Role of glioma stem cells in promoting tumor chemo- and radioresistance: A systematic review of potential targeted treatments

BACKGROUND Gliomas pose a significant challenge to effective treatment despite advancements in chemotherapy and radiotherapy.Glioma stem cells(GSCs),a subset within tumors,contribute to resistance,tumor heterogeneity,and plasticity.Recent studies reveal GSCs’role in therapeutic resistance,driven by DNA repair mechanisms and dynamic transitions between cellular states.Resistance mechanisms can involve different cellular pathways,most of which have been recently reported in the literature.Despite progress,targeted therapeutic approaches lack consensus due to GSCs’high plasticity.AIM To analyze targeted therapies against GSC-mediated resistance to radio-and chemotherapy in gliomas,focusing on underlying mechanisms.METHODS A systematic search was conducted across major medical databases(PubMed,Embase,and Cochrane Library)up to September 30,2023.The search strategy utilized relevant Medical Subject Heading terms and keywords related to including“glioma stem cells”,“radiotherapy”,“chemotherapy”,“resistance”,and“targeted therapies”.Studies included in this review were publications focusing on targeted therapies against the molecular mechanism of GSC-mediated re-sistance to radiotherapy resistance(RTR).RESULTS In a comprehensive review of 66 studies on stem cell therapies for SCI,452 papers were initially identified,with 203 chosen for full-text analysis.Among them,201 were deemed eligible after excluding 168 for various reasons.The temporal breakdown of studies illustrates this trend:2005-2010(33.3%),2011-2015(36.4%),and 2016-2022(30.3%).Key GSC models,particularly U87(33.3%),U251(15.2%),and T98G(15.2%),emerge as significant in research,reflecting their representativeness of glioma characteristics.Pathway analysis indicates a focus on phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin(mTOR)(27.3%)and Notch(12.1%)pathways,suggesting their crucial roles in resistance development.Targeted molecules with mTOR(18.2%),CHK1/2(15.2%),and ATP binding cassette G2(12.1%)as frequent targets underscore their importance in overcoming GSC-mediated resistance.Various therapeutic agents,notably RNA inhibitor/short hairpin RNA(27.3%),inhibitors(e.g.,LY294002,NVP-BEZ235)(24.2%),and monoclonal antibodies(e.g.,cetuximab)(9.1%),demonstrate versatility in targeted therapies.among 20 studies(60.6%),the most common effect on the chemotherapy resistance response is a reduction in temozolomide resistance(51.5%),followed by reductions in carmustine resistance(9.1%)and doxorubicin resistance(3.0%),while resistance to RTR is reduced in 42.4%of studies.CONCLUSION GSCs play a complex role in mediating radioresistance and chemoresistance,emphasizing the necessity for precision therapies that consider the heterogeneity within the GSC population and the dynamic tumor microenvironment to enhance outcomes for glioblastoma patients.

Stem cells tropism for malignant gliomas

Various studies have demonstrated the tremendous tropism of stem cells for malignant gliomas,making these cells a potential vehicle for delivery of therapeutic genes to disseminated glioma cells.However,little is known about the mechanisms underlying the glioma-induced tropism of stem cells.Soluble factors including chemokines or growth factors released and expressed by glioma cells at least mediate the tropism of stem cells for gliomas.Here we review the possible mechanisms of stem cells tropism for malignant gliomas.

Brain stem cells as the cell of origin in glioma

Glioma incidence rates in the United States are near 20000 new cases per year, with a median survival time of 14.6 mo for high-grade gliomas due to limited therapeutic options. The origins of these tumors and their many subtypes remain a matter of investigation. Evidence from mouse models of glioma and human clinical data have provided clues about the cell types and initiating oncogenic mutations that drive gliomagenesis, a topic we review here. There has been mixed evidence as to whether or not the cells of origin are neural stem cells, progenitor cells or differentiated progeny. Many of the existing murine models target cell populations defined by lineage-specific promoters or employ lineagetracing methods to track the potential cells of origin. Our ability to target specific cell populations will likely increase concurrently with the knowledge gleaned from an understanding of neurogenesis in the adult brain. The cell of origin is one variable in tumorigenesis, as oncogenes or tumor suppressor genes may differentially transform the neuroglial cell types. Knowledge of key driver mutations and susceptible cell types will allow us to understand cancer biology from a developmental standpoint and enable early interventional strategies and biomarker discovery.

