Therapeutic Effects of Mesenchymal/Stromal Stem Cells and Their Derived Extracellular Vesicles in Rheumatoid Arthritis

Currently available therapies for rheumatoid arthritis (RA) are inadequate to alleviate the inflammation and reduce joint damage. While the immune-regulatory effect of human mesenchymal/stromal stem cells (MSCs) extracellular vesicles (EVs) has been tested in many inflammation-related diseases, little is known regarding their effect on patients with RA. Thus, we assessed the effect of human MSCs and MSC-EVs (from naïve or IFN-β-primed MSCs) on CD4+ T cells from patients with RA. Moreover, we investigated the effect of MSC-EVs on RA patients-derived synovial fibroblasts (FLS). MSC-EVs were prepared using a PEG precipitation followed by ultracentrifugation-based protocol. Applied to RA CD4+ T cells, EVs from IFN-β-primed MSCs, suppressed the expression of more key RA-associated cytokines (IL-4, GM-CSF IFN-γ, IL-2, TNF-α), and decreased CD4+ T-cell polyfunctionality than MSCs or EVs from naïve MSCs. MSCs mediated a slight decrease in the frequency of T-regulatory cells, while MSC-EVs rescued the frequency of T-regulatory cells. MSCs significantly inhibited CD4+ T-cell proliferation (P < .05), while no inhibition was observed in response to EV preparations. EVs from IFN-β-primed MSCs inhibited (P < .01) RA FLS migration and downregulated (P < .05) RA FLS surface markers CD34 and HLA-DR. Collectively, we demonstrated the immune-modulatory function of MSCs and their derived EVs in RA CD4+ T cells, which could be further enhanced by priming MSCs with IFN-β. Moreover, EVs from IFN-β-primed MSCs more efficiently inhibit RA FLS migration, and expression of RA FLS-related surface markers, suggesting these EVs as a potent therapy for RA.

Mechanically activated mesenchymal-derived bone cells drive vessel formation via an extracellular vesicle mediated mechanism

Blood vessel formation is an important initial step for bone formation during development as well as during remodelling and repair in the adult skeleton. This results in a heavily vascularized tissue where endothelial cells and skeletal cells are constantly in crosstalk to facilitate homeostasis, a process that is mediated by numerous environmental signals, including mechanical loading. Breakdown in this communication can lead to disease and/or poor fracture repair. Therefore, this study aimed to determine the role of mature bone cells in regulating angiogenesis, how this is influenced by a dynamic mechanical environment, and understand the mechanism by which this could occur. Herein, we demonstrate that both osteoblasts and osteocytes coordinate endothelial cell proliferation, migration, and blood vessel formation via a mechanically dependent paracrine mechanism. Moreover, we identified that this process is mediated via the secretion of extracellular vesicles (EVs), as isolated EVs from mechanically stimulated bone cells elicited the same response as seen with the full secretome, while the EV-depleted secretome did not elicit any effect. Despite mechanically activated bone cell-derived EVs (MA-EVs) driving a similar response to VEGF treatment, MA-EVs contain minimal quantities of this angiogenic factor. Lastly, a miRNA screen identified mechanoresponsive miRNAs packaged within MA-EVs which are linked with angiogenesis. Taken together, this study has highlighted an important mechanism in osteogenic-angiogenic coupling in bone and has identified the mechanically activated bone cell-derived EVs as a therapeutic to promote angiogenesis and potentially bone repair.

Perinatal derivatives: How to best validate their immunomodulatory functions

Perinatal tissues, mainly the placenta and umbilical cord, contain a variety of different somatic stem and progenitor cell types, including those of the hematopoietic system, multipotent mesenchymal stromal cells (MSCs), epithelial cells and amnion epithelial cells. Several of these perinatal derivatives (PnDs), as well as their secreted products, have been reported to exert immunomodulatory therapeutic and regenerative functions in a variety of pre-clinical disease models. Following experience with MSCs and their extracellular vesicle (EV) products, successful clinical translation of PnDs will require robust functional assays that are predictive for the relevant therapeutic potency. Using the examples of T cell and monocyte/macrophage assays, we here discuss several assay relevant parameters for assessing the immunomodulatory activities of PnDs. Furthermore, we highlight the need to correlate the in vitro assay results with preclinical or clinical outcomes in order to ensure valid predictions about the in vivo potency of therapeutic PnD cells/products in individual disease settings.

