Mesenchymal stromal cells alone or expressing interferon-beta suppress pancreatic tumors in vivo, an effect countered by anti-inflammatory treatment

Umbilical cord-derived mesenchymal stromal/stem cells expressing IL-24 induce apoptosis in gliomas

Although much progress has been made in the treatment of gliomas, the prognosis for patients with gliomas is still very poor. Stem cell-based therapies may be promising options for glioma treatment. Recently, many studies have reported that umbilical cord-derived mesenchymal stromal/stem cells (UC-MSCs) are ideal gene vehicles for tumor gene therapy. Interleukin 24 (IL-24) is a pleiotropic immunoregulatory cytokine that has an apoptotic effect on many kinds of tumor cells and can inhibit the growth of tumors specifically without damaging normal cells. In this study, we investigated UC-MSCs as a vehicle for the targeted delivery of IL-24 to tumor sites. UC-MSCs were transduced with lentiviral vectors carrying green fluorescent protein (GFP) or IL-24 complementary DNA. The results indicated that UC-MSCs could selectively migrate to glioma cells in vitro and in vivo. Injection of IL-24-UC-MSCs significantly suppressed tumor growth of glioma xenografts. The restrictive efficacy of IL-24-UC-MSCs was associated with the inhibition of proliferation as well as the induction of apoptosis in tumor cells. These findings indicate that UC-MSC-based IL-24 gene therapy may be able to suppress the growth of glioma xenografts, thereby suggesting possible future therapeutic use in the treatment of gliomas.

Human mesenchymal stem cells promote tumor growth via MAPK pathway and metastasis by epithelial mesenchymal transition and integrin α5 in hepatocellular carcinoma

Mesenchymal stem cells (MSCs) appear to be a potential vehicle for anticancer drugs due to their excellent tumor tropism ability. However, the interactions between MSCs and hepatocellular carcinoma (HCC) are quite controversial and the underlying mechanisms are ambiguous. In this study, an investigation was conducted into the effect of human MSCs (hMSCs) on tumor proliferation and metastasis both in xenograft and orthotopic models. It was discovered that hMSCs could promote tumor growth though activating mitogen-activated protein kinase (MAPK) signaling pathway and promote metastasis by epithelial mesenchymal transition (EMT) in vivo. To test whether hMSCs could induce immunosuppressive effects, the expression of the Natural killer (NK) cell marker CD56 was measured by immunohistochemical staining and the expression of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were measured by qRT-PCR. It was found out that CD56 expression significantly decreased, while TNF-α and IL-6 expression increased in the hMSCs-treated tissues. Mechanistically, RNA sequencing was performed, which led to a discovery that integrin α5 (ITGA5) was over-expressed in hMSCs-treated HCC. ITGA5 siRNAs blocked the hMSCs-induced migration and invasion of HCC, while over-expression of ITGA5 promoted the migration and invasion ability in HCC-hMSCs, indicating that the expression of ITGA5 is associated with hMSCs-induced tumor metastasis. These findings suggest that hMSCs may play a vital role in HCC proliferation and metastasis and could be identified as a putative therapeutic target in HCC.

Antitumor effects of conditioned media of human fetal dermal mesenchymal stem cells on melanoma cells

Background: Malignant melanoma is the most lethal form of cutaneous tumor and has a high metastatic rate and motility capacity. Owing to the poor prognosis, it is urgent to seek an effective therapeutic regimen. Human mesenchymal stem cells (MSCs) can home to tumor cells and have been shown to play important roles in both promoting and inhibiting tumor development. Fetal dermal MSCs (FDMSCs), derived from fetal skin are a novel source of MSCs. Nevertheless, the antitumor capacity of FDMSCs on malignant melanoma is not clearly understood.

Materials and methods: FDMSCs were extracted from the dorsal skin of fetal tissues. A375 melanoma cells lines were obtained from American Type Culture Collection. The effects of conditioned media from FDMSCs (CM-FDMSC) on A375 melanoma cells were tested in vivo using tumor formation assay and in vitro using cell viability, 5-ethynyl-2ʹ-deoxyuridine incorporation, flow cytometry, TdT-mediated dUTP Nick-End Labeling (TUNEL), wound healing, transwell invasion, and Western blotting.

Results: CM-FDMSC inhibited A375 tumor formation in vivo. In vitro, CM-FDMSC inhibited the tumor-related activities of A375 melanoma cells, as evidenced reductions in viability, migration, and invasion. CM-FDMSC-treated A375 cells showed decreased phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), and extracellular signal-regulated kinase (ERK) phosphorylation, and up-regulation of Bcl-2-Associated X (BAX) and down-regulation of B-cell lymphoma-2 (BCL-2) expression.

Conclusion: CM-FDMSC can inhibit the tumor-forming behaviors of A375 melanoma cells and inhibit PI3K/AKT and mitogen-activated protein kinase signaling to shift their BCL-2/BAX ratio toward a proapoptotic state. Identification of the bioactive components in CM-FDMSC will be important for translating these findings into novel therapies for malignant melanoma.

Mesenchymal Stem Cells and Cancer: Clinical Challenges and Opportunities

Stem cell-based therapies exhibit profound therapeutic potential for treating various human diseases, including cancer. Among the cell types that can be used for this purpose, mesenchymal stem cells (MSCs) are considered as promising source of stem cells in personalized cell-based therapies. The inherent tumor-tropic property of MSCs can be used to target cancer cells. Although the impacts of MSCs on tumor progression remain elusive, they have been genetically modified or engineered as targeted anticancer agents which could inhibit tumor growth by blocking different processes of tumor. In addition, there are close interactions between MSCs and cancer stem cells (CSCs). MSCs can regulate the growth of CSCs through paracrine mechanisms. This review aims to focus on the current knowledge about MSCs-based tumor therapies, the opportunities and challenges, as well as the prospective of its further clinical implications.

The Different Effects of IFN-β and IFN-γ on the Tumor-Suppressive Activity of Human Amniotic Fluid-Derived Mesenchymal Stem Cells

Current studies have shown that type I or II interferon-modified mesenchymal stem cells have great potential for the application of tumor-targeted therapy, but the underlying mechanism remains largely elusive. Here, we compared the different effects of IFN-β and IFN-γ on the antitumor activity of human amniotic fluid-derived mesenchymal stem cells (AFMSCs) and revealed the potential mechanism. In detail, AFMSCs primed with IFN-β or IFN-β plus IFN-γ, not IFN-γ, inhibited the proliferation of cancer cells in an immunocompetent mouse H460 subcutaneous model, although they all inhibited the proliferation of cancer cells in an immunocompromised mouse H460 subcutaneous model. TRAIL expressed by IFN-β- or IFN-γ-primed AFMSCs specifically exerted the antitumor effect of AFMSCs. AFMSCs primed with IFN-γ highly expressed immunosuppressive molecule IDO1, but IFN-β counteracted the IFN-γ-initiated IDO1 expression. 1-MT (IDO1 inhibitor) decreased TRAIL, but increased IDO1 expression in AFMSCs primed with interferon. As a result, AFMSCs primed with IFN-β or IFN-γ had the antitumor activity, and 1-MT failed to enhance the antitumor effect of IFN-γ-primed AFMSC in vitro and in the immunocompromised mouse H460 subcutaneous model. Furthermore, the expression of TRAIL in AFMSCs was upregulated by apoptotic cancer cells and this positive feedback intensified the antitumor effects of IFNs-primed AFMSCs. The different target gene expression profiles of AFMSCs regulated by IFN-β and IFN-γ determined the different antitumor effects of IFN-β- and IFN-γ-primed AFMSCs on tumor cells. Our finding may help to explore a clinical strategy for cancer intervention by understanding the antitumor mechanisms of MSCs and interferon.

