- Research article
- Open Access
- Open Peer Review
Anti-angiogenesis therapy based on the bone marrow-derived stromal cells genetically engineered to express sFlt-1 in mouse tumor model
- M Hu†1, 2,
- J-L Yang†1Email author,
- H Teng†3,
- Y-Q Jia1,
- R Wang1,
- X-W Zhang1,
- Y Wu1,
- Y Luo1,
- X-C Chen1,
- R Zhang1,
- L Tian1,
- X Zhao1 and
- Y-Q Wei1
© Hu et al; licensee BioMed Central Ltd. 2008
- Received: 13 October 2007
- Accepted: 23 October 2008
- Published: 23 October 2008
Bone marrow-derived stromal cells (BMSCs) are important for development, tissue cell replenishment, and wound healing in physiological and pathological conditions. BMSCs were found to preferably reach sites undergoing the process of cell proliferation, such as wound and tumor, suggesting that BMSCs may be used as a vehicle for gene therapy of tumor.
Mouse BMSCs were loaded with recombinant adenoviruses which express soluble Vascular Endothelial Growth Factor Receptor-1 (sFlt-1). The anti-angiogenesis of sFlt-1 in BMSCs was determined using endothelial cells proliferation inhibition assay and alginate encapsulation assay. The anti-tumor effects of BMSCs expressing sFlt-1 through tail-vein infusion were evaluated in two mouse tumor metastases models.
BMSCs genetically modified with Adv-GFP-sFlt-1 could effectively express and secret sFlt-1. BMSCs loaded with sFlt-1 gene could preferentially home to tumor loci and decrease lung metastases and prolong lifespan in mouse tumor model through inducing anti-angiogenesis and apoptosis in tumors.
We demonstrated that BMSCs might be employed as a promising vehicle for tumor gene therapy which can effectively not only improve the concentration of anticancer therapeutics in tumors, but also modify the tumor microenvironment.
- Vascular Endothelial Growth Factor
- Conditioned Medium
- Osteogenesis Imperfecta
- Alginate Bead
- Recombinant Adenovirus
Bone marrow-derived stromal cells (BMSCs), also known as mesenchymal stem cells or nonhematopoietic progenitor cells, are precursors that can be differentiated into chondrocytes, osteoblasts, adipocytes, neurons and other cell types . They are important for development and cell replenishment of active proliferating tissues in physiological conditions, such as blood, skin and gut. In pathological conditions, they are involved in the process of wound healing and tissue regeneration. In animal and clinical experiments, BMSCs have been used for tissue damage repair and functional reconstruction of organs, such as myocardial infarction, osteogenesis imperfecta, syndrome of multiple organ failure and rebuilding of hematopoietic system after chemotherapy of breast cancer [2–5].
It has been reported that the conditions featured by enhanced cell proliferation and tissue remodeling, such as bone fractures, embryo growth and tumorigenesis, offer an appropriate microenvironment for migration, proliferation and differentiation of stem cells delivered systemically [3, 6–9]. The formation of tumor stroma is similar to that of wound healing and results in a microenvironment which is suitable for the proliferation of bone marrow-derived stem cells . Therefore, we hypothesize that systemically delivered BMSCs would preferentially home to tumor tissues and participate in the formation of tumor stroma. Therefore, it will be useful to develop a new targeting system based on genetically modified BMSCs for tumor gene therapy. The feasibility of this approach has been demonstrated by Matus Studeny's experimemt .
Metastasis is the most common and fundamental characteristics of solid tumors. Most deaths of cancerous patients result from the ruthless growth of metastases that are resistant to conventional remedies. This urges us to develop a novel therapeutic strategy for inhibiting tumor metastasis. The concept that tumor growth and metastasis relies on angiogenesis has been widely proven and accepted. The signal axis of vascular endothelial growth factor (VEGF) and its receptors (VEGFR-1, VEGFR-2 and VEGFR-3) is involved in the formation and progress of tumors. The soluble VEGF receptor-1 (sFlt-1) has been shown to be effective in inhibition of cancerous angiogenesis .
