac, a condition referred to as a preterm prelabor rupture of membranes (pPROM), is a leading cause of preterm birth. In some cases, these ruptured membranes heal spontaneously. Here, we investigated repair mechanisms of the amnion, a layer of epithelial cells in the amniotic sac closest to the embryo. Macrophages migrated to and resided at rupture sites in both human and mouse amnion. A process called epithelial-mesenchymal transition (EMT), in which epithelial cells acquire a mesenchymal phenotype and which is implicated in tissue repair, was observed at rupture sites. In dams bearing macrophage-depleted fetuses, the repair of amnion ruptures was compromised, and EMT was rarely detected at rupture sites. The migration of cultured amnion epithelial cells in wound healing assays was mediated by EMT through transforming growth factor-β (TGF-β)-Smad signaling. These findings suggest that fetal macrophages are crucial in amnion repair because of their ability to induce EMT in amnion epithelial cells.

Inhibition of Epithelial-Mesenchymal Transition Maintains Stemness in Human Amniotic Epithelial Cells

Human amniotic epithelial cells (hAECs), which are a type of placental stem cell, express stem cell marker genes and are capable of differentiating into all three germ layers under appropriate culture conditions. hAECs are known to undergo TGF-β-dependent epithelial-mesenchymal transition (EMT); however, the impact of EMT on the stemness or differentiation of hAECs has not yet been determined. Here, we first confirmed that hAECs undergo EMT immediately after starting primary culture. Comprehensive transcriptome analysis using RNA-seq revealed that inhibition of TGF-β-dependent EMT maintained the expression of stemness-related genes, including NANOG and POU5F1, in hAECs. Moreover, the maintenance of stemness did not affect the nontumorigenic characteristics of hAECs. We showed for the first time that TGF-β-dependent EMT negatively affected the stemness of hAECs, providing novel insight into cellular processes of placental stem cells.

In Vitro Differentiation of Human Amniotic Epithelial Cells into Hepatocyte-like Cells

Human amniotic epithelial cells (hAECs) represent an interesting clinical alternative to human embryonic (hESCs) and induced pluripotent (hiPSCs) stem cells in regenerative medicine. The potential of hAECs can be enhanced ex vivo by their partial pre-differentiation. The aim of this study was to evaluate the effectiveness of 18-day differentiation of hAECs into endodermal cells, hepatic precursor cells, and cells showing functional features of hepatocytes using culture media supplemented with high (100 ng/mL) concentrations of EGF or HGF. The cells obtained after differentiation showed changes in morphology and increased expression of AFP, ALB, CYP3A4, CYP3A7, and GSTP1 genes. HGF was more effective than EGF in increasing the expression of liver-specific genes in hAECs. However, EGF stimulated the differentiation process more efficiently and yielded more hepatocyte-like cells capable of synthesizing α-fetoprotein during differentiation. Additionally, after 18 days, GST transferases, albumin, and CYP P450s, which proved their partial functionality, were expressed. In summary, HGF and EGF at a dose of 100 ng/mL can be successfully used to obtain hepatocyte-like cells between days 7 and 18 of hAEC differentiation. However, the effectiveness of this process is lower compared with hiPSC differentiation; therefore, optimization of the composition of the medium requires further research.

Tendon Healing Response Is Dependent on Epithelial-Mesenchymal-Tendon Transition State of Amniotic Epithelial Stem Cells

Tendinopathies are at the frontier of advanced responses to health challenges and sectoral policy targets. Cell-based therapy holds great promise for tendon disorder resolution. To verify the role of stepwise trans-differentiation of amniotic epithelial stem cells (AECs) in tendon regeneration, in the present research three different AEC subsets displaying an epithelial (eAECs), mesenchymal (mAECs), and tendon-like (tdAECs) phenotype were allotransplanted in a validated experimental sheep Achilles tendon injury model. Tissue healing was analyzed adopting a comparative approach at two early healing endpoints (14 and 28 days). All three subsets of transplanted cells were able to accelerate regeneration: mAECs with a lesser extent than eAECs and tdAECs as indicated in the summary of the total histological scores (TSH), where at day 28 eAECs and tdAECs had better significant scores with respect to mAEC-treated tendons (p < 0.0001). In addition, the immunomodulatory response at day 14 showed in eAEC-transplanted tendons an upregulation of pro-regenerative M2 macrophages with respect to mAECs and tdAECs (p < 0.0001). In addition, in all allotransplanted tendons there was a favorable IL10/IL12 compared to CTR (p < 0.001). The eAECs and tdAECs displayed two different underlying regenerative mechanisms in the tendon. The eAECs positively influenced regeneration mainly through their greater ability to convey in the host tissue the shift from pro-inflammatory to pro-regenerative responses, leading to an ordered extracellular matrix (ECM) deposition and blood vessel remodeling. On the other hand, the transplantation of tdAECs acted mainly on the proliferative phase by impacting the density of ECM and by supporting a prompt recovery, inducing a low cellularity and angle alignment of the host cell compartment. These results support the idea that AECs lay the groundwork for production of different cell phenotypes that can orient tendon regeneration through a crosstalk with the host tissue. In particular, the obtained evidence suggests that eAECs are a practicable and efficient strategy for the treatment of acute tendinopathies, thus reinforcing the grounds to move their use towards clinical practice.

Human Amnion Epithelial Cells: A Potential Cell Source for Pulp Regeneration?

The aim of this study was to analyze the suitability of pluripotent stem cells derived from the amnion (hAECs) as a potential cell source for revitalization in vitro. hAECs were isolated from human placentas, and dental pulp stem cells (hDPSCs) and dentin matrix proteins (eDMPs) were obtained from human teeth. Both hAECs and hDPSCs were cultured with 10% FBS, eDMPs and an osteogenic differentiation medium (StemPro). Viability was assessed by MTT and cell adherence to dentin was evaluated by scanning electron microscopy. Furthermore, the expression of mineralization-, odontogenic differentiation- and epithelial–mesenchymal transition-associated genes was analyzed by quantitative real-time PCR, and mineralization was evaluated through Alizarin Red staining. The viability of hAECs was significantly lower compared with hDPSCs in all groups and at all time points. Both hAECs and hDPSCs adhered to dentin and were homogeneously distributed. The regulation of odontoblast differentiation- and mineralization-associated genes showed the lack of transition of hAECs into an odontoblastic phenotype; however, genes associated with epithelial–mesenchymal transition were significantly upregulated in hAECs. hAECs showed small amounts of calcium deposition after osteogenic differentiation with StemPro. Pluripotent hAECs adhere on dentin and possess the capacity to mineralize. However, they presented an unfavorable proliferation behavior and failed to undergo odontoblastic transition.

