A Potential Therapy Using Engineered Stem Cells Prevented Malignant Melanoma in Cellular and Xenograft Mouse Models

Genetically engineered neural stem cells expressing cytosine deaminase and interferon-beta enhanced T cell-mediated antitumor immunity against gastric cancer in a humanized mouse model

AIMS

Gastric cancer (GC) is an invasive, fatal disease with a poor prognosis. Gene-directed enzyme prodrug therapy via genetically engineered neural stem cells (GENSTECs) has been widely studied in various malignancies, such as breast, ovarian, and renal cancer. In this study, the human neural stem cells expressing cytosine deaminase and interferon beta (HB1.F3.CD.IFN-β) cells were applied to convert non-toxic 5-fluorocytosine to cytotoxic 5-fluorouracil and secrete IFN-β.

MATERIALS AND METHODS

Human lymphokine-activated killer cells (LAKs) were generated by stimulating human peripheral blood mononuclear cells (PBMCs) by interleukin-2, and we evaluated the cytotoxic activity and migratory ability of LAKs co-cultured with GNESTECs or their conditioned media in vitro. A GC-bearing human immune system (HIS) mouse model was generated by transplanting human PBMCs followed by subcutaneous engraftment of MKN45 cells in NSG-B2m mice to evaluate the involvement of T cell-mediated anti-cancer immune activity of GENSTECs.

KEY FINDINGS

In vitro studies showed the presence of HB1.F3.CD.IFN-β cells facilitated the migration ability of LAKs to MKN45 cells and activated their cytotoxic potential. In MKN45-xenografted HIS mice, treatment with HB1.F3.CD.IFN-β cells resulted in increased cytotoxic T lymphocyte (CTL) infiltration throughout the tumor, including the central area. Moreover, the group treated to HB1.F3.CD.IFN-β showed increased granzyme B expression in the tumor, eventually enhancing the tumor-killing potential of CTLs and significantly delaying tumor growth.

SIGNIFICANCE

These results indicate that the HB1.F3.CD.IFN-β cells exert anti-cancer effects on GC by facilitating the T cell-mediated immune response, and GENSTECs are a promising therapeutic strategy for GC.

Nanotechnology-based cell-mediated delivery systems for cancer therapy and diagnosis

The global prevalence of cancer is increasing, necessitating new additions to traditional treatments and diagnoses to address shortcomings such as ineffectiveness, complications, and high cost. In this context, nano and microparticulate carriers stand out due to their unique properties such as controlled release, higher bioavailability, and lower toxicity. Despite their popularity, they face several challenges including rapid liver uptake, low chemical stability in blood circulation, immunogenicity concerns, and acute adverse effects. Cell-mediated delivery systems are important topics to research because of their biocompatibility, biodegradability, prolonged delivery, high loading capacity, and targeted drug delivery capabilities. To date, a variety of cells including blood, immune, cancer, and stem cells, sperm, and bacteria have been combined with nanoparticles to develop efficient targeted cancer delivery or diagnosis systems. The review paper aimed to provide an overview of the potential applications of cell-based delivery systems in cancer therapy and diagnosis.

Treating Metastatic Brain Cancers With Stem Cells

Stem cell therapy may present an effective treatment for metastatic brain cancer and glioblastoma. Here we posit the critical role of a leaky blood-brain barrier (BBB) as a key element for the development of brain metastases, specifically melanoma. By reviewing the immunological and inflammatory responses associated with BBB damage secondary to tumoral activity, we identify the involvement of this pathological process in the growth and formation of metastatic brain cancers. Likewise, we evaluate the hypothesis of regenerating impaired endothelial cells of the BBB and alleviating the damaged neurovascular unit to attenuate brain metastasis, using the endothelial progenitor cell (EPC) phenotype of bone marrow-derived mesenchymal stem cells. Specifically, there is a need to evaluate the efficacy for stem cell therapy to repair disruptions in the BBB and reduce inflammation in the brain, thereby causing attenuation of metastatic brain cancers. To establish the viability of stem cell therapy for the prevention and treatment of metastatic brain tumors, it is crucial to demonstrate BBB repair through augmentation of vasculogenesis and angiogenesis. BBB disruption is strongly linked to metastatic melanoma, worsens neuroinflammation during metastasis, and negatively influences the prognosis of metastatic brain cancer. Using stem cell therapy to interrupt inflammation secondary to this leaky BBB represents a paradigm-shifting approach for brain cancer treatment. In this review article, we critically assess the advantages and disadvantages of using stem cell therapy for brain metastases and glioblastoma.

Genetically-Modified Stem Cell in Regenerative Medicine and Cancer Therapy; A New Era

Recently, genetic engineering by various strategies to stimulate gene expression in a specific and controllable mode is a speedily growing therapeutic approach. Genetic modification of human stem or progenitor cells, such as embryonic stem cells (ESCs), neural progenitor cells (NPCs), mesenchymal stem/stromal cells (MSCs), and hematopoietic stem cells (HSCs) for direct delivery of specific therapeutic molecules or genes has been evidenced as an opportune plan in the context of regenerative medicine due to their supported viability, proliferative features, and metabolic qualities. On the other hand, a large number of studies have investigated the efficacy of modified stem cells in cancer therapy using cells from various sources, disparate transfection means for gene delivery, different transfected yields, and wide variability of tumor models. Accordingly, cell-based gene therapy holds substantial aptitude for the treatment of human malignancy as it could relieve signs or even cure cancer succeeding expression of therapeutic or suicide transgene products; however, there exist inconsistent results in this regard. Herein, we deliver a brief overview of stem cell potential to use in cancer therapy and regenerative medicine and importantly discuss stem cells based gene delivery competencies to stimulate tissue repair and replacement in concomitant with their potential to use as an anti-cancer therapeutic strategy, focusing on the last two decades in vivo studies.

