title: Polyacrylamide gel substrates that simulate the mechanical stiffness of normal and malignant neuronal tissues increase protoporphyin IX synthesis in glioma cells.
abstract: Protoporphyrin IX (PPIX) produced following the administration of exogenous 5d-aminolevulinic acid is clinically approved for photodynamic therapy and fluorescence-guided resection in various jurisdictions around the world. For both applications, quantification of PPIX forms the basis for accurate therapeutic dose calculation and identification of malignant tissues for resection. While it is well established that the PPIX synthesis and accumulation rates are subject to the cell’s biochemical microenvironment, the effect of the physical microenvironment, such as matrix stiffness, has received little attention to date. Here we studied the proliferation rate and PPIX synthesis and accumulation in two glioma cell lines U373 and U118 cultured under five different substrate conditions, including the conventional tissue culture plastic and polyacrylamide gels that simulated tissue stiffness of normal brain (1 kPa) and glioblastoma tumors (12 kPa). We found that the proliferation rate increased with substrate stiffness for both cell lines, but not in a linear fashion. PPIX concentration was significantly higher in cells cultured on tissue-simulating gels than on the much stiffer tissue culture plastic for both cell lines. These findings, albeit preliminary, suggest that the physical microenvironment might be an important determinant of tumor aggressiveness and PPIX synthesis in glioma cells.
authors.affiliation: Princess Margaret Cancer Centre, 101 College Street, Toronto, Ontario M5G1L7, Canada.
authors.forename: Carolyn J
authors.initials: CJ
authors.lastname: Niu
authors.affiliation: University of Toronto, Department of Medical Biophysics, 101 College Street, Toronto, Ontario M5G1L7, Canada.
authors.forename: Carl
authors.initials: C
authors.lastname: Fisher
authors.affiliation: Princess Margaret Cancer Centre, 101 College Street, Toronto, Ontario M5G1L7, Canada.
authors.forename: Kira
authors.initials: K
authors.lastname: Scheffler
authors.affiliation: Princess Margaret Cancer Centre, 101 College Street, Toronto, Ontario M5G1L7, Canada.
authors.forename: Rachel
authors.initials: R
authors.lastname: Wan
authors.affiliation: University of Toronto, Department of Mechanical and Industrial Engineering, 5 King's College Road, Toronto, Ontario M5S3G8, Canada.
authors.forename: Hoda
authors.initials: H
authors.lastname: Maleki
authors.affiliation: University of Toronto, Department of Mechanical and Industrial Engineering, 5 King's College Road, Toronto, Ontario M5S3G8, Canada.
authors.forename: Haijiao
authors.initials: H
authors.lastname: Liu
authors.affiliation: University of Toronto, Department of Mechanical and Industrial Engineering, 5 King's College Road, Toronto, Ontario M5S3G8, Canada.
authors.forename: Yu
authors.initials: Y
authors.lastname: Sun
authors.affiliation: University of Toronto, Department of Mechanical and Industrial Engineering, 5 King's College Road, Toronto, Ontario M5S3G8, Canada.
authors.forename: Craig
authors.initials: C
authors.lastname: A Simmons
authors.affiliation: Universität zu Lübeck, Institut für Biomedizinische Optik, Peter-Monnik-Weg 4, 23562 Lübeck, Germany.
authors.forename: Reginald
authors.initials: R
authors.lastname: Birngruber
authors.affiliation: Princess Margaret Cancer Centre, 101 College Street, Toronto, Ontario M5G1L7, CanadabUniversity of Toronto, Department of Medical Biophysics, 101 College Street, Toronto, Ontario M5G1L7, Canada.
authors.forename: Lothar
authors.initials: L
authors.lastname: Lilge
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry* / Q000494:pharmacology; D002452:Cell Count; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D060833:Cellular Microenvironment / Q000187:drug effects*; D004548:Elasticity / Q000187:drug effects; D005909:Glioblastoma / Q000378:metabolism* / Q000503:physiopathology*; D005910:Glioma / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D010778:Photochemotherapy; D011524:Protoporphyrins / Q000378:metabolism*
chemical_list: D000180:Acrylic Resins; D011524:Protoporphyrins; C016680:polyacrylamide gels; C028025:protoporphyrin IX