hMSC-mediated concurrent delivery of endostatin and carboxylesterase to mouse xenografts suppresses glioma initiation and recurrence

Enhancing Anticancer Efficacy of Chemotherapeutics Using Targeting Ligand-Functionalized Synthetic Antigen Receptor-Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) have been studied for their potential in facilitating tumor-targeted delivery of chemotherapeutics due to their tumor-homing characteristics. We hypothesized that targeting effectiveness of MSCs can be further enhanced by incorporating tumor-targeting ligands on MSC surfaces that will allow for enhanced arrest and binding within the tumor tissue. We utilized a unique strategy of modifying MSCs with synthetic antigen receptors (SARs), targeting specific antigens overexpressed on cancer cells. MSCs were surface-functionalized by first incorporating recombinant protein G (PG) on the surface, followed by binding of the targeting antibody to the PG handle. We functionalized MSCs with antibodies targeting a tyrosine kinase transmembrane receptor protein, epidermal growth factor receptor (EGFR), overexpressed in non-small-cell lung cancer (NSCLC). The efficacy of MSCs functionalized with anti-EGFR antibodies (cetuximab and D8) was determined in murine models of NSCLC. Cetuximab-functionalized MSCs demonstrated improved binding to EGFR protein and to EGFR overexpressing A549 lung adenocarcinoma cells. Further, cetuximab-functionalized MSCs loaded with paclitaxel nanoparticles were efficient in slowing orthotopic A549 tumor growth and improving the overall survival relative to that of other controls. Biodistribution studies revealed a six-fold higher retention of EGFR-targeted MSCs than non-targeted MSCs. Based on these results, we conclude that targeting ligand functionalization could be used to enhance the concentration of therapeutic MSC constructs at the tumor tissue and to achieve improved antitumor response.

Application of Perinatal Derivatives on Oncological Preclinical Models: A Review of Animal Studies

The increasing cancer incidence has certified oncological management as one of the most critical challenges for the coming decades. New anticancer strategies are still needed, despite the significant advances brought to the forefront in the last decades. The most recent, promising therapeutic approaches have benefitted from the application of human perinatal derivatives (PnD), biological mediators with proven benefits in several fields beyond oncology. To elucidate preclinical results and clinic outcomes achieved in the oncological field, we present a narrative review of the studies resorting to animal models to assess specific outcomes of PnD products. Recent preclinical evidence points to promising anticancer effects offered by PnD mediators isolated from the placenta, amniotic membrane, amniotic fluid, and umbilical cord. Described effects include tumorigenesis prevention, uncontrolled growth or regrowth inhibition, tumor homing ability, and adequate cell-based delivery capacity. Furthermore, PnD treatments have been described as supportive of chemotherapy and radiological therapies, particularly when resistance has been reported. However, opposite effects of PnD products have also been observed, offering support and trophic effect to malignant cells. Such paradoxical and dichotomous roles need to be intensively investigated. Current hypotheses identify as explanatory some critical factors, such as the type of the PnD biological products used or the manufacturing procedure to prepare the tissue/cellular treatment, the experimental design (including human-relevant animal models), and intrinsic pathophysiological characteristics. The effective and safe translation of PnD treatments to clinical practice relies on the collaborative efforts of all researchers working with human-relevant oncological preclinical models. However, it requires proper guidelines and consensus compiled by experts and health workers who accurately describe the methodology of tissue collection, PnD isolation, manufacturing, preservation, and delivery to the final user.

Mesenchymal stem cells: A living carrier for active tumor-targeted delivery

The strategy of using mesenchymal stem cells (MSCs) as a living carrier for active delivery of therapeutic agents targeting tumor sites has been attempted in a wide range of studies to validate the feasibility and efficacy for tumor treatment. This approach reveals powerful tumor targeting and tumor penetration. In addition, MSCs have been confirmed to actively participate in immunomodulation of the tumor microenvironment. Thus, MSCs are not inert delivery vehicles but have a strong impact on the fate of tumor cells. In this review, these active properties of MSCs are addressed to highlight the advantages and challenges of using MSCs for tumor-targeted delivery. In addition, some of the latest examples of using MSCs to carry a variety of anti-tumor agents for tumor-targeted therapy are summarized. Recent technologies to improve the performance and safety of this delivery strategy will be introduced. The advances, applications, and challenges summarized in this review will provide a general understanding of this promising strategy for actively delivering drugs to tumor tissues.

To Explore the Stem Cells Homing to GBM: The Rise to the Occasion

Multiple efforts are currently underway to develop targeted therapeutic deliveries to the site of glioblastoma progression. The use of carriers represents advancement in the delivery of various therapeutic agents as a new approach in neuro-oncology. Mesenchymal stem cells (MSCs) and neural stem cells (NSCs) are used because of their capability in migrating and delivering therapeutic payloads to tumors. Two of the main properties that carrier cells should possess are their ability to specifically migrate from the bloodstream and low immunogenicity. In this article, we also compared the morphological and molecular features of each type of stem cell that underlie their migration capacity to glioblastoma. Thus, the major focus of the current review is on proteins and lipid molecules that are released by GBM to attract stem cells.