MiR-181b suppresses proliferation of and reduces chemoresistance to temozolomide in U87 glioma stem cells

MicroRNAs regulate self renewal and differentiation of cancer stem cells.There,we sought to identify the expression of miR-181b in glioma stem cells and investigate the biological effect of miR-181b on glioma stem cells in this study.MiR-181b expression was measured by real-time PCR in glioma stem cells isolated from U87 cells by FACS sorting.After miR-181b was overexpressed in U87 glioma stem cells by miR-181b lentiviral expression vector and/or treatment of temozolomide,secondary neurosphere assay,soft agar colony assay and MTT assay were performed.Compared with U87 cells,the expression of miR-181b was significantly decreased in U87 glioma stem cells.Overexpression of miR-181b decreased neurosphere formation by U87 glioma stem cells in vitro and suppressed colony formation in soft agar,and the cell growth inhibition rates increased in a time-dependent manner in U87 glioma stem cells infected with miR-181b lentivirus.Furthermore,miR-181b had a synergistic effect on temozolomide-induced inhibition of secondary neurosphere and soft agar colony,and on cell growth inhibition rates.MiR-181b functions as a tumor suppressor that suppresses proliferation and reduces chemoresistance to temozolomide in glioma stem cells.

Migration capacity of human umbilical cord mesenchymal stem cells towards glioma in vivo

High-grade glioma is the most common malignant primary brain tumor in adults. The poor prognosis of glioma, combined with a resistance tQ currently available treatments, necessitates the develop- ment of more effective tumor-selective therapies. Stem cell-based therapies are emerging as novel cell-based delivery vehicle for therapeutic agents. In the present study, we successfully isolated human umbilical cord mesenchymal stem cells by expiant culture. The human umbilical cord mes- enchymal stem cells were adherent to plastic surfaces, expressed specific surface phenotypes of mesenchymal stem cells as demonstrated by flow cytometry, and possessed multi-differentiation potentials in permissive induction media in vitro. Furthermore, human umbilical cord mesenchymal stem cells demonstrated excellent glioma-specific targeting capacity in established rat glioma models after intratumoral injection or contralateral ventricular administration in vivo. The excellent glioma-specific targeting ability and extensive intratumoral distribution of human umbilical cord mesenchymal stem cells indicate that they may serve as a novel cellular vehicle for delivering therapeutic molecules in glioma therapy.

Research on human glioma stem cells in China

Research on human glioma stem cells began early in the 21st century and since then has become a rapidly growing research field with the number of publications increasing year by year. The research conducted by our diverse group of investigators focused primarily on cell culture techniques, molecular regulation, signaling pathways, cancer treatment, the stem cell microenvironment and the cellular origin and function of glioma stem cells. In particular, we put forward our view that there are inverse or forward transformations among neural stem cells, glial cells and glioma stem cells in glioma tissues under certain conditions. Based on the background of the progress of international research on human glioma stem cells, we aim to share our progress and current findings of human glioma stem cell research in China with colleagues around the world.

The Effects of All-Trans Retinoic Acid on Vasculogenic Mimicry Formation Ability in CD133+ Glioma Stem Cells and Its Mechanisms

Objective: to investigate the effects of all-trans retinoic acid (ATRA) on vasculogenic mimicry formation in glioma stem cells. Methods: U87 stem cells were harvested through a suspension culture assay from the U87 cells, identified by CD133 and nestin, and counted by a flow cytometry. To investigate the VM formation ability of U87 stem cells with the treatment of various concentrations of ATRA, a Matrigel-based tube formation assay was used in the present study in vitro and tube-like structure (typical tube, TT;atypical tube AT) was observed and counted. Then the expressions of VEGF, VEGFR-2 and CD133 were measured throughout real time q-PCR, western blotting and immunofluorescence techniques. The data, presented as the mean ± standard deviation, were analyzed using SPSS software. One-way analysis of variance was used to compare groups and Fisher’s least significant difference tests were performed for subsequent comparisons between groups. P Results: Most of the harvested spheroid cells were positive for nestin and 88.4% were positive forCD133. The CD133+ U87 cells were cultured into tube like structure loaded on the top of Matrigel and the quantity of tubes was decreased under the treatment of ATRA. In addition, the expressions of VEGF, VEGFR-2 and CD133 were significantly reduced under the treatment of ATRA, particularly in the higher concentration groups (20 and 40 μmol, P Conclusions: ATRA may inhibit the establishment of VM differing from stem cells in glioma, and these effects may attribute to the effects of ATRA’s promotion of the differentiation of stem cells and/or down regulation of the expressions of proangiogenic factors VEGF and its receptor VEGFR-2. Thus, the results of the present study indicated a novel idea for the treatment of GBM and enriched the anti-glioma mechanisms of ARTA.

