Anti-Tumor Effects of TRAIL-Expressing Mesenchymal Stromal Cells in a Mouse Xenograft Model of Human Mesothelioma

Malignant mesothelioma (MM) remains a highly deadly malignancy with poor treatment option. The MM cells further promote a highly inflammatory microenvironment which contributes to tumor initiation, development, severity, and propagation. We reasoned that the anti-inflammatory actions of mesenchymal stromal cells (MSCs) and further anti-tumor effects of MSCs engineered to over-express TNF-related apoptosis inducing ligand (TRAIL) protein (MSC-TRAIL) would effectively inhibit mesothelioma growth. Using a mouse xenograft model of intraperitoneal human mesothelioma, native mouse (mMSC) or human (hMSC) MSCs were administered either systemically (IV) or intraperitoneally (IP) at various times following tumor inoculation. Both mMSCs and hMSCs localized at sites of MM tumor growth in vivo and decreased local inflammation. Further, a trend towards decrease in tumor burden was observed. Parallel studies of in vitro exposure of nine primary human mesothelioma cell lines to mMSCs or hMSCs demonstrated reduced tumor cell migration. In contrast MSC-TRAIL exposure induced apoptosis of TRAIL sensitive MM cells in vitro and both mouse and human MSC-TRAIL significantly reduced the inflammatory tumor environment in vivo. Moreover human MSC-TRAIL administration significantly reduced peritoneal tumor burden in vivo and increased tumor cell apoptosis. These proof-of-concept studies suggest that TRAIL-expressing MSCs may be useful against malignant mesothelioma

Mesenchymal stem cells as vectors for lung cancer therapy

Despite recent advances in treatment, lung cancer accounts for one third of all cancer-related deaths, underlining the need of development of new therapies. Mesenchymal stem cells (MSCs) possess the ability to specifically home into tumours and their metastases. This property of MSCs could be exploited for the delivery of various anti-tumour agents directly into tumours. However, MSCs are not simple delivery vehicles but cells with active physiological process. This review outlines various agents which can be delivered by MSCs with substantial emphasis on TRAIL (tumour necrosis factor-related apoptosis-inducing ligand)

Switch from alpha v beta 5 to alpha v beta 6 integrin expression protects squamous cell carcinomas from anoikis

Stratified squamous epithelia express the alphavbeta5 integrin, but in squamous cell carcinomas (SCCs) there is down-regulation of alphavbeta5 and up-regulation of alphavbeta6. To investigate the significance of this finding, we transduced an alphav-negative human SCC line with retroviral vectors encoding alphav integrins. alphavbeta5-expressing cells underwent suspension-induced apoptosis (anoikis), whereas alpha-negative cells and cells expressing alphavbeta6 did not. Resistance to anoikis correlated with PKB/Akt activation in suspension, but not with changes in PTEN or p110alpha P13 kinase levels

Regenerating human epithelia with cultured stem cells: feeder cells, organoids and beyond

More than 40 years ago, Howard Green's laboratory developed a method for long-term expansion of primary human epidermal keratinocytes by co-culture with 3T3 mouse embryonic fibroblasts. This was a breakthrough for in vitro cultivation of cells from human skin and later for other epithelia: it led to the first stem cell therapy using cultured cells and has vastly increased our understanding of epithelial stem cell biology. In recent years, new methods to expand epithelial cells as three-dimensional organoids have provided novel means to investigate the functions of these cells in health and disease. Here, we outline the history of stratified epithelial stem cell culture and the application of cultured epithelial cells in clinical therapies. We further discuss the derivation of organoids from other types of epithelia and the challenges that remain for the translation of novel stem cell therapies toward clinical use

Epithelial cell migration as a potential therapeutic target in early lung cancer.

