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Choi Y, Lee HK, Ahn D, Nam MW, Go RE, Choi KC. 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. Life Sci 2023; 328:121866. [PMID: 37331506 DOI: 10.1016/j.lfs.2023.121866] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/31/2023] [Accepted: 06/13/2023] [Indexed: 06/20/2023]
Abstract
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.
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Affiliation(s)
- Youngdong Choi
- Laboratory of Biochemistry and Immunology, College of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk, Republic of Korea
| | - Hong Kyu Lee
- Laboratory of Biochemistry and Immunology, College of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk, Republic of Korea
| | - Dohee Ahn
- Laboratory of Biochemistry and Immunology, College of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk, Republic of Korea
| | - Min-Woo Nam
- Laboratory of Biochemistry and Immunology, College of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk, Republic of Korea
| | - Ryeo-Eun Go
- Laboratory of Biochemistry and Immunology, College of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk, Republic of Korea
| | - Kyung-Chul Choi
- Laboratory of Biochemistry and Immunology, College of Veterinary Medicine, Chungbuk National University, Cheongju, Chungbuk, Republic of Korea.
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2
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Alimardani V, Rahiminezhad Z, DehghanKhold M, Farahavar G, Jafari M, Abedi M, Moradi L, Niroumand U, Ashfaq M, Abolmaali SS, Yousefi G. Nanotechnology-based cell-mediated delivery systems for cancer therapy and diagnosis. Drug Deliv Transl Res 2023; 13:189-221. [PMID: 36074253 DOI: 10.1007/s13346-022-01211-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2022] [Indexed: 12/13/2022]
Abstract
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.
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Affiliation(s)
- Vahid Alimardani
- Department of Pharmaceutical Nanotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran.,Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Zahra Rahiminezhad
- Department of Pharmaceutical Nanotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran.,Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mahvash DehghanKhold
- Department of Pharmaceutical Nanotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran.,Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Ghazal Farahavar
- Department of Pharmaceutical Nanotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran.,Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mahboobeh Jafari
- Department of Pharmaceutical Nanotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran.,Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mehdi Abedi
- Department of Pharmaceutical Nanotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran.,Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Leila Moradi
- Department of Pharmaceutical Nanotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran.,Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Uranous Niroumand
- Department of Pharmaceutical Nanotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran.,Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mohammad Ashfaq
- University Centre for Research & Development (UCRD), Chandigarh University, Gharaun, Mohali, 140413, Punjab, India. .,Department of Biotechnology, Chandigarh University, Gharaun, Mohali, 140413, Punjab, India.
| | - Samira Sadat Abolmaali
- Department of Pharmaceutical Nanotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran. .,Center for Drug Delivery in Nanotechnology, Shiraz University of Medical Sciences, Shiraz, Iran.
| | - Gholamhossein Yousefi
- Department of Pharmaceutics, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran. .,Center for Drug Delivery in Nanotechnology, Shiraz University of Medical Sciences, Shiraz, Iran.
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3
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Sadanandan N, Shear A, Brooks B, Saft M, Cabantan DAG, Kingsbury C, Zhang H, Anthony S, Wang ZJ, Salazar FE, Lezama Toledo AR, Rivera Monroy G, Vega Gonzales-Portillo J, Moscatello A, Lee JY, Borlongan CV. Treating Metastatic Brain Cancers With Stem Cells. Front Mol Neurosci 2021; 14:749716. [PMID: 34899179 PMCID: PMC8651876 DOI: 10.3389/fnmol.2021.749716] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 10/20/2021] [Indexed: 12/12/2022] Open
Abstract
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.
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Affiliation(s)
| | - Alex Shear
- University of Florida, Gainesville, FL, United States
| | - Beverly Brooks
- Department of Neurosurgery and Brain Repair, University of South Florida Morsani College of Medicine, Tampa, FL, United States
| | - Madeline Saft
- University of Michigan, Ann Arbor, MI, United States
| | | | - Chase Kingsbury
- Department of Neurosurgery and Brain Repair, University of South Florida Morsani College of Medicine, Tampa, FL, United States
| | - Henry Zhang
- University of Florida, Gainesville, FL, United States
| | - Stefan Anthony
- Lake Erie College of Osteopathic Medicine, Bradenton, FL, United States
| | - Zhen-Jie Wang
- Department of Neurosurgery and Brain Repair, University of South Florida Morsani College of Medicine, Tampa, FL, United States
| | - Felipe Esparza Salazar
- Centro de Investigación en Ciencias de la Salud (CICSA), Facultad de Ciencias de la Salud (FCS), Universidad Anáhuac México Campus Norte, Huixquilucan, Mexico
| | - Alma R. Lezama Toledo
- Centro de Investigación en Ciencias de la Salud (CICSA), Facultad de Ciencias de la Salud (FCS), Universidad Anáhuac México Campus Norte, Huixquilucan, Mexico
| | - Germán Rivera Monroy
- Centro de Investigación en Ciencias de la Salud (CICSA), Facultad de Ciencias de la Salud (FCS), Universidad Anáhuac México Campus Norte, Huixquilucan, Mexico
| | | | - Alexa Moscatello
- Department of Neurosurgery and Brain Repair, University of South Florida Morsani College of Medicine, Tampa, FL, United States
| | - Jea-Young Lee
- Department of Neurosurgery and Brain Repair, University of South Florida Morsani College of Medicine, Tampa, FL, United States
| | - Cesario V. Borlongan
- Department of Neurosurgery and Brain Repair, University of South Florida Morsani College of Medicine, Tampa, FL, United States
- Center of Excellence for Aging and Brain Repair, University of South Florida Morsani College of Medicine, Tampa, FL, United States
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Hassanzadeh A, Shamlou S, Yousefi N, Nikoo M, Verdi J. Genetically-Modified Stem Cell in Regenerative Medicine and Cancer Therapy; A New Era. Curr Gene Ther 2021; 22:23-39. [PMID: 34238158 DOI: 10.2174/1566523221666210707125342] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 04/20/2021] [Accepted: 04/25/2021] [Indexed: 11/22/2022]
Abstract
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.
