Tissue imaging is a research resource used by a broad range of investigators across the UC Irvine campus and UC Irvine Medical Center working in immunology, oncology and cell biology, including members of the Sue and Bill Gross Stem Cell Research Center (SCRC), the Institute for Clinical and Translational Science (ICTS), the Institute for Immunology, the Institute for Memory Impairments and Neurological Diseases (UCI MIND), the Cancer Research Institute (CRI) and the Chao Family Comprehensive Cancer Center (CFCCC). The SCRC maintains tissue imaging and flow cytometry facilities that are amongst the most efficiently operated and frequently utilized core services on our campus. The SCRC staff are widely consulted for their expertise as evidenced by their continuing roles in the SoCal Flow Summit meeting for southern California flow cytometry users that is held annually here at UCI. While the SCRC maintains several flow cytometers and sorters and a variety of fluorescence microscopes for tissue analyses, sorting and imaging, these instruments are limited in the number of parameters that can be assessed simultaneously. We are requesting funds for the purchase of a Fluidigm Hyperion mass imager. This instrument is a high-performance mass imager that allows for simultaneous detection of greater than 50 parameters. The instrument utilizes a time of flight mass spectrometer to detect heavy metal labeled biological probes, including antibodies, protein ligands and nucleic acid probes, allowing for simultaneous detection of a number of cellular markers. These features make the instrument particularly useful for stem cell applications, which often require analysis of multiple markers to identify particular rare cell populations. The instrument will be installed, operated and maintained by the SCRC within our core laboratory recharge facility. Since the Hyperion requires a Helios mass cytometer for functionality, the SCRC and other units on campus have joined together to fund the purchase of the Helios mass cytometer, as well as for its installation and the development of a CyTOF core that will offer services and reagents to the research community at UCI. User fees will be calculated and submitted to the UCI Budget Office for approval following all appropriate UCI policies and procedures. This new Fluidigm Hyperion will complement existing instruments by providing new experimental paradigms not currently available at UCI, enhance our translational efforts and offer unique training and outreach experiences. Thus, the purchase of a Fluidigm Hyperion will have a significant impact on the biomedical research enterprise at our campus. Within the parameters of the NIH S10 grant funding, priority usage will be given to listed major and minor users with NIH funding, but the instrument also will be available to all UCI researchers.