Extracellular protease imaging for cell mass tracking of xenografted human malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is locally aggressive and challenging to quantitate non-invasively in vivo, particularly in orthotopic models of disease. We describe imaging of extracellular protease activity, typically elevated in locally aggressive tumors, as a novel method for tracking MPM in vivo. Mice bearing human MPM subcutaneous flank xenografted tumors were imaged with ProSense 680, an optical imaging agent of extracellular cysteine protease activity. The relative contribution of extracellular cysteine proteases to the ProSense tumor signal was estimated using RT-PCR quantitation of cysteine protease RNA expression of the MPM cell lines and compared to ArrayExpress microarray RNA expression data from human MPM tumors. Feasibility of orthotopic intraperitoneal MPM cell mass tracking with fluorescence signal was evaluated using CellVue Maroon-coated MSTO-211H and compared to bioluminescent signal using luciferase-transfected MSTO-211H cells. ProSense 680 yielded a robust tumor signal in MPM subcutaneous grafts, primarily resulting from MPM secretion of cathepsin L demonstrated not only by RT-PCR data on MPM cell lines but also by microarray expression data from resected human patient tumors. CellVue Maroon intraperitoneal tumor signal was robust and durable indicating feasibility of intraperitoneal cell mass tracking of orthotopically-xenografted MPM. Optical imaging of extracellular cysteine protease activity is useful for tracking MPM tumor cell mass in vivo. Intraperitoneal MPM cell mass tracking of fluorescently labeled tumor is feasible.

Antifungal susceptibility against yeasts isolated from pediatric oncology patients

Yeast infections cause morbidity in children with cancer and we evaluated species distribution and antifungal susceptibilities of the etiologic agents in this group. Specimens from 58 children yielded 64 cultures positive for yeasts. Central venous catheters were present in 56 (97%) of the children and neutrophil counts were <500 cells/ml3 in 34% of the patients. Twenty-two (38%) had received recent antifungal treatment, with 15 (25%) receiving fluconazole (FLU) prophylaxis. The Candida isolates recovered from four (27%) of the children on FLU prophylaxis, were resistant to this drug. Candida albicans isolates were susceptible to 100% of antifungals tested, whereas non-C. albicans Candida spp. were variable in their susceptibility patterns. FLU prophylaxis minimally affected susceptibility.