Procedure for Horizontal Transfer of Patient-Derived Xenograft Tumors to Eliminate Corynebacterium bovis.

Human patient-derived xenograft (PDX) tumors, propagated in immunodeficient mice, are rapidly growing in use as amodelfor cancer research. Horizontal transfer between mice, without in vitro cell culture, allows these tumors to retainmany of their unique characteristics from their individual patient of origin. However, the immunodeficient mouse strainsused to grow these tumors are susceptible to numerous opportunistic pathogens, including Corynebacterium bovis. At ourinstitution, 2 in vivo tumor banks of PDX tumors had been maintained within nude mouse colonies enzootically infectedwith C. bovis. Elimination of C. bovis from these colonies required the aseptic harvest and horizontal transfer of tumor tissue between infected and naïve recipient mice without cross-contamination. Out of necessity, we developed a standard operating procedure using enhancements to traditional aseptic surgical technique with concurrent application of both procedural and physical barriers to prevent C. bovis transmission. By using these methods, all 61 unique PDX tumor models were successfullyharvested from C. bovis-infected mice and transferred into recipient mice without transmission of infection. Our datademonstrate that, in situations where C. bovis-free colonies can be established and maintained, this procedure can successfullybe used to eliminate C. bovis from an in vivo tumor bank of valuable PDX tumors.