Gene Expression in Amnion-Derived Cells Cultured on Recombinant Laminin 332-A Preliminary Study

Human amniotic cells (hAC) exhibit characteristics of undifferentiated cells and immunomodulatory properties. Recognition of the relationship between amniotic cells and components of the extracellular matrix is an important condition for their ex vivo preparation and further successful clinical application in regenerative medicine and transplantology. Laminin 332 (LN-332), as a natural component of the basement membrane of amniotic epithelial cells and a ligand for integrin receptors, may strongly influence the phenotype and fate of amniotic cells. We investigated the impact of recombinant LN-332 on hAC viability and expression of markers for pluripotency, early differentiation, adhesion, and immunomodulatory properties. During 14 days of culture, hAC were quantified and qualified by light microscopy, immunohistochemistry, immunocytochemistry, and flow cytometry. Gene expression was assessed with real-time polymerase chain reaction (RT-PCR) arrays and compared with differentiated cells originated from the three germ layers. LN-332 caused an over 2-fold increase in the total number of hAC, accompanied by a 75% reduction of SSEA-4-positive cells and an increase in HLA-ABC-positive cells. In particular, we observed that the presence of laminin 332 in the medium of a short-time culture modifies the effect of culture duration on hAC, enhancing time-dependent inhibition of expression of certain genes, including pluripotency and differentiation markers, laminin 332 subunits (which may be part of self-regulation of LN-332 synthesis by amniotic cells), and integrins. The changes observed in hAC were more distinct with respect to differentiated mesenchymal cells, resulting in more comparable phenotypes than those represented by differentiated endo- and ectodermal cells. We concluded that laminin 332 present in the culture medium influences to a certain extent proliferation, adhesion, and differentiation of amniotic cells in culture.

Chronic Wound Healing by Amniotic Membrane: TGF-β and EGF Signaling Modulation in Re-epithelialization

The application of amniotic membrane (AM) on chronic wounds has proven very effective at resetting wound healing, particularly in re-epithelialization. Historically, several aspects of AM effect on wound healing have been evaluated using cell models. In keratinocytes, the presence of AM induces the activation of mitogen-activated protein (MAP) kinase and c-Jun N-terminal kinase (JNK) pathways, together with the high expression of c-Jun, an important transcription factor for the progression of the re-epithelialization tongue. In general, the levels of transforming growth factor (TGF)-β present in a wound are critical for the process of wound healing; they are elevated during the inflammation phase and remain high in some chronic wounds. Interestingly, the presence of AM, through epidermal growth factor (EGF) signaling, produces a fine-tuning of the TGF-β signaling pathway that re-conducts the stalled process of wound healing. However, the complete suppression of TGF-β signaling has proven negative for the AM stimulation of migration, suggesting that a minimal amount of TGF-β signaling is required for proper wound healing. Regarding migration machinery, AM contributes to the dynamics of focal adhesions, producing a high turnover and thus speeding up remodeling. This is clear because proteins, such as Paxillin, are activated upon treatment with AM. On top of this, AM also produces changes in the expression of Paxillin. Although we have made great progress in understanding the effects of AM on chronic wound healing, a long way is still ahead of us to fully comprehend its effects.

Perinatal Derivatives: Where Do We Stand? A Roadmap of the Human Placenta and Consensus for Tissue and Cell Nomenclature

Progress in the understanding of the biology of perinatal tissues has contributed to the breakthrough revelation of the therapeutic effects of perinatal derivatives (PnD), namely birth-associated tissues, cells, and secreted factors. The significant knowledge acquired in the past two decades, along with the increasing interest in perinatal derivatives, fuels an urgent need for the precise identification of PnD and the establishment of updated consensus criteria policies for their characterization. The aim of this review is not to go into detail on preclinical or clinical trials, but rather we address specific issues that are relevant for the definition/characterization of perinatal cells, starting from an understanding of the development of the human placenta, its structure, and the different cell populations that can be isolated from the different perinatal tissues. We describe where the cells are located within the placenta and their cell morphology and phenotype. We also propose nomenclature for the cell populations and derivatives discussed herein. This review is a joint effort from the COST SPRINT Action (CA17116), which broadly aims at approaching consensus for different aspects of PnD research, such as providing inputs for future standards for the processing and in vitro characterization and clinical application of PnD.

Application of human amniotic epithelial cells in regenerative medicine: a systematic review

Human amniotic epithelial cells (hAECs) derived from placental tissues have gained considerable attention in the field of regenerative medicine. hAECs possess embryonic stem cell-like proliferation and differentiation capabilities, and adult stem cell-like immunomodulatory properties. Compared with other types of stem cell, hAECs have special advantages, including easy isolation, plentiful numbers, the obviation of ethical debates, and non-immunogenic and non-tumorigenic properties. During the past two decades, the therapeutic potential of hAECs for treatment of various diseases has been extensively investigated. Accumulating evidence has demonstrated that hAEC transplantation helps to repair and rebuild the function of damaged tissues and organs by different molecular mechanisms. This systematic review focused on summarizing the biological characteristics of hAECs, therapeutic applications, and recent advances in treating various tissue injuries and disorders. Relevant studies published in English from 2000 to 2020 describing the role of hAECs in diseases and phenotypes were comprehensively sought out using PubMed, MEDLINE, and Google Scholar. According to the research content, we described the major hAEC characteristics, including induced differentiation plasticity, homing and differentiation, paracrine function, and immunomodulatory properties. We also summarized the current status of clinical research and discussed the prospects of hAEC-based transplantation therapies. In this review, we provide a comprehensive understanding of the therapeutic potential of hAECs, including their use for cell replacement therapy as well as secreted cytokine and exosome biotherapy. Moreover, we showed that the powerful immune-regulatory function of hAECs reveals even more possibilities for their application in the treatment of immune-related diseases. In the future, establishing the optimal culture procedure, achieving precise and accurate treatment, and enhancing the therapeutic potential by utilizing appropriate preconditioning and/or biomaterials would be new challenges for further investigation.

Hyaluronic acid ameliorates the proliferative ability of human amniotic epithelial cells through activation of TGF-β/BMP signaling

Human amniotic epithelial cells (hAECs) are a useful and noncontroversial source of stem cells for cell therapy and regenerative medicine, but their limited proliferative ability hinders the acquisition of adequate quantities of cells for clinical use due to not expressing telomerase in hAECs. Our previous study showed that hyaluronic acid (HA), an important component of the extracellular matrix, promoted the proliferation of human amniotic mesenchymal stem cells. Herein, we hypothesize that HA might improve the proliferative capability of hAECs. In the present study, the role of HA on the proliferation of human amniotic epithelial cells (hAECs) in vitro was investigated for the first time. HA at molecular weight of 300 kDa showed an obvious pro-proliferation effect on hAECs. Furthermore, HA not only kept phenotypic characteristics and differentiation capabilities of hAECs, but significantly promoted the secretion of the anti-inflammatory factors such as IL-10 and TGF-β1, and the expression of stem cell pluripotent factors such as Oct4 and Nanog. Analysis of PCR microarray data and RT-qPCR validation showed that TGF-β/BMP signaling was activated in the presence of HA. Further study showed that SB431542, an inhibitor of the TGF-β/BMP signaling, significantly suppressed the mRNA expression of TGFBR3, BMP4, BMP7, BMPR1B, SMAD3, SMAD4, and the pro-proliferative effect of HA on hAECs. These data suggest that HA is a safe and effective enhancer for in vitro expansion of hAECs, whose regulatory mechanism involves the TGF-β/BMP signaling.

