In vitro characterization of 3D culture-based differentiation of human liver stem cells

Introduction: The lack of functional hepatocytes poses a significant challenge for drug safety testing and therapeutic applications due to the inability of mature hepatocytes to expand and their tendency to lose functionality in vitro. Previous studies have demonstrated the potential of Human Liver Stem Cells (HLSCs) to differentiate into hepatocyte-like cells within an in vitro rotary cell culture system, guided by a combination of growth factors and molecules known to regulate hepatocyte maturation. In this study, we employed a matrix multi-assay approach to comprehensively characterize HLSC differentiation. Methods: We evaluated the expression of hepatic markers using qRT-PCR, immunofluorescence, and Western blot analysis. Additionally, we measured urea and FVIII secretion into the supernatant and developed an updated indocyanine green in vitro assay to assess hepatocyte functionality. Results: Molecular analyses of differentiated HLSC aggregates revealed significant upregulation of hepatic genes, including CYP450, urea cycle enzymes, and uptake transporters exclusively expressed on the sinusoidal side of mature hepatocytes, evident as early as 1 day post-differentiation. Interestingly, HLSCs transiently upregulated stem cell markers during differentiation, followed by downregulation after 7 days. Furthermore, differentiated aggregates demonstrated the ability to release urea and FVIII into the supernatant as early as the first 24 h, with accumulation over time. Discussion: These findings suggest that a 3D rotation culture system may facilitate rapid hepatic differentiation of HLSCs. Despite the limitations of this rotary culture system, its unique advantages hold promise for characterizing HLSC GMP batches for clinical applications.

Extracellular Vesicles as Biomarkers of Acute Graft-vs.-Host Disease After Haploidentical Stem Cell Transplantation and Post-Transplant Cyclophosphamide

Even with high-dose post-transplant cyclophosphamide (PT-Cy) which was initially introduced for graft-versus-host disease (GvHD) prevention in the setting of HLA-haploidentical transplantation, both acute and chronic GvHDs remain a major clinical challenge. Despite improvements in the understanding of the pathogenesis of both acute and chronic GvHDs, reliable biomarkers that predict their onset have yet to be identified. We recently studied the potential correlation between extracellular vesicles (EVs) and the onset of acute (a)GvHD in transplant recipients from related and unrelated donors. In the present study, we further investigated the role of the expression profile of membrane proteins and their microRNA (miRNA) cargo (miRNA100, miRNA155, and miRNA194) in predicting the onset of aGvHD in haploidentical transplant recipients with PT-Cy. Thirty-two consecutive patients were included. We evaluated the expression profile of EVs, by flow cytometry, and their miRNA cargo, by real-time PCR, at baseline, prior, and at different time points following transplant. Using logistic regression and Cox proportional hazard models, a significant association between expression profiles of antigens such as CD146, CD31, CD140a, CD120a, CD26, CD144, and CD30 on EVs, and their miRNA cargo with the onset of aGvHD was observed. Moreover, we also investigated a potential correlation between EV expression profile and cargo with plasma biomarkers (e.g., ST2, sTNFR1, and REG3a) that had been associated with aGVHD previously. This analysis showed that the combination of CD146, sTNFR1, and miR100 or miR194 strongly correlated with the onset of aGvHD (AUROC >0.975). A large prospective multicenter study is currently in progress to validate our findings.

Human Liver Stem Cell-Derived Extracellular Vesicles Target Hepatic Stellate Cells and Attenuate Their Pro-fibrotic Phenotype

Liver fibrosis occurs in response to chronic liver injury and is characterized by an excessive deposition of extracellular matrix. Activated hepatic stellate cells are primarily responsible for this process. A possible strategy to counteract the development of hepatic fibrosis could be the reversion of the activated phenotype of hepatic stellate cells. Extracellular vesicles (EVs) are nanosized membrane vesicles involved in intercellular communication. Our previous studies have demonstrated that EVs derived from human liver stem cells (HLSCs), a multipotent population of adult stem cells of the liver with mesenchymal-like phenotype, exert in vivo anti-fibrotic activity in the liver. However, the mechanism of action of these EVs remains to be determined. We set up an in vitro model of hepatic fibrosis using a human hepatic stellate cell line (LX-2) activated by transforming growth factor-beta 1 (TGF-β1). Then, we investigated the effect of EVs obtained from HLSCs and from human bone marrow-derived mesenchymal stromal cells (MSCs) on activated LX-2. The incubation of activated LX-2 with HLSC-EVs reduced the expression level of alpha-smooth muscle actin (α-SMA). Conversely, MSC-derived EVs induced an increase in the expression of pro-fibrotic markers in activated LX-2. The analysis of the RNA cargo of HLSC-EVs revealed the presence of several miRNAs involved in the regulation of fibrosis and inflammation. Predictive target analysis indicated that several microRNAs (miRNAs) contained into HLSC-EVs could possibly target pro-fibrotic transcripts. In particular, we demonstrated that HLSC-EVs shuttled miR-146a-5p and that treatment with HLSC-EVs increased miR-146a-5p expression in LX-2. In conclusion, this study demonstrates that HLSC-EVs can attenuate the activated phenotype of hepatic stellate cells and that their biological effect may be mediated by the delivery of anti-fibrotic miRNAs, such as miR-146a-5p.

Human Liver Stem Cells: A Liver-Derived Mesenchymal Stromal Cell-Like Population With Pro-regenerative Properties

Human liver stem cells (HLSCs) were described for the first time in 2006 as a new stem cell population derived from healthy human livers. Like mesenchymal stromal cells, HLSCs exhibit multipotent and immunomodulatory properties. HLSCs can differentiate into several lineages under defined in vitro conditions, such as mature hepatocytes, osteocytes, endothelial cells, and islet-like cell organoids. Over the years, HLSCs have been shown to contribute to tissue repair and regeneration in different in vivo models, leading to more than five granted patents and over 15 peer reviewed scientific articles elucidating their potential therapeutic role in various experimental pathologies. In addition, HLSCs have recently completed a Phase 1 study evaluating their safety post intrahepatic injection in infants with inherited neonatal onset hyperammonemia. Even though a lot of progress has been made in understanding HLSCs over the past years, some important questions regarding the mechanisms of action remain to be elucidated. Among the mechanisms of interaction of HLSCs with their environment, a paracrine interface has emerged involving extracellular vesicles (EVs) as vehicles for transferring active biological materials. In our group, the EVs derived from HLSCs have been studied in vitro as well as in vivo. Our attention has mainly been focused on understanding the in vivo ability of HLSC–derived EVs as modulators of tissue regeneration, inflammation, fibrosis, and tumor growth. This review article aims to discuss in detail the role of HLSCs and HLSC-EVs in these processes and their possible future therapeutic applications.

