Native characterization and QC profiling of human amniotic mesenchymal stromal cell vesicular fractions for secretome-based therapy.

Human amniotic mesenchymal stromal cells (hAMSCs) have unique immunomodulatory properties making them attractive candidates for regenerative applications in inflammatory diseases. Most of their beneficial properties are mediated through their secretome. The bioactive factors concurring to its therapeutic activity are still unknown. Evidence suggests synergy between the two main components of the secretome, soluble factors and vesicular fractions, pivotal in shifting inflammation and promoting self-healing. Biological variability and the absence of quality control (QC) protocols hinder secretome-based therapy translation to clinical applications. Moreover, vesicular secretome contains a multitude of particles with varying size, cargos and functions whose complexity hinders full characterization and comprehension. This study achieved a significant advancement in secretome characterization by utilizing native, FFF-based separation and characterizing extracellular vesicles derived from hAMSCs. This was accomplished by obtaining dimensionally homogeneous fractions then characterized based on their protein content, potentially enabling the identification of subpopulations with diverse functionalities. This method proved to be successful as an independent technique for secretome profiling, with the potential to contribute to the standardization of a qualitative method. Additionally, it served as a preparative separation tool, streamlining populations before ELISA and LC-MS characterization. This approach facilitated the categorization of distinctive and recurring proteins, along with the identification of clusters associated with vesicle activity and functions. However, the presence of proteins unique to each fraction obtained through the FFF separation tool presents a challenge for further analysis of the protein content within these cargoes.

Reactive Oxygen Species Regulation of Chemoresistance and Metastatic Capacity of Melanoma: Role of the Cancer Stem Cell Marker CD271.

BRAF mutations are present in 30-50% of cases of cutaneous melanoma, and treatment with selective BRAF and MEK inhibitors has been introduced. However, the development of resistance to these drugs often occurs. Chemo-resistant melanoma cells show increased expression of CD271, a stem cell marker that features increased migration. Concordantly, resistance to the selective inhibitor of oncogenic BRAFV600E/K, vemurafenib, is mediated by the increased expression of CD271. It has recently been shown that the BRAF pathway leads to an overexpression of the NADPH oxidase Nox4, which produces reactive oxygen species (ROS). Here, we examined in vitro how Nox-derived ROS in BRAF-mutated melanoma cells regulates their drug sensitivity and metastatic potential. We demonstrated that DPI, a Nox inhibitor, reduced the resistance of a melanoma cell line (SK-MEL-28) and a primary culture derived from a BRAFV600E-mutated biopsy to vemurafenib. DPI treatment affected the expression of CD271 and the ERK and Akt signaling pathways, leading to a drop in epithelial-mesenchymal transition (EMT), which undoubtedly promotes an invasive phenotype in melanoma. More importantly, the scratch test demonstrated the efficacy of the Nox inhibitor (DPI) in blocking migration, supporting its use to counteract drug resistance and thus cell invasion and metastasis in BRAF-mutated melanoma.

Human Neuromuscular Junction on a Chip: Impact of Amniotic Fluid Stem Cell Extracellular Vesicles on Muscle Atrophy and NMJ Integrity.

Neuromuscular junctions (NMJs) are specialized synapses, crucial for the communication between spinal motor neurons (MNs) and skeletal muscle. NMJs become vulnerable in degenerative diseases, such as muscle atrophy, where the crosstalk between the different cell populations fails, and the regenerative ability of the entire tissue is hampered. How skeletal muscle sends retrograde signals to MNs through NMJs represents an intriguing field of research, and the role of oxidative stress and its sources remain poorly understood. Recent works demonstrate the myofiber regeneration potential of stem cells, including amniotic fluid stem cells (AFSC), and secreted extracellular vesicles (EVs) as cell-free therapy. To study NMJ perturbations during muscle atrophy, we generated an MN/myotube co-culture system through XonaTM microfluidic devices, and muscle atrophy was induced in vitro by Dexamethasone (Dexa). After atrophy induction, we treated muscle and MN compartments with AFSC-derived EVs (AFSC-EVs) to investigate their regenerative and anti-oxidative potential in counteracting NMJ alterations. We found that the presence of EVs reduced morphological and functional in vitro defects induced by Dexa. Interestingly, oxidative stress, occurring in atrophic myotubes and thus involving neurites as well, was prevented by EV treatment. Here, we provided and validated a fluidically isolated system represented by microfluidic devices for studying human MN and myotube interactions in healthy and Dexa-induced atrophic conditions-allowing the isolation of subcellular compartments for region-specific analyses-and demonstrated the efficacy of AFSC-EVs in counteracting NMJ perturbations.

