Glioblastoma (GBM) cell lines expressing red fluorescent proteins were evaluated as a tool for non-invasive imaging of orthotopic tumors.
Materials and methods: mKate2- and mCherry-transduced U251MG GBM lines were sorted by flow cytometry. The growth rates and drug sensitivity of the resulting cell lines were compared to those of the parental line. Following orthotopic implantation, mKate2-expressing cells were detected using multispectral imaging.
Results: Flow cytometry-sorted fluorescent populations exhibiting growth curves that were comparable to those of the parental line were selected. mKate2-expressing cells were inoculated orthotopically and formed tumors which were visualized non-invasively, allowing monitoring of tumor growth over time and the assessment of tumor response to temozolomide drug treatment.
Conclusion: The strategy reported here led to the successful development of GBM models expressing mKate2 or mCherry. The fluorescence signal intensity measured in the brain of live animals correlates with tumor size, thus providing a method to assess tumor progression and response to treatment.