The MAP3K1/c-JUN signaling axis regulates glioblastoma stem cell invasion and tumor progression

Glioblastoma (GBM) stem cells (GSCs) are responsible for GBM initiation, progression, infiltration, standard therapy resistance, and recurrence. However, the mechanisms underlying GSC invasion remain incompletely understood. Using public single-cell RNA-Seq data, we identified MAP3K1 as a master regulator of infiltrative GSCs through c-JUN signaling regulation. MAP3K1 knockdown significantly decreased GSC invasion capacity, proliferation, and stemness in vitro. Moreover, in an orthotopic xenograft model, knockdown of MAP3K1 prominently suppressed GSC infiltration along the corpus callosum and tumor progression and prolonged mouse survival. Mechanistically, MAP3K1 regulates GSC invasion through phosphorylation of downstream c-JUN at serine 63 and 73, as confirmed using the CPTAC phosphoproteome dataset. Furthermore, the c-JUN inhibitor JNK-IN-8 significantly decreased GSC invasion, proliferation, and stemness. Taken together, our study demonstrates that MAP3K1 regulates GSC invasion and tumor progression via activation of c-JUN signaling and indicates that the MAP3K1/c-JUN signaling axis is a therapeutic target for infiltrative GBM.

Pro-angiogenic activity and vasculogenic mimicry in the tumor microenvironment by leptin in cancer

The acquired ability to induce the formation of a functional vasculature is a hallmark of cancer. Blood vessels in tumors are formed through various mechanisms, among the most important in cancer biology, angiogenesis, and vasculogenic mimicry have been described. Leptin is one of the main adipokines secreted by adipocytes in normal breast tissue and the tumor microenvironment. Here, we provide information on the relationship between leptin and the development of angiogenesis and vasculogenic mimicry in different types of cancer. Here, we report that leptin activates different pathways such as JAK-STAT3, MAPK/ERK, PKC, JNK, p38, and PI3K-Akt to induce the expression of various angiogenic factors and vasculogenic mimicry. In vivo models, leptin induces blood vessel formation through the PI3K-Akt-mTOR pathway. Interestingly, the relationship between leptin and vasculogenic mimicry was more significant in breast cancer. The information obtained suggests that leptin could be playing an essential role in tumor survival and metastasis through the induction of vascular mechanisms such as angiogenesis and vasculogenic mimicry; thus, leptin-induced pathways could be suggested as a promising therapeutic target.

Intracerebral Administration of Autologous Mesenchymal Stem Cells as HSV-TK Gene Vehicle for Treatment of Glioblastoma Multiform: Safety and Feasibility Assessment

Widespread investigation has revealed the promising ability of suicidal genes in the treatment of glioma tumors; nevertheless, promoting their effects relies on the ability to apply suitable vehicles and techniques. In this study, the safety and feasibility of using bone marrow-derived mesenchymal stem cells (MSCs) in combination with prodrug for treatment of patients with primary and secondary glioblastoma multiform (GBM) was assessed. Five GBM patients were recruited. Following gross total resection of the tumor and adjuvant radiotherapy and chemotherapy, intracerebral injection of autologous MSCs transduced with lentivirus containing herpes simplex virus thymidine kinase (HSV-TK) was performed followed by intravenous administration of ganciclovir for 2 weeks. The treatment was well tolerated by all patients. Mild-to-moderate fever, headache, and cerebrospinal fluid leukocytosis were evident in three, two, and one patient, respectively. The progression-free survival (PFS) and overall survival (OS) of patients were 95.79 ± 51.40 and 128.85 ± 48.81 weeks, respectively. The 1-year PFS and OS were 60% and 100%, respectively, among our patients, and two patients had more than 3 years of OS and more than 2 years of PFS. It seems that intracerebral administration of bone marrow MSC containing the HSV-TK gene in combination with intravenous ganciclovir would be safe and feasible in the treatment of patients with GBM.

Stem cells for the treatment of glioblastoma: a 20-year perspective

Glioblastoma, the deadliest form of primary brain tumor, remains a disease without cure. Treatment resistance is in large part attributed to limitations in the delivery and distribution of therapeutic agents. Over the last 20 years, numerous preclinical studies have demonstrated the feasibility and efficacy of stem cells as antiglioma agents, leading to the development of trials to test these therapies in the clinic. In this review we present and analyze these studies, discuss mechanisms underlying their beneficial effect and highlight experimental progress, limitations and the emergence of promising new therapeutic avenues. We hope to increase awareness of the advantages brought by stem cells for the treatment of glioblastoma and inspire further studies that will lead to accelerated implementation of effective therapies.