Pre-Clinical In Vitro Models Used in Cancer Research: Results of a Worldwide Survey

Simple Summary

Cancer cell lines, grown on plastic dishes i.e., two-dimensional (2D), are routinely used in cancer research, e.g., when evaluating the effectiveness of potential anti-cancer drugs before proceeding to studies in animal models and then human clinical trials. Stop/go decisions are generally made from these initial studies. As only ~10% of potential anti-cancer drugs succeed during clinical development, this suggests that these models are inadequate. Cells grown as three-dimensional (3D) models, akin to a tumor mass and with other cells that would naturally occur in its environment, should be more clinically relevant. We performed a worldwide survey, open to cancer researchers at all stages and in all settings, to find out what models they use; for what purposes, and why they chose those models. The majority reported using 2D models only, mainly due to lack of experience and costs but expressed interest in 3D cultures. Guidelines on how to develop such models cost-effectively are needed.

Abstract

To develop and subsequently get cancer researchers to use organotypic three-dimensional (3D) models that can recapitulate the complexity of human in vivo tumors in an in vitro setting, it is important to establish what in vitro model(s) researchers are currently using and the reasons why. Thus, we developed a survey on this topic, obtained ethics approval, and circulated it throughout the world. The survey was completed by 101 researchers, across all career stages, in academia, clinical or industry settings. It included 40 questions, many with multiple options. Respondents reported on their field of cancer research; type of cancers studied; use of two-dimensional (2D)/monolayer, 2.5D and/or 3D cultures; if using co-cultures, the cell types(s) they co-culture; if using 3D cultures, whether these involve culturing the cells in a particular way to generate spheroids, or if they use additional supports/scaffolds; techniques used to analyze the 2D/2.5D/3D; and their downstream applications. Most researchers (>66%) only use 2D cultures, mainly due to lack of experience and costs. Despite most cancer researchers currently not using the 3D format, >80% recognize their importance and would like to progress to using 3D models. This suggests an urgent need to standardize reliable, robust, reproducible methods for establishing cost-effective 3D cell culture models and their subsequent characterization.

Exercise Training and Circulating Small Extracellular Vesicles: Appraisal of Methodological Approaches and Current Knowledge

In response to acute exercise, an array of metabolites, nucleic acids, and proteins are enriched in circulation. Collectively termed "exercise factors," these molecules represent a topical area of research given their speculated contribution to both acute exercise metabolism and adaptation to exercise training. In addition to acute changes induced by exercise, the resting profile of circulating exercise factors may be altered by exercise training. Many exercise factors are speculated to be transported in circulation as the cargo of extracellular vesicles (EVs), and in particular, a sub-category termed "small EVs." This review describes an overview of exercise factors, small EVs and the effects of exercise, but is specifically focused on a critical appraisal of methodological approaches and current knowledge in the context of changes in the resting profile small EVs induced by exercise training, and the potential bioactivities of preparations of these "exercise-trained" small EVs. Research to date can only be considered preliminary, with interpretation of many studies hindered by limited evidence for the rigorous identification of small EVs, and the conflation of acute and chronic responses to exercise due to sample timing in proximity to exercise. Further research that places a greater emphasis on the rigorous identification of small EVs, and interrogation of potential bioactivity is required to establish more detailed descriptions of the response of small EVs to exercise training, and consequent effects on exercise adaptation.

Evidence for the Need to Evaluate More Than One Source of Extracellular Vesicles, Rather Than Single or Pooled Samples Only, When Comparing Extracellular Vesicles Separation Methods

Simple Summary

Extracellular vesicles (EVs) are packages of information released from cells and are often described as mini maps of their cells of origin. EVs have many uses. For example, those found in the blood of cancer patients may inform us about tumor growth, spread, immune suppression, and drug response/resistance. EVs from other sources, inducing certain types of cells grown under laboratory conditions, have potential as therapeutics and drug delivery vehicles. For this reason, a few studies have compared methods of collecting EVs, but typically using only one EV source for the comparison. We had concerns that testing one source and extrapolating to others may not be adequate. To test this, we selected three HER2-positive breast cancer cell lines that grow in exactly the same type of fluid. We collected the fluid and tested two ways of separating the EVs from the fluid. We studied them based on seven characteristics. Both EV separation methods provided reproducible results for any of the given cell lines. However, the characteristics of the EV isolates were cell line- and method-dependent. Thus, we recommend not relying on a single EV source when comparing and selecting separation techniques for fundamental research or exploitation for clinical utility.