Formin mDia1 contributes to migration and epithelial-mesenchymal transition of tubular epithelial cells exposed to TGF-β1

Renal tubular epithelial cells may undergo epithelial-mesenchymal transition (EMT) in response to stimuli, such as transforming growth factor (TGF)-β1, leading to myofibroblast activation and renal fibrosis. The formin mDia1 is required for nucleation and polymerization of actin and the microtubule cytoskeleton. The present study sought to explore the role of mDia1 in EMT of tubular epithelial cells. A rat model of unilateral ureteral obstruction (UUO) was established. The expression of TGF-β1, collagen I, collagen III, and mDia1 in the kidneys was examined at day 7 after surgery. The effect of mDia1 on EMT was explored in NRK-52E cells by exposing them to TGF-β1. Increased expression of TGF-β1, collagen I, collagen III, and mDia1 was found in obstructive kidneys of UUO model rats. Exposing rat tubular epithelial cells to TGF-β1 promoted collagen I and collagen III expression but had no effect on mDia1 expression. Silencing mDia1 expression impeded epithelial cell migration as well as reduced TGF-β1, collagen, and Profilin1 expression, whereas mDia1 overexpression exerted an opposite effect. Furthermore, mDia1 regulated the expression of vimentin, α-smooth muscle actin, and E-cadherin and focal adhesion-kinase (FAK)/Src activation through Profilin1. Inhibition of the mDia1 activator RhoA by fasudil reversed EMT, and FAK/Src activation induced by mDia1. In conclusion, mDia1 regulated tubular epithelial cell migration, collagen expression, and EMT in NRK-52E cells exposed to TGF-β1. Thus, suppression of mDia1 activation might be a strategy to counteract renal fibrosis.

Reciprocal Signaling between Myeloid Derived Suppressor and Tumor Cells Enhances Cellular Motility and is Mediated by Structural Cues in the Microenvironment

Myeloid derived suppressor cells (MDSCs) have gained significant attention for their immunosuppressive role in cancer and their ability to contribute to tumor progression and metastasis. Understanding the role of MDSCs in driving cancer cell migration, a process fundamental to metastasis, is essential to fully comprehend and target MDSC-tumor cell interactions. This study employs microfabricated platforms, which simulate the structural cues present in the tumor microenvironment (TME) to elucidate the effects of MDSCs on the migratory phenotype of cancer cells at the single cell level. The results indicate that the presence of MDSCs enhances the motility of cancer-epithelial cells when directional cues (either topographical or spatial) are present. This behavior appears to be independent of cell-cell contact and driven by soluble byproducts from heterotypic interactions between MDSCs and cancer cells. Moreover, MDSC cell-motility is also impacted by the presence of cancer cells and the cancer cell secretome in the presence of directional cues. Epithelial dedifferentiation is the likely mechanism for changes in cancer cell motility in response to MDSCs. These results highlight the biochemical and biostructural conditions under which MDSCs can support cancer cell migration, and could therefore provide new avenues of research and therapy aimed at stemming cancer progression.

Progesterone Prolongs Viability and Anti-inflammatory Functions of Explanted Preterm Ovine Amniotic Membrane

Amniotic membrane (AM) is considered an important medical device with many applications in regenerative medicine. The therapeutic properties of AM are due to its resistant extracellular matrix and to the large number of bioactive molecules released by its cells. An important goal that still remains to be achieved is the identification of cultural and preservation protocols able to maintain in time the membrane morphology and the biological properties of its cells. Recently, our research group demonstrated that progesterone (P₄) is crucial in preventing the loss of the epithelial phenotype of amniotic epithelial cells in vitro. Followed by this premise, it has been evaluated whether P₄ may also affect AM properties in a short-term culture. Results confirm that P₄ preserves AM integrity and architecture with respect to untreated AM, which showed alterations in morphology. Transmission electron microscopy (TEM) analyses demonstrate that P₄ also maintains unaltered cell-cell junctions, nuclear status, and intracellular organelles. On the contrary, an untreated AM experienced an extensive cell death and a strong reduction of immunomodulatory properties, measured in terms of anti-inflammatory cytokine expression and secretion. Overall, these results could open to new strategies to ameliorate the protocols for cryopreservation and tissue culture, which represent preliminary stages of AM application in regenerative medicine.

The Bottlenecks in Translating Placenta-Derived Amniotic Epithelial and Mesenchymal Stromal Cells Into the Clinic: Current Discrepancies in Marker Reports

Placenta-derived amniotic cells have prominent features for application in regenerative medicine. However, there are still discrepancies in the characterization of human amniotic epithelial and mesenchymal stromal cells. It seems crucial that the characterization of human amniotic membrane cells be investigated to determine whether there are currently discrepancies in their characterization reports. In addition, possible causes for the witnessed discrepancies need to be addressed toward paving the way for further clinical application and safer practices. The objective of this review is to investigate the marker characterization as well as the potential causes of the discrepancies in the previous reports on placenta-derived amniotic epithelial and mesenchymal stromal cells. The current discrepancies could be potentially due to reasons including passage number and epithelial to mesenchymal transition (EMT), cell heterogeneity, isolation protocols and cross-contamination, the region of cell isolation on placental disk, measuring methods, and gestational age.

Transcriptomic and computational analysis identified LPA metabolism, KLHL14 and KCNE3 as novel regulators of Epithelial-Mesenchymal Transition

Epithelial-mesenchymal transition (EMT) is a complex biological program between physiology and pathology. Here, amniotic epithelial cells (AEC) were used as in vitro model of transiently inducible EMT in order to evaluate the transcriptional insights underlying this process. Therefore, RNA-seq was used to identify the differentially expressed genes and enrichment analyses were carried out to assess the intracellular pathways involved. As a result, molecules exclusively expressed in AEC that experienced EMT (GSTA1-1 and GSTM3) or when this process is inhibited (KLHL14 and KCNE3) were identified. Lastly, the network theory was used to obtain a computational model able to recognize putative controller genes involved in the induction and in the prevention of EMT. The results suggested an opposite role of lysophosphatidic acid (LPA) synthesis and degradation enzymes in the regulation of EMT process. In conclusion, these molecules may represent novel EMT regulators and also targets for developing new therapeutic strategies.