Serum Derived Extracellular Vesicles Mediated Delivery of Synthetic miRNAs in Human Endothelial Cells

Extracellular vesicles (EVs) have emerged in the last decades as a cell-to-cell communication mechanism. One of their mechanism of action is the direct delivery of their cargo, composed of bioactive molecules to target cells. Different methods (direct electroporation, cell transfection, chemical transfection) were developed to vehicle therapeutic molecules through EVs. However, most of these techniques presented some limitations such as EV disruption and aggregation. In the present study, we demonstrated that a direct temperature-controlled co-incubation of EVs with defined miRNAs is a stable method to deliver information to target cells without affecting EV constitutive content. We chose serum as an easy and abundant source of EVs applicable to autologous treatment after EV modification. Exogenous cel-miR-39 loaded on serum EVs (SEVs) was taken up by human endothelial cells, demonstrating an adequate miRNA loading efficacy based on the co-incubation method. Moreover, SEVs co-incubation with the angiomiRNA-126 (miR-126) enhanced their angiogenic properties in vitro and in vivo by increasing the capacity to induce capillary-like structure formation of human endothelial cells. MiR-126 loaded EVs were also shown to stimulate mouse endothelial cells to invade Matrigel plugs and create more vessels with respect to the EV naive counterpart. When SEVs were loaded with miR-19b, an anti-angiogenic miRNA, they were able to reduce Vascular endothelial growth factors (VEGF) pro-angiogenic capacity, supporting the selective biological effect mediated by the carried miRNA. Lastly, we identified Annexin A2 (ANXA2) as one of the molecules involved in the exogenous RNA binding to serum EV surface, favoring miRNA delivery to target endothelial cells for potential therapeutic application.

Coincubation as miR-Loading Strategy to Improve the Anti-Tumor Effect of Stem Cell-Derived EVs

Extracellular vesicles are considered a novel therapeutic tool, due to their ability to transfer their cargoes to target cells. Different strategies to directly load extracellular vesicles with RNA species have been proposed. Electroporation has been used for the loading of non-active vesicles; however, the engineering of vesicles already carrying a therapeutically active cargo is still under investigation. Here, we set up a coincubation method to increase the anti-tumor effect of extracellular vesicles isolated from human liver stem cells (HLSC-EVs). Using the coincubation protocol, vesicles were loaded with the anti-tumor miRNA-145, and their effect was evaluated on renal cancer stem cell invasion. Loaded HLSC-EVs maintained their integrity and miR transfer ability. Loaded miR-145, but not miR-145 alone, was protected by RNAse digestion, possibly due to its binding to RNA-binding proteins on HLSC-EV surface, such as Annexin A2. Moreover, miR-145 coincubated HLSC-EVs were more effective in inhibiting the invasive properties of cancer stem cells, in comparison to naïve vesicles. The protocol reported here exploits a well described property of extracellular vesicles to bind nucleic acids on their surface and protect them from degradation, in order to obtain an effective miRNA loading, thus increasing the activity of therapeutically active naïve extracellular vesicles.

Endothelial cell-derived extracellular vesicles exert cardio-protective effect via their protein cargo

Background

Extracellular vesicles (EV) are recognized as carriers of relevant biological effects and have been identified as regulators of cell-to-cell communication contributing to several patho-physiological processes. These processes include angiogenesis/coagulation/tissue repair/inflammation. In ischemia/reperfusion (I/R) settings, along with the direct effects of the I/R itself, paracrine mechanisms associated with the activation of the inflammatory response, primary involving endothelial cells, are crucial drivers of both vessel and cardiomyocyte damage.

Purpose

Since in models of myocardial I/R injury the role of EV released from endothelial cells is still unclear, our hypothesis was to provide insight on this specific topic. To this end, naïve endothelial cell (EC)-derived EV (eEV) and eEV released in response to the pro-inflammatory cytokine interleukin-3 (IL-3) (eEV-IL-3) have been evaluated on different I/R models.

Methods

eEV were characterized by MACSPlex-Exosome-Kit and western blot analysis. For the in-vitro hypoxia-reoxygenation (H/R) experiments, H9c2 or EC were pretreated with eEV, eEV-IL-3 (1x104 EV/cell) or IL-3 (10ng/ml) for 2 hours and then exposed to hypoxia (1% O2, 5% CO2) for additional 2 hours in the presence of eEV, eEV-IL-3 or IL-3 and subsequently reoxygenated (21% O2 and 5% CO2) for 1 hour. To verify the effect of EC treated with eEV, eEV-IL-3 or IL-3 on H9c2 and subjected to H/R protocol, transwell assay was used. At the end of the H/R protocol, cell viability was assessed. For ex-vivo experiments, isolated rat hearts, pretreated with a buffer containing EV (from EC pretreated or not with IL-3), were subjected to 30 minutes global normothermic ischemia and 1 hour reperfusion. Triton infusion was also used as a model of endothelial damage. At the end of I/R, the infarct size was measured and expressed as a percentage of total left ventricular mass (LVM). The role of eNOS/guanylyl-cyclase/MEK1/2 pathways in mediating eEV biological effects was also evaluated using different inhibitors both in in-vitro and ex-vivo models. Finally, protein profiles of eEV and eEV-IL-3 were analyzed using label free mass spectrometry.

Results

eEV and eEV-IL-3 protect EC, but not H9c2 exposed to H/R protocol, while eEV, but not eEV-IL-3-treatment limits I/R injury in the rat heart. Rat hearts pre-treated with triton significantly avoid eEV-induced cardio-protection. Transwell assay showed a reduction of H9C2 mortality after treatment with both eEV and eEV-IL-3. Proteomic analysis revealed that MEK1/2 and the endothelial-NOS (eNOS)-antagonist caveolin-1 were differentially expressed in eEV and eEV-IL-3. The use of eNOS/guanylyl-cyclase/MEK1/2 inhibitors prevented eEV-induced cardio-protection.

Conclusions

These observations indicate that eEV, but not eEV-IL-3, have cardio-protective effects when given as preconditioning agents. We have also shown that the activation of eNOS/GC/MEK1/2 pathway is crucial for eEV-mediated cardio-protection.