Abstract

To study and exploit extracellular vesicles (EVs) for clinical benefit as biomarkers, therapeutics, or drug delivery vehicles in diseases such as cancer, typically we need to separate them from the biofluid into which they have been released by their cells of origin. For cultured cells, this fluid is conditioned medium (CM). Previous studies comparing EV separation approaches have typically focused on CM from one cell line or pooled samples of other biofluids. We hypothesize that this is inadequate and that extrapolating from a single source of EVs may not be informative. Thus, in our study of methods not previous compared (i.e., the original differential ultracentrifugation (dUC) method and a PEG followed by ultracentrifugation (PEG + UC) method), we analyzed CM from three different HER2-positive breast cancer cell lines (SKBR3, EFM192A, HCC1954) that grow in the same culture medium type. CM from each was collected and equally divided between both protocols. The resulting isolates were compared on seven characteristics/parameters including particle size, concentration, structure/morphology, protein content, purity, detection of five EV markers, and presence of HER2. Both dUC and PEG + UC generated reproducible data for any given breast cancer cell lines’ CM. However, the seven characteristics of the EV isolates were cell line- and method-dependent. This suggests the need to include more than one EV source, rather than a single or pooled sample, when selecting an EV separation method to be advanced for either research or clinical purposes.

Mesenchymal Stem Cell Derived Extracellular Vesicles for Tissue Engineering and Regenerative Medicine Applications

Mesenchymal stem cells (MSCs) are being extensively investigated for their potential in tissue engineering and regenerative medicine. However, recent evidence suggests that the beneficial effects of MSCs may be manifest by their released extracellular vesicles (EVs); typically not requiring the administration of MSCs. This evidence, predominantly from pre-clinical in vitro and in vivo studies, suggests that MSC-EVs may exhibit substantial therapeutic properties in many pathophysiological conditions, potentially restoring an extensive range of damaged or diseased tissues and organs. These benefits of MSC EVs are apparently found, regardless of the anatomical or body fluid origin of the MSCs (and include e.g., bone marrow, adipose tissue, umbilical cord, urine, etc). Furthermore, early indications suggest that the favourable effects of MSC-EVs could be further enhanced by modifying the way in which the donor MSCs are cultured (for example, in hypoxic compared to normoxic conditions, in 3D compared to 2D culture formats) and/or if the EVs are subsequently bio-engineered (for example, loaded with specific cargo). So far, few human clinical trials of MSC-EVs have been conducted and questions remain unanswered on whether the heterogeneous population of EVs is beneficial or some specific sub-populations, how best we can culture and scale-up MSC-EV production and isolation for clinical utility, and in what format they should be administered. However, as reviewed here, there is now substantial evidence supporting the use of MSC-EVs in tissue engineering and regenerative medicine and further research to establish how best to exploit this approach for societal and economic benefit is warranted.

Minimal information for studies of extracellular vesicles 2018 (MISEV2018): a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines

The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles ("MISEV") guidelines for the field in 2014. We now update these "MISEV2014" guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points.

