Preclinical Imaging Evaluation of miRNAs’ Delivery and Effects in Breast Cancer Mouse Models: A Systematic Review

SIMPLE SUMMARY: The purpose of this systematic review was to assess the advancements in preclinical molecular imaging protocols used to study the delivery, tracking and therapeutic efficacy of miRNAs in mouse models of breast cancer. For this aim we have interrogated several browsers (PubMed, EMBASE, BIOSIS™ and Scopus) using the following terms: breast cancer, mouse, mice, microRNA(s) and miRNA(s). From 114 articles selected according to a PRISMA protocol, we focused on mouse models, routes of miRNA administration, therapy efficacy and molecular imaging. Importantly, we highlight here the advancements made in all imaging techniques’ applications used, providing a useful tool, on the basis of the current evidence, with which to suggest the best preclinical imaging protocol. ABSTRACT: Background: We have conducted a systematic review focusing on the advancements in preclinical molecular imaging to study the delivery and therapeutic efficacy of miRNAs in mouse models of breast cancer. Methods: A systematic review of English articles published in peer-reviewed journals using PubMed, EMBASE, BIOSIS™ and Scopus was performed. Search terms included breast cancer, mouse, mice, microRNA(s) and miRNA(s). Results: From a total of 2073 records, our final data extraction was from 114 manuscripts. The most frequently used murine genetic background was Balb/C (46.7%). The most frequently used model was the IV metastatic model (46.8%), which was obtained via intravenous injection (68.9%) in the tail vein. Bioluminescence was the most used frequently used tool (64%), and was used as a surrogate for tumor growth for efficacy treatment or for the evaluation of tumorigenicity in miRNA-transfected cells (29.9%); for tracking, evaluation of engraftment and for response to therapy in metastatic models (50.6%). Conclusions: This review provides a systematic and focused analysis of all the information available and related to the imaging protocols with which to test miRNA therapy in an in vivo mice model of breast cancer, and has the purpose of providing an important tool to suggest the best preclinical imaging protocol based on available evidence.