Funding Acknowledgement

Type of funding source: None

Islet-Like Structures Generated In Vitro from Adult Human Liver Stem Cells Revert Hyperglycemia in Diabetic SCID Mice

A potential therapeutic strategy for diabetes is the transplantation of induced-insulin secreting cells. Based on the common embryonic origin of liver and pancreas, we studied the potential of adult human liver stem-like cells (HLSC) to generate in vitro insulin-producing 3D spheroid structures (HLSC-ILS). HLSC-ILS were generated by a one-step protocol based on charge dependent aggregation of HLSC induced by protamine. 3D aggregation promoted the spontaneous differentiation into cells expressing insulin and several key markers of pancreatic β cells. HLSC-ILS showed endocrine granules similar to those seen in human β cells. In static and dynamic in vitro conditions, such structures produced C-peptide after stimulation with high glucose. HLSC-ILS significantly reduced hyperglycemia and restored a normo-glycemic profile when implanted in streptozotocin-diabetic SCID mice. Diabetic mice expressed human C-peptide and very low or undetectable levels of murine C-peptide. Hyperglycemia and a diabetic profile were restored after HLSC-ISL explant. The gene expression profile of in vitro generated HLSC-ILS showed a differentiation from HLSC profile and an endocrine commitment with the enhanced expression of several markers of β cell differentiation. The comparative analysis of gene expression profiles after 2 and 4 weeks of in vivo implantation showed a further β-cell differentiation, with a genetic profile still immature but closer to that of human islets. In conclusion, protamine-induced spheroid aggregation of HLSC triggers a spontaneous differentiation to an endocrine phenotype. Although the in vitro differentiated HLSC-ILS were immature, they responded to high glucose with insulin secretion and in vivo reversed hyperglycemia in diabetic SCID mice.

P1600KIDNEY PERFUSION WITH MESENCHYMAL STROMAL CELLS OR EXTRACELLULAR VESICLES PREVENTS ISCHAEMIC DAMAGE THROUGH CD73/ADO SYSTEM IN A RAT MODEL OF DCD DONATION

Background and Aims

Adenosine (Ado), the main substrate of ATP, is a potent endogenous anti-inflammatory nucleoside. Hypoxia induces ATP depletion, AMP extracellular increase that is phosphohydrolyzed to ADO by the enzyme ecto-5′-nucleotidase (CD73). Constitutive CD73 expression is higher in deep cortex outer medulla that is the most vulnerable region to ischemic injury. Notably CD73 is also expressed on Mesenchymal Stromal Cell (MSC) and is essential phenotypic marker.

Previously in a rat model of Donation after Circulatory Death (DCD), we demonstrated that the perfusion of ischemic kidney with MSC or MSC derived Extracellular Vesicles (EV) protects tissue up regulating mitochondrial energetic metabolism genes.

The aim of this study was to investigate the role of CD73/Ado system in MSC/EV protection from ischemia.

Method

Fisher rats were used as kidney donors and Lewis rats as MSC donors. MSC missing CD73 were produced by electroporation in the presence of specific siRNA to block CD73 expression (siMSC). EV were isolated from supernatants of MSC and siMSC (siEV) medium through differential ultracentrifugations. Size distribution and enumeration analysis were performed using NanoSight NS300. EV phenotypic characterization was performed in flow cytometer using CD45, CD49e, CD63, CD9, CD81 and CD73 monoclonal antibodies.

DCD model was obtained by renal artery clamping for 20 minutes. This warm ischemia time represents the “no touch period” imposed by the Italian law to death declaration. After nephrectomy, kidneys were perfused in hypothermia (4°C) with Belzer Solution (BS), or BS supplemented with 3x106 MSC (MSC) or BS supplemented with 28,5x109 EV/siEV (EV/siEV). The effluent fluid (EF) was collected at the beginning (T0), every hours (T1, T2, T3) and at the end of the perfusion (T4). Ado and ATP determinations in EF and tissues were performed by HPLC and ELISA, respectively.

Results

EF Ado was significantly higher in MSC vs BS from T1 and in EV vs BS from T0 to T4 (p<0,05). Only in EV, EF Ado concentration increased over time from T2 to T4 ( p<0,05), while in BS, MSC and siEV there was a steady trend over time. There was a negative correlation between EF and tissue levels of Ado (r=0,67 p=0,01). Tissue ATP was higher in EV and significantly in MSC vs BS (p<0,01). There was a negative correlation between tissue ATP and EF ADO levels (r= 0,79 p< 0,0001). Tissue ATP/Ado ratio was significantly higher in EV vs BS (p<0,01). There was a negative correlation between tissue ATP/Ado ratio and EF Ado (r= 0,84 p < 0.0001). siEV cancelled EV effects on ATP and Ado levels in EF and renal tissue.

Conclusion

CD73 expressed on MSC /EV impacts on cell energy metabolism pathway and ATP generation. This is the first evidence that MSC/EV act through CD73/Ado system to prevent ischaemic damage.

Mesenchymal Stem Cell Derived Extracellular Vesicles Ameliorate Kidney Injury in Aristolochic Acid Nephropathy

Limitations in the current therapeutic strategies for the prevention of progression of chronic kidney disease (CKD) to end stage renal disease has been a drawback to improving patient recovery. It is therefore imperative that a solution is found to alleviate this problem and improve the health and well-being of patients overall. Aristolochic acid (AA) induced nephropathy, a type of nephrotoxic CKD is characterised by cortical tubular injury, inflammation, leading to interstitial fibrosis. Extracellular vesicles derived from human bone marrow mesenchymal stem cells (MSC-EVs) display therapeutic properties in various disease models including kidney injury. In the current study, we intended to investigate the ability of MSC-EVs on ameliorating tubular injury and interstitial fibrosis in a mouse model of aristolochic acid nephropathy (AAN). The chronic model of AAN is comprised of an intraperitoneal injection of AA in NSG mice, followed by a three-day incubation period and then inoculation of MSC-EVs intravenously. This routine was performed on a weekly basis for four consecutive weeks, accompanied by the monitoring of body weight of all mice. Blood and tissue samples were collected post sacrifice. All animals administered with AA developed kidney injury and renal fibrosis. A gradual loss of body weight was observed, together with a deterioration in kidney function. Although no significant recovery was observed in weight loss following treatment with MSC-EVs, a significant reduction in: blood creatinine and blood urea nitrogen (BUN), tubular necrosis, and interstitial fibrosis was observed. In addition, infiltration of CD45 positive immune cells, fibroblasts, and pericytes which were elevated in the interstitium post AA induced injury, were also significantly reduced by MSC-EVs. Kidneys were also subjected to molecular analyses to evaluate the regulation of pro-fibrotic genes. MSC-EVs significantly reduced AA induction of the pro-fibrotic genes α-Sma, Tgfb1 and Col1a1. A downregulation in pro-fibrotic genes was also observed in fibroblasts activated by AA injured mTECs in vitro. Furthermore, meta-analyses of miRNAs downregulated by MSC-EVs, such as miR21, revealed the regulation of multiple pathways involved in kidney injury including fibrosis, inflammation, and apoptosis. These results therefore suggest that MSC-EVs could play a regenerative and anti-fibrotic role in AAN through the transfer of biologically active cargo that regulates the disease both at a protein and genetic level.

