Mesenchymal Stem Cells As Guideposts for Nanoparticle-Mediated Targeted Drug Delivery in Ovarian Cancer

Mesenchymal stem cells and ovarian cancer: Is there promising news?

Ovarian cancer (OC) is described as a heterogeneous complex condition with high mortality, weak prognosis, and late-stage presentation. OC has several subgroups based on different indices, like the origin and histopathology. The current treatments against OC include surgery followed by chemotherapy and radiotherapy; however, these methods have represented diverse side effects without enough effectiveness on OC. Recently, mesenchymal stem cell (MSC)-based therapy has acquired particular attention for treating diverse problems, such as cancer. These multipotent stem cells can be obtained from different sources, such as the umbilical cord, adipose tissues, bone marrow, and placenta, and their efficacy has been investigated against OC. Hence, in this narrative review, we aimed to review and discuss the present studies about the effects of various sources of MSCs on OC with a special focus on involved mechanisms.

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.

Incorporation of paclitaxel in mesenchymal stem cells using nanoengineering upregulates antioxidant response, CXCR4 expression and enhances tumor homing

Engineered mesenchymal stem cells (MSCs) have been investigated extensively for gene delivery and, more recently, for targeted small molecule delivery. While preclinical studies demonstrate the potential of MSCs for targeted delivery, clinical studies suggest that tumor homing of native MSCs may be inefficient. We report here a surprising finding that loading MSCs with the anticancer drug paclitaxel (PTX) by nanoengineering results in significantly improved tumor homing compared to naïve MSCs. Loading PTX in MSCs results in increased levels of mitochondrial reactive oxygen species (ROS). In response to this oxidative stress, MSCs upregulate two important set of proteins. First were critical antioxidant proteins, most importantly nuclear factor erythroid 2-like 2 (Nrf2), the master regulator of antioxidant responses; upregulation of antioxidant proteins may explain how MSCs protect themselves from drug-induced oxidative stress. The second was CXCR4, a direct target of Nrf2 and a key mediator of tumor homing; upregulation of CXCR4 suggested a mechanism that may underlie the improved tumor homing of nanoengineered MSCs. In addition to demonstrating the potential mechanism of improved tumor targeting of nanoengineered MSCs, our studies reveal that MSCs utilize a novel mechanism of resistance against drug-induced oxidative stress and cell death, explaining how MSCs can deliver therapeutic concentrations of cytotoxic payload while maintaining their viability.

Targeting the tumor stroma for cancer therapy

Tumors are comprised of both cancer cells and surrounding stromal components. As an essential part of the tumor microenvironment, the tumor stroma is highly dynamic, heterogeneous and commonly tumor-type specific, and it mainly includes noncellular compositions such as the extracellular matrix and the unique cancer-associated vascular system as well as a wide variety of cellular components including activated cancer-associated fibroblasts, mesenchymal stromal cells, pericytes. All these elements operate with each other in a coordinated fashion and collectively promote cancer initiation, progression, metastasis and therapeutic resistance. Over the past few decades, numerous studies have been conducted to study the interaction and crosstalk between stromal components and neoplastic cells. Meanwhile, we have also witnessed an exponential increase in the investigation and recognition of the critical roles of tumor stroma in solid tumors. A series of clinical trials targeting the tumor stroma have been launched continually. In this review, we introduce and discuss current advances in the understanding of various stromal elements and their roles in cancers. We also elaborate on potential novel approaches for tumor-stroma-based therapeutic targeting, with the aim to promote the leap from bench to bedside.

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.

In vitro and in vivo anti-cancer effects of hibernating common carp (Cyprinus carpio) plasma on metastatic triple-negative breast cancer