Enhanced MGMT expression contributes to temozolomide resistance in glioma stem-like cells

O6-methylguanine DNA methyltransferase(MGMT) can remove DNA alkylation adducts, thereby repairing damaged DNA and contributing to the drug resistance of gliomas to alkylating agents. In addition, glioma stem-like cells(GSCs) have been demonstrated to be involved in the recurrence and treatment resistance of gliomas. In this study, we aimed to investigate MGMT expression and regulatory mechanisms in GSCs and the association of MGMT with temozolomide(TMZ) sensitivity. GSCs were enriched from one MGMT-positive cell line(SF-767) and 7 MGMT-negative cell lines(U251, SKMG-4, SKMG-1, SF295, U87, MGR1, and MGR2) through serum-free clone culture. GSCs from the U251G, SKMG-4G, SF295G, and SKMG-1G cell lines became MGMT-positive, but those from the U87G, MGR1G, and MGR2G cell lines remained MGMT-negative. However, all the GSCs and their parental glioma cell lines were positive for nuclear factor-κB(NF-κB). In addition, GSCs were more resistant to TMZ than their parental glioma cell lines(P < 0.05). However, there was no significant difference in the 50% inhibition concentration(IC50) of TMZ between MGMT-positive and MGMT-negative GSCs(P > 0.05). When we treated the MGMT-positive GSCs with TMZ plus MG-132(an NF-κB inhibitor), the antitumor activity was significantly enhanced compared to that of GSCs treated with TMZ alone(P < 0.05). Furthermore, we found that MGMT expression decreased through the down-regulation of NF-κB expression by MG-132. Our results show that MG-132 may inhibit NF-κB expression and further decrease MGMT expression, resulting in a synergistic effect on MGMT-positive GSCs. These results indicate that enhanced MGMT expression contributes to TMZ resistance in MGMT-positive GSCs.

SOX transcription factors and glioma stem cells:Choosing between stemness and differentiation

Glioblastoma(GBM)is the most common,most aggressive and deadliest brain tumor.Recently,remarkable progress has been made towards understanding the cellular and molecular biology of gliomas.GBM tumor initiation,progression and relapse as well as resistance to treatments are associated with glioma stem cells(GSCs).GSCs exhibit a high proliferation rate and self-renewal capacity and the ability to differentiate into diverse cell types,generating a range of distinct cell types within the tumor,leading to cellular heterogeneity.GBM tumors may contain different subsets of GSCs,and some of them may adopt a quiescent state that protects them against chemotherapy and radiotherapy.GSCs enriched in recurrent gliomas acquire more aggressive and therapy-resistant properties,making them more malignant,able to rapidly spread.The impact of SOX transcription factors(TFs)on brain tumors has been extensively studied in the last decade.Almost all SOX genes are expressed in GBM,and their expression levels are associated with patient prognosis and survival.Numerous SOX TFs are involved in the maintenance of the stemness of GSCs or play a role in the initiation of GSC differentiation.The fine-tuning of SOX gene expression levels controls the balance between cell stemness and differentiation.Therefore,innovative therapies targeting SOX TFs are emerging as promising tools for combatting GBM.Combatting GBM has been a demanding and challenging goal for decades.The current therapeutic strategies have not yet provided a cure for GBM and have only resulted in a slight improvement in patient survival.Novel approaches will require the fine adjustment of multimodal therapeutic strategies that simultaneously target numerous hallmarks of cancer cells to win the battle against GBM.

Study on the migration of nerve stem cell in vitro Induced by glioma cells

Objective： Previous studies have shown that glioma cells induced the migration of nerve stem cells （NSCs） in vivo. This study was exploring whether this situation could happen in vitro. Methods： Supematant from 05 glioma cell lines or astrocytes cultured in serum-free medium growing in logarithmic phase were separately placed in lower chambers and NSCs were placed in the upper chambers of Trans-well culture system. After 36 h co-incubation, these NSCs spheres occurred on the middle membrane were counted. Results： Results demonstrated that the supematant from 05 glioma cell culture, not from the astrocytes, enhanced the migration of NSCs （ P 〈0.01）. Conclusion： Some components in 05 glioma cell culture can attract the migration of NSCs.