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Affiliation(s)
- Ali Hassanzadeh
- Department of Applied Cell Sciences, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Somayeh Shamlou
- Department of Applied Cell Sciences, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Niloufar Yousefi
- Department of Tissue Engineering and Applied Cell Sciences, School of Advanced Technologies in Medicine, Shahid Beheshti University of Medical Science, Tehran, Iran
| | - Marzieh Nikoo
- Department of Immunology, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Javad Verdi
- Department of Applied Cell Sciences, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
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5
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Zhang J, Yuan Z, Zhong W, Wei Y. Stem Cell as Vehicles of Antibody in Treatment of Lymphoma: a Novel and Potential Targeted Therapy. Stem Cell Rev Rep 2020; 17:829-841. [PMID: 33205352 DOI: 10.1007/s12015-020-10080-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/08/2020] [Indexed: 02/06/2023]
Abstract
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.
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Affiliation(s)
- Jiayi Zhang
- Department of Blood Transfusion, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, Guangdong, China.,Guangdong Engineering Research Center of Precise Transfusion, Guangzhou, Guangdong, China
| | - Zhaohu Yuan
- Department of Blood Transfusion, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, Guangdong, China
| | - Weijie Zhong
- Department of Geriatrics, Hematology & Oncology ward, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, Guangdong, China
| | - Yaming Wei
- Department of Blood Transfusion, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, Guangdong, China. .,Guangdong Engineering Research Center of Precise Transfusion, Guangzhou, Guangdong, China.
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6
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Tu GXE, Ho YK, Ng ZX, Teo KJ, Yeo TT, Too HP. A facile and scalable in production non-viral gene engineered mesenchymal stem cells for effective suppression of temozolomide-resistant (TMZR) glioblastoma growth. Stem Cell Res Ther 2020; 11:391. [PMID: 32917269 PMCID: PMC7488524 DOI: 10.1186/s13287-020-01899-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/28/2020] [Accepted: 08/24/2020] [Indexed: 12/11/2022] Open
Abstract
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.
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Affiliation(s)
- Geraldine Xue En Tu
- Department of Biochemistry, National University of Singapore, Singapore, 117596, Singapore
| | - Yoon Khei Ho
- Department of Biochemistry, National University of Singapore, Singapore, 117596, Singapore.
| | - Zhi Xu Ng
- Division of Neurosurgery, Department of General Surgery, Khoo Teck Puat Hospital, Singapore, 768828, Singapore
| | - Ke Jia Teo
- Division of Neurosurgery, Department of General Surgery, National University Hospital, National University Health Systems, Singapore, Singapore
| | - Tseng Tsai Yeo
- Division of Neurosurgery, Department of General Surgery, National University Hospital, National University Health Systems, Singapore, Singapore
| | - Heng-Phon Too
- Department of Biochemistry, National University of Singapore, Singapore, 117596, Singapore
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7
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Next-generation stem cells - ushering in a new era of cell-based therapies. Nat Rev Drug Discov 2020; 19:463-479. [PMID: 32612263 DOI: 10.1038/s41573-020-0064-x] [Citation(s) in RCA: 148] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2020] [Indexed: 02/06/2023]
Abstract
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.
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8
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Tamura R, Miyoshi H, Yoshida K, Okano H, Toda M. Recent progress in the research of suicide gene therapy for malignant glioma. Neurosurg Rev 2019; 44:29-49. [PMID: 31781985 DOI: 10.1007/s10143-019-01203-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 10/14/2019] [Accepted: 10/28/2019] [Indexed: 12/15/2022]
Abstract
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.
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Affiliation(s)
- Ryota Tamura
- Department of Neurosurgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Hiroyuki Miyoshi
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Kazunari Yoshida
- Department of Neurosurgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Hideyuki Okano
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Masahiro Toda
- Department of Neurosurgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
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