In this report, we developed a novel strategy of tumor gene therapy in which BMSCs loaded with recombinant adenoviruses expressing sFlt-1 could effectively suppress tumor growth through inhibiting angiogenesis and metastases and prolong the lifespan in mouse model, indicating that BMSCs might be employed as an effective carrier for tumor gene therapy.
BMSCs isolation and culture
BMSCs were isolated from femur bone marrow of male BALB/c mouse. Mononuclear cells were separated by centrifugation over a Ficoll gradient (Sigma Chemical Co., St. Louis, MO) of 1.077 g/ml. The cells were cultured in L-DMEM containing 10% fetal bovine serum (Gibco BRL, Inc) at an initial seeding density of 1 × 105 cells/cm2 at 37°C with 5% CO2 and 95% humidified atmosphere. The nonadherent cells were removed and washed with PBS after 24 hours, and the monolayer of adherent cells were cultured until they reached to confluence. The cells were then trypsinized (0.25% trypsin with 0.1% EDTA), subcultured at densities of 5000–6000 cells/cm2. and used for experiments during passages five to eight. CD34, CD29 and CD44 expressions in BMSCs were determined by flow cytometry. Briefly, the trypsinized BMSCs were adjusted to 1 × 107cells/ml in media (1% bovine serum albumin, 0.2% sodium azide in PBS), and then stained with FITC-conjugated monoclonal antibodies (BD Biosciences, San Jose, CA, USA) on ice according to the manufacturer's protocol, and followed by detection with flow cytometry.
Production of adenovirus and genetic modification of BMSCs
AdenoVec-GFP-sFlt-1 and AdenoVec-GFP (InvivoGen, San Diego, CA) were transfected into HEK-293 cells using jetPEI (Qbiogene, Nottingham, UK) according to the manufacturer's protocol. Seven to 14 days later, the recombinant adenoviruses were harvested from the cultures and the viruses were further amplified in 293 cells, and then tittered by plaque assay. BMSCs were infected with adenoviruses at a multiplicity of infection (MOI) of 3000 for 2 hours followed by replacing the infection medium. Twenty-four hours later, the virus-infected BMSCs were harvested for subsequent experiments .
Western blot analysis
Western blot analysis was performed as described previously . Briefly, the secreted proteins in supernatants of the culture were precipitated by TCA-DOC/acetone and the western blot assay was performed using standard method with primary monoclonal antibody of anti-sFlt-1 (1:500 dilution, Santa Cruz Biotechnology, Santa Cruz, CA, USA) and a biotinylated secondary antibody, and the proteins on the membrane were visualized by Vectastain ABC kit (Vector Laboratories, Burlingame, CA, USA).
Mouse endothelial cells proliferation inhibition assay
The mouse endothelial cells proliferation inhibition assay was performed as described previously for examining suppression of sFlt-1 in the conditioned media on VEGF-driven proliferation of endothelial cells . The conditioned media were obtained from BMSCs infected with Adv-GFP-sFlt-1, Adv-GFP, or PBS (mock infected), respectively. Endothelial cells were grown in 24-well plates at 37°C in DMEM containing 10% FBS. At 50% confluence, the cells were washed with PBS after removal of the DMEM media, and then 0.5 ml of conditioned media was added. Fifteen minutes later, VEGF was added to each well with a final concentration of 10 ng/ml and the cells were incubated at 37°C. After 72 h, the cells were trypsinized, and the number of viable cells was counted using a trypan blue assay.
Alginate encapsulation assay
Alginate-encapsulated tumor cell assays were performed as described previously . Briefly, tumor cells, BMSCs expressing sFlt-1 or mixed cells were resuspended in a 1.5% solution of sodium alginate and added dropwise into a swirling 37°C solution of 250 mM calcium chloride. Alginate beads were formed with about 1 × 105 cells per bead. After mice were anesthetized, 4 beads were implanted subcutaneously into an incision made on the dorsal side. Incisions were closed with surgical clamps. After 21 days, mice were injected intravenously with 100 μl of a 100 mg/kg FITC-dextran solution (Sigma). Beads were surgically removed, and FITC-dextran was quantified against a standard curve of FITC-dextran.