Isolation,cultivation and identification of brain glioma stem cells by magnetic bead sorting

This study describes a detailed process for obtaining brain glioma stem cells from freshly dissected human brain glioma samples using an immunomagnetic bead technique combined with serum-free media pressure screening. Furthermore, the proliferation, differentiation and self-renewal biological features of brain glioma stem cells were identified. Results showed that a small number of CD133 positive tumor cells isolated from brain glioma samples survived as a cell suspension in serum-free media and proliferated. Subcultured CD133 positive cells maintained a potent self-renewal and proliferative ability, and expressed the stem cell-specific markers CD133 and nestin. After incubation with fetal bovine serum, the number of glial fibrillary acidic protein and microtubule associated protein 2 positive cells increased significantly, indicating that the cultured brain glioma stem cells can differentiate into astrocytes and neurons. Western blot analysis showed that tumor suppressor phosphatase and tensin homolog was highly expressed in tumor spheres compared with the differentiated tumor cells. These experimental findings indicate that the immunomagnetic beads technique is a useful method to obtain brain glioma stem cells from human brain tumors.

IL-13Ra2-and glioma stem cell-pulsed dendritic cells induce glioma cell death in vitro

Objective Gliomas are the most common malignant tumors in the central nervous system.Despite multiple therapies including surgery,chemotherapy,and radiotherapy,the prognosis of patients remains poor.Immunotherapy is an alternative method of treating glioma,and the use of dendritic cell vaccines is one of the promising treatment options.However,there is no specific tumor cell antigen that can trigger dendritic cells(DCs).IL-13Ra2 is a specific antigen expressed in glioma cells;in the current study,we have attempted to explore whether IL-13Ra2 could be the antigen that triggers DCs and to envisage its application as potential therapy for glioma.Methods The expression of IL-13Ra2 was detected in U251 glioma cell lines and primary glioma tissues using different methods.DCs from human blood were isolated and pulsed with recombinant IL-13Ra2,following which the cytotoxicity of these DCs on glioma cells was detected and analyzed.Results About 55.9% human glioma tissue cells expressed IL-13Ra2,while normal brain tissue cells did not show any expression.DC vaccines loaded with IL-13Ra2,glioma cell antigen,and brain tumor stem cell(BTSC) antigen could significantly stimulate the proliferation of T lymphocytes and induce cell death in the glioma tissue.Compared to other groups,DC vaccines loaded with BTSC antigen showed the strongest ability to activate cytotoxic T lymphocytes(CTLs),while the glioma cell antigen group showed no significant difference.Conclusion IL-13Ra2,which is expressed in gliomas and by glioma stem cells,as well as IL-13Ra2 could prove to be potential antigens for DC vaccine-based immunotherapy.

Application of mesenchymal stem cells as a vehicle to deliver replication-competent adenovirus for treating malignant glioma

Although gene therapy was regarded as a promising approach for glioma treatment,its therapeutic efficacy was often disappointing because of the lack of efficient drug delivery systems.Mesenchymal stem cells(MSCs) have been reported to have a tropism for brain tumors and thus could be used as delivery vehicles for glioma therapy.Therefore,in this study,we attempted to treat glioma by using MSCs as a vehicle for delivering replication-competent adenovirus.We firstly compared the infectivity of type 3,type 5,and type 35 fiber-modified adenoviruses in MSCs.We also determined suitable adenovirus titer in vitro and then used this titer to analyze the ability of MSCs to deliver replication-competent adenovirus into glioma in vivo.Our results indicated that type 35 fiber-modified adenovirus showed higher infectivity than did naked type 3 or type 5 fiber-modified adenovirus.MSCs carrying replication-competent adenovirus significantly inhibited tumor growth in vivo compared with other control groups.In conclusion,MSCs are an effective vehicle that can successfully transport replication-competent adenovirus into glioma,making it a potential therapeutic strategy for treating malignant glioma.

Effect of conditioned medium from neural stem cells on glioma progression and its protein expression profile analysis

