The use of matrigel has no influence on tumor development or PET imaging in FaDu human head and neck cancer xenografts

BACKGROUND: In preclinical research Matrixgel(TM) Basement Membrane Matrix (MG) is used frequently for the establishment of syngeneic and xenograft cancer models. Limited information on its influence on parameters including; tumor growth, vascularization, hypoxia and imaging characteristics is currently available. This study evaluates the potential effect of matrigel use in a human head and neck cancer xenograft model (FaDu; hypopharyngeal carcinoma) in NMRI nude mice. The FaDu cell line was chosen based on its frequent use in studies of cancer imaging and tumor microenvironment.

METHODS: NMRI nude mice (n = 34) were divided into two groups and subcutaneously injected with FaDu cells in medium either including (+MG) or excluding matrigel (-MG). In sub study I seven mice from each group (+MG, n = 7; -MG, n = 7) were (18)F- fluorodeoxyglucose ((18)F-FDG) PET/CT scanned on Day 5, 8, 12, 15, and 19. In sub study II ten mice from each group (+MG, n = 10; -MG, n = 10) were included and tumors collected for immunohistochemistry (IHC) analysis of tumor microenvironment including; proliferation ratio, micro vessel density, average vessel area, hypoxia, nuclear density, and necrosis. Tumors for IHC were collected according to size (200-400 mm(3), 500-700 mm(3), 800-1100 mm(3)).

RESULTS: FDG uptake and tumor growth was statistically compatible for the tumors established with or without MG. The IHC analysis on all parameters only identified a significantly higher micro vessel density for tumor size 500-700 mm(3) and 800-1100 mm(3) and average vessel area for tumor size 500-700 mm(3) in the -MG group. Comparable variations were observed for tumors of both the +MG and -MG groups. No difference in tumor take rate was observed between groups in study.

CONCLUSIONS: Matrigel did not affect tumor growth or tumor take for the FaDu xenograft model evaluated. Tumors in the -MG group displayed increased angiogenesis compared to the +MG tumors. No difference in (18)F-FDG PET uptake for tumors of different groups was found. Based on these observations the influence of matrigel on tumor imaging and tumor microenvironment seems minor for this particular xenograft model.