Murine tumor metastases models and treatment
The colon carcinoma CT26, Lewis lung cancer LLC and fibrosarcoma MethA cell lines were used in this study. Metastasis models of LLC and CT26 were generated as described previously . Briefly, female C57BL/6 and BALB/c mice were received i.m. injections of 2×105 LLC in leg or i.v. injection of 2×105 CT26 cells from tail vein in 100 μl of PBS, respectively and then the animals were randomly divided into four groups (10 mice/group). After 4 days for CT26 model and 10 days for LLC model of tumor inoculation, 1×106 of BMSCs infected with Adv-GFP-sFlt-1, BMSCs infected with Adv-GFP, unifected BMSCs or 100 μl of 0.9% NaCl solution alone were administered via tail vein for four doses at 3 days intervals for CT26 model and 5 days intervals for LLC model. Mice received LLC or CT26 injection were sacrificed on day 32 or day 16 after inoculation, respectively, when control mice became moribund, and the lungs from each mouse were removed and the surface lung metastases (>3 mm) were measured and scored . The lungs of animals were also fixed in 10% buffered formalin followed by histological analysis. All of the mice used in this study were approved by the West China Hospital Cancer Center's Animal Care and Use Committee. In the handling and care of animals, all possible steps were taken to avoid animals' suffering and efforts were made to use the minimum number of animals.
The tissues were fixed in 10% neutral buffered formalin solution and embedded in paraffin. Sections of 3–5 μm were stained with hematoxylin and eosin (H.E.). Frozen sections were fixed in acetone, incubated, and stained with anti-CD31 antibody, then visualized with DAKO LSAB kit (DAKO, Carpinteria, CA), as described previously. Vessel density was determined by counting the number of microvessels per high-power field in the sections, as described . Apoptosis in tumor tissues was determined by terminal dUTP nick-end labeling (TUNEL) method using an in situ cell death detection kit (Roche Molecular Biochemicals) following the manufacturer's protocol [17, 18]. Sections in H&E staining and immunohistochemical staining were observed by two pathologists in a blinded manner.
Fluorescent in situ hybridization (FISH)
Fluorescent in situ hybridization was performed according to the mouse Y chromosome probe manual (STAR*FISH; Cambio, Cambridge, England) with some modifications. Cryostat sections of 5 μm in thickness were fixed in Carnoy's fixative for three times, 10 min each, and the sections were incubated in pepsin solution (1% in 0.1N HCl) for 10 minutes and rinsed in PBS. Serial ethanol dehydration was done (1.5 min each), and the slides were air-dried at room temperature. Sections were denatured at 65°C for 2 min in preheated 70% formamide and 2×SSC buffer, pH 7.0, and were then 'quenched' with ice-cold 70% ethanol for 1.5 min. Serial ethanol dehydration was done again. The mouse Y chromosome probe labeled with Cy3 was denatured at 65°C for 10 min and applied to the sections. The sections were coverslipped and sealed with rubber cement for incubation overnight in a hydrated slide box at 37°C. The next day, the coverslips were carefully removed. The sections were washed twice in preheated 50% formamide in 2×SSC buffer for 5 min each at 45°C and were then gently washed twice in preheated 1×SSC buffer for 5 min each at 45°C.
Significance was determined using one-way ANOVA and log-rank test (SPSS 11.0 for windows). Difference between groups were significant at a value of P < 0.05.
BMSCs isolation, genetic modification and sFlt-1 function validation
Inhibition of angiogenesis and induction of apoptosis
Verification of BMSCs' homing to tumor
BMSCs have been used in the therapy of myocardial infarction, osteogenesis imperfecta, syndrome of multiple organ failure and rebuilding of haematopoietic function after chemotherapy of breast cancer in pre-clinical and clinical experiments [2–5]. In this report, we demonstrated that systemically delivered BMSCs loaded with sFlt-1 gene could preferentially home to tumor loci and induce anti-angiogenesis as well as apoptosis of cancerous cells, resulting in the decrease of lung metastases and prolongation of lifespan in mouse tumor model.
