title: Intravital microscopy for evaluating tumor perfusion of nanoparticles exposed to non-invasive radiofrequency electric fields.
abstract: Poor biodistribution and accumulation of chemotherapeutics in tumors due to limitations on diffusive transport and high intra-tumoral pressures (Jain RK, Nat Med. 7(9):987-989, 2001) have prompted the investigation of adjunctive therapies to improve treatment outcomes. Hyperthermia has been widely applied in attempts to meet this need, but it is limited in its ability to reach tumors in deeply located body regions. High-intensity radiofrequency (RF) electric fields have the potential to overcome such barriers enhancing delivery and extravasation of chemotherapeutics. However, due to factors, including tumor heterogeneity and lack of kinetic information, there is insufficient understanding of time-resolved interaction between RF fields and tumor vasculature, drug molecules and nanoparticle (NP) vectors. Intravital microscopy (IVM) provides time-resolved high-definition images of specific tumor microenvironments, overcoming heterogeneity issues, and can be integrated with a portable RF device to enable detailed observation over time of the effects of the RF field on kinetics and biodistribution at the microvascular level. Herein, we provide a protocol describing the safe integration of IVM with a high-powered non-invasive RF field applied to 4T1 orthotopic breast tumors in live mice. Results show increased perfusion of NPs in microvasculature upon RF hyperthermia treatment and increased perfusion, release and spreading of injected reagents preferentially in irregular vessels during RF exposure.
authors.affiliation: Department of Surgery, Division of Surgical Research, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030 USA.
authors.forename: Norman A
authors.initials: NA
authors.lastname: Lapin
authors.affiliation: Department of Surgery, Division of Surgical Research, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030 USA ; Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, 30-387 Poland.
authors.forename: Martyna
authors.initials: M
authors.lastname: Krzykawska-Serda
authors.affiliation: Department of Surgery, Division of Surgical Research, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030 USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Ware
authors.affiliation: Department of Surgery, Division of Surgical Research, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030 USA ; Department of Mechanical Engineering & Materials Science, Rice University, Houston, 77005 TX USA.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Curley
authors.affiliation: Department of Surgery, Division of Surgical Research, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030 USA ; Department of Chemistry, Rice University, Houston, 77005 TX USA ; Department of Biomedical Engineering, University of Houston, Houston, 77204 TX USA.
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Corr
keywords: Cancer; Hyperthermia; Intravital microscopy; Quantum dots; Radiofrequency fields; Vasculature