Uncontrollable proliferation is a hallmark of cancer cells. Cell proliferation and migration are significantly depressed during hibernation state. Many studies believe some factors in the plasma of hibernating animals cause these effects. This study aimed to assess the anti-cancer effects of hibernating common carp (Cyprinus carpio) plasma on 4T1 cancer cells in vitro and in vivo. The effect of hibernating plasma on cell viability, morphology, migration, apoptosis rate, and cell cycle distribution of 4T1 cells was investigated in vitro and in vivo. Hibernating plasma at a concentration of 16 mg/ml significantly reduced the viability of 4T1 cancer cells, without any toxicity on L929 normal fibroblast cells. It could change the morphology of cancer cells, induced apoptosis and cell cycle arrest at the G2/M phase, and inhibited migration. Furthermore, intratumoral injection of hibernating plasma (200 µl, 16 mg/ml) in the tumor-bearing mice caused a significant inhibition of 4T1 breast tumors volume (46.9%) and weight (58.8%) compared with controls. A significant decrease in the number of metastatic colonies at the lungs (80%) and liver (52.8%) of hibernating plasma-treated animals was detected which increased the survival time (21.9%) compared to the control groups. Immunohistochemical analysis revealed a considerable reduction in the Ki-67-positive cells in the tumor section of the hibernating plasma-treated animals compared with controls. Taken together, the SDS-PAGE and mass spectrometry analysis indicated the alpha-2-macroglobulin level in the hibernating fish plasma was significantly increased. It could exert an anti-cancer effect on breast cancer cells and suggested as a novel cancer treatment strategy.

Mesenchymal Stem Cell: A Friend or Foe in Anti-Tumor Immunity

Mesenchymal stem cells (MSCs) are self-renewable, multipotent stem cells that regulate the phenotype and function of all immune cells that participate in anti-tumor immunity. MSCs modulate the antigen-presenting properties of dendritic cells, affect chemokine and cytokine production in macrophages and CD4+ T helper cells, alter the cytotoxicity of CD8+ T lymphocytes and natural killer cells and regulate the generation and expansion of myeloid-derived suppressor cells and T regulatory cells. As plastic cells, MSCs adopt their phenotype and function according to the cytokine profile of neighboring tumor-infiltrated immune cells. Depending on the tumor microenvironment to which they are exposed, MSCs may obtain pro- and anti-tumorigenic phenotypes and may enhance or suppress tumor growth. Due to their tumor-homing properties, MSCs and their exosomes may be used as vehicles for delivering anti-tumorigenic agents in tumor cells, attenuating their viability and invasive characteristics. Since many factors affect the phenotype and function of MSCs in the tumor microenvironment, a better understanding of signaling pathways that regulate the cross-talk between MSCs, immune cells and tumor cells will pave the way for the clinical use of MSCs in cancer immunotherapy. In this review article, we summarize current knowledge on the molecular and cellular mechanisms that are responsible for the MSC-dependent modulation of the anti-tumor immune response and we discuss different insights regarding therapeutic potential of MSCs in the therapy of malignant diseases.

Intravenously Infused Stem Cells for Cancer Treatment

Despite the recent influx of immunotherapies and small molecule drugs to treat tumors, cancer remains a leading cause of death in the United States, in large part due to the difficulties of treating metastatic cancer. Stem cells, which are inherently tumoritropic, provide a useful drug delivery vehicle to target both primary and metastatic tumors. Intravenous infusions of stem cells carrying or secreting therapeutic payloads show significant promise in the treatment of cancer. Stem cells may be engineered to secrete cytotoxic products, loaded with oncolytic viruses or nanoparticles containing small molecule drugs, or conjugated with immunotherapies. Herein we describe these preclinical and clinical studies, discuss the distribution and migration of stem cells following intravenous infusion, and examine both the limitations of and the methods to improve the migration and therapeutic efficacy of tumoritropic, therapeutic stem cells.

Synthetic Receptor-Based Targeting Strategies to Improve Tumor Drug Delivery

Heterogeneity in tumor expression as well as expression in normal tissues of various targets limit the usefulness of current ligand-based active targeting approaches. Incorporation of synthetic receptors, which can be recognized by delivery systems engineered to present specific functional groups on the surface, is a novel approach to improve tumor targeting. Alternatively, introduction of synthetic functionalities on cellular carriers can also enhance tumor targeting. We review various strategies that have been utilized for the introduction of synthetic targets in tumor tissues. The introduction of synthetic functional groups in the tumor through improved strategies is anticipated to result in improved target specificity and reduced heterogeneity in target expression.