Stem cell-mediated delivery of nanogels loaded with ultrasmall iron oxide nanoparticles for enhanced tumor MR imaging

The development of new nanoplatforms with enhanced tumor accumulation for accurate diagnosis still remains a great challenge in current precision nanomedicine. Herein, we report the design of stem cell-mediated delivery of nanogels (NGs) loaded with ultrasmall iron oxide (Fe3O4) nanoparticles (NPs) for enhanced magnetic resonance (MR) imaging of tumors. In this study, sodium citrate-stabilized ultrasmall Fe3O4 NPs with a size of 3.16 ± 1.30 nm were first synthesized using a solvothermal route, coated with polyethyleneimine (PEI), and used as crosslinkers to crosslink alginate (AG) NGs formed via a double emulsion approach, where the AG carboxyl groups were pre-activated with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride. The thus prepared Fe3O4 NP-loaded NGs (AG/PEI-Fe3O4 NGs) with a size of 47.68 ± 3.41 nm are water-dispersible, colloidally stable, cytocompatible in a given concentration range, display a relatively high r1 relaxivity (r1 = 1.5 mM-1 s-1), and are able to be taken up by bone mesenchymal stem cells without compromising cell viability and stem cell characteristics. Due to the tumor-chemotaxis or tumor tropism, the BMSCs are able to mediate the enhanced delivery of AG/PEI-Fe3O4 NGs to the tumor site after intravenous injection, thus enabling significantly strengthened MR imaging of tumors when compared to free NGs. These findings suggest that the developed AG/PEI-Fe3O4NGs, once mediated by stem cells may serve as a novel, safe, effective and targeted platform for enhanced MR imaging of tumors.

Soluble TRAIL Armed Human MSC As Gene Therapy For Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is still one of the most aggressive adult cancers with an unacceptable prognosis. For this reason novel therapies accounting for PDAC peculiarities, such as the relevant stromal reaction, are urgently needed. Here adipose mesenchymal stromal/stem cells (AD-MSC) have been armed to constantly release a soluble trimeric and multimeric variant of the known anti-cancer TNF-related apoptosis-inducing ligand (sTRAIL). This cancer gene therapy strategy was in vitro challenged demonstrating that sTRAIL was thermally stable and able to induce apoptosis in the PDAC lines BxPC-3, MIA PaCa-2 and against primary PDAC cells. sTRAIL released by AD-MSC relocated into the tumor stroma was able to significantly counteract tumor growth in vivo with a significant reduction in tumor size, in cytokeratin-7+ cells and by an anti-angiogenic effect. In parallel, histology on PDAC specimens form patients (n = 19) was performed to investigate the levels of TRAIL DR4, DR5 and OPG receptors generating promising insights on the possible clinical translation of our approach. These results indicate that adipose MSC can very efficiently vehicle a novel TRAIL variant opening unexplored opportunities for PDAC treatment.

Mesenchymal stem cells in suppression or progression of hematologic malignancy: current status and challenges

Mesenchymal stem cells (MSCs) are known for being multi-potent. However, they also possess anticancer properties, which has prompted efforts to adapt MSCs for anticancer therapies. However, MSCs have also been widely implicated in pathways that contribute to tumor growth. Numerous studies have been conducted to adapt MSCs for further clinical use; however, the results have been inconclusive, possibly due to the heterogeneity of MSC populations. Moreover, the conflicting roles of MSCs in tumor inhibition and tumor growth impede their adaptation for anticancer therapies. Antitumorigenic and protumorigenic properties of MSCs in hematologic malignancies are not as well established as they are for solid malignancies, and data comparing them are still limited. Herein the effect of MSCs on hematologic malignancies, such as leukemia and lymphoma, their mechanisms, sources of MSCs, and their effects on different types of cancer, have been discussed. This review describes how MSCs preserve both antitumorigenic and protumorigenic effects, as they tend to not only inhibit tumor growth by suppressing tumor cell proliferation but also promote tumor growth by suppressing tumor cell apoptosis. Thus clinical studies trying to adapt MSCs for anticancer therapies should consider that MSCs could actually promote hematologic cancer progression. It is necessary to take extreme care while developing MSC-based cell therapies in order to boost anticancer properties while eliminating tumor-favoring effects. This review emphasizes that research on the therapeutic applications of MSCs must consider that they exert both antitumorigenic and protumorigenic effects on hematologic malignancies.

Mesenchymal stem cell-based drug delivery strategy: from cells to biomimetic

Owing to the diversity and ease of preparation of nanomaterials, the rational nanocarriers with a rational design have become increasingly popular in medical researches. Although nanoparticle-based drug delivery exhibits great potential, there are some challenges facing like rapid plasma clearance, triggering or aggravation of immune response, etc. Herein, cell-based targeted drug delivery systems have drawn more and more attention owing to low immunogenicity and intrinsic mutation rate, and innate ability to allow targeted delivery. Mesenchymal stem cells (MSCs) have been used in gene and drug delivery. The use of MSCs is a promising approach for the development of gene transfer systems and drug loading strategies because of their intrinsic properties, including homing ability and tumor tropism. By combining the inherent cell properties and merits of synthetic nanoparticles (NPs), cell membrane coated NPs emerge as the time requires. Overall, we provide a comprehensive overview of the utility of MSCs in drug and gene delivery as well as MSC membrane coated nanoparticles for therapy and drug delivery, aiming to figure out the significant room for development and highlight the potential future directions.

Mesenchymal stem cells in preclinical cancer cytotherapy: a systematic review

Mesenchymal stem cells (MSC) comprise a heterogeneous population of rapidly proliferating cells that can be isolated from adult (e.g., bone marrow, adipose tissue) as well as fetal (e.g., umbilical cord) tissues (termed bone marrow (BM)-, adipose tissue (AT)-, and umbilical cord (UC)-MSC, respectively) and are capable of differentiation into a wide range of non-hematopoietic cell types. An additional, unique attribute of MSC is their ability to home to tumor sites and to interact with the local supportive microenvironment which rapidly conceptualized into MSC-based experimental cancer cytotherapy at the turn of the century. Towards this purpose, both naïve (unmodified) and genetically modified MSC (GM-MSC; used as delivery vehicles for the controlled expression and release of antitumorigenic molecules) have been employed using well-established in vitro and in vivo cancer models, albeit with variable success. The first approach is hampered by contradictory findings regarding the effects of naïve MSC of different origins on tumor growth and metastasis, largely attributed to inherent biological heterogeneity of MSC as well as experimental discrepancies. In the second case, although the anti-cancer effect of GM-MSC is markedly improved over that of naïve cells, it is yet apparent that some protocols are more efficient against some types of cancer than others. Regardless, in order to maximize therapeutic consistency and efficacy, a deeper understanding of the complex interaction between MSC and the tumor microenvironment is required, as well as examination of the role of key experimental parameters in shaping the final cytotherapy outcome. This systematic review represents, to the best of our knowledge, the first thorough evaluation of the impact of experimental anti-cancer therapies based on MSC of human origin (with special focus on human BM-/AT-/UC-MSC). Importantly, we dissect the commonalities and differences as well as address the shortcomings of work accumulated over the last two decades and discuss how this information can serve as a guide map for optimal experimental design implementation ultimately aiding the effective transition into clinical trials.