Reversible EMT and MET mediate amnion remodeling during pregnancy and labor

The amnion is remodeled during pregnancy to protect the growing fetus it contains, and it is particularly dynamic just before and during labor. By combining ultrastructural, immunohistochemical, and Western blotting analyses, we found that human and mouse amnion membranes during labor were subject to epithelial-to-mesenchymal transition (EMT), mediated, in part, by the p38 mitogen-activated protein kinase (MAPK) pathway responding to oxidative stress. Primary human amnion epithelial cell cultures established from amnion membranes from nonlaboring, cesarean section deliveries exhibited EMT after exposure to oxidative stress, and the pregnancy maintenance hormone progesterone (P4) reversed this process. Oxidative stress or transforming growth factor-β (TGF-β) stimulated EMT in a manner that depended on TGF-β-activated kinase 1 binding protein 1 (TAB1) and p38 MAPK. P4 stimulated the reverse transition, MET, in primary human amnion mesenchymal cells (AMCs) through progesterone receptor membrane component 2 (PGRMC2) and c-MYC. Our results indicate that amnion membrane cells dynamically transition between epithelial and mesenchymal states to maintain amnion integrity and repair membrane damage, as well as in response to inflammation and mechanical damage to protect the fetus until parturition. An irreversible EMT and the accumulation of AMCs characterize the amnion membranes at parturition.

Silencing TBX1 Exerts Suppressive Effects on Epithelial-Mesenchymal Transition and Inflammation of Chronic Rhinosinusitis Through Inhibition of the TGF-Smad2/3 Signaling Pathway in Mice

Background

Chronic rhinosinusitis (CRS) is a multifactorial inflammatory disease characterized by high prevalence and morbidity, and little is known about the mechanisms that underlie its pathogenesis.

Objective

This study focuses on the effect of T-box 1 (TBX1) on the epithelial–mesenchymal transition (EMT) and inflammation of CRS via the transforming growth factor (TGF)β-Smad2/3 signaling pathway.

Methods

CRS mice models were established by Merocel nasal packing material, followed by the streptococcus pneumoniae cultivation. The expression levels of TBX1 in the sinus mucosa tissues of mice were measured accordingly. The successfully modeled mice were subsequently injected with TBX1 mimic or TBX1 inhibitor and the TGFβ-Smad2/3 signaling pathway inhibitor (SB-431542) to elucidate the influence of TBX1 on EMT and inflammation in CRS, with the expression of the EMT-related factors (E-cadherin, Vimentin, alpha-smooth muscle actin [α-SMA]), Th1 cytokines (interleukin [IL]-2, interferon-γ), and Th2 cytokines (IL-4, IL-8, total immunoglobulin E) assayed.

Results

TBX1 expression exhibited upregulated levels in the sinus mucosa tissues of the mice. In addition, TBX1 downregulation was found to inhibit the expression of TGFβ as well as the extent of Smad2 and Smad3 phosphorylation. Silencing TBX1 was shown to elevate the expression of Th1 cytokines and E-cadherin, while diminishing expression of Th2 cytokines, Vimentin and α-SMA.

Conclusions

Taken together, the key findings of our study highlight the inhibitory role of TBX1 in the process of EMT and inflammation in CRS mice via the inhibition of the TGFβ-Smad2/3 signaling pathway, underlining the promise of TBX1 as a potential target for CRS therapy.

In vitro osteodifferentiation of intact human amniotic membrane is not beneficial in the context of bone repair

The human amniotic membrane (hAM) is an attractive biomaterial for regenerative medicine, as it contains amniotic mesenchymal stromal cells (hAMSC), epithelial cells (hAEC) and growth factors. We examined the potential use of hAM in orthopaedic and maxillofacial bone surgery, integrating the requirements of current regulations regarding advanced therapy medicinal products (ATMP) in the European Union. Previous studies have described the potential osteodifferentiation of intact hAM during whole-tissue culture in osteogenic conditions. The present study aims to determine whether in vitro osteodifferentiation of hAM is needed in the context bone repair, and the influence of this process on tissue structure, cell phenotype and cell function. Different conditions (fresh or cultured hAM; intact or hAM-derived cells) were tested. Phenotypic and functional analyses were performed with standard approaches (cell culture and staining, histological and immunolabelling) as well as original approaches (tissue staining, energy dispersive X-ray and X-ray diffraction). In our study, non-osteodifferentiated hAM (i.e., fresh or native hAM) exhibited innate pre-osteoblastic potential. Osteodifferentiation of fresh hAM induced a change in tissue structure, cell phenotype and function. Therefore, we hypothesize that pre-osteodifferentiation may not be necessary, especially if it induces unwanted changes. To our surprise, in these osteogenic conditions, hAEC had a mesenchymal phenotype with osteocyte function, and even native synthesis of hydroxyapatite, focusing osteogenic potential mainly in this epithelial layer. In conclusion, in vitro osteodifferentiation by tissue culture does not appear to be necessary for hAM to be used as an innovative ATMP for bone repair.

In Vitro Effect of Estradiol and Progesterone on Ovine Amniotic Epithelial Cells

Amniotic epithelial cells (AECs), an emerging source of extrafoetal stem cells, have recently attracted attention for their great regenerative potential. Since AEC amplifications are accompanied by the loss of their native epithelial phenotype and by the progressive reduction of relevant biological properties, the issue to be addressed is the development of effective culture protocols. In this context, recently, it has been demonstrated that progesterone (P₄) supplementation during ovine AEC (oAEC) expansion could prevent the undesirable epithelial-mesenchymal transition (EMT). In contrast, there is no information to date on the role of the other pregnancy steroids in culture. With this aim, the present study has been designed to clarify the impact of estradiol (E₂), alone or in combination with P₄ (12.5 μM and 25 μM), during oAEC amplification. Steroid supplementations were assessed by testing oAEC proliferation, stemness, EMT, and osteogenic or chondrogenic plasticity. The results indicated that EMT can be prevented exclusively in the presence of high doses of P₄, while it occurred rapidly in cells exposed to E₂ as denoted by protein (cytokeratin-8 and alpha-SMA) and gene expression (vimentin and snail) profiles. Moreover, steroid exposure was able to influence highly oAEC plasticity. Particularly, P₄-treated cells displayed a precommitment towards osteogenic lineage, confirmed by the upregulation of OCN, RUNX2, and the greater deposition of calcium nodules. Conversely, P₄ exposure inhibited oAEC chondrogenic differentiation, which was induced in E₂-treated cells as confirmed by the upregulation of chondrogenesis-related genes (SOX9, ACAN, and COL2A1) and by the accumulation of Alcian blue-positive extracellular matrix. Simultaneously, E₂-treated cells remained unresponsive to osteogenic inductive stimuli. In conclusion, media supplementation with high doses of steroids may be adopted to modulate phenotype and plasticity during oAEC amplification. Relevantly, the osteo or chondro steroid-induced precommitment may open unprecedented cell-based therapies to face the unsolved orthopaedic issues related to osteochondral regeneration.