The BMSCs' capability of tissue repairing and homing has been attracted great attention of scientists. Grove reported that up to 20% of lung epithelium could be derived from circulating BMSCs after lung injury, and a large portion of lung damage could be repaired by forming entire alveoli. Meantime, these adult stem cells could be effectively used to deliver therapeutic gene to lung while retaining the ability to differentiate into lung cells . Darwin J Prockpop demonstrated that injured tissue create a milieu that enhances homing, proliferation and differentiation of BMSCs . It has been found that there are high concentrations of fibroblast growth factor, transforming growth factor β, platelet-derived growth factor, and epidermal growth factor in injured tissue and in the microenvironment of tumor, in which these facters are needed in the process of homing, proliferation and differentiation of BMSCs [22, 23]. Therefore, we hypothesize that tissue rebuilding in tumorigenesis, wound healing and fetal development entitles the microenvironments the capability of attracting the systemically administered BMSCs.
Suppression of VEGF by sFlt-1 adenoviruses administered systemically was proved to contribute to inhibition of tumor growth . In our study, we employed BMSCs as a gene vehicle loaded with sflt-1 recombinant adenovirus for tumor therapy, and found that the BMSCs expressing sFlt-1 preferentially homed to and survived in the tumor loci where its strong anti-angiogenesis and anti-metastasis effect has been observed. We also observed that BMSCs expressing IL-12 induced a stronger antitumor effect than administration with IL-12 adenoviruses alone (data not shown). This vehicle may be useful and effective in tumor gene therapy for four reasons. Firstly, the BMSCs after ex vivo administration may survive for hundreds of days, which enable them to offer a relatively long effect for chronic diseases . Secondly, the capacity of BMSCs homing to tumor sites and protecting viruses against the immune surveillance would strengthen the effect of recombinant adenovirus gene therapy, which is unsatisfactory when systemically administered alone because of nonspecific distribution and serious hepatotoxicity [11, 25]. Thirdly, the lower immunogenicity, which is the result of low expression of MHC and costimulatory molecules, enables BMSCs advantageous for allogeneic or xenogeneic applications . Last, BMSCs are easy to be expanded in vitro and to be genetically modified, which means convenience and cost effectiveness in the future preclinical or clinical applications.
However, in the experiments performed by our lab (data not shown) and others, the naive BMSCs seemed to promote growth of tumors. On the other hand, Aarif reported that mesenchymal stem cells injected intravenously homed to neoplasm and potently inhibited tumor growth in Kaposi sarcoma model . The relationship between the stem cells and the cancer cells may depend on the microenvironment which is created by these two kinds of cells and others [28–31]. Besides, the possible transformation and the consequent tumorigenesis of BMSCs themselves remains to be clarified. Jakub and his colleagues reported that bone marrow-derived mesenchymal stem cells showed cytogenetic aberrations after several passages in vitro, which resulted in malignant lesions when infused to secondary recipients [32, 33]. All of these contradictions indicated that the fate and effect of BMSCs on tumor growth should be further investigated.
In conclusion, we demonstrated that BMSCs might be employed as a promising vehicle for tumor gene therapy which can effectively not only improve the concentration of anticancer therapeutics in tumors, but also modify the tumor microenvironment. However, the fate and effect on tumor growth of BMSCs systemically administrated should be further evaluated.
This work was supported by National Key Basic Research Program of China (2004CB518800), Project of National Natural Sciences Foundation of China, Natural 863 Projects.