Enhanced Antitumor Efficacy of Oncolytic Adenovirus-loaded Menstrual Blood-derived Mesenchymal Stem Cells in Combination with Peripheral Blood Mononuclear Cells

Several studies have evaluated the efficacy of using human oncolytic adenovirus (OAdv)-loaded mesenchymal stem cells (MSC) for cancer treatment. For example, we have described the antitumor efficacy of CELYVIR, autologous bone marrow-mesenchymal stem cells infected with the OAdv ICOVIR-5, for treatment of patients with neuroblastoma. Results from this clinical trial point out the role of the immune system in the clinical outcome. In this context, a better understanding of the immunophenotypic changes of human MSCs upon adenoviral infection and how these changes affect human autologous or allogeneic peripheral blood mononuclear cells (PBMC) could guide strategies to improve the antitumor efficacy of infected MSCs. In this work, we show how infection by an OAdv induces toll-like receptor 9 overexpression and activation of the NFĸB pathway in menstrual blood-derived MSCs, leading to a specific cytokine secretion profile. Moreover, a proinflammatory environment, mainly mediated by monocyte activation that leads to the activation of both T cells and natural killer cells (NK cell), is generated when OAdv-loaded MSCs are cocultured with allogeneic PBMCs. This combination of allogeneic PBMCs and OAdv-loaded MSCs enhances antitumor efficacy both in vitro and in vivo, an effect partially mediated by monocytes and NK cells. Altogether our results demonstrate not only the importance of the immune system for the OAdv-loaded MSCs antitumor efficacy, but in particular the benefits of using allogeneic MSCs for this therapy.

A Novel Approach for Image-Guided 131I Therapy of Pancreatic Ductal Adenocarcinoma Using Mesenchymal Stem Cell-Mediated NIS Gene Delivery

The sodium iodide symporter (SLC5A5/NIS) as theranostic gene would allow for non-invasive imaging of functional NIS expression and therapeutic radioiodine application. Genetically engineered mesenchymal stem cells (MSC), based on their tumor-homing abilities, show great promise as tumor-selective NIS gene delivery vehicles for non-thyroidal tumors. As a next step towards clinical application, tumor specificity and efficacy of MSCs were investigated in an advanced genetically engineered mouse model of pancreatic ductal adenocarcinoma (PDAC). Syngeneic murine MSCs were stably transfected with a NIS-expressing plasmid driven by the CMV-promoter (NIS-MSC). In vivo ¹²³I-scintigraphy and ¹²⁴I-PET revealed significant perchlorate-sensitive NIS-mediated radioiodide accumulation in PDAC after systemic injection of NIS-MSCs. Active MSC recruitment into the tumor stroma was confirmed using NIS immunohistochemistry (IHC). A therapeutic strategy, consisting of three cycles of systemic MSC-mediated NIS delivery, followed by ¹³¹I application, resulted in a significant delay and reduction in tumor growth as compared to controls. Furthermore, IHC analysis of α-SMA and Ki67 revealed differences in the amount and behavior of activated fibroblasts in tumors of mice injected with NIS-MSCs as compared with saline-treated mice. Taken together, MSCs as NIS gene delivery vehicles in this advanced endogenous PDAC mouse model demonstrated high stromal targeting of NIS by selective recruitment of NIS-MSCs after systemic application resulting in an impressive ¹³¹I therapeutic effect. IMPLICATIONS: These data expand the prospect of MSC-mediated radioiodine imaging-guided therapy of pancreatic cancer using the sodium iodide symporter as a theranostic gene in a clinical setting.

Enhanced tumor growth inhibition by mesenchymal stem cells derived from iPSCs with targeted integration of interleukin24 into rDNA loci

Induced pluripotent stem cells (iPSCs) are a promising source of mesenchymal stem cells (MSCs) for clinical applications. In this study, we transformed human iPSCs using a non-viral vector carrying the IL24 transgene pHrn-IL24. PCR and southern blotting confirmed IL24 integration into the rDNA loci in four of 68 iPSC clones. We then differentiated a high expressing IL24-iPSC clone into MSCs (IL24-iMSCs) that showed higher expression of IL24 in culture supernatants and in cell lysates than control iMSCs. IL24-iMSCs efficiently differentiated into osteoblasts, chondrocytes and adipocytes. Functionally, IL24-iMSCs induced in vitro apoptosis in B16-F10 melanoma cells more efficiently than control iMSCs when co-cultured in Transwell assays. In vivo tumor xenograft studies in mice demonstrated that IL24-iMSCs inhibited melanoma growth more than control iMSCs did. Immunofluorescence and histochemical analysis showed larger necrotic areas and cell nuclear aggregation in tumors with IL24-iMSCs than control iMSCs, indicating that IL24-iMSCs inhibited tumor growth by inducing apoptosis. These findings demonstrate efficient transformation of iPSCs through gene targeting with non-viral vectors into a rDNA locus. The ability of these genetically modified MSCs to inhibit in vivo melanoma growth is suggestive of the clinical potential of autologous cell therapy in cancer.

IFNα-Expressing Amniotic Fluid-Derived Mesenchymal Stem Cells Migrate to and Suppress HeLa Cell-Derived Tumors in a Mouse Model

Background

Immunotherapy for cervical cancer with type I interferon (IFN) is limited because of the cytotoxicity that accompanies the high doses that are administered. In this study, we investigated the utilization of amniotic fluid-derived mesenchymal stem cells (AF-MSCs) as a means for delivering IFNα to local tumor sites for the suppression of cervical cancer in a mouse model using HeLa cell xenografts.

Methods

The tumor tropism ability of AF-MSCs and AF-MSCs genetically modified to overexpress IFNα (IFNα-AF-MSCs) was examined through Transwell in vitro and through fluorescent images and immunohistochemistry in a mouse model. Tumor size and tumor apoptosis were observed to evaluate the efficacy of the targeting therapy. Mechanistically, tumor cell apoptosis was detected by cytometry and TUNEL, and oncogenic proteins c-Myc, p53, and Bcl-2 as well as microvessel density were detected by immunohistochemistry.

Results

In this model, intravenously injected AF-MSCs selectively migrated to the tumor sites, participated in tumor construction, and promoted tumor growth. After being genetically modified to overexpress IFNα, the IFNα-AF-MSCs maintained their tumor tropism but could significantly suppress tumor growth. The restrictive efficacy of IFNα-AF-MSCs was associated with the suppression of angiogenesis, inhibition of tumor cell proliferation, and induction of apoptosis in tumor cells. Neither AF-MSCs nor IFNα-AF-MSCs trigger tumor formation.

Conclusions

IFNα-AF-MSC-based therapy is feasible and shows potential for treating cervical cancer, suggesting that AF-MSCs may be promising vehicles for delivering targeted anticancer therapy.