Placental Stem Cells from Domestic Animals: Translational Potential and Clinical Relevance

The field of regenerative medicine is moving toward clinical practice in veterinary science. In this context, placenta-derived stem cells isolated from domestic animals have covered a dual role, acting both as therapies for patients and as a valuable cell source for translational models. The biological properties of placenta-derived cells, comparable among mammals, make them attractive candidates for therapeutic approaches. In particular, stemness features, low immunogenicity, immunomodulatory activity, multilineage plasticity, and their successful capacity for long-term engraftment in different host tissues after autotransplantation, allo-transplantation, or xenotransplantation have been demonstrated. Their beneficial regenerative effects in domestic animals have been proven using preclinical studies as well as clinical trials starting to define the mechanisms involved. This is, in particular, for amniotic-derived cells that have been thoroughly studied to date. The regenerative role arises from a mutual tissue-specific cell differentiation and from the paracrine secretion of bioactive molecules that ultimately drive crucial repair processes in host tissues (e.g., anti-inflammatory, antifibrotic, angiogenic, and neurogenic factors). The knowledge acquired so far on the mechanisms of placenta-derived stem cells in animal models represent the proof of concept of their successful use in some therapeutic treatments such as for musculoskeletal disorders. In the next future, legislation in veterinary regenerative medicine will be a key element in order to certify those placenta-derived cell-based protocols that have already demonstrated their safety and efficacy using rigorous approaches and to improve the degree of standardization of cell-based treatments among veterinary clinicians.

Amnion epithelial cell-derived exosomes induce inflammatory changes in uterine cells

BACKGROUND

Fetal endocrine signals are generally considered to contribute to the timing of birth and the initiation of labor. Fetal tissues under oxidative stress release inflammatory mediators that lead to sterile inflammation within the maternal-fetal interface. Importantly, these inflammatory mediators are packaged into exosomes, bioactive cell-derived extra cellular vesicles that function as vectors and transport them from the fetal side to the uterine tissues where they deposit their cargo into target cells enhancing uterine inflammatory load. This exosome-mediated signaling is a novel mechanism for fetal-maternal communication.

OBJECTIVE

This report tested the hypothesis that oxidative stress can induce fetal amnion cells to produce exosomes, which function as a paracrine intermediary between the fetus and mother and biochemically signal readiness for parturition.

STUDY DESIGN

Primary amnion epithelial cells were grown in normal cell culture (control) or exposed to oxidative stress conditions (induced by cigarette smoke extract). Exosomes were isolated from cell supernatant by sequential ultracentrifugation. Exosomes were quantified and characterized based on size, shape, and biochemical markers. Myometrial, decidual, and placental cells (BeWo) were treated with 2 × 105, 2 × 107, and 2 × 109 control or oxidative stress-derived amnion epithelial cell exosomes for 24 hours. Entry of amnion epithelial cell exosomes into cells was confirmed by confocal microscopy of fluorescent-labeled exosomes. The effect of amnion epithelial cell exosomes on target cell inflammatory status was determined by measuring production of interleukin-6, interleukin-8, interleukin-1β, tumor necrosis factor-α, and prostaglandin E2 by enzyme-linked immunosorbent assay and inflammatory gene transcription factor (nuclear factor-κβ) activation status by immunoblotting for phosphorylated RelA/p65. Localization of NANOG in term human myometrium and decidua obtained from women before labor and during labor was performed using immunohistochemistry. Data were analyzed by Wilcoxon-Mann-Whitney test to compare effects of exosomes from control and oxidative stress-treated amnion epithelial cells on inflammatory status of target cells.

RESULTS

Amnion epithelial cells released ∼125 nm, cup-shaped exosomes with ∼899 and 1211 exosomes released per cell from control and oxidative stress-induced cells, respectively. Amnion epithelial cell exosomes were detected in each target cell type after treatment using confocal microscopy. Treatment with amnion epithelial cell exosomes increased secretion of interleukin-6, interleukin-8, and PGE2 and activation of NF-κβ (each P < .05) in myometrial and decidual cells. Exosome treatments had no effect on interleukin-6 and PGE2 production in BeWo cells. NANOG staining was higher in term labor myometrium and decidua compared to tissues not in labor.

CONCLUSION

In vitro, amnion epithelial cell exosomes lead to an increased inflammatory response in maternal uterine cells whereas placental cells showed refractoriness. Fetal cell exosomes may function to signal parturition by increasing maternal gestational cell inflammation.

Amniotic Epithelial Stem Cells: Salient Features and Possible Therapeutic Role

This is a study of amniotic epithelial cells, which form the innermost layer of the amniotic membrane. These cells can be easily isolated and display peculiar and unique properties, such as plasticity and differentiation potential toward the 3 germinal layers, that may aid regeneration and/or repair of damaged or diseased tissues and organs. A robust literature based on in vitro, experimental, and clinical studies in large animals demonstrates that these cells can enhance the regeneration of tendons, bone, and articular cartilage. On the basis of these considerations, allotransplantation of human amniotic epithelial cells could be proposed for clinical trials in human orthopedic conditions.

Haemophilus parasuis Infection Disrupts Adherens Junctions and Initializes EMT Dependent on Canonical Wnt/β-Catenin Signaling Pathway

In this study, animal experimentation verified that the canonical Wnt/β-catenin signaling pathway was activated under a reduced activity of p-β-catenin (Ser33/37/Thr41) and an increased accumulation of β-catenin in the lungs and kidneys of pigs infected with a highly virulent strain of H. parasuis. In PK-15 and NPTr cells, it was also confirmed that infection with a high-virulence strain of H. parasuis induced cytoplasmic accumulation and nuclear translocation of β-catenin. H. parasuis infection caused a sharp degradation of E-cadherin and an increase of the epithelial cell monolayer permeability, as well as a broken interaction between β-catenin and E-cadherin dependent on Wnt/β-catenin signaling pathway. Moreover, Wnt/β-catenin signaling pathway also contributed to the initiation of epithelial-mesenchymal transition (EMT) during high-virulence strain of H. parasuis infection with expression changes of epithelial/mesenchymal markers, increased migratory capabilities as well as the morphologically spindle-like switch in PK-15 and NPTr cells. Therefore, we originally speculated that H. parasuis infection activates the canonical Wnt/β-catenin signaling pathway leading to a disruption of the epithelial barrier, altering cell structure and increasing cell migration, which results in severe acute systemic infection characterized by fibrinous polyserositis during H. parasuis infection.