Extracellular Vesicles After Allogeneic Hematopoietic Cell Transplantation: Emerging Role in Post-Transplant Complications

Extracellular vesicles (EVs) play an important role in the cellular crosstalk by transferring bioactive molecules through biological barriers from a cell to another, thus influencing recipient cell functions and phenotype. Therefore, EVs are increasingly being explored as biomarkers of disease progression or response to therapy and as potential therapeutic agents in different contexts including in hematological malignancies. Recently, an EV role has emerged in allogeneic hematopoietic cell transplantation (allo-HCT) as well. Allogeneic hematopoietic cell transplantation often represents the only curative option in several hematological disorders, but it is associated with potentially life-threatening complications that can have a significant impact on clinical outcomes. The most common complications have been well-established and include graft-versus-host disease and infections. Furthermore, relapse remains an important cause of treatment failure. The aim of this review is to summarize the current knowledge, the potential applications, and clinical relevance of EVs in allo-HCT. Herein, we will mainly focus on the immune-modulating properties of EVs, in particular those derived from mesenchymal stromal cells, as potential therapeutic strategy to improve allo-HCT outcome. Moreover, we will briefly describe the main findings on EVs as biomarkers to monitor graft-versus-host disease onset and tumor relapse.

Extracellular vesicles from human liver stem cells inhibit renal cancer stem cell-derived tumor growth in vitro and in vivo

Cancer stem cells (CSCs) are considered as responsible for initiation, maintenance and recurrence of solid tumors, thus representing the key for tumor eradication. The antitumor activity of extracellular vesicles (EVs) derived from different stem cell sources has been investigated with conflicting results. In our study, we evaluated, both in vitro and in vivo, the effect of EVs derived from human bone marrow mesenchymal stromal cells (MSCs) and from a population of human liver stem cells (HLSCs) of mesenchymal origin on renal CSCs. In vitro, both EV sources displayed pro‐apoptotic, anti‐proliferative and anti‐invasive effects on renal CSCs, but not on differentiated tumor cells. Pre‐treatment of renal CSCs with EVs, before subcutaneous injection in SCID mice, delayed tumor onset. We subsequently investigated the in vivo effect of MSC‐ and HLSC‐EVs systemic administration on progression of CSC‐generated renal tumors. Tumor bio‐distribution analysis identified intravenous treatment as best route of administration. HLSC‐EVs, but not MSC‐EVs, significantly impaired subcutaneous tumor growth by reducing tumor vascularization and inducing tumor cell apoptosis. Moreover, intravenous treatment with HLSC‐EVs improved metastasis‐free survival. In EV treated tumor explants, we observed both the transfer and the induction of miR‐145 and of miR‐200 family members. In transfected CSCs, the same miRNAs affected cell growth, invasion and survival. In conclusion, our results showed a specific antitumor effect of HLSC‐EVs on CSC‐derived renal tumors in vivo, possibly ascribed to the transfer and induction of specific antitumor miRNAs. Our study provides further evidence for a possible clinical application of stem cell‐EVs in tumor treatment.

What's new?

Stem cell‐derived extracellular vesicles (EVs) can reprogram target cells and promote tissue repair by transferring their cargo. However, the anti‐tumor activity of EVs derived from different stem cell sources has been investigated with conflicting results. Here, the authors demonstrate for the first time the anti‐tumor effect of EVs from human liver stem cells (HLSC‐EVs) in a systemic intravenous administration model. HLSC‐EVs had a selective effect on cancer stem cells that could be ascribed to the transfer and induction of anti‐tumor miRNAs. This study highlights the potential clinical use of stem cell‐derived EVs, alone or in combination with other cancer therapies.

Extracellular Vesicles Derived from Induced Pluripotent Stem Cells Promote Renoprotection in Acute Kidney Injury Model

Induced pluripotent stem cells (iPSC) have been the focus of several studies due to their wide range of application, including in cellular therapy. The use of iPSC in regenerative medicine is limited by their tumorigenic potential. Extracellular vesicles (EV) derived from stem cells have been shown to support renal recovery after injury. However, no investigation has explored the potential of iPSC-EV in the treatment of kidney diseases. To evaluate this potential, we submitted renal tubule cells to hypoxia-reoxygenation injury, and we analyzed cell death rate and changes in functional mitochondria mass. An in vivo model of ischemia-reperfusion injury was used to evaluate morphological and functional alterations. Gene array profile was applied to investigate the mechanism involved in iPSC-EV effects. In addition, EV derived from adipose mesenchymal cells (ASC-EV) were also used to compare the potential of iPSC-EV in support of tissue recovery. The results showed that iPSC-EV were capable of reducing cell death and inflammatory response with similar efficacy than ASC-EV. Moreover, iPSC-EV protected functional mitochondria and regulated several genes associated with oxidative stress. Taken together, these results show that iPSC can be an alternative source of EV in the treatment of different aspects of kidney disease.

miR-130a and Tgfβ Content in Extracellular Vesicles Derived from the Serum of Subjects at High Cardiovascular Risk Predicts their In-Vivo Angiogenic Potential

Serum-derived extracellular vesicles (sEV) from healthy donors display in-vivo pro-angiogenic properties. To identify patients that may benefit from autologous sEV administration for pro-angiogenic purposes, sEV angiogenic capability has been evaluated in type 2 diabetic (T2DM) subjects (D), in obese individuals with (OD) and without (O) T2DM, and in subjects with ischemic disease (IC) (9 patients/group). sEV display different angiogenic properties in such cluster of individuals. miRNomic profile and TGFβ content in sEV were evaluated. We found that miR-130a and TGFβ content correlates with sEV in-vitro and in-vivo angiogenic properties, particularly in T2DM patients. Ingenuity Pathway Analysis (IPA) identified a number of genes as among the most significant miR-130a interactors. Gain-of-function experiments recognized homeoboxA5 (HOXA5) as a miR-130a specific target. Finally, ROC curve analyses revealed that sEV ineffectiveness could be predicted (Likelihood Ratio+ (LH+) = 3.3 IC 95% from 2.6 to 3.9) by comparing miR-130a and TGFβ content 'in Series'. We demonstrate that sEV from high cardiovascular risk patients have different angiogenic properties and that miR-130a and TGFβ sEV content predicts 'true ineffective sEVs'. These results provide the rationale for the use of these assays to identify patients that may benefit from autologous sEV administration to boost the angiogenetic process.

