1 Volume: 2017; Issue: 05 Archives on Veterinary Science and Technology Research Article ZaidanDagli ML, et al. Arch Vet Sci Technol, 2017: AVST-122. Effects of Methylene Blue Mediated Photodynamic Therapy on Sol- idEhrlich Tumor and Second Ehrlich Tumor Implant in Mice MuriloPenteado Del-Grande, Lucas Martins Chaible, Maria Lucia ZaidanDagli * Laboratory of Experimental and Comparative Oncology, Department of Pathology, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, SP, Brazil. * Corresponding author: Maria Lucia ZaidanDagli, Laboratory of Experimental and Comparative Oncology, Department of Pathol- ogy, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, SP, Brazil; Tel: +00-55 11 3091 7712; Fax: +00-55 11 3091 7829; E-mail: mlzdagli@usp.br Citation: Del-Grande MP, Chaible LM, ZaidanDagli ML (2017) Effects of Methylene Blue Mediated Photodynamic Therapy on Solid Ehrlich Tumor and Second Ehrlich Tumor Implant in Mice. Arch Vet Sci Technol, 2017: AVST-122. DOI:10.29011/AVST- 122/100022 Received Date: 20 June, 2017; Accepted Date: 21 June, 2017; Published Date: 28 June, 2017 Abstract PhotoDynamic Therapy (PDT) uses interaction of light, photosensitizing agent and production of reactive oxygen species, leading to cell death. Methylene Blue (MB) issued for PDT due to its photochemical properties. Here we investigated theeffects of Methylene Blue Mediated Photodynamic Therapy (MB-PDT) on the solidEhrlich tumor and second Ehrlich tumor implant in mice. For MB-PDT, MB at 1%and diode laser were used. Swiss male mice received dorsal inoculation of Ehrlichtumor cells and, 9 days after, mice were separated into 3 groups: MB-PDT (Group1) surgically removed (Group 2), or untreated (Group 3). One day after treatment,all groups received a second Ehrlich tumor implant on the left footpad, measured for17 days. Spleen, lymph nodes and tumor mass were weighed upon necropsy andprocessed for histopathology. Group 1 Ehrlich tumors showed signifcant sizereduction after MB-PDT. Morphometry of second Ehrlich tumor in Group 1 miceshowed signifcantly lower volume fraction of tumor cells, higher infammatoryinfltrate and necrosis. Relative spleen weight was higher in Group 1 mice, withwhite pulp hyperplasia. Per these results, MB-PDT reduced primary Ehrlich tumorgrowth and impacted the growth of a second tumor. These results point towardspossible biotechnological applications of MB-PDT. Keywords:Photodynamic Therapy, Methylene Blue, Ehrlich Tumor, CancerTreatment. Introduction Current treatment of solid tumors is mainly based on their surgical excision.Radiotherapy and chemotherapy are adjuvant treatment modalities commonly used,depending on tumor type. PhotoDynamic Therapy (PDT) is a method to treat cancer based on theinteraction between a photosensitizing agent, light and mo- lecular oxygen. There arenumerous types of photosensitizers, which can be administered by intravenous, oralor topical routes. The illumination of the tumor with visible light in order to ac- tivatethe photosensitizer is taken after certain time of agent ad- ministration, leading toproduction of Reactive Oxygen Species (ROS), determining cellular death by necrosisand/or apoptosis [1]. Methylene Blue (MB) is a molecule that has been consideredas a drug for photodynamic therapy (PDT). According to [2], MB has the potential to treat a variety of cancerous and non-cancer- ous diseases,with low toxicity and no side effects. An interesting feature of PDT is that it may activate the immune systemagainst tumor cells. The phototoxic effects on cell membrane release a number ofnfammatory mediators leading to innate immune sys- tem activation. Localinfammation and neoplastic cell death pro- voke tumor antigen presentation[3]. Antigenpresentation promotes activation of adaptive immune system and there issensitization of T lymphocytes (CD8 +) leading to a specifc response to the treat- edtumor. This adaptive immune response would be involved in the killing of tumorcells. In addition, B lymphocytes are sensitized to tumor antigens, promoting a long-termtumor control. The produc- tion of antitumor antibodies may be suggested,although this has not yet been shown through experimental modelsin this study[4], we aimed to verify if treating a primary Ehrlich tumor with Meth- ylene Blue (MB) at 1% based PDT (MB-PDT) could present any systemicinfuence on the growth and behavior of a second Ehrlich tumor implant in mice. DOI:10.29011/AVST-122/100022