- Pittenger Mark, Mackay Alastair, Beck Stephen, Jaiswal Rama, Douglas Robin, Mosca Joseph, Moorman Mark, Simonetti Donald, Craig Stewart, Marshak Daniel: Multilineage potential of adult human mesenchymal stem cells. Science. 1999, 284: 143-147. 10.1126/science.284.5411.143.View ArticlePubMedGoogle Scholar
- Mangi AA, Noiseux N, Kong D, He H, Rezvani M, Ingwall JS, Dzau VJ: Mesenchymal stem cells modified with Akt prevent remodeling and restore performance of infarcted hearts. Nat Med. 2003, 9: 1195-1201. 10.1038/nm912.View ArticlePubMedGoogle Scholar
- Horwitz EM, Prockop DJ, Fitzpatrick LA, Koo WW, Gordon PL, Neel M, Sussman M, Orchard P, Marx JC, Pyeritz RE, Brenner MK: Transplantability and therapeutic effects of bone marrow-derived mesenchymal cells in children with osteogenesis imperfecta. Nat Med. 1999, 5: 309-313. 10.1038/6529.View ArticlePubMedGoogle Scholar
- Chapel A, Bertho JM, Bensidhoum M, Fouillard L, Young RG, Frick J, Demarquay C, Cuvelier F, Mathieu E, Trompier F, Dudoignon N, Germain C, Mazurier C, Aigueperse J, Borneman J, Gorin NC, Gourmelon P, Thierry D: Mesenchymal stem cells home to injured tissues when co-infused with hematopoietic cells to treat a radiation-induced multi-organ failure syndrome. J Gene Med. 2003, 5 (12): 1028-38. 10.1002/jgm.452.View ArticlePubMedGoogle Scholar
- Koç Omer, Gerson Stanton, Cooper Brenda, Dyhouse Stephanie, Haynesworth Stephen, Caplan Arnold, Lazarus Hillard: Rapid hematopoietic recovery after coinfusion of autologous-blood stem cells and culture-expanded marrow mesenchymal stem cells in advanced breast cancer patients receiving high-dose chemotherapy. J Clin Oncol. 2000, 18: 307-316.PubMedGoogle Scholar
- Liechty KW, MacKenzie TC, Shaaban AF, Radu A, Moseley AM, Deans R, Marshak DR, Flake AW: Human mesenchymal stem cells engraft and demonstrate site-specific differentiation after in utero transplantation in sheep. Nat Med. 2000, 6: 1282-1286. 10.1038/81395.View ArticlePubMedGoogle Scholar
- Hanahan D, Weinberg RA: The hallmarks of cancer. Cell. 2000, 100: 57-70. 10.1016/S0092-8674(00)81683-9.View ArticlePubMedGoogle Scholar
- MacKenzie TC, Flake AW: Human mesenchymal stem cells persist, demonstrate site-specific multipotential differentiation, and are present in sites of wound healing and tissue regeneration after transplantation into fetal sheep. Blood Cells Mol Dis. 2001, 27: 601-604. 10.1006/bcmd.2001.0424.View ArticlePubMedGoogle Scholar
- Watt FM, Hogan BL: Out of Eden: Stem Cells and Their Niches. Science. 2000, 287: 1427-1430. 10.1126/science.287.5457.1427.View ArticlePubMedGoogle Scholar
- Tumors Dvorak: wounds that do not heal. Similarities between tumor stroma generation and wound healing. N Engl J Med. 1986, 315: 1650-1659.View ArticleGoogle Scholar
- Studeny Matus, Marini Frank, Champlin Richard, Zompetta Claudia, Isaiah Fidler, Andreeff Michael: Bone marrow-derived mesenchymal stem cells as vehicles for interferon- beta delivery into tumors. Can Res. 2002, 62: 3603-3608.Google Scholar
- Mori A, Arii S, Furutani M, Mizumoto M, Uchida S, Furuyama H, Kondo Y, Gorrin-Rivas MJ, Furumoto K, Kaneda Y, Imamura M: Soluble Flt-1 gene therapy for peritoneal metastases using HVJ-cationic liposomes. Gene Therapy. 2000, 7: 1027-1033. 10.1038/sj.gt.3301202.View ArticlePubMedGoogle Scholar