Glioblastoma is the deadliest and most common form of brain tumor, for which there is no cure. It is very difficult to deliver medicine to the tumor cells, because they spread out widely into the normal brain, and local blood vessels represent a barrier that most medicines cannot cross. It was shown, in many studies over the last 20 years, that stem cells are attracted toward the tumor and that they can deliver many kinds of therapeutic agents directly to brain cancer cells and shrink the tumor. In this review we analyze these studies and present new discoveries that can be used to make stem cell therapies for glioblastoma more effective to prolong the life of patients with brain tumors.

Contemporary Mouse Models in Glioma Research

Despite advances in understanding of the molecular pathogenesis of glioma, outcomes remain dismal. Developing successful treatments for glioma requires faithful in vivo disease modeling and rigorous preclinical testing. Murine models, including xenograft, syngeneic, and genetically engineered models, are used to study glioma-genesis, identify methods of tumor progression, and test novel treatment strategies. Since the discovery of highly recurrent isocitrate dehydrogenase (IDH) mutations in lower-grade gliomas, there is increasing emphasis on effective modeling of IDH mutant brain tumors. Improvements in preclinical models that capture the phenotypic and molecular heterogeneity of gliomas are critical for the development of effective new therapies. Herein, we explore the current status, advancements, and challenges with contemporary murine glioma models.

Mesenchymal Stem Cells: An Overview of Their Potential in Cell-Based Therapy for Diabetic Nephropathy

Diabetic nephropathy (DN) is a devastating complication associated with diabetes mellitus, and it is the leading cause of end-stage renal diseases (ESRD). Over the last few decades, numerous studies have reported the beneficial effects of stem cell administration, specifically mesenchymal stem or stromal cells (MSCs), on tissue repair and regeneration. MSC therapy has been considered a promising strategy for ameliorating the progression of DN largely based on results obtained from several preclinical studies and recent Phase I/II clinical trials. This paper will review the recent literature on MSC treatment in DN. In addition, the roles and potential mechanisms involved in MSC treatment of DN will be summarized, which may present much needed new drug targets for this disease. Moreover, the potential benefits and related risks associated with the therapeutic action of MSCs are elucidated and may help in achieving a better understanding of MSCs.

Investigating curcumin potential for diabetes cell therapy, in vitro and in vivo study

AIMS

An important obstacle on the way of cell-based therapy is the risk of tumorigenicity in the patients benefit from these transplanted cells due to undifferentiated cells which participate in transplantation. Curcumin, the main compound of spice turmeric -as one of the natural products-was demonstrated to possess effective anti-cancer properties, with no significant effect on normal cells in dose and/or time-dependent manner. Furthermore many studies have been accomplished using curcumin for diabetes treatment. Therefore in this study we examined the efficacy of IPCs treated with curcumin in vivo.

MAIN METHODS

Differentiation efficiency investigated by flowcytometry. RNA extraction and real-time PCR performed for important genes in IPC differentiation and tumorigenesis including Insulin, Nestin, Ngn3, Pdx1, P21, and P53. Finally we investigated the efficiency of these differentiated and treated cells in diabetic rats.

KEY FINDINGS

Our data indicates that nanocurcumin -in a specific dose-reduces the expression of Nestin with no significant effect on insulin expression in mRNA and protein level. Besides blood glucose level of diabetic rats which treated with DNC + cells, decreased from average 350 (mg/dI) to 100 (mg/dI). Checking out the pancreases of these rats, demonstrated that their endocrine segment was rebuilt. Moreover hematoxylin & eosin staining and IF results revealed that the Langerhans Islands were reformed.

SIGNIFICANCE

IPCs' which treated with DNC were able to efficiently control the blood glucose level in diabetic rats which these cells were transplanted to them. Hence Curcumin has the potential to be employed in this kind of cell therapy.

Engineered Mesenchymal Stem Cells for Targeting Solid Tumors: Therapeutic Potential beyond Regenerative Therapy

Mesenchymal stem cells (MSCs) have previously demonstrated considerable promise in regenerative medicine based on their ability to proliferate and differentiate into cells of different lineages. More recently, there has been a significant interest in using MSCs as cellular vehicles for targeted cancer therapy by exploiting their tumor homing properties. Initial studies focused on using genetically modified MSCs for targeted delivery of various proapoptotic, antiangiogenic, and therapeutic proteins to a wide variety of tumors. However, their use as drug delivery vehicles has been limited by poor drug load capacity. This review discusses various strategies for the nongenetic modification of MSCs that allows their use in tumor-targeted delivery of small molecule chemotherapeutic agents. SIGNIFICANCE STATEMENT: There has been considerable interest in exploiting the tumor homing potential of MSCs to develop them as a vehicle for the targeted delivery of cytotoxic agents to tumor tissue. The inherent tumor-tropic and drug-resistant properties make MSCs ideal carriers for toxic payload. While significant progress has been made in the area of the genetic modification of MSCs, studies focused on identification of molecular mechanisms that contribute to the tumor tropism along with optimization of the engineering conditions can further improve their effectiveness as drug delivery vehicles.