Extracellular Vesicles From Adipose Stem Cells Prevent Muscle Damage and Inflammation in a Mouse Model of Hind Limb Ischemia: Role of Neuregulin-1

OBJECTIVES

Critical hindlimb ischemia is a severe consequence of peripheral artery disease. Surgical treatment does not prevent skeletal muscle impairment or improve long-term patient outcomes. The present study investigates the protective/regenerative potential and the mechanism of action of adipose stem cell-derived extracellular vesicles (ASC-EVs) in a mouse model of hindlimb ischemia. Approach and Results: We demonstrated that ASC-EVs exert a protective effect on muscle damage by acting both on tissue microvessels and muscle cells. The genes involved in muscle regeneration were up-regulated in the ischemic muscles of ASC-EV-treated animals. MyoD expression has also been confirmed in satellite cells. This was followed by a reduction in muscle function impairment in vivo. ASC-EVs drive myoblast proliferation and differentiation in the in vitro ischemia/reoxygenation model. Moreover, ASC-EVs have shown an anti-apoptotic effect both in vitro and in vivo. Transcriptomic analyses have revealed that ASC-EVs carry a variety of pro-angiogenic mRNAs, while proteomic analyses have demonstrated an enrichment of NRG1 (neuregulin 1). A NRG1 blocking antibody used in vivo demonstrated that NRG1 is relevant to ASC-EV-induced muscle protection, vascular growth, and recruitment of inflammatory cells. Finally, bioinformatic analyses on 18 molecules that were commonly detected in ASC-EVs, including mRNAs and proteins, confirmed the enrichment of pathways involved in vascular growth and muscle regeneration/protection.

CONCLUSIONS

This study demonstrates that ASC-EVs display pro-angiogenic and skeletal muscle protective properties that are associated with their NRG1/mRNA cargo. We, therefore, propose that ASC-EVs are a useful tool for therapeutic angiogenesis and muscle protection.

HLSC-Derived Extracellular Vesicles Attenuate Liver Fibrosis and Inflammation in a Murine Model of Non-alcoholic Steatohepatitis

Extracellular vesicles (EVs) are membrane vesicles released virtually by all cell types. Several studies have shown that stem cell-derived EVs may mimic both in vitro and in vivo the biological effects of the cells. We recently demonstrated that non-alcoholic steatohepatitis (NASH) is inhibited by treatment with human liver stem cells (HLSCs). The aim of the present study was to evaluate whether EVs released by HLSCs influence the progression of NASH, induced by a diet deprived of methionine and choline, in immunocompromised mice. EV treatment was initiated after 2 weeks of diet with a biweekly administration of three different doses. Bio-distribution evaluated by optical imaging showed a preferential accumulation in normal and, in particular, in fibrotic liver. EV treatment significantly improved liver function and reduced signs of liver fibrosis and inflammation at both morphological and molecular levels. In particular, we observed that, out of 29 fibrosis-associated genes upregulated in NASH liver, 28 were significantly downregulated by EV treatment. In conclusion, HLSC-derived EVs display anti-fibrotic and anti-inflammatory effects in a model of chronic liver disease, leading to an improvement of liver function.

Renal Regenerative Potential of Extracellular Vesicles Derived from miRNA-Engineered Mesenchymal Stromal Cells

Extracellular vesicles (EVs) derived from mesenchymal stromal cells (MSCs) possess pro-regenerative potential in different animal models with renal injury. EVs contain different molecules, including proteins, lipids and nucleic acids. Among the shuttled molecules, miRNAs have a relevant role in the pro-regenerative effects of EVs and are a promising target for therapeutic interventions. The aim of this study was to increase the content of specific miRNAs in EVs that are known to be involved in the pro-regenerative effect of EVs, and to assess the capacity of modified EVs to contribute to renal regeneration in in vivo models with acute kidney injuries. To this purpose, MSCs were transiently transfected with specific miRNA mimics by electroporation. Molecular analyses showed that, after transfection, MSCs and derived EVs were efficiently enriched in the selected miRNAs. In vitro and in vivo experiments indicated that EVs engineered with miRNAs maintained their pro-regenerative effects. Of relevance, engineered EVs were more effective than EVs derived from naïve MSCs when used at suboptimal doses. This suggests the potential use of a low amount of EVs (82.5 × 10⁶) to obtain the renal regenerative effect.

Stem cell-derived extracellular vesicles inhibit and revert fibrosis progression in a mouse model of diabetic nephropathy

Extracellular vesicles (EVs) that are derived from mesenchymal stromal cells (MSCs) have been shown to reprogram injured cells by activating regenerative processes. We herein investigate the potential therapeutic effect of EVs, shed by human bone marrow MSCs and by human liver stem-like cells (HLSCs), on the progression and reversion of fibrosis in a mouse model of diabetic nephropathy, as induced by streptozotocin. After the development of nephropathy, stem cell-derived EVs were administered weekly to diabetic mice for four weeks. The stem cell-derived EV treatment, but not the fibroblast EV treatment that was used as a control, significantly ameliorated functional parameters, such as albumin/creatinine excretion, plasma creatinine and blood urea nitrogen, which are altered in diabetic mice. Moreover, the renal fibrosis that develops during diabetic nephropathy progression was significantly inhibited in stem cell EV-treated animals. A correlation was found between the down regulation of several pro-fibrotic genes in renal tissues and the anti-fibrotic effect of HLSC and MSC EVs. A comparative analysis of HLSC and MSC EV miRNA content highlighted some common and some specific patterns of miRNAs that target predicted pro-fibrotic genes. In conclusion, stem cell-derived EVs inhibit fibrosis and prevent its progression in a model of diabetes-induced chronic kidney injury.