- Liu Ji-yan, Wei Yu-quan, Yang Li, Zhao Xia, Tian Ling, Hou Jian-mei, Niu Ting, Liu Fen, Jiang Yu, Hu Bing, Wu Yang, Su Jing-mei, Lou Yan-yan, He Qiu-ming, Wen Yan-jun, Yang Jin-liang, Kan Bing, Mao Yong-qiu, Luo Feng, Peng Feng: Immunotherapy of tumors with vaccine based on quail homologous vascular endothelial growth factor receptor-2. Blood. 2003, 102: 1815-1823. 10.1182/blood-2002-12-3772.View ArticlePubMedGoogle Scholar
- Mahasreshti Parameshwar, Navarro Jesus, Kataram Manjula, Wang Ming, Carey Delicia, Siegal Gene, Barnes Mack, Nettelbeck Dirk, Alvarez Ronald, Hemminki Akseli, Curiel David: Adenovirus-mediated Soluble FLT-1 Gene Therapy for Ovarian Carcinoma. Clin Can Res. 2001, 7: 2057-2066.Google Scholar
- Su Jing-Mei, Wei Yu-Quan, Tian Ling, Zhao Xia, Yang Li, He Qiu-Ming, Wang Yu, Lu You, Wu Yang, Liu Fen, Liu Ji-Yan, Yang Jin-Liang, Lou Yan-Yan, Hu Bing, Niu Ting, Wen Yan-Jun, Xiao Fei, Deng Hong-Xin, Li Jiong, Kan Bing: Active Immunogene Therapy of Cancer with Vaccine On the Basis of Chicken Homologous Matrix Metalloproteinase-2. Can Res. 2003, 63: 600-607.Google Scholar
- Blezinger P, Wang J, Gondo M, Quezada A, Mehrens D, French M: Systemic inhibition of tumor growth and tumor metastases by intramuscular administration of the endostatin gene. Nat Biotechnol. 1999, 17: 343-348. 10.1038/7895.View ArticlePubMedGoogle Scholar
- Kasahara Yasunori, Tuder Rubin, Taraseviciene-Stewart Laimute, Le Cras Timothy, Abman Steven, Hirth Peter: Inhibition of VEGF receptors causes lung cell apoptosis and emphysema. J Clin Invest. 2000, 106: 1311-1319. 10.1172/JCI10259.View ArticlePubMedPubMed CentralGoogle Scholar
- Xiao F, Wei Y, Yang L, Zhao X, Tian L, Ding Z, Yuan S, Lou Y, Liu F, Wen Y, Li J, Deng H, Kang B, Mao Y, Lei S, He Q, Su J, Lu Y, Niu T, Hou J, Huang MJ: A gene therapy for cancer based on the angiogenesis inhibitor, vasostatin. Gene Ther. 2002, 9: 1207-1213. 10.1038/sj.gt.3301788.View ArticlePubMedGoogle Scholar
- Folkman J: What is the evidence that tumors are angiogenesis dependent?. J Natl Cancer Ins. 1990, 82: 4-6. 10.1093/jnci/82.1.4.View ArticleGoogle Scholar
- Meyerrose Todd, De Ugarte Daniel, A Alex Hofling, Herrbrich Phillip, Cordonnier Taylor, Shultz Leonard, Eagon J Chris, Wirthlin Louisa, Sands Mark, Hedrick Marc, Nolta Jan: In Vivo Distribution of Human Adipose-Derived Mesenchymal Stem Cells in Novel Xenotransplantation Models. Stem Cells. 2007, 25 (1): 220-227. 10.1634/stemcells.2006-0243.View ArticlePubMedGoogle Scholar
- Theise ND, Henegariu O, Grove J, Jagirdar J, Kao PN, Crawford JM, Badve S, Saxena R, Krause DS: Radiation pneumonitis in mice: a severe injury model for pneumocyte engraftment from bone marrow. Exp Hematol. 2002, 30: 1333-1338. 10.1016/S0301-472X(02)00931-1.View ArticlePubMedGoogle Scholar
- Prockop Darwin, Gregory Carl, Spees Jeffery: One strategy for cell and gene therapy: Harnessing the power of adult stem cells to repair tissues. PNAS. 2003, 30: 11917-11923. 10.1073/pnas.1834138100.View ArticleGoogle Scholar
- Sasaki Mikako, Abe Riichiro, Fujita Yasuyuki, Ando Satomi, Inokuma Daisuke, Shimizu Hiroshi: Mesenchymal Stem Cells Are Recruited into Wounded Skin and Contribute to Wound Repair by Transdifferentiation into Multiple Skin Cell Type. J Immunol. 2008, 180: 2581-2587.View ArticlePubMedGoogle Scholar