Application of Mesenchymal Stem Cells for Therapeutic Agent Delivery in Anti-tumor Treatment

Mesenchymal stem cells (MSCs) are non-hematopoietic progenitor cells, which can be isolated from different types of tissues including bone marrow, adipose tissue, tooth pulp, and placenta/umbilical cord blood. There isolation from adult tissues circumvents the ethical concerns of working with embryonic or fetal stem cells, whilst still providing cells capable of differentiating into various cell lineages, such as adipocytes, osteocytes and chondrocytes. An important feature of MSCs is the low immunogenicity due to the lack of co-stimulatory molecules expression, meaning there is no need for immunosuppression during allogenic transplantation. The tropism of MSCs to damaged tissues and tumor sites makes them a promising vector for therapeutic agent delivery to tumors and metastatic niches. MSCs can be genetically modified by virus vectors to encode tumor suppressor genes, immunomodulating cytokines and their combinations, other therapeutic approaches include MSCs priming/loading with chemotherapeutic drugs or nanoparticles. MSCs derived membrane microvesicles (MVs), which play an important role in intercellular communication, are also considered as a new therapeutic agent and drug delivery vector. Recruited by the tumor, MSCs can exhibit both pro- and anti-oncogenic properties. In this regard, for the development of new methods for cancer therapy using MSCs, a deeper understanding of the molecular and cellular interactions between MSCs and the tumor microenvironment is necessary. In this review, we discuss MSC and tumor interaction mechanisms and review the new therapeutic strategies using MSCs and MSCs derived MVs for cancer treatment.

The distinct roles of mesenchymal stem cells in the initial and progressive stage of hepatocarcinoma

Increasing evidences suggest that mesenchymal stem cells (MSCs) could migrate to the tumor site and play a vital role in tumorigenesis and progression. However, it is still a lively debate whether MSCs exert a pro- or anticancer action. Cancer development and progression is a multistep process. Therefore, we investigated the effect of MSCs on hepatocarcinoma and whether the role of MSCs depends on the stage of cancer development. In our study, chronically exposing rats to N-diethylnitrosamine (DEN) was employed as hepatocarcinoma model. And to evaluate the effect of MSCs on hepatocarcinoma, the animals were divided into three groups: rats were injected with MSCs in the initial (DEN + MSC (Is) group) or progressive stage (DEN + MSC (Ps) group) of hepatocarcinoma, respectively. Rats injected with PBS were used as control (DEN group). Interestingly, we found that MSCs had a tumor-suppressive effect in the Is of hepatocarcinoma, yet a tumor-promotive effect in the Ps. In the Is, MSCs showed a protective role against drug damage, possibly through reducing DNA damage and ROS accumulation. Meanwhile, MSCs in the Is also exhibited anti-inflammatory and anti-liver fibrosis effect. Further, in the Ps, MSCs facilitated tumor formation not only by enhancing cancer cell proliferation but also through promoting stem cell-like properties and epithelial–mesenchymal transition of liver cancer cells. Taken together, MSCs have a paradoxical role in the different stages of hepatocarcinogenesis, which sheds new light on the role of MSCs in hepatocarcinoma and cautions the therapeutic application of MSCs for liver cancer.

The future of mesenchymal stem cell-based therapeutic approaches for cancer - From cells to ghosts

Mesenchymal stem cells (MSCs) are multipotent stromal cells which can differentiate into a variety of cell types including osteoblasts, adipocytes and chondrocytes. They are normally resident in adipose tissue, bone marrow and the umbilical cord, but can also be found in other tissues and are known to be recruited to sites of wound healing as well as growing tumours. The therapeutic potential of MSCs has been explored in a number of phase I/II and III clinical trials, of which several were targeted against graft-versus-host disease and to support engraftment of haematopoietic stem cells (HSCs), but currently only very few in the oncology field. There are now three clinical trials either ongoing or recruiting patients that use MSCs to treat tumour disease. In these, MSCs target gastrointestinal, lung and ovarian cancer, respectively. The first study uses MSCs loaded with a HSV-TK expression construct under the control of the CCL5 promoter, and has recently reported successful completion of Phase I/II. While no adverse side effects were seen during this study, no outcomes with respect to therapeutic benefits have been published. The other clinical trials targeting lung and ovarian cancer will be using MSCs expressing cytokines as therapeutic payload. Despite these encouraging early steps towards their clinical use, many questions are still unanswered regarding the biology of MSCs in normal and pathophysiological settings. In this review, in addition to summarising the current state of MSC-based therapeutic approaches for cancer, we will describe the remaining questions, obstacles and risks, as well as novel developments such as MSC-derived nanoghosts.

pIL6-TRAIL-engineered umbilical cord mesenchymal/stromal stem cells are highly cytotoxic for myeloma cells both in vitro and in vivo

Background

Mesenchymal/stromal stem cells (MSCs) are favorably regarded in anti-cancer cytotherapies for their spontaneous chemotaxis toward inflammatory and tumor environments associated with an intrinsic cytotoxicity against tumor cells. Placenta-derived or TRAIL-engineered adipose MSCs have been shown to exert anti-tumor activity in both in-vitro and in-vivo models of multiple myeloma (MM) while TRAIL-transduced umbilical cord (UC)-MSCs appear efficient inducers of apoptosis in a few solid tumors. However, apoptosis is not selective for cancer cells since specific TRAIL receptors are also expressed by a number of normal cells. To overcome this drawback, we propose to transduce UC-MSCs with a bicistronic vector including the TRAIL sequence under the control of IL-6 promoter (pIL6) whose transcriptional activation is promoted by the MM milieu.

Methods

UC-MSCs were transduced with a bicistronic retroviral vector (pMIGR1) encoding for green fluorescent protein (GFP) and modified to include the pIL6 sequence upstream of the full-length human TRAIL cDNA. TRAIL expression after stimulation with U-266 cell conditioned medium, or IL-1α/IL-1β, was evaluated by flow cytometry, confocal microscopy, real-time PCR, western blot analysis, and ELISA. Apoptosis in MM cells was assayed by Annexin V staining and by caspase-8 activation. The cytotoxic effect of pIL6-TRAIL⁺-GFP⁺-UC-MSCs on MM growth was evaluated in SCID mice by bioluminescence and ex vivo by caspase-3 activation and X-ray imaging. Statistical analyses were performed by Student’s t test, ANOVA, and logrank test for survival curves.

Results

pIL6-TRAIL⁺-GFP⁺-UC-MSCs significantly expressed TRAIL after stimulation by either conditioned medium or by IL-1α/IL-1β, and induced apoptosis in U-266 cells. Moreover, when systemically injected in SCID mice intratibially xenografted with U-266, those cells underwent within MM tibia lesions and significantly reduced the tumor burden by specific induction of apoptosis in MM cells as revealed by caspase-3 activation.

Conclusions

Our tumor microenvironment-sensitive model of anti-MM cytotherapy is regulated by the axis pIL6/IL-1α/IL-1β and appears suitable for further preclinical investigation not only in myeloma bone disease in which UC-MSCs would even participate to bone healing as described, but also in other osteotropic tumors whose milieu is enriched of cytokines triggering the pIL6.

Tumor-educated mesenchymal stem cells promote pro-metastatic phenotype

Multipotent mesenchymal stem cells (MSCs) are recruited into tumor microenvironment in response to multiple signals produced by cancer cells. Molecules involved in their homing to tumors are the same inflammatory mediators produced by injured tissues: chemokines, cytokines and growth factors. When MSCs arrive into the tumor microenvironment these are "educated" to have pro-metastatic behaviour. Firstly, they promote cancer immunosuppression modulating both innate and adaptive immune systems. Moreover, tumor associated-MSCs trans-differentiating into cancer-associated fibroblasts can induce epithelial-mesenchymal-transition program in tumor cells. This process determinates a more aggressive phenotype of cancer cells by increasing their motility and invasiveness and favoring their dissemination to distant sites. In addition, MSCs are involved in the formation and modelling of pre-metastatic niches creating a supportive environment for colonization of circulating tumor cells. The development of novel therapeutic approaches targeting the different functions of MSCs in promoting tumor progression as well as the mechanisms underlying their activities could enhance the efficacy of conventional and immune anti-cancer therapies. Furthermore, many studies report the use of MSCs engineered to express different genes or as vehicle to specifically deliver novel drugs to tumors exploiting their strong tropism. Importantly, this approach can enhance local therapeutic efficacy and reduce the risk of systemic side effects.