The effect of lipopolysaccharide on the expression level of immunomodulatory and immunostimulatory factors of human amniotic epithelial cells

Objective

Human amniotic epithelial cells (hAECs) are a novel source of stem cells and have immunomodulatory effects on both the innate and adoptive immune system. hAECs can differentiate into multiple cell lineages that make them a suitable cell source for regenerative medicine. These cells express multiple toll-like receptors (TLRs) and respond to various TLR ligands. This study aimed to evaluate the effect of lipopolysaccharide (LPS), a TLR4 ligand, on the level of immunomodulatory and immunostimulatory factors of hAECs.

Results

Our results indicated that LPS had the ability to up-regulate the expression of prostaglandin E2 synthase and transforming growth factor-beta1 in hAECs. However, there was no change in the level of interleukin-1beta, interleukin-6 and interleukin-10 in hAECs when were stimulated with LPS. In addition, we observed tumor necrosis factor-alpha was only expressed at very low level in some of hAECs samples which its expression was independent of the effects of LPS.

Electronic supplementary material

The online version of this article (10.1186/s13104-018-3411-9) contains supplementary material, which is available to authorized users.

The enzymatic de-epithelialization technique determines denuded amniotic membrane integrity and viability of harvested epithelial cells

The human amniotic membrane (HAM) is widely used for its wound healing effect in clinical practice, as a feeder for the cell cultivation, or a source of cells to be used in cell therapy. The aim of this study was to find effective and safe enzymatic HAM de-epithelialization method leading to harvesting of both denuded undamaged HAM and viable human amniotic epithelial cells (hAECs). The efficiency of de-epithelialization using TrypLE Express, trypsin/ ethylenediaminetetraacetic (EDTA), and thermolysin was monitored by hematoxylin and eosin staining and by the measurement of DNA concentration. The cell viability was determined by trypan blue staining. Scanning electron microscopy and immunodetection of collagen type IV and laminin α5 chain were used to check the basement membrane integrity. De-epithelialized hAECs were cultured and their stemness properties and proliferation potential was assessed after each passage. The HAM was successfully de-epithelialized using all three types of reagents, but morphological changes in basement membrane and stroma were observed after the thermolysin application. About 60% of cells remained viable using trypsin/EDTA, approximately 6% using TrypLE Express, and all cells were lethally damaged after thermolysin application. The hAECs isolated using trypsin/EDTA were successfully cultured up to the 5^th passage with increasing proliferation potential and decreased stem cell markers expression (NANOG, SOX2) in prolonged cell culture. Trypsin/EDTA technique was the most efficient for obtaining both undamaged denuded HAM and viable hAECs for consequent culture.

Amniotic fluid stem cell exosomes: Therapeutic perspective

It is widely accepted that the therapeutic potential of stem cells can be largely mediated by paracrine factors, also included into exosomes. Thus, stem cell-derived exosomes represent a major therapeutic option in regenerative medicine avoiding, if compared to stem cells graft, abnormal differentiation and tumor formation. Exosomes derived from mesenchymal stem cells (MSC) induce damaged tissue repair, and can also exert immunomodulatory effects on the differentiation, activation and function of different lymphocytes. Therefore, MSC exosomes can be considered as a potential treatment for inflammatory diseases and also an ideal candidate for allogeneic therapy due to their low immunogenicity. Amniotic fluid stem cells (AFSCs) are broadly multipotent, can be expanded in culture, and can be easily cryopreserved in cellular banks. In this study, morphology, phenotype, and protein content of exosomes released into amniotic fluid in vivo and from AFSC during in vitro culture (conditioned medium) were examined. We found that AFSC-derived exosomes present different molecules than amniotic fluid ones, some of them involved in immunomodulation, such transforming growth factor beta and hepatic growth factors. The immunomodulatory effect of AFSC's exosomes on peripheral blood mononuclear cells stimulated with phytohemagglutinin was compared to that of the supernatant produced by such conditioned media deprived of exosomes. We present evidence that the principal effect of AFSC conditioned media (without exosomes) is the induction of apoptosis in lymphocytes, whereas exposure to AFSC-derived exosomes decreases the lymphocyte's proliferation, supporting the hypothesis that the entire secretome of stem cells differently affects immune-response. © 2017 BioFactors, 44(2):158-167, 2018.

Amniotic Epithelial Cell Culture

Ovine amniotic epithelial cells (oAEC) are a subset of placental stem cells with great regenerative and immunomodulatory properties. Indeed, oAEC are object of intense study for regenerative medicine thanks to the several advantages in developing pre-clinical studies on a high value translational animal model, such as sheep. For this reason, a critical standardization of cultural practices is fundamental to preserve in vitro oAEC native phenotype, thus improving their in vivo therapeutic potential and clinical outcomes. Here is described an improved oAEC cultural protocol able to preserve the native epithelial phenotype also after the in vitro amplification.

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.

Amniotic membrane stimulates cell migration by modulating transforming growth factor-β signalling

Keratinocyte migration is a mandatory aspect of wound healing. We have previously shown that amniotic membrane (AM) applied to chronic wounds assists healing through a process resulting in the overexpression of c-Jun at the wound's leading edge. We have also demonstrated that AM modifies the genetic programme induced by transforming growth factor-ß (TGF-ß) in chronic wounds. Here we used a scratch assay of mink lung epithelial cells (Mv1Lu) and a spontaneously immortalized human keratinocyte cell line (HaCaT) cells to examine the influence of AM application on the underlying signalling during scratch closure. AM application induced c-Jun phosphorylation at the leading edge of scratch wounds in a process dependent on MAPK and JNK signalling. Strikingly, when the TGF-ß-dependent Smad-activation inhibitor SB431542 was used together with AM, migration improvement was partially restrained, whereas the addition of TGF-ß had a synergistic effect on the AM-induced cell migration. Moreover, antagonizing TGF-ß with specific antibodies in both cell lines or knocking out TGF-ß receptors in Mv1Lu cells had similar effects on cell migration as using SB431542. Furthermore, we found that AM was able to attenuate TGF-ß-Smad signalling specifically at the migrating edge; AM treatment abated Smad2 and Smad3 nuclear localization in response to TGF-ß in a process dependent on mitogen-activated protein kinase kinase 1 (MEK1) activation but independent of EGF receptor or JNK activation. The involvement of Smad signalling on AM effects on HaCaT keratinocytes was further corroborated by overexpression of either Smad2 or Smad3 and the use of Smad phosphorylation-specific inhibitors, revealing a differential influence on AM-induced migration for each Smad. Thus, AM TGF-ß-Smad signalling abating is essential for optimal cell migration and wound closure.