Nanocarriers and nonviral methods for delivering antiangiogenic factors for glioblastoma therapy: the story so far

Angiogenesis, the formation of new blood vessels, is an essential component of glioblastoma (GB) progression. The development of angiogenesis inhibitor therapy, including treatments targeting vascular endothelial growth factor (VEGF) in particular, raised new hopes for the treatment of GB, but no Phase III clinical trial to date has reported survival benefits relative to standard treatment. There are several possible reasons for this limited efficacy, including VEGF-independent angiogenesis, induction of tumor invasion, and inefficient antiangiogenic factor delivery to the tumor. Efforts have been made to overcome these limitations by identifying new angiogenesis inhibitors that target angiogenesis through different mechanisms of action without inducing tumor invasion, and through the development of viral and nonviral delivery methods to improve antiangiogenic activity. Herein, we describe the nonviral methods, including convection-enhanced delivery devices, implantable polymer devices, nanocarriers, and cellular vehicles, to deliver antiangiogenic factors. We focus on those evaluated in intracranial (orthotopic) animal models of GB, the most relevant models of this disease, as they reproduce the clinical scenario of tumor progression and therapy response encountered in GB patients.

Mesenchymal stem cells enhance tumorigenic properties of human glioblastoma through independent cell-cell communication mechanisms

Mesenchymal stem cells (MSC) display tumor tropism and have been addressed as vehicles for delivery of anti-cancer agents. As cellular components of the tumor microenvironment, MSC also influence tumor progression. However, the contribution of MSC in brain cancer is not well understood since either oncogenic or tumor suppressor effects have been reported for these cells. Here, MSC were found capable of stimulating human Glioblastoma (GBM) cell proliferation through a paracrine effect mediated by TGFB1. Moreover, when in direct cell-cell contact with GBM cells, MSC elicited an increased proliferative and invasive tumor cell behavior under 3D conditions, as well as accelerated tumor development in nude mice, independently of paracrine TGFB1. A secretome profiling of MSC-GBM co-cultures identified 126 differentially expressed proteins and 10 proteins exclusively detected under direct cell-cell contact conditions. Most of these proteins are exosome cargos and are involved in cell motility and tissue development. These results indicate a dynamic interaction between MSC and GBM cells, favoring aggressive tumor cell traits through alternative and independent mechanisms. Overall, these findings indicate that MSC may exert pro-tumorigenic effects when in close contact with tumor cells, which must be carefully considered when employing MSC in targeted cell therapy protocols against cancer.

Nano-Engineered Mesenchymal Stem Cells Increase Therapeutic Efficacy of Anticancer Drug Through True Active Tumor Targeting

Tumor-targeted drug delivery has the potential to improve therapeutic efficacy and mitigate non-specific toxicity of anticancer drugs. However, current drug delivery approaches rely on inefficient passive accumulation of the drug carrier in the tumor. We have developed a unique, truly active tumor-targeting strategy that relies on engineering mesenchymal stem cells (MSC) with drug-loaded nanoparticles. Our studies using the A549 orthotopic lung tumor model show that nano-engineered MSCs carrying the anticancer drug paclitaxel (PTX) home to tumors and create cellular drug depots that release the drug payload over several days. Despite significantly lower doses of PTX, nano-engineered MSCs resulted in significant inhibition of tumor growth and superior survival. Anticancer efficacy of nano-engineered MSCs was confirmed in immunocompetent C57BL/6 albino female mice bearing orthotopic Lewis Lung Carcinoma (LL/2-luc) tumors. Furthermore, at doses that resulted in equivalent therapeutic efficacy, nano-engineered MSCs had no effect on white blood cell count, whereas PTX solution and PTX nanoparticle treatments caused leukopenia. Biodistribution studies showed that nano-engineered MSCs resulted in greater than 9-fold higher AUC_lung of PTX (1.5 μg.day/g) than PTX solution and nanoparticles (0.2 and 0.1 μg.day/g tissue, respectively) in the target lung tumors. Furthermore, the lung-to-liver and the lung-to-spleen ratios of PTX were several folds higher for nano-engineered MSCs relative to those for PTX solution and nanoparticle groups, suggesting that nano-engineered MSCs demonstrate significantly less off-target deposition. In summary, our results demonstrate that nano-engineered MSCs can serve as an efficient carrier for tumor-specific drug delivery and significantly improved anti-cancer efficacy of conventional chemotherapeutic drugs. Mol Cancer Ther; 17(6); 1196-206. ©2018 AACR.

Cell-mediated enzyme prodrug cancer therapies

Cell-directed gene therapy is a promising new frontier for the field of targeted cancer therapies. Here we discuss the current pre-clinical and clinical use of cell-mediated enzyme prodrug therapy (EPT) directed against solid tumors and avenues for further development. We also discuss some of the challenges encountered upon translating these therapies to clinical trials. Upon sufficient development, cell-mediated enzyme prodrug therapy has the potential to maximize the distribution of therapeutic enzymes within the tumor environment, localizing conversion of prodrug to active drug at the tumor sites thereby decreasing off-target toxicities. New combinatorial possibilities are also promising. For example, when combined with viral gene-delivery vehicles, this may result in new hybrid vehicles that attain heretofore unmatched levels of therapeutic gene expression within the tumor.