Genetically modified mesenchymal stromal cells in cancer therapy

The cell therapy industry has grown rapidly over the past 3 decades, and multiple clinical trials have been performed to date covering a wide range of diseases. The most frequently used cell is mesenchymal stromal cells (MSCs), which have been used largely for their anti-inflammatory actions and in situations of tissue repair and although they have demonstrated a good safety profile, their therapeutic efficacy has been limited. In addition to these characteristics MSCs are being used for their homing and engraftment properties and have been genetically modified to enable targeted delivery of a variety of therapeutic agents in both malignant and nonmalignant conditions. This review discusses the science and technology behind genetically modified MSC therapy in malignant disease and how potential problems have been overcome to enable their use in two novel clinical trials in metastatic gastrointestinal and lung cancer.

Human Menstrual Blood-Derived Mesenchymal Stem Cells as Potential Cell Carriers for Oncolytic Adenovirus

Antitumor efficacy of systemically administered oncolytic adenoviruses (OAdv) is limited due to diverse factors such as liver sequestration, neutralizing interactions in blood, elimination by the immune system, and physical barriers in tumors. It is therefore of clinical relevance to improve OAdv bioavailability and tumor delivery. Among the variety of tumor-targeting strategies, the use of stem cells and specifically bone marrow-derived mesenchymal stem cells (BM-MSCs) is of particular interest due to their tumor tropism and immunomodulatory properties. Nonetheless, the invasive methods to obtain these cells, the low number of MSCs present in the bone marrow, and their restricted in vitro expansion represent major obstacles for their use in cancer treatments, pointing out the necessity to identify an alternative source of MSCs. Here, we have evaluated the use of menstrual blood-derived mesenchymal stem cells (MenSCs) as cell carriers for regional delivery of an OAdv in the tumor. Our results indicate that MenSCs can be isolated without invasive methods, they have an increased proliferation rate compared to BM-MSCs, and they can be efficiently infected with different serotype 5-based capsid-modified adenoviruses, leading to viral replication and release. In addition, our in vivo studies confirmed the tumor-homing properties of MenSCs after regional administration.

Mesenchymal Stem Cells Induce Epithelial to Mesenchymal Transition in Colon Cancer Cells through Direct Cell-to-Cell Contact

We previously reported that in an orthotopic nude mouse model of human colon cancer, bone marrow-derived mesenchymal stem cells (MSCs) migrated to the tumor stroma and promoted tumor growth and metastasis. Here, we evaluated the proliferation and migration ability of cancer cells cocultured with MSCs to elucidate the mechanism of interaction between cancer cells and MSCs. Proliferation and migration of cancer cells increased following direct coculture with MSCs but not following indirect coculture. Thus, we hypothesized that direct contact between cancer cells and MSCs was important. We performed a microarray analysis of gene expression in KM12SM colon cancer cells directly cocultured with MSCs. Expression of epithelial-mesenchymal transition (EMT)-related genes such as fibronectin (FN), SPARC, and galectin 1 was increased by direct coculture with MSCs. We also confirmed the upregulation of these genes with real-time polymerase chain reaction. Gene expression was not elevated in cancer cells indirectly cocultured with MSCs. Among the EMT-related genes upregulated by direct coculture with MSCs, we examined the immune localization of FN, a well-known EMT marker. In coculture assay in chamber slides, expression of FN was seen only at the edges of cancer clusters where cancer cells directly contacted MSCs. FN expression in cancer cells increased at the tumor periphery and invasive edge in orthotopic nude mouse tumors and human colon cancer tissues. These results suggest that MSCs induce EMT in colon cancer cells via direct cell-to-cell contact and may play an important role in colon cancer metastasis.

Ultrasound-Mediated Mesenchymal Stem Cells Transfection as a Targeted Cancer Therapy Platform

Mesenchymal stem cells (MSCs) hold tremendous potential as a targeted cell-based delivery platform for inflammatory and cancer therapy. Genetic manipulation of MSCs, however, is challenging, and therefore, most studies using MSCs as therapeutic cell carriers have utilized viral vectors to transduce the cells. Here, we demonstrate, for the first time, an alternative approach for the efficient transfection of MSCs; therapeutic ultrasound (TUS). Using TUS with low intensities and moderate frequencies, MSCs were transfected with a pDNA encoding for PEX, a protein that inhibits tumor angiogenesis, and studied as a cell vehicle for in vivo tumor therapy. TUS application did not alter the MSCs' stemness or their homing capabilities, and the transfected MSCs transcribed biologically active PEX. Additionally, in a mouse model, 70% inhibition of prostate tumor growth was achieved following a single I.V. administration of MSCs that were TUS-transfected with pPEX. Further, the repeated I.V. administration of TUS-pPEX transfected-MSCs enhanced tumor inhibition up to 84%. Altogether, these results provide a proof of concept that TUS-transfected MSCs can be effectively used as a cell-based delivery approach for the prospective treatment of cancer.

Characterization of the Tumor Microenvironment and Tumor-Stroma Interaction by Non-invasive Preclinical Imaging

Tumors are often characterized by hypoxia, vascular abnormalities, low extracellular pH, increased interstitial fluid pressure, altered choline-phospholipid metabolism, and aerobic glycolysis (Warburg effect). The impact of these tumor characteristics has been investigated extensively in the context of tumor development, progression, and treatment response, resulting in a number of non-invasive imaging biomarkers. More recent evidence suggests that cancer cells undergo metabolic reprograming, beyond aerobic glycolysis, in the course of tumor development and progression. The resulting altered metabolic content in tumors has the ability to affect cell signaling and block cellular differentiation. Additional emerging evidence reveals that the interaction between tumor and stroma cells can alter tumor metabolism (leading to metabolic reprograming) as well as tumor growth and vascular features. This review will summarize previous and current preclinical, non-invasive, multimodal imaging efforts to characterize the tumor microenvironment, including its stromal components and understand tumor-stroma interaction in cancer development, progression, and treatment response.

Alternative new mesenchymal stem cell source exerts tumor tropism through ALCAM and N-cadherin via regulation of microRNA-192 and -218

Gliomas are the most common type of malignant primary brain tumors. Some treatments of gliomas exist, but they are rarely curative. Mesenchymal stem cells (MSCs) are emerging as potential modes of targeted cancer therapy owing to their capacity for homing toward tumor sites. It has been proposed that MSCs derived from various sources, such as bone marrow, adipose tissue and umbilical cord blood, can be used as cell-based therapy for brain tumors. Here, MSCs obtained from the synovial fluid of osteoarthritis or rheumatoid arthritis patients were investigated as therapeutic candidates. Specifically, we compared migratory and adhesive abilities, as well as expression levels of related genes and microRNA in bone marrow derived-MSCs (BMMSCs), adipose derived-MSCs (ADMSCs), and synovial fluid derived-MSCs (SFMSCs) after treatment with conditioned medium from gliomas. Migration and adhesion of SFMSCs increased through upregulation of the activated lymphocyte cell adhesion molecule (ALCAM) and N-cadherin by microRNA-192 and -218 downregulation, similar to BMMSCs and ADMSCs. Migratory capacities of all types of MSCs were evaluated in vivo, and SFMSCs migrated intensively toward gliomas. These results suggest that SFMSCs have potential for use in cell-based antitumor therapies.