Extracellular vesicles from human liver stem cells inhibit tumor angiogenesis

Human liver stem-like cells (HLSC) and derived extracellular vesicles (EVs) were previously shown to exhibit anti-tumor activity. In our study, we investigated whether HLSC-derived EVs (HLSC-EVs) were able to inhibit tumor angiogenesis in vitro and in vivo, in comparison with EVs derived from mesenchymal stem cells (MSC-EVs). The results obtained indicated that HLSC-EVs, but not MSC-EVs, inhibited the angiogenic properties of tumor-derived endothelial cells (TEC) both in vitro and in vivo in a model of subcutaneous implantation in Matrigel. Treatment of TEC with HLSC-EVs led to the down-regulation of pro-angiogenic genes. Since HLSC-EVs carry a specific set of microRNAs (miRNAs) that could target these genes, we investigated their potential role by transfecting TEC with HLSC-EV specific miRNAs. We observed that four miRNAs, namely miR-15a, miR-181b, miR-320c and miR-874, significantly inhibited the angiogenic properties of TEC in vitro, and decreased the expression of some predicted target genes (ITGB3, FGF1, EPHB4 and PLAU). In parallel, TEC treated with HLSC-EVs significantly enhanced expression of miR-15a, miR-181b, miR-320c and miR-874 associated with the down-regulation of FGF1 and PLAU. In summary, HLSC-EVs possess an anti-tumorigenic effect, based on their ability to inhibit tumor angiogenesis.

Human Liver Stem Cell-Derived Extracellular Vesicles Prevent Aristolochic Acid-Induced Kidney Fibrosis

With limited therapeutic intervention in preventing the progression to end-stage renal disease, chronic kidney disease (CKD) remains a global health-care burden. Aristolochic acid (AA) induced nephropathy is a model of CKD characterised by inflammation, tubular injury, and interstitial fibrosis. Human liver stem cell-derived extracellular vesicles (HLSC-EVs) have been reported to exhibit therapeutic properties in various disease models including acute kidney injury. In the present study, we aimed to investigate the effects of HLSC-EVs on tubular regeneration and interstitial fibrosis in an AA-induced mouse model of CKD. NSG mice were injected with HLSC-EVs 3 days after administering AA on a weekly basis for 4 weeks. Mice injected with AA significantly lost weight over the 4-week period. Deterioration in kidney function was also observed. Histology was performed to evaluate tubular necrosis, interstitial fibrosis, as well as infiltration of inflammatory cells/fibroblasts. Kidneys were also subjected to gene array analyses to evaluate regulation of microRNAs (miRNAs) and pro-fibrotic genes. The effect of HLSC-EVs was also tested in vitro to assess pro-fibrotic gene regulation in fibroblasts cocultured with AA pretreated tubular epithelial cells. Histological analyses showed that treatment with HLSC-EVs significantly reduced tubular necrosis, interstitial fibrosis, infiltration of CD45 cells and fibroblasts, which were all elevated during AA induced injury. At a molecular level, HLSC-EVs significantly inhibited the upregulation of the pro-fibrotic genes α-Sma, Tgfb1, and Col1a1 in vivo and in vitro. Fibrosis gene array analyses revealed an upregulation of 35 pro-fibrotic genes in AA injured mice. Treatment with HLSC-EVs downregulated 14 pro-fibrotic genes in total, out of which, 5 were upregulated in mice injured with AA. Analyses of the total mouse miRnome identified several miRNAs involved in the regulation of fibrotic pathways, which were found to be modulated post-treatment with HLSC-EVs. These results indicate that HLSC-EVs play a regenerative role in CKD possibly through the regulation of genes and miRNAs that are activated during the progression of the disease.

Renal Regenerative Potential of Different Extracellular Vesicle Populations Derived from Bone Marrow Mesenchymal Stromal Cells

Extracellular vesicles (EVs) derived from human bone marrow mesenchymal stromal cells (MSCs) promote the regeneration of kidneys in different animal models of acute kidney injury (AKI) in a manner comparable with the cells of origin. However, due to the heterogeneity observed in the EVs isolated from MSCs, it is unclear which population is responsible for the proregenerative effects. We therefore evaluated the effect of various EV populations separated by differential ultracentrifugation (10K population enriched with microvesicles and 100K population enriched with exosomes) on AKI recovery. Only the exosomal-enriched population induced an improvement of renal function and morphology comparable with that of the total EV population. Interestingly, the 100K EVs exerted a proproliferative effect on murine tubular epithelial cells, both in vitro and in vivo. Analysis of the molecular content from the different EV populations revealed a distinct profile. The 100K population, for instance, was enriched in specific mRNAs (CCNB1, CDK8, CDC6) reported to influence cell cycle entry and progression; miRNAs involved in regulating proliferative/antiapoptotic pathways and growth factors (hepatocyte growth factor and insulin-like growth factor-1) that could explain the effect of renal tubular cell proliferation. On the other hand, the EV population enriched in microvesicles (10K) was unable to induce renal regeneration and had a molecular profile with lower expression of proproliferative molecules. In conclusion, the different molecular composition of exosome- and microvesicle-enriched populations may explain the regenerative effect of EVs observed in AKI.

Exosome and Microvesicle-Enriched Fractions Isolated from Mesenchymal Stem Cells by Gradient Separation Showed Different Molecular Signatures and Functions on Renal Tubular Epithelial Cells

Several studies have suggested that extracellular vesicles (EVs) released from mesenchymal stem cells (MSCs) may mediate MSC paracrine action on kidney regeneration. This activity has been, at least in part, ascribed to the transfer of proteins/transcription factors and different RNA species. Information on the RNA/protein content of different MSC EV subpopulations and the correlation with their biological activity is currently incomplete. The aim of this study was to evaluate the molecular composition and the functional properties on renal target cells of MSC EV sub-populations separated by gradient floatation. The results demonstrated heterogeneity in quantity and composition of MSC EVs. Two peaks of diameter were observed (90-110 and 170-190 nm). The distribution of exosomal markers and miRNAs evaluated in the twelve gradient fractions showed an enrichment in fractions with a flotation density of 1.08-1.14 g/mL. Based on this observation, we evaluated the biological activity on renal cell proliferation and apoptosis resistance of low (CF1), medium (CF2) and high (CF3) floatation density fractions. EVs derived from all fractions, were internalized by renal cells, CF1 and CF2 but not CF3 fraction stimulated significant cell proliferation. CF2 also inhibited apoptosis on renal tubular cells submitted to ischemia-reperfusion injury. Comparative miRNomic and proteomic profiles reveal a cluster of miRNAs and proteins common to all three fractions and an enrichment of selected molecules related to renal regeneration in CF2 fraction. In conclusion, the CF2 fraction enriched in exosomal markers was the most active on renal tubular cell proliferation and protection from apoptosis.