Abstract LB-116: Neuromedin U drives increased expression of TGFβ1 in HER2-positive breast cancer cells and their extracellular vesicles: a novel biomarker of response to HER-targeted drugs

HER-targeted therapies are an attractive approach for HER2-overexpressing breast cancer; unfortunately, not all tumours are responsive and some that initially respond later develop resistance to therapy. Such drug-resistance is often associated with enhanced evasion from the anti-tumour immune response, further compromising the outcome for patients. Neuromedin U (NmU) is a neuropeptide belonging to the neuromedin family. Recently, a significant association between NmU signalling and cancer has been described by our group, with NmU expression correlated with increased aggressiveness and resistance to targeted anti-cancer therapy, although the mechanism through which it exerts this effect remains unexplained. To elucidate this mechanism and find out whether NmU also enhances immune evasion, HER2-positive breast cancer cells were cultured continuously in the presence of HER-targeting drugs lapatinib and neratinib to obtain resistant variants; cells stably transfected with NmU were also used. Extracellular vesicles (EVs) released by different cell variants were analysed for the presence of markers associated with immunosuppression. HER-targeted drug resistant cell lines showed increased secreted levels of TGFβ1, a well-known immunosuppressive cytokine produced by cancer stem cells. TGFβ1 levels were also increased in EVs derived from these cells; these effects were at least partly mediated by NmU, as overexpression of this peptide also resulted in increased TGFβ1 in cell supernatant and EVs. Blocking of TGFβ1 with a neutralising antibody decreased cell migration mediated by NmU, suggesting that TGFβ1 is a downstream mediator of NmU effects. Moreover, NmU-transfected cells also showed increased expression of EMT marker β-catenin, indicating increased function of TGFβ1 in NmU-overexpressing cells. Interestingly, TGFβ1 levels were substantially lower in EVs isolated from the serum of HER2-positive breast cancer patients showing complete (n = 13) or partial (n = 15) response to HER-targeting drug treatment compared to those that did not respond (n = 2). Altogether, our results show a new mechanism of action of NmU in HER2-positive breast cancer cells that promotes a more aggressive phenotype and likely enhances evasion of the anti-tumour immune response. Interestingly, EV levels of TGFβ1 correlate with levels of HER-targeted drug resistance, suggesting it could be used as a biomarker of response in breast cancer patients.

Acknowledgements: HRB's Health Research Award [HRA-POR-2014-658]; Irish Cancer Society's Breast-Predict [CCRC13GAL]; and HEA's PRTLI Cycle 5 support of TBSI.

Citation Format: Vanesa G. Martinez, Lorraine O’Driscoll. Neuromedin U drives increased expression of TGFβ1 in HER2-positive breast cancer cells and their extracellular vesicles: a novel biomarker of response to HER-targeted drugs. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-116.

Docetaxel-resistance in prostate cancer: evaluating associated phenotypic changes and potential for resistance transfer via exosomes

Background

Hormone-refractory prostate cancer remains hindered by inevitable progression of resistance to first-line treatment with docetaxel. Recent studies suggest that phenotypic changes associated with cancer may be transferred from cell-to-cell via microvesicles/exosomes. Here we aimed to investigate phenotypic changes associated with docetaxel-resistance in order to help determine the complexity of this problem and to assess the relevance of secreted exosomes in prostate cancer.

Methodology/Principal Findings

Docetaxel-resistant variants of DU145 and 22Rv1 were established and characterised in terms of cross-resistance, morphology, proliferation, motility, invasion, anoikis, colony formation, exosomes secretion their and functional relevance. Preliminary analysis of exosomes from relevant serum specimens was also performed. Acquired docetaxel-resistance conferred cross-resistance to doxorubicin and induced alterations in motility, invasion, proliferation and anchorage-independent growth. Exosomes expelled from DU145 and 22Rv1 docetaxel-resistant variants (DU145RD and 22Rv1RD) conferred docetaxel-resistance to DU145, 22Rv1 and LNCap cells, which may be partly due to exosomal MDR-1/P-gp transfer. Exosomes from prostate cancer patients’ sera induced increased cell proliferation and invasion, compared to exosomes from age-matched controls. Furthermore, exosomes from sera of patients undergoing a course of docetaxel treatment compared to matched exosomes from the same patients prior to commencing docetaxel treatment, when applied to both DU145 and 22Rv1 cells, showed a correlation between cellular response to docetaxel and patients’ response to treatment with docetaxel.

Conclusions/Significance

Our studies indicate the complex and multifaceted nature of docetaxel-resistance in prostate cancer. Furthermore, our in vitro observations and preliminary clinical studies indicate that exosomes may play an important role in prostate cancer, in cell-cell communication, and thus may offer potential as vehicles containing predictive biomarkers and new therapeutic targets.