Acceleration of Fracture Healing by Overexpression of Basic Fibroblast Growth Factor in the Mesenchymal Stromal Cells

In this study, we engineered mesenchymal stem cells (MSCs) to over‐express basic fibroblast growth factor (bFGF) and evaluated its effects on fracture healing. Adipose‐derived mouse MSCs were transduced to express bFGF and green fluorescence protein (ADSC^bFGF‐GFP). Closed‐femoral fractures were performed with osterix‐mCherry reporter mice of both sexes. The mice received 3 × 10⁵ ADSCs transfected with control vector or bFGF via intramuscular injection within or around the fracture sites. Mice were euthanized at days 7, 14, and 35 to monitor MSC engraftment, osteogenic differentiation, callus formation, and bone strength. Compared to ADSC culture alone, ADSC^bFGF increased bFGF expression and higher levels of bFGF and vascular endothelial growth factor (VEGF) in the culture supernatant for up to 14 days. ADSC^bFGF treatment increased GFP‐labeled MSCs at the fracture gaps and these cells were incorporated into the newly formed callus. quantitative reverse transcription polymerase chain reaction (qRT‐PCR) from the callus revealed a 2‐ to 12‐fold increase in the expression of genes associated with nervous system regeneration, angiogenesis, and matrix formation. Compared to the control, ADSC^bFGF treatment increased VEGF expression at the periosteal region of the callus, remodeling of collagen into mineralized callus and bone strength. In summary, MSC^bFGF accelerated fracture healing by increasing the production of growth factors that stimulated angiogenesis and differentiation of MSCs to osteoblasts that formed new bone and accelerated fracture repair. This novel treatment may reduce the time required for fracture healing. Stem Cells Translational Medicine2017;6:1880–1893

Progesterone prevents epithelial-mesenchymal transition of ovine amniotic epithelial cells and enhances their immunomodulatory properties

The in vitro expansion is detrimental to therapeutic applications of amniotic epithelial cells (AEC), an emerging source of fetal stem cells. This study provides molecular evidences of progesterone (P4) role in preventing epithelial-mesenchymal transition (EMT) in ovine AEC (oAEC). oAEC amplified under standard conditions spontaneously acquired mesenchymal properties through the up-regulation of EMT-transcription factors. P4 supplementation prevented phenotype shift by inhibiting the EMT-inducing mechanism such as the autocrine production of TGF-β and the activation of intracellular-related signaling. The effect of P4 still persisted for one passage after steroid removal from culture as well as steroid supplementation promptly reversed mesenchymal phenotype in oAEC which have experienced EMT during amplification. Furthermore, P4 promoted an acute up-regulation of pluripotent genes whereas enhanced basal and LPS-induced oAEC anti-inflammatory response with an increase in anti-inflammatory and a decrease in pro-inflammatory cytokines expression. Altogether, these results indicate that P4 supplementation is crucial to preserve epithelial phenotype and to enhance biological properties in expanded oAEC. Therefore, an innovative cultural approach is proposed in order to improve therapeutic potential of this promising source of epithelial stem cells.

Amniotic membrane application for the healing of chronic wounds and ulcers

Wound healing usually follows a predictable sequence and prognosis of events. Its evolutionary process is the result of a complicated interaction between patient-related factors, the wound, the treatment used and the skills and knowledge of the professionals who treat them. Only through a meticulous initial assessment of the wound is it possible to identify the factors that contribute to its complexity. The challenge for professionals will be to implement efficient therapies at the right time and in the most cost-efficient way in order to reduce associated problems, treat the symptoms and expectations of the patients and achieve adequate wound healing whenever possible. This is particularly evident in big chronic wounds with considerable tissue loss, which become senescent in the process of inflammation or proliferation losing the ability to epithelialize. Generally, chronic wounds do not respond to current treatments, therefore they need special interventions. AM is a tissue of particular interest as a biological dressing and it has well-documented reepithelialization effects which are in part related to its capacity to synthesize and release biological active factors. Our studies have demonstrated that amniotic membrane (AM) is able to induce epithelialization in chronic wounds that were unable to epithelialize. AM induces several signaling pathways that are involved in cell migration and/or proliferation. Additionally, AM is able to selectively antagonize the anti-proliferative effect of transforming growth factor-ß (TGF-β) by modifying the genetic program that TGF-β induces on keratinocytes. The combined effect of AM on keratinocytes, promoting cell proliferation/migration and antagonizing the effect of TGF-β is the perfect combination, allowing chronic wounds to move out of their non-healing state and progress into epithelialization.

The Role of Epithelial to Mesenchymal Transition in Human Amniotic Membrane Rupture

CONTEXT

Biochemical weakening of the amnion is a major factor preceding preterm premature rupture of membranes (PPROMs), leading to preterm birth. Activation of matrix metalloproteinases (MMPs) is known to play a key role in collagen degradation of the amnion; however, epithelial to mesenchymal transition (EMT) that is also induced by MMP activation has not been investigated as a mechanism for amnion weakening.

OBJECTIVE

To measure amniotic EMT associated with vaginal delivery (VD) compared with unlabored cesarean sections (CSs), and to assess changes in amniotic mechanical strength with pharmacologic inhibitors and inducers of EMT, thus testing the hypothesis that EMT is a key biochemical event that promotes amniotic rupture.

FINDINGS

(1) Amnions taken from VD contained a significantly increased number of mesenchymal cells relative to epithelial cells compared with unlabored CS by fluorescence-activated cell sorting analysis (60% vs 10%); (2) tumor necrosis factor (TNF)-α stimulation of amniotic epithelial cells increased expression of the mesenchymal marker vimentin after 2 days; (3) EMT inhibitor, etodolac, significantly increased the time and mechanical pressure required to rupture the amnion; and (4) TNF-α and another pharmacologic EMT inducer, ethacridine, decreased the time and mechanical pressure required for amnion rupture, further confirming that the mesenchymal phenotype significantly weakens the amnion.

CONCLUSIONS

This work demonstrated amniotic cell EMT was associated with labor and EMT decreased the tensile strength of the amnion. These findings suggest a role for EMT in the pathophysiology of PPROM and may provide a basis for development of therapies to prevent preterm labor.

Regulation of Matrix Metalloproteinases-2 and -9 Gene Expression in Cultured Human Fetal Membrane Cells by Influenza Virus Infection

In order to understand a possible etiology of adverse pregnancy outcomes associated with intrauterine influenza virus infection, we examined the effect of influenza virus infection on gene expression of matrix metalloproteinases (MMPs) in cultured amnion epithelial, amnion mesenchymal and chorion trophoblast cells prepared from human fetal membrane tissues by gelatin zymography, Western blotting and reverse transcriptase-PCR. The cells were infected with influenza A (H1N1) virus. The levels of pro-MMP-9 activity in culture supernatants of three types of cells were increased during the period of 24-48 h after the virus infection as compared to those of mock infection. Chorion trophoblast cells spontaneously released a much greater level of pro-MMP-2 activity than amnion epithelial and amnion mesenchymal cells. The cleavage of pro-MMP-2 into an active intermediate form was enhanced in chorion trophoblast cells by the virus infection. The activity levels of MMP-2 and MMP-9 in culture supernatants were consistent with their protein levels. The virus infection induced the mRNA expression of MMP-9, but not MMP-2, in three types of cells. These results suggest that influenza virus infection induces the gene expression of MMP-9 and the cleavage of pro-MMP-2 into an active intermediate form in human fetal membrane cells, resulting in weakening of the membranes through extracellular matrix degradation. Therefore, it is possible that the regulation of MMPs gene expression in fetal membrane cells by influenza virus infection is implicated in a part of the etiology of adverse pregnancy outcomes associated with intrauterine infection with the virus.