Stem Cell as Vehicles of Antibody in Treatment of Lymphoma: a Novel and Potential Targeted Therapy

Lymphoma is a heterogeneous malignancy and its incidence is increasing in the past decades all over the world. Although more than half of lymphoma patients achieve complete or partial remission from the standard first-line ABVD or R-CHOP based therapy, patients who fail to respond to these regimens will give rise to relapsed or refractory (R/R) lymphoma and may lead to a worse prognosis. Developing novel agents is important for R/R lymphoma. Based on the homing ability and being genetically modified easily, stem cells are usually used as vehicles in cell-based anti-tumor therapy, which can not only retain their own biological characteristics, but also make anti-tumor agents secrete constantly in tumor environment, to eventually kill the tumor cells more effectively. In this review, we will briefly introduce the properties of antibody therapy carried by stem cells, especially the hopes and hurdles of stem cell-mediated antibody secretion in the treatment of lymphoma.

A facile and scalable in production non-viral gene engineered mesenchymal stem cells for effective suppression of temozolomide-resistant (TMZR) glioblastoma growth

BACKGROUND

Mesenchymal stem cells (MSCs) serve as an attractive vehicle for cell-directed enzyme prodrug therapy (CDEPT) due to their unique tumour-nesting ability. Such approach holds high therapeutic potential for treating solid tumours including glioblastoma multiforme (GBM), a devastating disease with limited effective treatment options. Currently, it is a common practice in research and clinical manufacturing to use viruses to deliver therapeutic genes into MSCs. However, this is limited by the inherent issues of safety, high cost and demanding manufacturing processes. The aim of this study is to identify a facile, scalable in production and highly efficient non-viral method to transiently engineer MSCs for prolonged and exceptionally high expression of a fused transgene: yeast cytosine deaminase::uracil phosphoribosyl-transferase::green fluorescent protein (CD::UPRT::GFP).

METHODS

MSCs were transfected with linear polyethylenimine using a cpg-free plasmid encoding the transgene in the presence of a combination of fusogenic lipids and β tubulin deacetylase inhibitor (Enhancer). Process scalability was evaluated in various planar vessels and microcarrier-based bioreactor. The transfection efficiency was determined with flow cytometry, and the therapeutic efficacy of CD::UPRT::GFP expressing MSCs was evaluated in cocultures with temozolomide (TMZ)-sensitive or TMZ-resistant human glioblastoma cell lines. In the presence of 5-fluorocytosine (5FC), the 5-fluorouracil-mediated cytotoxicity was determined by performing colometric MTS assay. In vivo antitumor effects were examined by local injection into subcutaneous TMZ-resistant tumors implanted in the athymic nude mice.

RESULTS

At > 90% transfection efficiency, the phenotype, differentiation potential and tumour tropism of MSCs were unaltered. High reproducibility was observed in all scales of transfection. The therapeutically modified MSCs displayed strong cytotoxicity towards both TMZ-sensitive and TMZ-resistant U251-MG and U87-MG cell lines only in the presence of 5FC. The effectiveness of this approach was further validated with other well-characterized and clinically annotated patient-derived GBM cells. Additionally, a long-term suppression (> 30 days) of the growth of a subcutaneous TMZ-resistant U-251MG tumour was demonstrated.

CONCLUSIONS

Collectively, this highly efficient non-viral workflow could potentially enable the scalable translation of therapeutically engineered MSC for the treatment of TMZ-resistant GBM and other applications beyond the scope of this study.

Next-generation stem cells - ushering in a new era of cell-based therapies

Naturally occurring stem cells isolated from humans have been used therapeutically for decades. This has primarily involved the transplantation of primary cells such as haematopoietic and mesenchymal stem cells and, more recently, derivatives of pluripotent stem cells. However, the advent of cell-engineering approaches is ushering in a new generation of stem cell-based therapies, greatly expanding their therapeutic utility. These next-generation stem cells are being used as 'Trojan horses' to improve the delivery of drugs and oncolytic viruses to intractable tumours and are also being engineered with angiogenic, neurotrophic and anti-inflammatory molecules to accelerate the repair of injured or diseased tissues. Moreover, gene therapy and gene editing technologies are being used to create stem cell derivatives with improved functionality, specificity and responsiveness compared with their natural counterparts. Here, we review these engineering approaches and areas in which they will help broaden the utility and clinical applicability of stem cells.

Recent progress in the research of suicide gene therapy for malignant glioma

Malignant glioma, which is characterized by diffuse infiltration into the normal brain parenchyma, is the most aggressive primary brain tumor with dismal prognosis. Over the past 40 years, the median survival has only slightly improved. Therefore, new therapeutic modalities must be developed. In the 1990s, suicide gene therapy began attracting attention for the treatment of malignant glioma. Some clinical trials used a viral vector for suicide gene transduction; however, it was found that viral vectors cannot cover the large invaded area of glioma cells. Interest in this therapy was recently revived because some types of stem cells possess a tumor-tropic migratory capacity, which can be used as cellular delivery vehicles. Immortalized, clonal neural stem cell (NSC) line has been used for patients with recurrent high-grade glioma, which showed safety and efficacy. Embryonic and induced pluripotent stem cells may be considered as sources of NSC because NSC is difficult to harvest, and ethical issues have been raised. Mesenchymal stem cells are alternative candidates for cellular vehicle and are easily harvested from the bone marrow. In addition, a new type of nonlytic, amphotropic retroviral replicating vector encoding suicide gene has shown efficacy in patients with recurrent high-grade glioma in a clinical trial. This replicating viral capacity is another possible candidate as delivery vehicle to tackle gliomas. Herein, we review the concept of suicide gene therapy, as well as recent progress in preclinical and clinical studies in this field.