Mesenchymal stromal cells for the delivery of oncolytic viruses in gliomas

Mesenchymal stromal cells (MSCs) are a type of adult stem cell that has been exploited for the treatment of a variety of diseases, including cancer. In particular, MSCs have been studied extensively for their ability to treat glioblastoma (GBM), the most common and deadly form of brain cancer in adults. MSCs are attractive therapeutics because they can be obtained relatively easily from patients, are capable of being expanded numerically in vitro, can be easily engineered and are inherently capable of homing to tumors, making them ideal vehicles for delivering biological antitumoral agents. Oncolytic viruses are promising biological therapeutic agents that have been used in the treatment of GBMs, and MSCs are currently being explored as a means of delivering these viruses. Here we review the role of MSCs in the treatment of GBMs, focusing on the intersection of MSCs and oncolytic viruses.

Combined Fluorescence and Magnetic Resonance Imaging of Primary Macrophage Migration to Sites of Acute Inflammation Using Near-Infrared Fluorescent Magnetic Nanoparticles

PURPOSE

This study aimed to track the migration of primary macrophages labeled with near-infrared (NIR) fluorescent magnetic nanoparticles toward chemically induced acute inflammatory lesions in mice and to visualize the effect of anti-inflammatory drugs on macrophage migration using combined fluorescence and magnetic resonance imaging (FLI/MRI).

PROCEDURES

Primary macrophages were labeled with NIR fluorescent magnetic nanoparticles, and labeled cells were injected into mice intravenously. One day later, inflammation was induced by subcutaneous injection of 1% carrageenan (CG) solution to footpads of the right hind leg, and phosphate-buffered saline (PBS) as control treatment was subcutaneously injected to footpad of the left hind leg. To evaluate the effect of drug treatment on macrophage migration, a single dose of dexamethasone (DEX) was intraperitoneally administered to the mice immediately after the induction of inflammation and was followed by combined FLI/MRI at predetermined time points.

RESULTS

No difference in cellular viability or phagocytic activity was observed between the labeled and parent macrophages. In vivo optical imaging revealed an increase in FLI signals in CG-injected footpads in a time-dependent manner, but not in PBS-treated footpads. DEX treatment inhibited the migration of the labeled macrophages to the CG-injected footpads, with relative decreases in FLI activity. In accordance with FLI, T2*-weighted MR images showed hypo-intense signals in the CG-injected footpads but not in the PBS-injected footpads. The DEX-treated mice did not show a dark signal loss zone on MR images in the CG-treated paw.

CONCLUSIONS

We successfully tracked the migration of macrophages to inflammatory lesions using both FLI and MRI with NIR fluorescent magnetic nanoparticles and demonstrated the inhibitory effects of DEX on macrophage migration to inflammation sites.

Mesenchymal stem cells secretome as a modulator of the neurogenic niche: basic insights and therapeutic opportunities

Neural stem cells (NSCs) and mesenchymal stem cells (MSCs) share few characteristics apart from self-renewal and multipotency. In fact, the neurogenic and osteogenic stem cell niches derive from two distinct embryonary structures; while the later originates from the mesoderm, as all the connective tissues do, the first derives from the ectoderm. Therefore, it is highly unlikely that stem cells isolated from one niche could form terminally differentiated cells from the other. Additionally, these two niches are associated to tissues/systems (e.g., bone and central nervous system) that have markedly different needs and display diverse functions within the human body. Nevertheless they do share common features. For instance, the differentiation of both NSCs and MSCs is intimately associated with the bone morphogenetic protein family. Moreover, both NSCs and MSCs secrete a panel of common growth factors, such as nerve growth factor (NGF), glial derived neurotrophic factor (GDNF), and brain derived neurotrophic factor (BDNF), among others. But it is not the features they share but the interaction between them that seem most important, and worth exploring; namely, it has already been shown that there are mutually beneficially effects when these cell types are co-cultured in vitro. In fact the use of MSCs, and their secretome, become a strong candidate to be used as a therapeutic tool for CNS applications, namely by triggering the endogenous proliferation and differentiation of neural progenitors, among other mechanisms. Quite interestingly it was recently revealed that MSCs could be found in the human brain, in the vicinity of capillaries. In the present review we highlight how MSCs and NSCs in the neurogenic niches interact. Furthermore, we propose directions on this field and explore the future therapeutic possibilities that may arise from the combination/interaction of MSCs and NSCs.