Tumor-homing effect of human mesenchymal stem cells in a TH-MYCN mouse model of neuroblastoma

BACKGROUND

Human mesenchymal stem cells (hMSCs) are multipotent stem-like cells that are reported to have tumor-suppression effects and migration ability toward damaged tissues or tumors. The aim of this study was to analyze the tumor-homing ability of hMSCs and antitumor potency in a transgenic TH-MYCN mouse model of neuroblastoma (NB).

METHODS

hMSCs (3×10⁶) labeled with DiR, a lipophilic near-infrared dye, were intraperitoneally (i.p.) or intravenously (i.v.) administered to the TH-MYCN mice. hMSC in vivo kinetics were assayed using the IVIS® imaging system for 24h after injection. Immunohistochemistry using human CD90 antibody was also performed to confirm the location of hMSCs in various organs and tumors. Furthermore, the survival curve of TH-MYCN mice treated with hMSCs was compared to a control group administered PBS.

RESULTS

i.p. hMSCs were recognized in the tumors of TH-MYCN mice by IVIS. hMSCs were also located inside the tumor tissue. Conversely, most of the i.v. hMSCs were captured by the lungs, and migration into the tumors was not noted. There was no significant difference in the survival between the hMSC and control groups.

CONCLUSION

The present study suggested that hMSCs may be potential tumor-specific therapeutic delivery vehicles in NB according to their homing potential to tumors.

Human endometrial mesenchymal stem cells exhibit intrinsic anti-tumor properties on human epithelial ovarian cancer cells

Epithelial ovarian cancer (EOC) is the most lethal tumor of all gynecologic tumors. There is no curative therapy for EOC thus far. The tumor-homing ability of adult mesenchymal stem cells (MSCs) provide the promising potential to use them as vehicles to transport therapeutic agents to the site of tumor. Meanwhile, studies have showed the intrinsic anti-tumor properties of MSCs against various kinds of cancer, including epithelial ovarian cancer. Human endometrial mesenchymal stem cells (EnSCs) derived from menstrual blood are a novel source for adult MSCs and exert restorative function in some diseases. Whether EnSCs endow innate anti-tumor properties on EOC cells has never been reported. By using tumor-bearing animal model and ex vivo experiments, we found that EnSCs attenuated tumor growth by inducing cell cycle arrest, promoting apoptosis, disturbing mitochondria membrane potential and decreasing pro-angiogenic ability in EOC cells in vitro and/or in vivo. Furthermore, EnSCs decreased AKT phosphorylation and promoted nuclear translocation of Forkhead box O-3a (FoxO3a) in EOC cells. Collectively, our findings elucidated the potential intrinsic anti-tumor properties of EnSCs on EOC cells in vivo and in vitro. This research provides a potential strategy for EnSC-based anti-cancer therapy against epithelial ovarian cancer.

Engineered Mesenchymal Stem Cells as an Anti-Cancer Trojan Horse

Cell-based gene therapy holds a great promise for the treatment of human malignancy. Among different cells, mesenchymal stem cells (MSCs) are emerging as valuable anti-cancer agents that have the potential to be used to treat a number of different cancer types. They have inherent migratory properties, which allow them to serve as vehicles for delivering effective therapy to isolated tumors and metastases. MSCs have been engineered to express anti-proliferative, pro-apoptotic, and anti-angiogenic agents that specifically target different cancers. Another field of interest is to modify MSCs with the cytokines that activate pro-tumorigenic immunity or to use them as carriers for the traditional chemical compounds that possess the properties of anti-cancer drugs. Although there is still controversy about the exact function of MSCs in the tumor settings, the encouraging results from the preclinical studies of MSC-based gene therapy for a large number of tumors support the initiation of clinical trials.

Mesenchymal stem cells as a double-edged sword in suppression or progression of solid tumor cells

Tumor cells are able to attract mesenchymal stem cells (MSCs) to primary tumor site. On the other hand, MSCs secrete various factors to attract tumor cells towards BM. In this review, in addition to assessment of MSCs function at tumor sites and their impact on growth and metastasis of tumor cells, the importance of MSC in attraction of malignant cells to BM and their involvement in drug resistance of tumor cells have also been studied. Relevant literature was identified by a PubMed search (2000-2015) of English-language literature using the terms mesenchymal stem cells, cancer cell, metastasis, and tumor microenvironment. MSCs migrate towards tumor microenvironment and are involved in both pro-tumorigenic and antitumorigenic functions. The dual function of MSCs at tumor sites is dependent upon a variety of factors, including the type and origin of MSCs, the cancer cell line under study, in vivo or in vitro conditions, the factors secreted by MSCs and interactions between MSCs, host immune cells and cancer cells. Therefore, MSCs can be regarded both as friends and enemies of cancer cells. Although the role of a number of pathways, including IL-6/STAT3 pathway, has been indicated in controlling the interaction between MSCs and tumor cells, other mechanisms by which MSCs can control the tumor cells are not clear yet. A better understanding of these mechanisms through further studies can determine the exact role of MSCs in cancer progression and identify them as important therapeutic agents or targets.

Human umbilical cord mesenchymal stem cells delivering sTRAIL home to lung cancer mediated by MCP-1/CCR2 axis and exhibit antitumor effects

Mesenchymal stem cells (MSCs) are believed to be a potential vehicle delivering antitumor agents for their tumor-homing capacity, while the underlying mechanism is yet to be explored. The apoptotic ligand TNF-related apoptosis-inducing ligand (TRAIL) has been suggested as a promising candidate for cancer gene therapy owing to its advantage of selectively inducing apoptosis in cancer cells while sparing normal cells. An isoleucine zipper (ISZ) added to the N-terminal of secretable soluble TRAIL (sTRAIL) can generate the trimeric form of TRAIL (ISZ-sTRAIL) and increase its antitumor potential. However, the inefficient delivery and toxicity are still obstacles for its use. In this study, the migration of human umbilical cord mesenchymal stem cells (HUMSCs) to lung cancer was observed through transwell migration assay and animal bioluminescent imaging both in vitro and in vivo. We found that the homing ability of HUMSCs was suppressed after either knocking down the expression of monocyte chemoattractant protein-1(MCP-1) in lung cancer cells or blocking CCR2 expressed on the surface of HUMSCs, indicating the important role of MCP-1/CCR2 axis in the tropism of HUMSCs to lung cancer. Furthermore, we genetically modified HUMSCs to deliver ISZ-sTRAIL to tumor sites specifically. This targeted therapeutic system exhibited promising apoptotic induction and antitumor potential in a xenograft mouse model without obvious side effects. In conclusion, HUMSCs expressing ISZ-sTRAIL might be an efficient therapeutic approach against lung cancer and MCP-1/CCR2 axis is essential for the tumor tropism of HUMSCs.

Dextran-coated iron oxide nanoparticles turn protumor mesenchymal stem cells (MSCs) into antitumor MSCs

dex-IO NPs can activate the antitumor mechanism (tumor tropism) but inactivate protumor mechanisms to transform protumor MSCs (pT-MSCs) into antitumor MSCs (aT-MSCs).