Effect of the Enrichment in c-Kit Stem Cell Potential of Foetal Human Amniotic Fluid Cells: Characterization from Single Cell Analysis to the Secretome Content.

Human amniotic fluid cells (hAFSCs) are a fascinating foetal cell-type that have important stem cell characteristics; however, they are a heterogeneous population that ranges from totally differentiated or progenitor cells to highly multipotent stem cells. There is no single approach to isolating the stem cell component, but the selection of a subpopulation of hAFSCs expressing c-Kit is widely employed, while a deep characterization of the two populations is still lacking. Here we performed single-cell and bulk RNAseq analysis to compare the gene expression profiles of adherent amniotic fluid cells and their subpopulation c-Kit+. Information deriving from this high throughput technology on the transcriptome was then confirmed for specific targets with protein expression experiments and functional analysis. In particular, transcriptome profiling identified changes in cellular distribution among the different clusters that correlated with significant differential expression in pathways related to stemness, proliferation, and cell cycle checkpoints. These differences were validated by RT-PCR, immunofluorescence, WB, and cell cycle assays. Interestingly, the two populations produced secretomes with different immune-modulating and pro-regenerative potentials. Indeed, the presence of TGFß, HGF, IDO was higher in EVs deriving from c-Kit+ cells, unlike IL-6. These results suggest the existence of deep intra-population differences that can influence the stemness profile of hAFSCs. This study represents a proof-of-concept of the importance of selecting c-Kit positive fractions with higher potential in regenerative medicine applications.

Evidence for mitochondrial Lonp1 expression in the nucleus.

The coordinated communication between the mitochondria and nucleus is essential for cellular activities. Nonetheless, the pathways involved in this crosstalk are scarcely understood. The protease Lonp1 was previously believed to be exclusively located in the mitochondria, with an important role in mitochondrial morphology, mtDNA maintenance, and cellular metabolism, in both normal and neoplastic cells. However, we recently detected Lonp1 in the nuclear, where as much as 22% of all cellular Lonp1 can be found. Nuclear localization is detectable under all conditions, but the amount is dependent on a response to heat shock (HS). Lonp1 in the nucleus interacts with heat shock factor 1 (HSF1) and modulates the HS response. These findings reveal a novel extramitochondrial function for Lonp1 in response to stress.

Exosomes Derived from Human Amniotic Fluid Mesenchymal Stem Cells Preserve Microglia and Neuron Cells from Aß.

BACKGROUND: Neuroinflammation is involved in neuronal cell death that occurs in neurodegenerative diseases such as Alzheimer's disease (AD). Microglia play important roles in regulating the brain amyloid beta (Aß) levels, so immunomodulatory properties exerted by mesenchymal stem cells may be exploited to treat this pathology. The evidence suggests that the mechanism of action of human amniotic fluid stem cells (hAFSCs) is through their secretome, which includes exosomes (exo). METHODS: We examined the effect of exosomes derived from human amniotic fluid stem cells (hAFSCs-exo) on activated BV-2 microglia cells by lipopolysaccharide (LPS) as a neuroinflammation model. To investigate the exo effect on the interplay between AD neurons and microglia, SH-SY5Y neuroblastoma cells treated with Aß were exposed to a conditioned medium (CM) obtained from activated BV-2 or co-culture systems. RESULTS: We found that the upregulation of the markers of pro-inflammatory microglia was prevented when exposed to hAFSC-exo whereas the markers of the anti-inflammatory macrophage phenotype were not affected. Interestingly, the hAFSC-exo pretreatment significantly inhibited the oxidative stress rise and apoptosis occurring in the neurons in presence of both microglia and Aß. CONCLUSION: We demonstrated that hAFSC-exo mitigated an inflammatory injury caused by microglia and significantly recovered the neurotoxicity, suggesting that hAFSC-exo may be a potential therapeutic agent for inflammation-related neurological conditions, including AD.

The Interplay between HGF/c-met Axis and Nox4 in BRAF Mutated Melanoma.

BACKGROUND: Melanoma is the leading cause of death due to cutaneous malignancy and its incidence is on the rise. Several signaling pathways, including receptor tyrosine kinases, have a role in the development and progression of melanocytic lesions and malignant melanoma. Among those, the hepatocyte growth factor (HGF)/c-met axis is emerging as a critical player because it can play a role in drug resistance. Indeed, 50% of melanoma patients present BRAF mutations, however, all responders develop resistance to the inhibitors typically within one year of treatment. Interestingly, BRAF inhibitors induce reactive oxygen species (ROS) in melanoma cells, therefore, the aim of this study was to investigate a possible interplay between HGF/c-met and ROS sources, such as NADPH oxidases (Nox). METHODS: The expression of c-met and Nox were quantified in 60 patients with primary cutaneous melanoma. In vitro experiments on melanoma primary cells and the cell line were performed to dissect the underpinned molecular mechanism. RESULTS: The outcome of interest was the correlation between the high positivity for both Nox4 and c-met and metastasis occurring at least 1 year later than melanoma diagnosis in BRAF mutated patients, in contrast to nonmutated. In vitro experiments demonstrated that the axis HGF/c-met/Nox4/ROS triggers the epithelial-mesenchymal transition. CONCLUSIONS: The observed correlation suggests an interplay between c-met and Nox4 in promoting the onset of metastasis. This study suggests that Nox4 inhibitors could be associated to the current therapy used to treat melanoma patients with BRAF mutations.

Unravelling Heterogeneity of Amplified Human Amniotic Fluid Stem Cells Sub-Populations.

Human amniotic fluid stem cells (hAFSCs) are broadly multipotent immature progenitor cells with high self-renewal and no tumorigenic properties. These cells, even amplified, present very variable morphology, density, intracellular composition and stemness potential, and this heterogeneity can hinder their characterization and potential use in regenerative medicine. Celector® (Stem Sel ltd.) is a new technology that exploits the Non-Equilibrium Earth Gravity Assisted Field Flow Fractionation principles to characterize and label-free sort stem cells based on their solely physical characteristics without any manipulation. Viable cells are collected and used for further studies or direct applications. In order to understand the intrapopulation heterogeneity, various fractions of hAFSCs were isolated using the Celector® profile and live imaging feature. The gene expression profile of each fraction was analysed using whole-transcriptome sequencing (RNAseq). Gene Set Enrichment Analysis identified significant differential expression in pathways related to Stemness, DNA repair, E2F targets, G2M checkpoint, hypoxia, EM transition, mTORC1 signalling, Unfold Protein Response and p53 signalling. These differences were validated by RT-PCR, immunofluorescence and differentiation assays. Interestingly, the different fractions showed distinct and unique stemness properties. These results suggest the existence of deep intra-population differences that can influence the stemness profile of hAFSCs. This study represents a proof-of-concept of the importance of selecting certain cellular fractions with the highest potential to use in regenerative medicine.

Amniotic Fluid Stem Cell-Derived Extracellular Vesicles Counteract Steroid-Induced Osteoporosis In Vitro.

Background-Osteoporosis is characterized by defects in both quality and quantity of bone tissue, which imply high susceptibility to fractures with limitations of autonomy. Current therapies for osteoporosis are mostly concentrated on how to inhibit bone resorption but give serious adverse effects. Therefore, more effective and safer therapies are needed that even encourage bone formation. Here we examined the effect of extracellular vesicles secreted by human amniotic fluid stem cells (AFSC) (AFSC-EV) on a model of osteoporosis in vitro. Methods-human AFSC-EV were added to the culture medium of a human pre-osteoblast cell line (HOB) induced to differentiate, and then treated with dexamethasone as osteoporosis inducer. Aspects of differentiation and viability were assessed by immunofluorescence, Western blot, mass spectrometry, and histological assays. Since steroids induce oxidative stress, the levels of reactive oxygen species and of redox related proteins were evaluated. Results-AFSC-EV were able to ameliorate the differentiation ability of HOB both in the case of pre-osteoblasts and when the differentiation process was affected by dexamethasone. Moreover, the viability was increased and parallelly apoptotic markers were reduced. The presence of EV positively modulated the redox unbalance due to dexamethasone. Conclusion-these findings demonstrated that EV from hAFSC have the ability to recover precursor cell potential and delay local bone loss in steroid-related osteoporosis.

Oxidative Stress in Alzheimer's Disease: In Vitro Therapeutic Effect of Amniotic Fluid Stem Cells Extracellular Vesicles.

Alzheimer's disease (AD) is characterized by abnormal protein aggregation, deposition of extracellular ß-amyloid proteins (Aß), besides an increase of oxidative stress. Amniotic fluid stem cells (AFSCs) should have a therapeutic potential for neurodegenerative disorders, mainly through a paracrine effect mediated by extracellular vesicles (EV). Here, we examined the effect of EV derived from human AFSCs (AFSC-EV) on the disease phenotypes in an AD neuron primary culture. We observed a positive effect of AFSC-EV on neuron morphology, viability, and Aß and phospho-Tau levels. This could be due to the apoptotic and autophagic pathway modulation derived from the decrease in oxidative stress. Indeed, reactive oxygen species (ROS) were reduced, while GSH levels were enhanced. This modulation could be ascribed to the presence of ROS regulating enzymes, such as SOD1 present into the AFSC-EV themselves. This study describes the ROS-modulating effects of extracellular vesicles alone, apart from their deriving stem cell, in an AD in vitro model, proposing AFSC-EV as a therapeutic tool to stop the progression of AD.

Prolonged hypoxia delays aging and preserves functionality of human amniotic fluid stem cells.

Human amniotic fluid stem cells (hAFSCs) are an emerging tool in regenerative medicine because they have the ability to differentiate into various lineages and efficiently improve tissue regeneration with no risk of tumorigenesis. Although hAFSCs are easily isolated from the amniotic fluid, their expansion ex vivo is limited by a quick exhaustion which impairs replicative potential and differentiation capacity. In this study, we evaluate various aging features of hAFSCs cultured at different oxygen concentrations. We show that low oxygen (1% O2) extends stemness and proliferative features, and delays induction of senescence-associated markers. Hypoxic hAFSCs activate a metabolic shift and increase resistance to pro-apoptotic stimuli. Moreover, we observe that cells at low oxygen remain capable of osteogenesis for prolonged periods of time, suggesting a more youthful phenotype. Together, these data demonstrate that low oxygen concentrations might improve the generation of functional hAFSCs for therapeutic use by delaying the onset of cellular aging.

Comparison of the therapeutic effect of amniotic fluid stem cells and their exosomes on monoiodoacetate-induced animal model of osteoarthritis.

The cartilage tissue engineering associated with stem cell-related therapies is becoming very interesting since adult articular cartilage has limited intrinsic capacity for regeneration upon injury. Amniotic fluid stem cells (AFSC) have been shown to produce exosomes with growth factors and immunomodulating molecules that could stop tissue degradation and induce cartilage repair. Based on this state of the art, the main aim of this study was to explore the efficacy of the secreted exosomes, compared to their AFSC source, in MIA-induced animal model of osteoarthritis mimicking a chronic and degenerative process, where inflammation is also involved and lead to irreversible joint damage. Exosomes, obtained by the use of a commercial kit, prior to the injection in animal knee joints, were characterized for the presence of typical markers and HGF, TGFß, and IDO. Then, analyses were performed by histology, immunohistochemistry, and behavioral scoring up to 3 weeks after the treatment. Exosome-treated defects showed enhanced pain tolerance level and improved histological scores than the AFSC-treated defects. Indeed by 3 weeks, TGFß-rich exosome samples induced an almost complete restoration of cartilage with good surface regularity and with the characteristic of hyaline cartilage. Moreover, cells positive for resolving macrophage marker were more easily detectable into exosome-treated joints. Therefore, a modulating role for exosomes on macrophage polarization is conceivable, as demonstrated also by experiments performed on THP1 macrophages. In conclusion, this study demonstrates for the first time the efficacy of human AFSC exosomes in counteract cartilage damage, showing a positive correlation with their TGFß content.

A new approach for the separation, characterization and testing of potential prionoid protein aggregates through hollow-fiber flow field-flow fractionation and multi-angle light scattering.

Protein misfolding and aggregation are the common mechanisms in a variety of aggregation-dependent diseases. The compromised proteins often assemble into toxic, accumulating amyloid-like structures of various lengths and their toxicity can also be transferred both in vivo and in vitro a prion-like behavior. The characterization of protein interactions, degradation and conformational dynamics in biological systems still represents an analytical challenge in the prion-like protein comprehension. In our work, we investigated the nature of a transferable cytotoxic agent, presumably a misfolded protein, through the coupling of a multi-detector, non-destructive separation platform based on hollow-fiber flow field-flow fractionation with imaging and downstream in vitro tests. After purification with ion exchange chromatography, the transferable cytotoxic agentwas analyzed with Atomic Force Microscopy and statistical analysis, showing that the concentration of protein dimers and low n-oligomer forms was higher in the cytotoxic sample than in the control preparation. To assess whether the presence of these species was the actual toxic and/or self-propagating factor, we employed HF5 fractionation, with UV and Multi-Angle Light Scattering detection, to define proteins molar mass distribution and abundance, and fractionate the sample into size-homogeneous fractions. These fractions were then tested individually in vitro to investigate the direct correlation with cytotoxicity. Only the later-eluted fraction, which contains high-molar mass aggregates, proved to be toxic onto cell cultures. Moreover, it was observed that the selective transfer of toxicity also occurs for one lower-mass fraction, suggesting that two different mechanisms, acute and later induced toxicity, are in place. These results strongly encourage the efficacy of this platform to enable the identification of protein toxicants.

Influence of selenium on the emergence of neuro tubule defects in a neuron-like cell line and its implications for amyotrophic lateral sclerosis.

Impairment of the axonal transport system mediated by intracellular microtubules (MTs) is known to be a major drawback in neurodegenerative processes. Due to a growing interest on the neurotoxic effects of selenium in environmental health, our study aimed to assess the relationship between selenium and MTs perturbation, that may favour disease onset over a genetic predisposition to amyotrophic lateral sclerosis. We treated a neuron-like cell line with sodium selenite, sodium selenate and seleno-methionine and observed that the whole cytoskeleton was affected. We then investigated the protein interactome of cells overexpressing αTubulin-4A (TUBA4A) and found that selenium increases the interaction of TUBA4A with DNA- and RNA-binding proteins. TUBA4A ubiquitination and glutathionylation were also observed, possibly due to a selenium-dependent increase of ROS, leading to perturbation and degradation of MTs. Remarkably, the TUBA4A mutants R320C and A383 T, previously described in ALS patients, showed the same post-translational modifications to a similar extent. In conclusion this study gives insights into a specific mechanism characterizing selenium neurotoxicity.

Melanoma types by in vivo reflectance confocal microscopy correlated with protein and molecular genetic alterations: A pilot study.

Cutaneous melanoma (CM) is one of the most prevalent skin cancers, which lacks both a prognostic marker and a specific and lasting treatment, due to the complexity of the disease and heterogeneity of patients. Reflectance confocal microscopy (RCM) in vivo analysis is a versatile approach offering immediate morphological information, enabling the identification of four primary cutaneous RCM CM types. Whether RCM CM types are associated with a specific protein and molecular genetic profiles at the tissue level remains unclear. The current pilot study was designed to identify potential correlations between RCM CM types and specific biological characteristics, combining immunohistochemistry (IHC) and molecular analyses. Eighty primary CMs evaluated at patient bedside with RCM (type 1 [19, 24%], type 2 [12, 15%], type 3 [7, 9%] and type 4 [42, 52%]) were retrospectively evaluated by IHC stains (CD271, CD20, CD31, cyclin D1), fluorescence in situ hybridization FISH for MYC gain and CDKN2A loss and molecular analysis for somatic mutations (BRAF, NRAS and KIT). RCM CM types correlated with markers of stemness property, density of intra-tumoral lymphocytic B infiltrate and cyclin D1 expression, while no significant association was found with blood vessel density nor molecular findings. RCM CM types show a different marker profile expression, suggestive of a progression and an increase in aggressiveness, according to RCM morphologies.

Clusterin enhances AKT2-mediated motility of normal and cancer prostate cells through a PTEN and PHLPP1 circuit.

Clusterin (CLU) is a chaperone-like protein with multiple functions. sCLU is frequently upregulated in prostate tumor cells after chemo- or radiotherapy and after surgical or pharmacological castration. Moreover, CLU has been documented to modulate the cellular homolog of murine thymoma virus akt8 oncogene (AKT) activity. Here, we investigated how CLU overexpression influences phosphatidylinositol 3'-kinase (PI3K)/AKT signaling in human normal and cancer epithelial prostate cells. Human prostate cells stably transfected with CLU were broadly profiled by reverse phase protein array (RPPA), with particular emphasis on the PI3K/AKT pathway. The effect of CLU overexpression on normal and cancer cell motility was also tested. Our results clearly indicate that CLU overexpression enhances phosphorylation of AKT restricted to isoform 2. Mechanistically, this can be explained by the finding that the phosphatase PH domain leucine-rich repeat-containing protein phosphatase 1 (PHLPP1), known to dephosphorylate AKT2 at S474, is markedly downregulated by CLU, whereas miR-190, a negative regulator of PHLPP1, is upregulated. Moreover, we found that phosphatase and tensin homolog (PTEN) was heavily phosphorylated at the inhibitory site S380, contributing to the hyperactivation of AKT signaling. By keeping AKT2 phosphorylation high, CLU dramatically enhances the migratory behavior of prostate epithelial cell lines with different migratory and invasive phenotypes, namely prostate normal epithelial 1A (PNT1A) and prostatic carcinoma 3 (PC3) cells. Altogether, our results unravel for the first time a circuit by which CLU can switch a low migration phenotype toward a high migration phenotype, through miR-190-dependent downmodulation of PHLPP1 expression and, in turn, stabilization of AKT2 phosphorylation.

Nuclear Nox4 interaction with prelamin A is associated with nuclear redox control of stem cell aging.

Mesenchymal stem cells have emerged as an important tool that can be used for tissue regeneration thanks to their easy preparation, differentiation potential and immunomodulatory activity. However, an extensive culture of stem cells in vitro prior to clinical use can lead to oxidative stress that can modulate different stem cells properties, such as self-renewal, proliferation, differentiation and senescence. The aim of this study was to investigate the aging process occurring during in vitro expansion of stem cells, obtained from amniotic fluids (AFSC) at similar gestational age.The analysis of 21 AFSC samples allowed to classify them in groups with different levels of stemness properties. In summary, the expression of pluripotency genes and the proliferation rate were inversely correlated with the content of reactive oxygen species (ROS), DNA damage signs and the onset premature aging markers, including accumulation of prelamin A, the lamin A immature form. Interestingly, a specific source of ROS, the NADPH oxidase isoform 4 (Nox4), can localize into PML nuclear bodies (PML-NB), where it associates to prelamin A. Besides, Nox4 post translational modification, involved in PML-NB localization, is linked to its degradation pathway, as it is also for prelamin A, thus possibly modulating the premature aging phenotype occurrence.

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.

Development of a novel method for amniotic fluid stem cell storage.

BACKGROUND AIMS: Current procedures for collection of human amniotic fluid stem cells (hAFSCs) indicate that cells cultured in a flask for 2 weeks can then be used for research. However, hAFSCs can be retrieved directly from a small amount of amniotic fluid that can be obtained at the time of diagnostic amniocentesis. The aim of this study was to determine whether direct freezing of amniotic fluid cells is able to maintain or improve the potential of a sub-population of stem cells. METHODS: We compared the potential of the hAFSCs regarding timing of freezing, cells obtained directly from amniotic fluid aspiration (D samples) and cells cultured in a flask before freezing (C samples). Colony-forming-unit ability, proliferation, morphology, stemness-related marker expression, senescence, apoptosis and differentiation potential of C and D samples were compared. RESULTS: hAFSCs isolated from D samples expressed mesenchymal stem cells markers until later passages, had a good proliferation rate and exhibited differentiation capacity similar to hAFSCs of C samples. Interestingly, direct freezing induced a higher concentration of cells positive for pluripotency stem cell markers, without teratoma formation in vivo. CONCLUSIONS: This study suggests that minimal processing may be adequate for the banking of amniotic fluid cells, avoiding in vitro passages before the storage and exposure to high oxygen concentration, which affect stem cell properties. This technique might be a cost-effective and reasonable approach to the process of Good Manufacturing Process accreditation for stem-cell banks.

Human biliary tree stem/progenitor cells immunomodulation: Role of hepatocyte growth factor.

AIM: Human biliary tree stem/progenitor cells (hBTSC) are multipotent epithelial stem cells with the potential for allogenic transplant in liver, biliary tree, and pancreatic diseases. Human mesenchymal stem cells, but also epithelial stem cells, are able to modulate immune responses with different types of secretion molecules. METHODS: The initial aim of the present study was to develop for the first time a culture protocol in order to expand hBTSC in vitro through passages, allowing to maintain a similar stem cell and secretome profile. Furthermore, we investigated the secretome profile of the hBTSC to assess the production of molecules capable of affecting immune feedback. RESULTS: We found that hepatocyte growth factor produced by hBTSC exerts its cytoprotective role inducing apoptosis in human immune cells, such as lymphocytes. CONCLUSIONS: The present study, therefore, supports the hypothesis that hBTSC can be useful for the purpose of regenerative medicine, as they can be banked and expanded, and they can secrete immunoregulatory factors.