Two mature products of MIR-491 coordinate to suppress key cancer hallmarks in glioblastoma

MIR-491 is commonly co-deleted with its adjacent CDKN2A on chromosome 9p21.3 in glioblastoma multiforme (GBM). However, it is not known whether deletion of MIR-491 is only a passenger event or has an important role. Small-RNA sequencing of samples from GBM patients demonstrated that both mature products of MIR-491 (miR-491-5p and -3p) are downregulated in tumors compared with the normal brain. The integration of GBM data from The Cancer Genome Atlas (TCGA), miRNA target prediction and reporter assays showed that miR-491-5p directly targets EGFR, CDK6 and Bcl-xL, whereas miR-491-3p targets IGFBP2 and CDK6. Functionally, miR-491-3p inhibited glioma cell invasion; overexpression of both miR-491-5p and -3p inhibited proliferation of glioma cell lines and impaired the propagation of glioma stem cells (GSCs), thereby prolonging survival of xenograft mice. Moreover, knockdown of miR-491-5p in primary Ink4a-Arf-null mouse glial progenitor cells exacerbated cell proliferation and invasion. Therefore, MIR-491 is a tumor suppressor gene that, by utilizing both mature forms, coordinately controls the key cancer hallmarks: proliferation, invasion and stem cell propagation.

Inflammatory Chemokines MIP-1δ and MIP-3α Are Involved in the Migration of Multipotent Mesenchymal Stromal Cells Induced by Hepatoma Cells

In vivo, bone marrow-derived multipotent mesenchymal stromal cells (MSC) have been identified at sites of tumors, suggesting that specific signals mobilize and activate MSC to migrate to areas surrounding tumors. The signals and migratory mechanisms that guide MSC are not well understood. Here, we investigated the migration of human MSC induced by conditioned medium of Huh-7 hepatoma cells (Huh-7 CM). Using a transwell migration system, we showed that human MSC migration was increased in the presence of Huh-7 CM. Using a human cytokine antibody array, we detected increased levels of MIP-1δ and MIP-3α in Huh-7 CM. Recombinant chemokines MIP-1δ and MIP-3α induced MSC migration. Anti-MIP-1δ and anti-MIP-3α antibodies added to Huh-7 CM decreased MSC migration, further suggesting that MIP-1δ and MIP-3α were implicated in the Huh-7 CM-induced MSC migration. By real-time polymerase chain reaction, we observed an absence of chemokine receptors CCR2 and CXCR2 and low expression of CCR1, CCR5, and CCR6 in MSC. Expression of these chemokine receptors was not regulated by Huh-7 CM. Furthermore, matrix metalloproteinase 1 (MMP-1) expression was strongly increased in MSC after incubation with Huh-7 CM, suggesting that MSC migration depends on MMP-1 activity. The signaling pathway MAPK/ERK was activated by Huh-7 CM but its inhibition by PD98059 did not impair Huh-7 CM-induced MSC migration. Further, long-term incubation of MSC with MIP-1δ increased α-smooth muscle actin expression, suggesting its implication in the Huh-7 CM-induced evolvement of MSC into myofibroblasts. In conclusion, we report that two inflammatory cytokines, MIP-1δ and MIP-3α, are able to increase MSC migration in vitro. These cytokines might be responsible for migration and evolvement of MSC into myofibroblasts around tumors.

Conditioned media from human adipose tissue-derived mesenchymal stem cells and umbilical cord-derived mesenchymal stem cells efficiently induced the apoptosis and differentiation in human glioma cell lines in vitro

Human mesenchymal stem cells (MSCs) have an intrinsic property for homing towards tumor sites and can be used as tumor-tropic vectors for tumor therapy. But very limited studies investigated the antitumor properties of MSCs themselves. In this study we investigated the antiglioma properties of two easily accessible MSCs, namely, human adipose tissue-derived mesenchymal stem cells (ASCs) and umbilical cord-derived mesenchymal stem cells (UC-MSCs). We found (1) MSC conditioned media can significantly inhibit the growth of human U251 glioma cell line; (2) MSC conditioned media can significantly induce apoptosis in human U251 cell line; (3) real-time PCR experiments showed significant upregulation of apoptotic genes of both caspase-3 and caspase-9 and significant downregulation of antiapoptotic genes such as survivin and XIAP after MSC conditioned media induction in U 251 cells; (4) furthermore, MSCs conditioned media culture induced rapid and complete differentiation in U251 cells. These results indicate MSCs can efficiently induce both apoptosis and differentiation in U251 human glioma cell line. Whereas UC-MSCs are more efficient for apoptosis induction than ASCs, their capability of differentiation induction is not distinguishable from each other. Our findings suggest MSCs themselves have favorable antitumor characteristics and should be further explored in future glioma therapy.