Mesenchymal Stem Cell-Mediated Effects of Tumor Support or Suppression

Mesenchymal stem cells (MSCs) can exhibit a marked tropism towards site of tumors. Many studies have reported that tumor progression and metastasis increase by MSCs. In contrast, other studies have shown that MSCs suppress growth of tumors. MSCs contribute to tumor growth promotion by several mechanisms: (1) transition to tumor-associated fibroblasts; (2) suppression of immune response; (3) promotion of angiogenesis; (4) stimulation of epithelial-mesenchymal transition (EMT); (5) contribution to the tumor microenvironment; (6) inhibition of tumor cell apoptosis; and (7) promotion of tumor metastasis. In contrast to the tumor-promoting properties, MSCs inhibit tumor growth by increasing inflammatory infiltration, inhibiting angiogenesis, suppressing Wnt signaling and AKT signaling, and inducing cell cycle arrest and apoptosis. In this review, we will discuss potential mechanisms by which MSC mediates tumor support or suppression and then the possible tumor-specific therapeutic strategies using MSCs as delivery vehicles, based on their homing potential to tumors.

Mesenchymal stem cell transplantation for treatment of digestive diseases

Treatment of diseases using mesenchymal stem cells (MSCs) has gained great breakthrough with the discovery of properties of MSCs since 1990s. So far, MSC transplantation in the treatment of digestive tract diseases is mainly focused on hepatic cirrhosis, liver failure, acute or chronic pancreatitis, inflammatory bowel disease and digestive tumors. In the current editorial, we rely primarily on the existing evidence to gain a comprehensive perspective toward this area.

Intracellular expression profile and clinical significance of the CCR9-CCL25 chemokine receptor complex in nasopharyngeal carcinoma

OBJECTIVES

This study aimed to investigate the association of C-C chemokine receptor type 9 (CCR9) and C-C motif chemokine 25 (CCL25) expression levels with clinical and tumour-node-metastasis stage in nasopharyngeal carcinoma.

METHODS

A total of 42 nasopharyngeal carcinoma patients (nasopharyngeal carcinoma group) and 18 patients with a normal nasopharynx (control group) were included in this study. Tissues were collected during surgery and medical examinations. The CCR9 and CCL25 messenger RNA and protein levels were measured using quantitative reverse transcription polymerase chain reaction, Western blotting and immunohistochemical analysis.

RESULTS

CCR9 and CCL25 messenger RNA and protein levels were significantly increased in the nasopharyngeal carcinoma group compared with the control group (p < 0.05). Both CCR9 and CCL25 messenger RNA and protein levels were significantly higher in advanced-stage nasopharyngeal carcinoma (stages III and IV) patients compared with early-stage nasopharyngeal carcinoma (stages I and II) patients (p < 0.05).

CONCLUSION

The extent of CCR9 and CCL25 upregulation in nasopharyngeal carcinoma correlates with the tumour-node-metastasis stage.

Multipotent Mesenchymal Stromal Cells: Possible Culprits in Solid Tumors?

The clinical use of bone marrow derived multipotent mesenchymal stromal cells (BM-MSCs) in different settings ranging from tissue engineering to immunotherapies has prompted investigations on the properties of these cells in a variety of other tissues. Particularly the role of MSCs in solid tumors has been the subject of many experimental approaches. While a clear phenotypical distinction of tumor associated fibroblasts (TAFs) and MSCs within the tumor microenvironment is still missing, the homing of bone marrow MSCs in tumor sites has been extensively studied. Both, tumor-promoting and tumor-inhibiting effects of BM-MSCs have been described in this context. This ambiguity requires a reappraisal of the different studies and experimental methods employed. Here, we review the current literature on tumor-promoting and tumor-inhibiting effects of BM-MSCs with a particular emphasis on their interplay with components of the immune system and also highlight a potential role of MSCs as cell of origin for certain mesenchymal tumors.

New targeted therapies in pancreatic cancer

Patients with pancreatic cancer have a poor prognosis with a median survival of 4-6 mo and a 5-year survival of less than 5%. Despite therapy with gemcitabine, patient survival does not exceed 6 mo, likely due to natural resistance to gemcitabine. Therefore, it is hoped that more favorable results can be obtained by using guided immunotherapy against molecular targets. This review summarizes the new leading targeted therapies in pancreatic cancers, focusing on passive and specific immunotherapies. Passive immunotherapy may have a role for treatment in combination with radiochemotherapy, which otherwise destroys the immune system along with tumor cells. It includes mainly therapies targeting against kinases, including epidermal growth factor receptor, Ras/Raf/mitogen-activated protein kinase cascade, human epidermal growth factor receptor 2, insulin growth factor-1 receptor, phosphoinositide 3-kinase/Akt/mTOR and hepatocyte growth factor receptor. Therapies against DNA repair genes, histone deacetylases, microRNA, and pancreatic tumor tissue stromal elements (stromal extracellular matric and stromal pathways) are also discussed. Specific immunotherapies, such as vaccines (whole cell recombinant, peptide, and dendritic cell vaccines), adoptive cell therapy and immunotherapy targeting tumor stem cells, have the role of activating antitumor immune responses. In the future, treatments will likely include personalized medicine, tailored for numerous molecular therapeutic targets of multiple pathogenetic pathways.

Human mesenchymal stem cells enhance cancer cell proliferation via IL-6 secretion and activation of ERK1/2

Human mesenchymal stem cells (hMSC) are frequently used in tissue engineering. Due to their strong tumor tropism, hMSC seem to be a promising vehicle for anticancer drugs. However, interactions between hMSC and cancer are ambiguous. Particularly the cytokines and growth factors seem to play an important role in cancer progression and metastasis. The present study evaluated the effects of hMSC on head and neck squamous cell carcinoma (HNSCC) cell lines (FaDu and HLaC78) in vitro. hMSC released several cytokines and growth factors. FaDu and HLaC78 showed a significant enhancement of cell proliferation after cultivation with hMSC-conditioned medium as compared to control. This proliferation improvement was inhibited by the addition of anti-IL-6. The western blot showed an activation of Erk1/2 in FaDu and HLaC78 by hMSC-conditioned medium. HNSCC cell lines expressed EGFR. The current study confirms the importance of cytokines secreted by hMSC in cancer biology. Especially IL-6 seems to play a key role in cancer progression. Thus, the use of hMSC as a carrier for cancer therapy must be discussed critically. Future studies should evaluate the possibility of generating genetically engineered hMSC with, for example, the absence of IL-6 secretion.

Mesenchymal stromal cell delivery of full-length tumor necrosis factor-related apoptosis-inducing ligand is superior to soluble type for cancer therapy

Background aims

Mesenchymal stromal cell (MSC) delivery of pro-apoptotic tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is an attractive strategy for anticancer therapy. MSCs expressing full-length human TRAIL (flT) or its soluble form (sT) have previously been shown to be effective for cancer killing. However, a comparison between the two forms has never been performed, leaving it unclear which approach is most effective. This study addresses the issue for the possible clinical application of TRAIL-expressing MSCs in the future.

Methods

MSCs were transduced with lentiviruses expressing flT or an isoleucine zipper-fused sT. TRAIL expression was examined and cancer cell apoptosis was measured after treatment with transduced MSCs or with MSC-derived soluble TRAIL.