- Bartholomew A, Patil S, Mackay A, Nelson M, Buyaner D, Hardy W, Mosca J, Sturgeon C, Siatskas M, Mahmud N, Ferrer K, Deans R, Moseley A, Hoffman R, Devine SM: Baboon mesenchymal stem cells can be genetically modified to secrete human erythropoietin in vivo. Hum Gene Ther. 2001, 12: 1527-1541. 10.1089/10430340152480258.View ArticlePubMedGoogle Scholar
- Steitz J, Bruck J, Knop J, Tuting T: Adenovirus-transduced dendritic cells stimulate cellular immunity to melanoma via a CD4+ T cell-dependent mechanism. Gene Ther. 2001, 8: 1255-1263. 10.1038/sj.gt.3301521.View ArticlePubMedGoogle Scholar
- Saito Takayuki, Kuang Jin-Qiang, Bittira Bindu, Al-Khaldi Abdulaziz, Chiu Ray: Xenotransplant cardiac chimera: immune tolerance of adult stem cells. Ann Thorac Surg. 2002, 74 (1): 19-24. 10.1016/S0003-4975(02)03591-9.View ArticlePubMedGoogle Scholar
- Khakoo Aarif, Pati Shibani, Anderson Stasia, Reid William, Elshal Mohamed, Rovira Ilsa, Nguyen Ahn, Malide Daniela, Combs Christian, Hall Gentzon, Zhang Jianhu, Raffeld Mark, Rogers Terry, Stetler-Stevenson William, Frank Joseph, Reitz Marvin, Finkel Toren: Human mesenchymal stem cells exert potent antitumorigenic effects in a model of Kaposi's sarcoma. J Exp Med. 2006, 203 (5): 1235-1247. 10.1084/jem.20051921.View ArticlePubMedPubMed CentralGoogle Scholar
- Djouad F, Plence P, Bony C, Tropel P, Apparailly F, Sany J, Noël Danièle, Christian Jorgensen: Immunosuppressive effect of mesenchymal stem cells favors tumor growth in allogeneic animals. Blood. 2003, 102: 3837-3844. 10.1182/blood-2003-04-1193.View ArticlePubMedGoogle Scholar
- Glennie Sarah, Soeiro Inês, Dyson Peter, Lam Eric, Dazzi Francesco: Bone marrow mesenchymal stem cells induce division arrest anergy of activated T cells. Blood. 2005, 105 (7): 2821-2827. 10.1182/blood-2004-09-3696.View ArticlePubMedGoogle Scholar
- Haniffa Muzlifah, Wang Xiao-Nong, Holtick Udo, Rae Michelle, Isaacs John, Dickinson Anne, Hilkens Catharien, Collin Matthew: Adult Human Fibroblasts Are Potent Immunoregulatory Cells and Functionally Equivalent to Mesenchymal Stem Cells. J Immunol. 2007, 179: 1595-1604.View ArticlePubMedGoogle Scholar
- Blankenstein Thomas: The role of tumor stroma in the interaction between tumor and immune system. Curr Opin Immunol. 2005, 17 (2): 180-186. 10.1016/j.coi.2005.01.008.View ArticlePubMedGoogle Scholar
- Tolar Jakub, Nauta Alma, Osborn Mark, Mortari Angela, McElmurry Ron, Bell Scott, Xia Lily, Zhou Ning, Riddle Megan, Schroeder Tania, Westendorf Jennifer, McIvor R Scott, Hogendoorn Pancras, Szuhai Karoly, Oseth LeAnn, Hirsch Betsy, Yant Stephen, Kay Mark, Peister Alexandra, Prockop Darwin, Fibbe Willem, Blazar Bruce: Sarcoma Derived from Cultured Mesenchymal Stem Cells. Stem Cells. 2007, 25: 371-379. 10.1634/stemcells.2005-0620.View ArticlePubMedGoogle Scholar
- Bernardo Maria, Zaffaroni Nadia, Novara Francesca, Cometa Angela, Avanzini Maria, Moretta Antonia, Montagna Daniela, Maccario Rita, Villa Raffaella, Daidone Maria, Zuffardi Orsetta, Locatelli Franco: Human Bone Marrow-Derived Mesenchymal Stem Cells Do Not Undergo Transformation after Long-term In vitro Culture and Do Not Exhibit Telomere Maintenance Mechanisms. Can Res. 2007, 67: 9142-9149. 10.1158/0008-5472.CAN-06-4690.View ArticleGoogle Scholar
- The pre-publication history for this paper can be accessed here:http://0-www.biomedcentral.com.brum.beds.ac.uk/1471-2407/8/306/prepub
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