Mesenchymal stem cells as a vector for the inflammatory prostate microenvironment

Mesenchymal stem cells (MSCs) have an inherent tropism for sites of inflammation, which are frequently present in sites of cancer, including prostatic lesions. MSCs have been defined as CD73/CD90/CD105 triple-positive cells in the absence of hematopoietic lineage markers with the ability to differentiate into multiple mesodermal lineages, including osteoblasts, adipocytes, and chondrocytes. Our group has previously demonstrated that MSCs represent between 0.01 and 1.1% of the total cells present in human prostatectomy tissue. In addition to their multi-lineage differentiation potential, MSCs are immunoprivileged in nature and have a range of immunomodulatory effects on both the innate and adaptive arms of the immune system. MSCs have been detected in an increasing array of tissues, and evidence suggests that they are likely present in perivascular niches throughout the body. These observations suggest that MSCs represent critical mediators of the overall immune response during physiological homeostasis and likely contribute to pathophysiological conditions as well. Chronic inflammation has been suggested as an initiating event and progression factor in prostate carcinogenesis, a process in which the immunosuppressive properties of MSCs may play a role. MSCs have also been shown to influence malignant progression through a variety of other mechanisms, including effects on tumor proliferation, angiogenesis, survival, and metastasis. Additionally, human bone marrow-derived MSCs have been shown to traffic to human prostate cancer xenografts in immunocompromised murine hosts. The trafficking properties and immunoprivileged status of MSCs suggest that they can be exploited as an allogeneic cell-based vector to deliver cytotoxic or diagnostic agents for therapy.

Human mesenchymal stem cells and their paracrine factors for the treatment of brain tumors

Glioblastoma multiforme (GBM or World Health Organization (WHO) grade IV) is the most malignant tumor of the brain. Despite conventional combination treatment of surgery, radiotherapy and chemotherapy, the survival of patients with GBM is generally <1 year. It is a great challenge to identify an effective drug that could efficiently inhibit (i) the growth of cancer cells; (ii) angiogenesis; (iii) metastasis; (iv) tumor-associated inflammation; (v) inactivate proliferative signal, (vi) induce specific apoptosis, and yet causes minimal harm to normal cells. Mesenchymal stem cells (MSCS) do possess some unique features (inherent tumor tropism; anti-inflammatory and immunosuppressive properties) that are not commonly found in current anticancer agents. These cells are known to secrete a vast array of proteins including growth factors, cytokines, chemokines and so on that regulate their biology in an autocrine or paracrine manner in accordance to the surrounding microenvironment. This review briefly summarizes the biology of MSCs and discusses their properties and new development for brain cancer treatment.

AF-MSCs fate can be regulated by culture conditions

Human mesenchymal stem cells (hMSCs) represent a population of multipotent adherent cells able to differentiate into many lineages. In our previous studies, we isolated and expanded fetal MSCs from second-trimester amniotic fluid (AF) and characterized them based on their phenotype, pluripotency and proteomic profile. In the present study, we investigated the plasticity of these cells based on their differentiation, dedifferentiation and transdifferentiation potential in vitro. To this end, adipocyte-like cells (AL cells) derived from AF-MSCs can regain, under certain culture conditions, a more primitive phenotype through the process of dedifferentiation. Dedifferentiated AL cells derived from AF-MSCs (DAF-MSCs), gradually lost the expression of adipogenic markers and obtained similar morphology and differentiation potential to AF-MSCs, together with regaining the pluripotency marker expression. Moreover, a comparative proteomic analysis of AF-MSCs, AL cells and DAF-MSCs revealed 31 differentially expressed proteins among the three cell populations. Proteins, such as vimentin, galectin-1 and prohibitin that have a significant role in stem cell regulatory mechanisms, were expressed in higher levels in AF-MSCs and DAF-MSCs compared with AL cells. We next investigated whether AL cells could transdifferentiate into hepatocyte-like cells (HL cells) directly or through a dedifferentiation step. AL cells were cultured in hepatogenic medium and 4 days later they obtained a phenotype similar to AF-MSCs, and were termed as transdifferentiated AF-MSCs (TRAF-MSCs). This finding, together with the increase in pluripotency marker expression, indicated the adaption of a more primitive phenotype before transdifferentiation. Additionally, we observed that AF-, DAF- and TRAF-MSCs displayed similar clonogenic potential, secretome and proteome profile. Considering the easy access to this fetal cell source, the plasticity of AF-MSCs and their potential to dedifferentiate and transdifferentiate, AF may provide a valuable tool for cell therapy and tissue engineering applications.

Current status of gene therapy for brain tumors

Glioblastoma (GBM) is the most common and deadliest primary brain tumor in adults, with current treatments having limited impact on disease progression. Therefore the development of alternative treatment options is greatly needed. Gene therapy is a treatment strategy that relies on the delivery of genetic material, usually transgenes or viruses, into cells for therapeutic purposes, and has been applied to GBM with increasing promise. We have included selectively replication-competent oncolytic viruses within this strategy, although the virus acts directly as a complex biologic anti-tumor agent rather than as a classic gene delivery vehicle. GBM is a good candidate for gene therapy because tumors remain locally within the brain and only rarely metastasize to other tissues; the majority of cells in the brain are post-mitotic, which allows for specific targeting of dividing tumor cells; and tumors can often be accessed neurosurgically for administration of therapy. Delivery vehicles used for brain tumors include nonreplicating viral vectors, normal adult stem/progenitor cells, and oncolytic viruses. The therapeutic transgenes or viruses are typically cytotoxic or express prodrug activating suicide genes to kill glioma cells, immunostimulatory to induce or amplify anti-tumor immune responses, and/or modify the tumor microenvironment such as blocking angiogenesis. This review describes current preclinical and clinical gene therapy strategies for the treatment of glioma.

