title: Handheld confocal laser endomicroscopic imaging utilizing tumor-specific fluorescent labeling to identify experimental glioma cellsin vivo.
abstract: BACKGROUND
  We have reported that handheld confocal laser endomicroscopy (CLE) can be used with various nonspecific fluorescent dyes to improve the microscopic identification of brain tumor and its boundaries. Here, we show that CLE can be used experimentally with tumor-specific fluorescent labeling to define glioma marginsin vivo.
  
  
  METHODS
  Thirteen rats underwent craniectomy andin vivoimaging 21 days after implantation with green fluorescent protein (GFP)-labeled U251 (n= 7) cells or epidermal growth factor receptor (EGFR) overexpressing F98 cells (n= 6). Fluorescein isothiocyanate (FITC) conjugated EGFR fluorescent antibody (FITC-EGFR) was applied for contrast in F98 tumors. Confocal images of normal brain, obvious tumor, and peritumoral zones were collected using the CLE system. Bench-top confocal microscopy and hematoxylin and eosin-stained sections were correlated with CLE images.
  
  
  RESULTS
  GFP and FITC-EGFR fluorescence of glioma cells were detected byin vivovisible-wavelength fluorescence CLE. CLE of GFP-labeled tumors revealed bright individual satellite tumor cells within peritumoral tissue, a definitive tumor border, and subcellular structures. Imaging with FITC-EGFR labeling provided weaker contrast in F98-EGFR tumors but was able to delineate tumor cells. Imaging with both methods in various tumor regions correlated with standard confocal imaging and clinical histology.
  
  
  CONCLUSIONS
  These data suggest thatin vivoCLE of selectively tagged neoplasms could allow specific interactive identification of tumoral areas. Imaging of GFP and FITC-EGFR provides real-time histologic information precisely related to the site of microscopic imaging of tumor.
authors.affiliation: Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center Phoenix, Arizona, USA.
authors.forename: Nikolay L
authors.initials: NL
authors.lastname: Martirosyan
authors.affiliation: School of Life Sciences, Arizona State University, Tempe, Arizona, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Georges
authors.affiliation: Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center Phoenix, Arizona, USA.
authors.forename: M Yashar S
authors.initials: MY
authors.lastname: Kalani
authors.affiliation: Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center Phoenix, Arizona, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Nakaji
authors.affiliation: Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center Phoenix, Arizona, USA.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Spetzler
authors.affiliation: School of Life Sciences, Arizona State University, Tempe, Arizona, USA; College of Medicine, University of Arizona, Phoenix, Arizona, USA.
authors.forename: Burt G
authors.initials: BG
authors.lastname: Feuerstein
authors.affiliation: Department of Neurosurgery, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center Phoenix, Arizona, USA.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Preul
keywords: Confocal laser endomicroscopy; confocal microscopy; fluorescent antibody; green fluorescent protein; malignant gliomas; molecular imaging