The effects of glomerular and tubular renal progenitors and derived extracellular vesicles on recovery from acute kidney injury

Background

Mesenchymal stromal cells (MSCs) and renal stem/progenitors improve the recovery of acute kidney injury (AKI) mainly through the release of paracrine mediators including the extracellular vesicles (EVs). Several studies have reported the existence of a resident population of MSCs within the glomeruli (Gl-MSCs). However, their contribution towards kidney repair still remains to be elucidated. The aim of the present study was to evaluate whether Gl-MSCs and Gl-MSC-EVs promote the recovery of AKI induced by ischemia-reperfusion injury (IRI) in SCID mice. Moreover, the effects of Gl-MSCs and Gl-MSC-EVs were compared with those of CD133⁺ progenitor cells isolated from human tubules of the renal cortical tissue (T-CD133⁺ cells) and their EVs (T-CD133⁺-EVs).

Methods

IRI was performed in mice by clamping the left renal pedicle for 35 minutes together with a right nephrectomy. Immediately after reperfusion, the animals were divided in different groups to be treated with: Gl-MSCs, T-CD133⁺ cells, Gl-MSC-EVs, T-CD133⁺-EVs or vehicle. To assess the role of vesicular RNA, EVs were either isolated by floating to avoid contamination of non-vesicles-associated RNA or treated with a high dose of RNase. Mice were sacrificed 48 hours after surgery.

Results

Gl-MSCs, and Gl-MSC-EVs both ameliorate kidney function and reduce the ischemic damage post IRI by activating tubular epithelial cell proliferation. Furthermore, T-CD133⁺ cells, but not their EVs, also significantly contributed to the renal recovery after IRI compared to the controls. Floating EVs were effective while RNase-inactivated EVs were ineffective. Analysis of the EV miRnome revealed that Gl-MSC-EVs selectively expressed a group of miRNAs, compared to EVs derived from fibroblasts, which were biologically ineffective in IRI.

Conclusions

In this study, we demonstrate that Gl-MSCs may contribute in the recovery of mice with AKI induced by IRI primarily through the release of EVs.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0478-5) contains supplementary material, which is available to authorized users.

Human liver stem cells and derived extracellular vesicles improve recovery in a murine model of acute kidney injury

INTRODUCTION

Several cellular sources of stem cells have been tested in the attempt to yield innovative interventions in acute kidney injury (AKI). Human liver stem cells (HLSCs) are cells isolated from the normal adult human liver which are gaining attention for their therapeutic potential. In the present study, we investigated whether HLSCs and the derived extracellular vesicles may promote tubular regeneration after AKI induced by glycerol injection in severe-combined immune-deficient mice.

METHODS

HLSCs were expanded and conditioned medium (CM) and extracellular vesicles (EVs) were purified. HLSCs and their bioproducts were tested in a model of AKI induced by intra-muscle glycerol injection. Renal function and morphology were evaluated five days after induction of damage. The effect of EVs on proliferation and apoptosis of murine renal tubular cells was tested in vitro.

RESULTS

We found that intravenous injection of 3.5×10⁵ HLSCs into mice three days after induction of AKI significantly improved functional and morphological recovery. The injection of HLSCs decreased creatinine and urea, as well as hyaline cast formation, tubular necrosis and enhanced in vivo tubular cell proliferation. The effect of soluble factors release by HLSCs in the regenerative processes was also studied. CM produced by HLSCs, mimicked the effect of the cells. However, depletion of EVs significantly reduced the functional and morphological recovery of CM. Moreover, we found that purified HLSC-derived EVs ameliorated renal function and morphology in a manner comparable to the cells. In vitro HLSC-derived EVs were shown to stimulate proliferation and inhibit apoptosis of murine renal tubular cells.

CONCLUSIONS

These results indicate that HLSCs increase recovery after AKI. EVs are the main component of HLSC-derived CM capable of promoting regeneration in experimental AKI.

Protective effect and localization by optical imaging of human renal CD133+ progenitor cells in an acute kidney injury model

Recent approaches of regenerative medicine can offer a therapeutic option for patients undergoing acute kidney injury. In particular, mesenchymal stem cells were shown to ameliorate renal function and recovery after acute damage. We here evaluated the protective effect and localization of CD133⁺ renal progenitors from the human inner medulla in a model of glycerol‐induced acute tubular damage and we compared the results with those obtained with bone marrow‐derived mesenchymal stem cells. We found that CD133⁺ progenitor cells promoted the recovery of renal function, preventing tubular cell necrosis and stimulating resident cell proliferation and survival, similar to mesenchymal stem cells. In addition, by optical imaging analysis, CD133⁺ progenitor cells accumulated within the renal tissue, and a reduced entrapment in lung, spleen, and liver was observed. Mesenchymal stem cells were detectable at similar levels in the renal tissue, but a higher signal was present in extrarenal organs. Both cell types produced several cytokines/growth factors, suggesting that a combination of different mediators is involved in their biological action. These results indicate that human CD133⁺ progenitor cells are renotropic and able to improve renal regeneration in acute kidney injury.

In the present study, we found that administration of human CD133⁺ renal progenitors promoted renal repair after murine AKI, similar to mesenchymal stem cells. In addition, these cells showed a high renal localization evaluated by optical imaging analysis, and the production of renoprotective factors. Mesenchymal stem cells were detectable at similar levels in the renal tissue, but a higher signal was present in extrarenal organs.

Oncogenic micro-RNAs and Renal Cell Carcinoma

Tumor formation is a complex process that occurs in different steps and involves many cell types, including tumor cells, endothelial cells, and inflammatory cells, which interact to promote growth of the tumor mass and metastasization. Epigenetic alterations occurring in transformed cells result in de-regulation of miRNA expression (a class of small non-coding RNA that regulates multiple functions), which contributes to tumorigenesis. The specific miRNAs, which have an aberrant expression in tumors, are defined as oncomiRNAs, and may be either over- or under-expressed, but down-regulation is most commonly observed. Renal cell carcinoma (RCC) is a frequent form of urologic tumor, associated with an alteration of multiple signaling pathways. Many molecules involved in the progression of RCCs, such as HIF, VEGF, or mammalian target of rapamycin, are possible targets of de-regulated miRNAs. Within tumor mass, the cancer stem cell (CSC) population is a fundamental component that promotes tumor growth. The CSC hypothesis postulates that CSCs have the unique ability to self-renew and to maintain tumor growth and metastasis. CSCs present in RCC were shown to express the mesenchymal stem cell marker CD105 and to exhibit self-renewal and clonogenic properties, as well as the ability to generate serially transplantable tumors. The phenotype of CSC has been related to the potential to undergo the epithelial–mesenchymal transition, which has been linked to the expression pattern of tumorigenic miRNAs or down-regulation of anti-tumor miRNAs. In addition, the pattern of circulating miRNAs may allow discrimination between healthy and tumor patients. Therefore, a miRNA signature may be used as a tumor biomarker for cancer diagnosis, as well as to classify the risk of relapse and metastasis, and for a guide for therapy.