Advances in stem cell therapy against gliomas

Malignant gliomas are one of the most lethal cancers, and despite extensive research very little progress has been made in improving prognosis. Multimodality treatment combining surgery, radiation, and chemotherapy is the current gold standard, but effective treatment remains difficult due to the invasive nature and high recurrence of gliomas. Stem cell-based therapy using neural, mesenchymal, or hematopoietic stem cells may be an alternative approach because it is tumor selective and allows targeted therapy that spares healthy brain tissue. Stem cells can be used to establish a long-term antitumor response by stimulating the immune system and delivering prodrug, metabolizing genes, or oncolytic viruses. In this review, we discuss current trends and the latest developments in stem cell therapy against malignant gliomas from both the experimental laboratory and the clinic.

Convergence of gene and cell therapy

Gene therapy and cell therapy have followed similar roller coaster paths of rising public expectations and disappointment over the past two decades. There is now reason to believe that momentum in the field has reached the point where the successes will be more frequent. The use of gene-modified cells has opened new avenues for engineering desired cell properties, for the use of cells as vehicles for gene delivery, and for tracking cells and controlling cell persistence after transplantation. Some notable recent clinical developments in cellular engineering by gene transfer offer lessons on how the field has emerged, and hint at additional future clinical applications.

Applications of amniotic membrane and fluid in stem cell biology and regenerative medicine

The amniotic membrane (AM) and amniotic fluid (AF) have a long history of use in surgical and prenatal diagnostic applications, respectively. In addition, the discovery of cell populations in AM and AF which are widely accessible, nontumorigenic and capable of differentiating into a variety of cell types has stimulated a flurry of research aimed at characterizing the cells and evaluating their potential utility in regenerative medicine. While a major focus of research has been the use of amniotic membrane and fluid in tissue engineering and cell replacement, AM- and AF-derived cells may also have capabilities in protecting and stimulating the repair of injured tissues via paracrine actions, and acting as vectors for biodelivery of exogenous factors to treat injury and diseases. Much progress has been made since the discovery of AM and AF cells with stem cell characteristics nearly a decade ago, but there remain a number of problematic issues stemming from the inherent heterogeneity of these cells as well as inconsistencies in isolation and culturing methods which must be addressed to advance the field towards the development of cell-based therapies. Here, we provide an overview of the recent progress and future perspectives in the use of AM- and AF-derived cells for therapeutic applications.

Anti-angiogenic gene therapy in the treatment of malignant gliomas

More than four decades ago, Dr. Judah Folkman hypothesized that angiogenesis was a critical process in tumor growth. Since that time, there have been significant advances in understanding tumor biology and groundbreaking research in cancer therapy that have validated his hypothesis. However, in spite of extensive research, glioblastoma multiforme (GBM), the most common and malignant primary brain tumor, has gained little in the way of improved median survival. There have been several angiogenesis targets that have resulted in drugs that are in clinical trials or FDA approved for clinical use in several cancers. GBM is a highly angiogenic tumor and several drugs are showing promise in clinical trials with one (bevacizumab), clinically approved for use. We will review several possible angiogenic targets in GBM as well as the vector methodologies used for delivery. In addition, GBMs present several therapeutic challenges related to structure, tumor immune microenvironment and resistance to angiogenesis. To overcome these challenges will require novel approaches to improve therapeutic gene expression and vector biodistribution in the glioma.

Antiangiogenic and anticancer molecules in cartilage

Cartilage is one of the very few naturally occurring avascular tissues where lack of angiogenesis is the guiding principle for its structure and function. This has attracted investigators who have sought to understand the biochemical basis for its avascular nature, hypothesising that it could be used in designing therapies for treating cancer and related malignancies in humans through antiangiogenic applications. Cartilage encompasses primarily a specialised extracellular matrix synthesised by chondrocytes that is both complex and unique as a result of the myriad molecules of which it is composed. Of these components, a few such as thrombospondin-1, chondromodulin-1, the type XVIII-derived endostatin, SPARC (secreted protein acidic and rich in cysteine) and the type II collagen-derived N-terminal propeptide (PIIBNP) have demonstrated antiangiogenic or antitumour properties in vitro and in vivo preclinical trials that involve several complicated mechanisms that are not completely understood. Thrombospondin-1, endostatin and the shark-cartilage-derived Neovastat preparation have also been investigated in human clinical trials to treat several different kinds of cancers, where, despite the tremendous success seen in preclinical trials, these molecules are yet to show success as anticancer agents. This review summarises the current state-of-the-art antiangiogenic characterisation of these molecules, highlights their most promising aspects and evaluates the future of these molecules in antiangiogenic applications.