BACKGROUND Emerging evidence suggests that the spread of glioma to the subventricular zone(SVZ)is closely related to glioma recurrence and patient survival.Neural stem cells(NSCs)are the main cell type in the SVZ region and exhibit tumor-homing ability.AIM To evaluate the effects of conditioned medium(CM)derived from SVZ NSCs on the cancer-related behaviors of glioma cells.METHODS The characteristics of SVZ hNSCs were identified by immunofluorescence.The normoxic-hNSC-CM and hypoxic-hNSC-CM(3%O2,oxygen-glucose deprived[OGD]culturing)were collected from 80%-90%confluent SVZ NSCs in sterile conditions.The CCK8 and Transwell assays were used to compare and evaluate the effects of normoxic-CM and hypoxic-CM on glioma proliferation and invasion.Then proteins secreted from SVZ NSCs into the CM were investigated by mass spectrometry,and the potential effects of candidate protein NCAN in the regulation of glioma progression were examined by CCK8 and Transwell assays.RESULTS The CM from SVZ NSCs significantly increased the proliferation and invasion of glioma cells,particularly the CM from OGD NSCs induced under hypoxic conditions.Furthermore,the secreted protein neurocan(NCAN)in CM from OGD NSCs was identified by proteomic analysis.NCAN was expressed in glioma cells and played regulatory roles in mediating the progression of glioma cells mainly via the Rho/Rho-associated protein kinase pathway.CONCLUSION Our study identified a potential interactive mechanism between SVZ NSCs and glioma cells,in which SVZ NSCs promote glioma progression via the secreted protein NCAN.These findings suggested that exploring the CM derived from cells could be a novel strategy for optimizing treatments and that NCAN derived from SVZ NSCs may be a potential new target in glioma progression.

Molecular Study on Differentiation-Associated Genes Involved in Both Malignant Progression of Glioma and Differentiation of Human Fetal Neural Stem Cells

OBJECTIVE It is unclear whether differentiation disturbances or deregulation of neural stem cells (NSCs) are the early key steps for gliomagenesis and tumor development. Furthermore, relevant molecular changes and gene-regulation pathways are unknown. This study focused on screening and validating differentiation-associated genes from both human NSCs and glioma cells with malignant progression, for the purpose of offering an experimental basis for the cellular origin of gilomas and molecular pathology of gliomagenesis. METHODS The differential-gene expression profiles of malignant progression of gliomas were established, then the differentiation related genes were screened out with a bioinformatics analysis. Expression levels of these genes was further analyzed in cultured human fetal NSCs undergoing differentiation processes with a semi-quantitative RT-PCR assay. RESULTS Eight genes were screened out from the gene-expression profiling of which the expression levels were associated with the differentiation processes of NSCs, namely CXCR4, TN-C, GLT1, IL1-RI, EGFR-8, CDC2, Ndr3 and MAPKK4. Three of them, ie., GLT1, CDC2 and MAPKK4, were further analyzed, showing that expression levels decreased with the differentiation processes of NSCs, and increased with the malignant progression of ganglioglioma. CONCLUSION Three differentiation associated genes were found negatively associated with NSCs differentiation and positively associated with malignant progression of gliomas, suggesting that differentiation disturbances of neural stem cells may be involved in oncogenesis, and that further studies on their roles in gliomagenesis should be conducted.

Rapamycin induces differentiation of glioma stem/progenitor cells by activating autophagy

Glioma stem/progenitor cells(GSPCs) are considered to be responsible for the initiation,propagation,and recurrence of gliomas.The factors determining their differentiation remain poorly defined.Accumulating evidences indicate that alterations in autophagy may influence cell fate during mammalian development and differentiation.Here,we investigated the role of autophagy in GSPC differentiation.SU-2 cells were treated with rapamycin,3-methyladenine(3-MA) plus rapamycin,E64d plus rapamycin,or untreated as control.SU-2 cell xenografts in nude mice were treated with rapamycin or 3-MA plus rapamycin,or untreated as control.Western blotting and immunocytochemistry showed up-regulation of microtubule-associated protein light chain-3(LC3)-II in rapamycin-treated cells.The neurosphere formation rate and the number of cells in each neurosphere were significantly lower in the rapamycin treatment group than in other groups.Real-time PCR and immunocytochemistry showed down-regulation of stem/progenitor cell markers and up-regulation of differentiation markers in rapamycin-treated cells.Transmission electron microscopy revealed autophagy activation in rapamycin-treated tumor cells in mice.Immunohistochemistry revealed decreased Nestin-positive cells and increased GFAP-positive cells in rapamycin-treated tumor sections.These results indicate that rapamycin induces differentiation of GSPCs by activating autophagy.