Quantum Dots as a Good Carriers of Unsymmetrical Bisacridines for Modulating Cellular Uptake and the Biological Response in Lung and Colon Cancer Cells

Nanotechnology-based drug delivery provides a promising area for improving the efficacy of cancer treatments. Therefore, we investigate the potential of using quantum dots (QDs) as drug carriers for antitumor unsymmetrical bisacridine derivatives (UAs) to cancer cells. We examine the influence of QD-UA hybrids on the cellular uptake, internalization (Confocal Laser Scanning Microscope), and the biological response (flow cytometry and light microscopy) in lung H460 and colon HCT116 cancer cells. We show the time-dependent cellular uptake of QD-UA hybrids, which were more efficiently retained inside the cells compared to UAs alone, especially in H460 cells, which could be due to multiple endocytosis pathways. In contrast, in HCT116 cells, the hybrids were taken up only by one endocytosis mechanism. Both UAs and their hybrids induced apoptosis in H460 and HCT116 cells (to a greater extent in H460). Cells which did not die underwent senescence more efficiently following QDs-UAs treatment, compared to UAs alone. Cellular senescence was not observed in HCT116 cells following treatment with both UAs and their hybrids. Importantly, QDgreen/red themselves did not provoke toxic responses in cancer or normal cells. In conclusion, QDs are good candidates for targeted UA delivery carriers to cancer cells while protecting normal cells from toxic drug activities.

Pharmacokinetic-Pharmacodynamic Modeling of Tumor Targeted Drug Delivery Using Nano-Engineered Mesenchymal Stem Cells

Nano-engineered mesenchymal stem cells (nano-MSCs) are promising targeted drug delivery platforms for treating solid tumors. MSCs engineered with paclitaxel (PTX) loaded poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs) are efficacious in treating lung and ovarian tumors in mouse models. The quantitative description of pharmacokinetics (PK) and pharmacodynamics (PD) of nano-MSCs is crucial for optimizing their therapeutic efficacy and clinical translatability. However, successful translation of nano-MSCs is challenging due to their complex composition and physiological mechanisms regulating their pharmacokinetic-pharmacodynamic relationship (PK-PD). Therefore, in this study, a mechanism-based preclinical PK-PD model was developed to characterize the PK-PD relationship of nano-MSCs in orthotopic A549 human lung tumors in SCID Beige mice. The developed model leveraged literature information on diffusivity and permeability of PTX and PLGA NPs, PTX release from PLGA NPs, exocytosis of NPs from MSCs as well as PK and PD profiles of nano-MSCs from previous in vitro and in vivo studies. The developed PK-PD model closely captured the reported tumor growth in animals receiving no treatment, PTX solution, PTX-PLGA NPs and nano-MSCs. Model simulations suggest that increasing the dosage of nano-MSCs and/or reducing the rate of PTX-PLGA NPs exocytosis from MSCs could result in improved anti-tumor efficacy in preclinical settings.

Past, Present, and Future of Anticancer Nanomedicine

This review aims to summarize the methods that have been used till today, highlight methods that are currently being developed, and predict the future roadmap for anticancer therapy. In the beginning of this review, established approaches for anticancer therapy, such as conventional chemotherapy, hormonal therapy, monoclonal antibodies, and tyrosine kinase inhibitors are summarized. To counteract the side effects of conventional chemotherapy and to increase limited anticancer efficacy, nanodrug- and stem cell-based therapies have been introduced. However, current level of understanding and strategies of nanodrug and stem cell-based therapies have limitations that make them inadequate for clinical application. Subsequently, this manuscript reviews methods with fewer side effects compared to those of the methods mentioned above which are currently being investigated and are already being applied in the clinic. The newer strategies that are already being clinically applied include cancer immunotherapy, especially T cell-mediated therapy and immune checkpoint inhibitors, and strategies that are gaining attention include the manipulation of the tumor microenvironment or the activation of dendritic cells. Tumor-associated macrophage repolarization is another potential strategy for cancer immunotherapy, a method which activates macrophages to immunologically attack malignant cells. At the end of this review, we discuss combination therapies, which are the future of cancer treatment. Nanoparticle-based anticancer immunotherapies seem to be effective, in that they effectively use nanodrugs to elicit a greater immune response. The combination of these therapies with others, such as photothermal or tumor vaccine therapy, can result in a greater anticancer effect. Thus, the future of anticancer therapy aims to increase the effectiveness of therapy using various therapies in a synergistic combination rather than individually.