Biodistribution of mesenchymal stem cell-derived extracellular vesicles in a model of acute kidney injury monitored by optical imaging

Mesenchymal stem cells (MSCs) contribute to the recovery of tissue injury, providing a paracrine support. Cell-derived extracellular vesicles (EVs), carrying membrane and cytoplasmatic constituents of the cell of origin, have been described as a fundamental mechanism of intercellular communication. We previously demonstrated that EVs derived from human MSCs accelerated recovery following acute kidney injury (AKI) in vivo. The aim of the present study was to investigate the biodistribution and the renal localization of EVs in AKI. For this purpose, two methods for EV labeling suitable for in vivo tracking with optical imaging (OI), were employed using near infrared (NIR) dye (DiD): i) labeled EVs were generated by MSCs pre-incubated with NIR dye and collected from cell supernatants; ii) purified EVs were directly labeled with NIR dye. EVs obtained with these two procedures were injected intravenously (i.v.) into mice with glycerol-induced AKI and into healthy mice to compare the efficacy of the two labeling methods for in vivo detection of EVs at the site of damage. We found that the labeled EVs accumulated specifically in the kidneys of the mice with AKI compared with the healthy controls. After 5 h, the EVs were detectable in whole body images and in dissected kidneys by OI with both types of labeling procedures. The directly labeled EVs showed a higher and brighter fluorescence compared with the labeled EVs produced by cells. The signal generated by the directly labeled EVs was maintained in time, but provided a higher background than that of the labeled EVs produced by cells. The comparison of the two methods indicated that the latter displayed a greater specificity for the injured kidney.

Abstract C213: Sorafenib blocks tumor growth, angiogenesis, and metastatic potential in preclinical models of osteosarcoma through the inhibition of ERK1/2, MCL-1, and ezrin pathways

Osteosarcoma (OS) is the most common primary bone tumor in children and young adults. Despite improved prognosis, metastatic or relapsed OS remains largely incurable and no significant improvement has been observed in the last 20 years. Therefore, the search for alternative agents in OS is mandatory.

We explored phospho-ERK 1/2, MCL-1, phospho-Ezrin/Radixin/Moesin (P-ERM) as potential therapeutic targets. The activation of these pathways was shown by immunohistochemistry in about 70% of cases and in all OS cell lines analyzed. Mutational analysis revealed no activating mutations in KRAS. While, BRAF gene was found mutated in 4/30 OS samples from patients. Based on these results we tested the multikinases inhibitor sorafenib (BAY 43-9006) in preclinical models of OS. Sorafenib inhibited OS cell lines proliferation, induced apoptosis and downregulated P-ERK1/2, MCL-1, P-ERM in a dose dependent manner. ERM dephosphorylation is not due to ERK inhibition. The downregulation of MCL-1 increased apoptosis in OS cell lines. In chick embryo chorioallantoic membrane the angiogenesis induced by OS supernatants was blocked by sorafenib treatments. Indeed, sorafenib reduced VEGF and MMP2 production. Sorafenib treatment dramatically reduced tumor volume of OS xenografts and lung metastasis in SCID mice.

In conclusion, ERK1/2, MCL-1 and ERM pathways are active in OS. Sorafenib is able to interrupt their routes in vitro and in vivo displaying antitumoral activity, antiangiogenic effect and reducing metastasis colonies formation in lungs. These data support the testing of sorafenib as a potential therapeutic option in metastatic or relapsed OS patients failing standard treatments.

Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C213.

Sorafenib blocks tumour growth, angiogenesis and metastatic potential in preclinical models of osteosarcoma through a mechanism potentially involving the inhibition of ERK1/2, MCL-1 and ezrin pathways

BACKGROUND

Osteosarcoma (OS) is the most common primary bone tumour in children and young adults. Despite improved prognosis, metastatic or relapsed OS remains largely incurable and no significant improvement has been observed in the last 20 years. Therefore, the search for alternative agents in OS is mandatory.

RESULTS

We investigated phospho-ERK 1/2, MCL-1, and phospho-Ezrin/Radixin/Moesin (P-ERM) as potential therapeutic targets in OS. Activation of these pathways was shown by immunohistochemistry in about 70% of cases and in all OS cell lines analyzed. Mutational analysis revealed no activating mutations in KRAS whereas BRAF gene was found to be mutated in 4/30 OS samples from patients. Based on these results we tested the multi-kinase inhibitor sorafenib (BAY 43-9006) in preclinical models of OS. Sorafenib inhibited OS cell line proliferation, induced apoptosis and downregulated P-ERK1/2, MCL-1, and P-ERM in a dose-dependent manner. The dephosphorylation of ERM was not due to ERK inhibition. The downregulation of MCL-1 led to an increase in apoptosis in OS cell lines. In chick embryo chorioallantoic membranes, OS supernatants induced angiogenesis, which was blocked by sorafenib and it was also shown that sorafenib reduced VEGF and MMP2 production. In addition, sorafenib treatment dramatically reduced tumour volume of OS xenografts and lung metastasis in SCID mice.

CONCLUSION

In conclusion, ERK1/2, MCL-1 and ERM pathways are shown to be active in OS. Sorafenib is able to inhibit their signal transduction, both in vitro and in vivo, displaying anti-tumoural activity, anti-angiogenic effects, and reducing metastatic colony formation in lungs. These data support the testing of sorafenib as a potential therapeutic option in metastatic or relapsed OS patients unresponsive to standard treatments.

Illicit treatments in cattle and urinary 6beta-hydroxycortisol/cortisol ratio

Dexamethasone (DXM) is often illegally used as a growth promoter. To identify indirect biomarkers of illicit treatments, the urinary ratio between 6beta-hydroxycortisol (6beta-OHF) and cortisol (F) was measured in urines obtained from bulls experimentally treated per os and intramuscularly (i.m.) with different DXM dosages. Dexamethasone, given per os at low doses elicited an early and lasting significant reduction of 6beta-OHF/F. No significant variations were seen in urines from bulls given DXM intramuscularly. These results suggest 6beta-OHF/F as a rapid, non-invasive, screening test for oral, low-dose, long-term corticosteroid treatment in cattle. Further studies are required to go deep inside the biochemical and molecular events underlying such an effect.