High Speed Multimodal Fluorescence Imaging System for Isolated Mouse Hearts

Baudenbacher, Franz

Abstract

We request funds to purchase a shared mouse Langendorff heart recording system for simultaneous optical fluorescence imaging, contractility measurements and ECG recordings. This system will have six major NIH-funded user groups, whose current project aims will be supported by the shared instrument. Three of the funded NIH projects specifically require the use of optical imaging techniques to address the specific aims. Preliminary data were obtained using either existing optical imaging systems to record transmembrane potentials in whole heart rabbit preparations or the existing mouse Langendorff recording systems without optical imaging capability. The existing optical imaging system currently represents a particular bottleneck, given the increasing demand for mouse heart optical mapping studies by the NIH-funded investigators. Furthermore, it is optimized for rabbit preparations, which significantly limits the experimental throughput and image resolution for mouse hearts. The existing imaging system needs to be retooled every time for mouse preparations, it requires large volumes, has a fixed excitation wavelength, does not allow multicolor or ratiometric calcium imaging, and it has limited spatial and temporal resolution to measure distributions of action potentials and conduction velocities in the much smaller mouse hearts. It also lacks the ability to perform contractile measurements, which is required for three of the funded NIH projects. The existing mouse Langendorff system is already heavily used for other projects and cannot be retrofitted for optical imaging at its current location. Therefore, we request funds to purchase a dedicated mouse Langendorff working heart recording system and a microscope-based high speed, dynamic range and brightness CMOS-camera imaging system in combination with an excitation wavelength switcher, as described in detail in the proposal. The mouse Langendorff working heart is a commercially available turn-key system that includes recording and data analysis software designed specifically for multi-user support (ADInstruments, Inc). The funding of the proposed instrument will lead to a shared core facility for imaging of isolated mouse working hearts. The shared resource will be located in the Vanderbilt Institute for Integrative Biosystems Research and Education (VIIBRE), which has an extensive track record of providing shared instrument use, including scheduling, training, and equipment maintenance for over 100 local lab groups. The facility is centrally located on the Vanderbilt campus, with easy access for all major user groups. Instrument maintenance will be provided by VIIBRE technicians as part of the institutional support guaranteed by Vanderbilt University. An hourly user-fee will be charged to each user to cover equipment replacement cost and ensure long-term functionality of the instrument. All major users will have equal access to the instrument and scheduling through the existing web-based VIIBRE scheduling system. Public Health Relevance: Abnormal heart rhythms - arrhythmias - account for about 10 percent of all deaths in the United States. The proposed shared imaging workstation for isolated hearts would allow measuring multiple physiological variables to study the origin, treatment and prevention of life-threatening arrhythmias in mouse models of human cardiac disease and strategies for repair after ischemic injury. This shared instrumentation would directly benefit the research of 6 NIH-funded principal investigators at Vanderbilt University, generate further research momentum in a multidisciplinary environment and bridge the gap from single cells to human physiology.