title: Influence of mesenchymal stem cells on metastasis development in mice in vivo.
abstract: BACKGROUND
  In recent years, mesenchymal stem cells (MSCs) have been demonstrated to play an important role in carcinogenesis. However, the effect of MSCs on tumor and metastasis development and the mechanisms underlying the interaction of cancer and stem cells are not completely understood. This study investigated the effect of MSCs on breast cancer metastasis formation by using the methods of in vivo fluorescence and luminescence imaging.
  
  
  METHODS
  MSCs were isolated from bone marrow of normal donors, characterized, and genetically labeled with luciferase (luc2). The effects of MSCs on MDA-MB-231 cancer cell proliferation were evaluated in conditioned medium from MSCs. To generate lung metastases, MDA-MB-231 cells stably expressing red fluorescent protein Turbo FP650 were injected intravenously into nude mice. On day 10 after the cancer cell injection, mice were injected via the tail vein with MSCs-luc2 cells (the MET+MSCs group). Animals that received the injection of MDA-MB-231-Turbo FP650 alone (the MET group) and no injections (the intact control group) served as controls. Fluorescence and bioluminescence imaging was performed for monitoring of the metastasis formation and MSC distribution in the recipient's body.
  
  
  RESULTS
  We found that the proliferative activity of the cancer cells in the presence of MSC conditioned medium was lower than that of the cells grown in conventional culture medium. The metastasis formation in the MET+MSCs group was delayed in time as compared with the MET group. Macroscopic and histological examination of isolated lungs 8 weeks after cancer cell injection showed that the total number of metastases in animals of the MET+MSCs group was significantly lower. Using bioluminescence imaging in vivo, we found that MSCs-luc2 cells survived in the host animal for at least 7 weeks and re-migrated to the lung 6 to 7 weeks after injection. Immunohistochemical analysis revealed the presence of MSCs-luc2 in metastases and lung tissue.
  
  
  CONCLUSIONS
  Long-term in vivo bioluminescence imaging of intravenously injected MSCs-luc2 cells showed distribution of MSCs to the lungs and abdominal organs within the first 2 to 3 weeks and re-migration to the lungs in weeks 6 to 7. It was found that MSCs reduced the proliferative activity of cancer cells in vitro and lung metastasis formation in mice.
authors.affiliation: Nizhny Novgorod State Medical Academy, Minin and Pozharsky Square, 10/1, Nizhny, Novgorod, 603005, Russia. almele@ya.ru.|Nizhny Novgorod State University, Gagarin Avenue, 23, Nizhny, Novgorod, 603950, Russia. almele@ya.ru.
authors.forename: Aleksandra V
authors.initials: AV
authors.lastname: Meleshina
authors.affiliation: Nizhny Novgorod State Medical Academy, Minin and Pozharsky Square, 10/1, Nizhny, Novgorod, 603005, Russia. cherkasova.el@yandex.ru.|Nizhny Novgorod State University, Gagarin Avenue, 23, Nizhny, Novgorod, 603950, Russia. cherkasova.el@yandex.ru.
authors.forename: Elena I
authors.initials: EI
authors.lastname: Cherkasova
authors.affiliation: Nizhny Novgorod State Medical Academy, Minin and Pozharsky Square, 10/1, Nizhny, Novgorod, 603005, Russia. shirmanovam@mail.ru.
authors.forename: Marina V
authors.initials: MV
authors.lastname: Shirmanova
authors.affiliation: Nizhny Novgorod State Medical Academy, Minin and Pozharsky Square, 10/1, Nizhny, Novgorod, 603005, Russia. nvklementieva@gmail.com.
authors.forename: Natalia V
authors.initials: NV
authors.lastname: Klementieva
authors.affiliation: Koltzov Institute of Developmental Biology of Russian Academy of Science, Vavilova st., 26, Moscow, 119334, Russia. evkiseleva@mail.ru.
authors.forename: Ekaterina V
authors.initials: EV
authors.lastname: Kiseleva
authors.affiliation: Nizhny Novgorod State Medical Academy, Minin and Pozharsky Square, 10/1, Nizhny, Novgorod, 603005, Russia. lsnopova@gma.nnov.ru.
authors.forename: Ludmila В
authors.initials: LВ
authors.lastname: Snopova
authors.affiliation: Nizhny Novgorod State Medical Academy, Minin and Pozharsky Square, 10/1, Nizhny, Novgorod, 603005, Russia. nnp.71@mail.ru.
authors.forename: Natalia N
authors.initials: NN
authors.lastname: Prodanets
authors.affiliation: Nizhny Novgorod State Medical Academy, Minin and Pozharsky Square, 10/1, Nizhny, Novgorod, 603005, Russia. ezagaynova@gmail.com.|Nizhny Novgorod State University, Gagarin Avenue, 23, Nizhny, Novgorod, 603950, Russia. ezagaynova@gmail.com.
authors.forename: Elena V
authors.initials: EV
authors.lastname: Zagaynova
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000473:pathology; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D017077:Culture Media, Conditioned / Q000494:pharmacology*; D004195:Disease Models, Animal; D005260:Female; D008175:Lung Neoplasms / Q000473:pathology / Q000556:secondary*; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D061848:Optical Imaging / Q000379:methods
chemical_list: D017077:Culture Media, Conditioned