Improved Mobilization of Exogenous Mesenchymal Stem Cells to Bone for Fracture Healing and Sex Difference

Mesenchymal stem cell (MSC) transplantation has been tested in animal and clinical fracture studies. We have developed a bone-seeking compound, LLP2A-Alendronate (LLP2A-Ale) that augments MSC homing to bone. The purpose of this study was to determine whether treatment with LLP2A-Ale or a combination of LLP2A-Ale and MSCs would accelerate bone healing in a mouse closed fracture model and if the effects are sex dependent. A right mid-femur fracture was induced in two-month-old osterix-mCherry (Osx-mCherry) male and female reporter mice. The mice were subsequently treated with placebo, LLP2A-Ale (500 μg/kg, IV), MSCs derived from wild-type female Osx-mCherry adipose tissue (ADSC, 3 x 10⁵ , IV) or ADSC + LLP2A-Ale. In phosphate buffered saline-treated mice, females had higher systemic and surface-based bone formation than males. However, male mice formed a larger callus and had higher volumetric bone mineral density and bone strength than females. LLP2A-Ale treatment increased exogenous MSC homing to the fracture gaps, enhanced incorporation of these cells into callus formation, and stimulated endochondral bone formation. Additionally, higher engraftment of exogenous MSCs in fracture gaps seemed to contribute to overall fracture healing and improved bone strength. These effects were sex-independent. There was a sex-difference in the rate of fracture healing. ADSC and LLP2A-Ale combination treatment was superior to on callus formation, which was independent of sex. Increased mobilization of exogenous MSCs to fracture sites accelerated endochondral bone formation and enhanced bone tissue regeneration. Stem Cells 2016;34:2587-2600.

Osteogenic differentiation of human amniotic epithelial cells and its application in alveolar defect restoration

The present study investigated the detailed in vitro osteogenic differentiation process and in vivo bone regenerative property of human amniotic epithelial cells (hAECs). The in vitro osteogenic differentiation process of hAECs was evaluated by biochemical staining, real-time polymerase chain reaction, and immunofluorescence. Next, β-tricalcium phosphate (β-TCP) scaffolds alone or loaded with hAECs were implanted into the alveolar defects of rats. Micro-computed tomography evaluation and histologic studies were conducted. Our results validated the in vitro osteogenic capacity of hAECs by upregulation of Runx2, osterix, alkaline phosphatase, collagen I, and osteopontin, with positive biochemical staining for osteoblasts. An epithelial-mesenchymal transformation process might be involved in the osteogenic differentiation of hAECs by increased expression of transforming growth factor-β1. Our data also demonstrated that in vivo implantation of hAECs loaded on β-TCP scaffolds, not only improved bone regeneration by direct participation, but also reduced the early host immune response to the scaffolds. The presented data indicate that hAECs possess proper osteogenic differentiation potential and a modulatory influence on the early tissue remodeling process, making these cells a potential source of progenitor cells for clinical restoration of the alveolar defect.

Human Amniotic Membrane-Derived Mesenchymal and Epithelial Cells Exert Different Effects on Monocyte-Derived Dendritic Cell Differentiation and Function

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 monocyte-derived 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-α and the increase in IL-10 in supernatants taken from monocyte-DCs cocultured with hAMTCs and hAECs in contact and Transwell settings. The inflammatory factors IL-8, CXCL9, and MIP-1α 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-1β 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.

Therapeutic effect of human amniotic membrane-derived cells on experimental arthritis and other inflammatory disorders

OBJECTIVE

Rheumatoid arthritis (RA) is an autoimmune disease caused by loss of immunologic self tolerance and characterized by chronic joint inflammation. Cells isolated from human amniotic membrane (HAMCs) were recently found to display immunosuppressive properties. The aim of this study was to characterize the effect of HAMCs on antigen-specific T cell responses in RA patients and to evaluate their therapeutic potential in a preclinical experimental model of RA.

METHODS

We investigated the effects of HAMCs on collagen-reactive T cell proliferation and cytokine production, on the production of mediators of inflammation by synoviocytes, and on the generation of Treg cells in peripheral blood mononuclear cells and synovial membrane cells isolated from RA patients. Mice with collagen-induced arthritis (CIA) were treated with HAMCs after disease onset, and clinical scores and joint levels of mediators of inflammation were evaluated. We determined Th1/Th17-mediated autoreactive responses in the mice by measuring the proliferation and the cytokine profile of lymph node cells restimulated with collagen.

RESULTS

Treatment with HAMCs suppressed synovial inflammatory responses and antigen-specific Th1/Th17 activation in cells isolated from RA patients. Moreover, HAMCs stimulated the generation of human CD4+CD25+FoxP3+ Treg cells with a capacity to suppress collagen-specific T cell responses. Systemic infusion of HAMCs significantly reduced the incidence and severity of CIA by down-regulating the 2 deleterious components of disease: Th1-driven autoimmunity and inflammation. In mice with CIA, HAMC treatment decreased the production of various inflammatory cytokines and chemokines in the joints, impaired antigen-specific Th1/Th17 cell expansion in the lymph nodes, and generated peripheral antigen-specific Treg cells. HAMCs also protected the mice from experimental sepsis, inflammatory bowel disease, and autoimmune encephalomyelitis.

CONCLUSION

HAMCs have emerged as attractive candidates for a cell-based therapy for RA.

Amniotic membrane-derived stem cells: immunomodulatory properties and potential clinical application

Epithelial and mesenchymal cells isolated from the amniotic membrane (AM) possess stem cell characteristics, differentiation potential toward lineages of different germ layers, and immunomodulatory properties. While their expansion and differentiation potential have been well studied and characterized, knowledge about their immunomodulatory properties and the mechanisms involved is still incomplete. These mechanisms have been evaluated on various target cells of the innate and the adaptive system and in animal models of different inflammatory diseases. Some results have evidenced that the immunomodulatory effect of AM-derived cells is dependent on cell-cell contact, but many of them have demonstrated that these properties are mediated through the secretion of suppressive molecules. In this review, we present an update on the described immunomodulatory properties of the derived amniotic cells and some of the proposed involved mechanisms. Furthermore, we describe some assays in animal models of different inflammatory diseases which reveal the potential use of these cells to treat such diseases.