Lung cancer is the most lethal cancer type worldwide, with the majority of patients presenting with advanced stage disease. Targeting early stage disease pathogenesis would allow dramatic improvements in lung cancer patient survival. Recently, cell migration has been shown to be an integral process in early lung cancer ontogeny, with preinvasive lung cancer cells shown to migrate across normal epithelium prior to developing into invasive disease. TP53 mutations are the most abundant mutations in human nonsmall cell lung cancers and have been shown to increase cell migration via regulation of Rho-GTPase protein activity. In this review, we explore the possibility of targeting TP53-mediated Rho-GTPase activity in early lung cancer and the opportunities for translating this preclinical research into effective therapies for early stage lung cancer patients

TRAIL delivery by MSC-derived extracellular vesicles is an effective anticancer therapy

Extracellular vesicles (EVs) are lipid membrane-enclosed nanoparticles released by cells. They mediate intercellular communication by transferring biological molecules and therefore have potential as innovative drug delivery vehicles. TNF-related apoptosis-inducing ligand (TRAIL) selectively induces apoptosis of cancer cells. Unfortunately, the clinical application of recombinant rTRAIL has been hampered by its low bioavailability and resistance of cancer cells. EV-mediated TRAIL delivery may circumvent these problems. Mesenchymal stromal cells (MSCs) produce EVs and could be a good source for therapeutic EV production. We investigated if TRAIL could be expressed in MSC-derived EVs and examined their cancer cell-killing efficacy. EVs were isolated by ultracentrifugation and were membranous particles of 50–70 nm in diameter. Both MSC- and TRAIL-expressing MSC (MSCT)-derived EVs express CD63, CD9 and CD81, but only MSCT-EVs express surface TRAIL. MSCT-EVs induced apoptosis in 11 cancer cell lines in a dose-dependent manner but showed no cytotoxicity in primary human bronchial epithelial cells. Caspase activity inhibition or TRAIL neutralisation blocked the cytotoxicity of TRAIL-positive EVs. MSCT-EVs induced pronounced apoptosis in TRAIL-resistant cancer cells and this effect could be further enhanced using a CDK9 inhibitor. These data indicate that TRAIL delivery by MSC-derived EVs is an effective anticancer therapy

Hyperthermia treatment of tumors by mesenchymal stem cell-delivered superparamagnetic iron oxide nanoparticles.

Magnetic hyperthermia - a potential cancer treatment in which superparamagnetic iron oxide nanoparticles (SPIONs) are made to resonantly respond to an alternating magnetic field (AMF) and thereby produce heat - is of significant current interest. We have previously shown that mesenchymal stem cells (MSCs) can be labeled with SPIONs with no effect on cell proliferation or survival and that within an hour of systemic administration, they migrate to and integrate into tumors in vivo. Here, we report on some longer term (up to 3 weeks) post-integration characteristics of magnetically labeled human MSCs in an immunocompromized mouse model. We initially assessed how the size and coating of SPIONs dictated the loading capacity and cellular heating of MSCs. Ferucarbotran(®) was the best of those tested, having the best like-for-like heating capability and being the only one to retain that capability after cell internalization. A mouse model was created by subcutaneous flank injection of a combination of 0.5 million Ferucarbotran-loaded MSCs and 1.0 million OVCAR-3 ovarian tumor cells. After 2 weeks, the tumors reached ~100 µL in volume and then entered a rapid growth phase over the third week to reach ~300 µL. In the control mice that received no AMF treatment, magnetic resonance imaging (MRI) data showed that the labeled MSCs were both incorporated into and retained within the tumors over the entire 3-week period. In the AMF-treated mice, heat increases of ~4°C were observed during the first application, after which MRI indicated a loss of negative contrast, suggesting that the MSCs had died and been cleared from the tumor. This post-AMF removal of cells was confirmed by histological examination and also by a reduced level of subsequent magnetic heating effect. Despite this evidence for an AMF-elicited response in the SPION-loaded MSCs, and in contrast to previous reports on tumor remission in immunocompetent mouse models, in this case, no significant differences were measured regarding the overall tumor size or growth characteristics. We discuss the implications of these results on the clinical delivery of hyperthermia therapy to tumors and on the possibility that a preferred therapeutic route may involve AMF as an adjuvant to an autologous immune response