RESUMO
Glioblastoma (GBM) is an infiltrative tumor that is difficult to eradicate. Treating GBM with mesenchymal stem cells (MSCs) that have been modified with the HSV-Tk suicide gene has brought significant advances mainly because MSCs are chemoattracted to GBM and kill tumor cells via a bystander effect. To use this strategy, abundantly present adipose-tissue-derived mesenchymal stem cells (AT-MSCs) were evaluated for the treatment of GBM in mice. AT-MSCs were prepared using a mechanical protocol to avoid contamination with animal protein and transduced with HSV-Tk via a lentiviral vector. The U-87 glioblastoma cells cultured with AT-MSC-HSV-Tk died in the presence of 25 or 50 µM ganciclovir (GCV). U-87 glioblastoma cells injected into the brains of nude mice generated tumors larger than 3.5 mm2 after 4 weeks, but the injection of AT-MSC-HSV-Tk cells one week after the U-87 injection, combined with GCV treatment, drastically reduced tumors to smaller than 0.5 mm2. Immunohistochemical analysis of the tumors showed the presence of AT-MSC-HSV-Tk cells only within the tumor and its vicinity, but not in other areas of the brain, showing chemoattraction between them. The abundance of AT-MSCs and the easier to obtain them mechanically are strong advantages when compared to using MSCs from other tissues.
Assuntos
Tecido Adiposo/metabolismo , Glioblastoma/metabolismo , Células-Tronco Mesenquimais/enzimologia , Simplexvirus/genética , Timidina Quinase/biossíntese , Transdução Genética , Proteínas Virais/biossíntese , Tecido Adiposo/patologia , Animais , Efeito Espectador/efeitos dos fármacos , Linhagem Celular Tumoral , Feminino , Ganciclovir/farmacologia , Glioblastoma/patologia , Glioblastoma/terapia , Humanos , Células-Tronco Mesenquimais/patologia , Camundongos , Camundongos Nus , Simplexvirus/enzimologia , Timidina Quinase/genética , Proteínas Virais/genéticaRESUMO
Suicide gene therapy has met limited success for the treatment of rat pituitary tumors. In order to determine the cause of primary pituitary tumor resistance to suicide gene therapy, we studied the transgene expression of an adenoviral (Ad.RSV.beta gal.nls) and a herpes simplex virus-derived (tsK/beta-gal) vector, both harboring the beta-galactosidase reporter gene in rat prolactinomas. Rats carrying experimental prolactinomas received bilateral 1 microl intrapituitary injections of either saline (saline group), 5 x 10(5) plaque-forming units (pfu) tsK/beta-gal (HSV Group) or 5 x 10(5) pfu Ad.RSV.beta gal.nls (RAd Group). Two or seven days later the tumors were examined. Macroscopic inspection of glands injected with either vector showed that the tissue expressing beta-gal was concentrated at the ventral area around the site reached by the tip of the needle. Almost no transgene expression was observed in other sites. Cellularity and lactotrophic cell density was not affected by saline or virus injection. In the injected areas, apoptotic levels were (x +/-S.E.M.): 9.3+/-0.5, 22.1+/-1.1 and 31.7+/-1.4%, for the saline, RAd and HSV groups, respectively. Serum prolactin and growth hormone levels were not affected by virus injection. We conclude that the low diffusibility of viral suspensions in the pituitary tissue may constitute a significant obstacle for achieving full remission of in situ pituitary tumors in rats.