title: Far-red tracer analysis of traumatic cerebrovascular permeability.
abstract: BACKGROUND
  Blood brain barrier (BBB) compromise is a key pathophysiological component of secondary traumatic brain injury characterized by edema and neuroinflammation in a previously immune-privileged environment. Current assays for BBB permeability are limited by working size, harsh extraction processes, suboptimal detection via absorbance, and wide excitation fluorescence spectra. In this study, we evaluate the feasibility of Alexa Fluor 680, a far-red dye bioconjugated to dextran, as an alternative assay to improve resolution and sensitivity.
  
  
  METHODS
  Alexa Fluor was introduced intravenously on the day of sacrifice to three groups: sham, controlled cortical impact (CCI), and CCI treated with a cell based therapy known to reduce BBB permeability. The brains were sectioned coronally and imaged using an infrared laser scanner to generate intensity plot profiles as well as signal threshold images to distinguish regions with varying degrees of permeability.
  
  
  RESULTS
  Linear plot profile analysis demonstrated greater signal intensity from CCI than treated rats at corresponding injury depths. