The Truth Is Out There: Biological Features and Clinical Indications of Extracellular Vesicles from Human Perinatal Stem Cells

The potential of perinatal tissues to provide cellular populations to be used in different applications of regenerative medicine is well established. Recently, the efforts of researchers are being addressed regarding the evaluation of cell products (secreted molecules or extracellular vesicles, EVs) to be used as an alternative to cellular infusion. The data regarding the effective recapitulation of most perinatal cells' properties by their secreted complement point in this direction. EVs secreted from perinatal cells exhibit key therapeutic effects such as tissue repair and regeneration, the suppression of inflammatory responses, immune system modulation, and a variety of other functions. Although the properties of EVs from perinatal derivatives and their significant potential for therapeutic success are amply recognized, several challenges still remain that need to be addressed. In the present review, we provide an up-to-date analysis of the most recent results in the field, which can be addressed in future research in order to overcome the challenges that are still present in the characterization and utilization of the secreted complement of perinatal cells and, in particular, mesenchymal stromal cells

Human Wharton’s jelly-derived mesenchymal stem cells express several immunomodulatory molecules both in their naïve state and hepatocyte-like differentiated progeny: prospects for their use in liver diseases.

Wharton’s jelly (WJ), the main constituent of umbilical cord, is a reliable source of mesenchymal stem cells (MSC). WJ-MSC show unique ability in crossing lineage borders. As other extraembryonic mesenchymal populations (placenta and amnionderived cells), WJ-MSC express several immunomodulatory molecules, essential during the initial phases of human development. Indeed, our recent work pointed out the expression of non-classical HLA molecules as HLA-G in such cells, together with a favorable combination of B7 costimulators. Very few data in literature suggest that some of the immune features of the naïve cells are maintained after performing differentiation. The aim of this work was extending the knowledge on the expression of immunomodulatory molecules by naïve and differentiated WJ-MSC. To this purpose, WJMSC underwent differentiation to osteoblasts, adipocytes and hepatocyte-like cells. Differentiated cells were characterized, by both RT-PCR, ICC and histological stains for the acquisistion of the desired phenotypical features. RT-PCR and ICC were used to investigate the differential expression of immune-related molecules in control and differentiated cells. WJ-MSC resulted expressing diverse immunomodulatory molecules which spans from non-classical type I HLAs (i.e. HLA-E, -F, -G) , to further members of the B7 family, and of the CEA superfamily, for all of which in vivo immunomodulating functions are known. In addition, we demonstrated for the first time that the expression of these molecules is maintained after performing osteogenic, adipogenic or hepatogenic differentiation. Further experiments are undergoing to better evaluating the implications of these findings in the evolving field of liver regenerative medicine

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

Novel in vitro and in vivo data on the cellular localization of Hsp10 in smokers affected by COPD and in lung-derived cell lines exposed to cigarette smoke extract as stressor

Cigarette smoke is a potent stressor for the respiratory system, contributing to pathogenesis, for instance in chronic obstructive pulmonary disease (COPD), but its effects on the expression, function, and cellular localization of mitochondrial chaperonins are still largely unknown. We studied in vivo (airways biopsies) the localization of Hsp10 and Hsp60 in patients (smokers and non-smokers) affected by mild-moderate COPD, and characterized the effects of non-lethal doses of cigarette smoke extract (CSE) on the expression of these molecules in two human cell lines: lung fibroblasts (HFL-1) and bronchial epithelial (16HBE). We applied various in vitro methods: immunohistochemistry (IHC), subcellular fractionation analyses (SFA), Western blotting (WB), immunocytochemistry (ICC), and transmission electron microscopy (TEM) immunogold, and used bioinformatics and databases searches to gather structural in silico data for interpreting and complementing the in vitro results. IHC showed that in smokers and non-smokers COPD patients Hsp10 was localized in both, the cytoplasm and the nucleus of epithelial and lamina propria cells, while Hsp60 was present only in the cytosol. ICC, SFA, and WB on both CSE-exposed cell lines confirmed the presence of nuclear Hsp10, with an increasing trend in parallel to CSE concentration. TEM immunogold further confirmed Hsp10 in the nucleus, in addition to its presence in the cytoplasm and mitochondria, on both cell lines. Bioinformatics and in silico structural analyses indicated that Hsp10 can localize in extramitochondrial sites, such as the nucleus, even if Hsp10 lacks known DNA-binding motifs or nuclear import signals in its primary sequence. Our data suggest a link between exposure to exogenous oxidative stress and cell response, involving Hsp10, which would play roles different from its canonical functions. It is known that Hsp10 can display an array of functions depending on its location: cytoplasm, mitochondria, or extracellular. Here, we show for the first time the presence of Hsp10 in the nucleus of epithelial and stromal human-lung cell lines, paralleling the observations in vivo in COPD patients, and indicating that intranuclear Hsp10 levels are affected by oxidative stress due to an exogenous stressor like cigarette-smoke. The questions now are by what mechanism Hsp10 becomes a resident of the nucleus and what are its functions there.

Nuclear localization and new isoforms detection give new insights on Hsp10 functions in normal and cigarette smoke-stressed lung cells

Heat-shock protein (Hsp)10 is the co-chaperone for Hsp60 inside mitochondria, but it also resides outside the organelle. Variations in its levels and intracellular dis- tribution have been documented in pathological conditions, e.g. cancer and chronic obstructive pulmonary disease (COPD). Cigarette smoke (CS) is a potent stressor for the respiratory system, but its effects on the expression, function, and cellular locali- zation of mitochondrial chaperonins are still largely unknown. We studied in vivo (airways biopsies) the localization of Hsp10 and Hsp60 in patients (smokers and non-smokers) affected by mild-moderate COPD, and charac- terized the effects of non-lethal doses of CS extract (CSE) on the expression of these molecules in two human cell lines: lung fibroblasts (HFL-1) and bronchial epithelial cells (16HBE). We applied various in vitro methods: IHC, subcellular fractionation analyses (SFA), western blotting (WB), ICC, transmission electron microscopy (TEM) immunogold, chromati protein extracts (CPE), as well as 2D-gel based proteomics analyses. Bioinformatics was used to gather structural in silico data. IHC showed that Hsp10 occurred in nuclei of epithelial and lamina propria cells of bronchial mucosa from non-smokers and smokers. ICC, SFA, and WB showed that 16HBE and HFL-1 cells featured nuclear Hsp10, before and after CSE exposure; TEM immunogold further confirmed this observation. Proteomics data showed that CSE stimulation did not increase the levels of Hsp10 but did elicit qualitative changes as indicated by molecular weight and isoelectric point shifts. Bioinformatics analyses indicated that Hsp10 can localize in extramitochondrial sites, such as the nucleus, even if Hsp10 lacks known DNA-binding motifs or nuclear import signals. Hsp10 nuclear levels increased after CSE stimulation in HFL-1, indicating cytosol to nucleus migration, and although Hsp10 did not bind DNA, it bound a DNA-associated protein as suggested by CPE/gel retardation experiments. Data reported here indicate that in human cells of the respiratory mucosa there are at least three different intracellular locales for Hsp10: mitochondrial, nuclear, and cyto- solic. Further experiments are en route for the definition of the mechanisms underlying the transfer of Hsp10 to the nucleus and other cellular/extracellular compartments. This work was supported by grants from University of Palermo (FFR 2012) to GLR

A multipronged approach to unveil the emerging role of Hsp60 in chronic obstructive pulmonary disease

Inflammation is a major component of chronic obstructive pulmonary disease (COPD) and its cause and mechanisms are still incompletely understood. For example, the role of heat shock proteins (Hsps), many of which are molecular chaperones, has not been explored in detail in COPD, despite the fact that these molecules are known to participate in inflammation in other diseases. It has been shown that extracellular Hsps can signal certain types of T cells, macrophages, dendritic cells, and neutrophils and, thereby, elicit inflammation and immunity. However, these phenomena have not been investigated in COPD despite: a) the increasing awareness of Hsp participation in inflammation and immunity; and b) the fact that this disease is waiting for new knowledge to benefit from effective treatment and continues to be one of the commonest and most serious illnesses in the Western countries. We developed a strategy to study Hsps in COPD involving a multipronged approach, using in vivo and in vitro methods, which would, at least in part, compensate for the limitations inherent to the analysis of human diseases. We determined the levels of six Hsps in bronchial mucosa biopsies, as well as several inflammatory markers, from patients at various stages compared to smoker and non-smoker controls by immunohistochemistry, and found significant increase of Hsp60, Hsp10, and Hsp40 in COPD but no changes for Hsp27, Hsp70 and Hsp90. We also found that the increase in Hsp60 positively correlated with number of neutrophils, and it localized in them. Hsp60 has been implicated in human inflammatory pathology; hence it was pertinent to investigate whether the chaperonin originated only in the neutrophils or also in other cells. In vitro experiments showed that in bronchial epithelial cells submitted to oxidative stress, a characteristic of COPD mucosa, Hsp60 was overexpressed and was released into the extracellular medium. Other measurements indicated that NFkB-p65 was involved in the hsp60-gene upregulation whereas HSF-1 apparently was not. All the data we obtained using a battery of complementary in vivo and in vitro methods coincided to indicate that Hsp60 plays an active role in inflammation in COPD. Hence, one can infer that the chaperonin does contribute to the etiology and/or pathogenesis of COPD and that it is pertinent to investigate this aspect of Hsp60 biology-COPD pathology with renewed intensity. The results could have a significant impact on the developing of strategies for diagnosis, determining prognosis, and treatment that should be centered on Hsp60

Convergent Sets of Data from In Vivo and In Vitro Methods Point to an Active Role of Hsp60 in Chronic Obstructive Pulmonary Disease Pathogenesis

BACKGROUND: It is increasingly clear that some heat shock proteins (Hsps) play a role in inflammation. Here, we report results showing participation of Hsp60 in the pathogenesis of chronic obstructive pulmonary diseases (COPD), as indicated by data from both in vivo and in vitro analyses. METHODS AND RESULTS: Bronchial biopsies from patients with stable COPD, smoker controls with normal lung function, and non-smoker controls were studied. We quantified by immunohistochemistry levels of Hsp10, Hsp27, Hsp40, Hsp60, Hsp70, Hsp90, and HSF-1, along with levels of inflammatory markers. Hsp10, Hsp40, and Hsp60 were increased during progression of disease. We found also a positive correlation between the number of neutrophils and Hsp60 levels. Double-immunostaining showed that Hsp60-positive neutrophils were significantly increased in COPD patients. We then investigated in vitro the effect on Hsp60 expression in bronchial epithelial cells (16HBE) caused by oxidative stress, a hallmark of COPD mucosa, which we induced with H\u2082O\u2082. This stressor determined increased levels of Hsp60 through a gene up-regulation mechanism involving NFkB-p65. Release of Hsp60 in the extracellular medium by the bronchial epithelial cells was also increased after H\u2082O\u2082 treatment in the absence of cell death. CONCLUSIONS: This is the first report clearly pointing to participation of Hsps, particularly Hsp60, in COPD pathogenesis. Hsp60 induction by NFkB-p65 and its release by epithelial cells after oxidative stress can have a role in maintaining inflammation, e.g., by stimulating neutrophils activity. The data open new scenarios that might help in designing efficacious anti-inflammatory therapies centered on Hsp60 and applicable to COP