Results

The transduction does not adversely affect cell phenotype. The sT-transduced MSCs (MSC-sT) secrete abundant levels of soluble TRAIL but do not present the protein on the cell surface. Interestingly, the flT-transduced MSCs (MSC-flT) not only express cell-surface TRAIL but also release flT into medium. These cells were examined for inducing apoptosis in 20 cancer cell lines. MSC-sT cells showed very limited effects. By contrast, MSC-flT cells demonstrated high cancer cell-killing efficiency. More importantly, MSC-flT cells can overcome some cancer cell resistance to recombinant TRAIL. In addition, both cell surface flT and secreted flT are functional for inducing apoptosis. The secreted flT was found to have higher cancer cell-killing capacity than either recombinant TRAIL or MSC-secreted sT.

Conclusions

These observations demonstrate that MSC delivery of flT is superior to MSC delivery of sT for cancer therapy.

Targeting delivery of lipocalin 2-engineered mesenchymal stem cells to colon cancer in order to inhibit liver metastasis in nude mice

One of the major obstacles in cancer therapy is the lack of anticancer agent specificity to tumor tissues. The strategy of cell-based therapy is a promising therapeutic option for cancer treatment. The specific tumor-oriented migration of mesenchymal stem cells (MSCs) makes them a useful vehicle to deliver anticancer agents. In this study, we genetically manipulated bone marrow-derived mesenchymal stem cells with their lipocalin 2 (Lcn2) in order to inhibit liver metastasis of colon cancer in nude mice. Lcn2 was successfully overexpressed in transfected MSCs. The PCR results of SRY gene confirmed the presence of MSCs in cancer liver tissue. This study showed that Lcn2-engineered MSCs (MSC-Lcn2) not only inhibited liver metastasis of colon cancer but also downregulated the expression of vascular endothelial growth factor (VEGF) in the liver. Overall, MSCs by innate tropism toward cancer cells can deliver the therapeutic agent, Lcn2, and inhibit cancer metastasis. Hence, it could be a new modality for efficient targeted delivery of anticancer agent to liver metastasis.

The protective effect of CDDO-Me on lipopolysaccharide-induced acute lung injury in mice

CDDO-Me, initiated in a phase II clinical trial, is a potential useful therapeutic agent for cancer and inflammatory dysfunctions, whereas the therapeutic efficacy of CDDO-Me on LPS-induced acute lung injury (ALI) has not been reported as yet. The purpose of the present study was to explore the protective effect of CDDO-Me on LPS-induced ALI in mice and to investigate its possible mechanism. BalB/c mice received CDDO-Me (0.5mg/kg, 2mg/kg) or dexamethasone (5mg/kg) intraperitoneally 1h before LPS stimulation and were sacrificed 6h later. W/D ratio, lung MPO activity, number of total cells and neutrophils, pulmonary histopathology, IL-6, IL-1β, and TNF-α in the BALF were assessed. Furthermore, we estimated iNOS, IL-6, IL-1β, and TNF-α mRNA expression and NO production as well as the activation of the three main MAPKs, AkT, IκB-α and p65. Pretreatment with CDDO-Me significantly ameliorated W/D ratio, lung MPO activity, inflammatory cell infiltration, and inflammatory cytokine production in BALF from the in vivo study. Additionally, CDDO-Me had beneficial effects on the intervention for pathogenesis process at molecular, protein and transcriptional levels in vitro. These analytical results provided evidence that CDDO-Me could be a potential therapeutic candidate for treating LPS-induced ALI.

In vivo cell tracking with bioluminescence imaging

Molecular imaging is a fast growing biomedical research that allows the visual representation, characterization and quantification of biological processes at the cellular and subcellular levels within intact living organisms. In vivo tracking of cells is an indispensable technology for development and optimization of cell therapy for replacement or renewal of damaged or diseased tissue using transplanted cells, often autologous cells. With outstanding advantages of bioluminescence imaging, the imaging approach is most commonly applied for in vivo monitoring of transplanted stem cells or immune cells in order to assess viability of administered cells with therapeutic efficacy in preclinical small animal models. In this review, a general overview of bioluminescence is provided and recent updates of in vivo cell tracking using the bioluminescence signal are discussed.

Gene therapy in pancreatic cancer

Pancreatic cancer (PC) is a highly lethal disease and notoriously difficult to treat. Only a small proportion of PC patients are eligible for surgical resection, whilst conventional chemoradiotherapy only has a modest effect with substantial toxicity. Gene therapy has become a new widely investigated therapeutic approach for PC. This article reviews the basic rationale, gene delivery methods, therapeutic targets and developments of laboratory research and clinical trials in gene therapy of PC by searching the literature published in English using the PubMed database and analyzing clinical trials registered on the Gene Therapy Clinical Trials Worldwide website (http://www. wiley.co.uk/genmed/ clinical). Viral vectors are main gene delivery tools in gene therapy of cancer, and especially, oncolytic virus shows brighter prospect due to its tumor-targeting property. Efficient therapeutic targets for gene therapy include tumor suppressor gene p53, mutant oncogene K-ras, anti-angiogenesis gene VEGFR, suicide gene HSK-TK, cytosine deaminase and cytochrome p450, multiple cytokine genes and so on. Combining different targets or combination strategies with traditional chemoradiotherapy may be a more effective approach to improve the efficacy of cancer gene therapy. Cancer gene therapy is not yet applied in clinical practice, but basic and clinical studies have demonstrated its safety and clinical benefits. Gene therapy will be a new and promising field for the treatment of PC.

Molecular imaging for assessment of mesenchymal stem cells mediated breast cancer therapy

The tumor tropism of mesenchymal stem cells (MSCs) makes them an excellent delivery vehicle used in anticancer therapy. However, the exact mechanisms of MSCs involved in tumor microenvironment are still not well defined. Molecular imaging technologies with the versatility in monitoring the therapeutic effects, as well as basic molecular and cellular processes in real time, offer tangible options to better guide MSCs mediated cancer therapy. In this study, an in situ breast cancer model was developed with MDA-MB-231 cells carrying a reporter system encoding a double fusion (DF) reporter gene consisting of firefly luciferase (Fluc) and enhanced green fluorescent protein (eGFP). In mice breast cancer model, we injected human umbilical cord-derived MSCs (hUC-MSCs) armed with a triple fusion (TF) gene containing the herpes simplex virus truncated thymidine kinase (HSV-ttk), renilla luciferase (Rluc) and red fluorescent protein (RFP) into tumor on day 13, 18, 23 after MDA-MB-231 cells injection. Bioluminescence imaging of Fluc and Rluc provided the real time monitor of tumor cells and hUC-MSCs simultaneously. We found that tumors were significantly inhibited by hUC-MSCs administration, and this effect was enhanced by ganciclovir (GCV) application. To further demonstrate the effect of hUC-MSCs on tumor cells in vivo, we employed the near infrared (NIR) imaging and the results showed that hUC-MSCs could inhibit tumor angiogenesis and increased apoptosis to a certain degree. In conclusion, hUC-MSCs can inhibit breast cancer progression by inducing tumor cell death and suppressing angiogenesis. Moreover, molecular imaging is an invaluable tool in tracking cell delivery and tumor response to hUC-MSCs therapies as well as cellular and molecular processes in tumor.

The challenge of pancreatic cancer therapy and novel treatment strategy using engineered mesenchymal stem cells

Mesenchymal stem cells (MSCs) have attracted significant attention in cancer research as a result of their accessibility, tumor-oriented homing capacity, and the feasibility of auto-transplantation. This review provides a comprehensive overview of current challenges in pancreatic cancer therapy, and we propose a novel strategy for using MSCs as means of delivering anticancer genes to the site of pancreas. We aim to provide a practical platform for the development of MSC-based therapy for pancreatic cancer.