The top cited articles on glioma stem cells in Web of Science

BACKGROUND： Glioma is the most common intracranial tumor and has a poor patient prognosis. The presence of brain tumor stem cells was gradually being understood and recognized, which might be beneficial for the treatment of glioma. OBJECTIVE： To use bibliometric indexes to track study focuses on glioma stem cell, and to investigate the relationships among geographic origin, impact factors, and highly cited articles indexed in Web of Science. METHODS： A list of citation classics for glioma stem cells was generated by searching the database of Web of Science-Expanded using the terms ＂glioma stem cell＂ or ＂glioma, stem cell＇＂ or ＂brain tumor stem cell＂. The top 63 cited research articles which were cited more than 100 times were retrieved by reading the abstract or full text if needed. Each eligible article was reviewed for basic information on subject categories, country of origin, journals, authors, and source of journals. Inclusive criteria： （1） articles in the field of glioma stem cells which was cited more than 100 times; （2） fundamental research on humans or animals, clinical trials and case reports; （3） research article; （4） year of publication： 1899-2012; and （5） citation database： Science Citation Index-Expanded. Exclusive criteria： （1） articles needing to be manually searched or accessed only by telephone; （2） unpublished articles; and （3） reviews, conference proceedings, as well as corrected papers. RESULTS： Of 2 040 articles published, the 63 top-cited articles were published between 1992 and 2010. The number of citations ranged from 100 to 1 754, with a mean of 280 citations per article. These citation classics came from nineteen countries, of which 46 articles came from the United States. Duke University and University of California, San Francisco led the list of classics with seven papers each. The 63 top-cited articles were published in 28 journals, predominantly Cancer Research and Cancer Cell, followed by Cell Stem Cell and Nature. CONCLUSION： Our bibliometric analysis provides a historical perspective on the progress of glioma stem cell research. Articles originating from outstanding institutions of the United States and published in high-impact journals are most likely to be cited.

Migration characteristics of neural stem cells for glioma cells in vivo and in vitro

This study analyzed migration characteristics of neural stem cells （NSCs） in vitro and in vivo, as well as exogenous gene expression in the brain following transfection of NSCs with an enhanced green fluorescent protein （EGFP） gene expression vector plRES2-EGFP plasmid, in glioma experimental models. NSCs slowly migrated towards glioma cells （C6 cells） in culture, although mouse embryonic fibroblasts 3T3 cells did not migrate. NSCs rapidly migrated to the tumor bed, and to tissues surrounding the tumor and metastatic lesions. A large number of EGFP-expressing cells formed distinct colonies in and surrounding the tumor following NSCs-EGFP transfection. EGFP-positive cells aggregated in incubation sites following 3T3-EGFP treatment. Results suggested that NSCs could be used to track tumor cells in vitro. In vivo, transplanted NSCs survived expressed transfected exogenous genes, migrated to the tumor bed, and expressed exogenous genes.

Migration to gliomas of bone mesenchymal stem cells transfected with cytosine deaminase gene following transplantation in vivo

This experiment sought to observe the migration and distribution of bone mesenchymal stem cells transfected with the cytosine deaminase gone （BMSCs-CD/eGFP） after transplantation in vivo through three pathways. In addition, we examined the tropism of these cells to glioma. Intracranial C6 glioma models were established in Sprague-Dawley rats using an intracranial stereotactic inoculation method. When tumors were 7 days old, rats were inoculated with lx106 BMSCs-CD/eGFP cells via the tumor-bearing internal carotid artery, the contralateral hemisphere and the tumor-bearing glioma. Fluorescence microscopy revealed that BMSCs-CD/eGFP exhibited a strong capacity for migration to tumors. BMSCs-CD/eGFP transplanted via the tumor-bearing intemal carotid artery were observed to distribute in glioma tissues. BMSCs-CD/eGFP inoculated via the ipsilateral glioma mainly located within and at the edge of glioma tissues. BMSCs-CD/eGFP inoculated via the contralateral hemisphere mainly distributed at the proximal end of the tumor at the incubation site.

Inhibitory effects of cytosine deaminase gene-transfected bone marrow mesenchymal stem cells on glioma cell proliferation

Bone marrow mesenchymal stem cells were isolated from C57BL mice, transfected with the cytosine deaminase （CD） gene using a lentivirus vector and co-cultured with C6 glioma cells to verify anti-tumor effects of bone marrow mesenchymal stem cells carrying CD genes. C57MSC-CD/eGFP cells converted 5-fluorocytosine to 5-fluorouracil and exhibited significant inhibition of proliferation and apoptosis in C6 glioma cells. C57MSC-CD/eGFP cells were then implanted into rat models of brain C6 glioma. Rats were also intraperitoneally injected with 5-fluorocytosine after 7 days. MSC-CD/eGFP cells were irregularly distributed at the margin of the glioma, as well as encased and reduced the volume of the glioma. CD-transfected bone marrow mesenchymal stem cells inhibit the in vivo growth and in vitro proliferation of glioma.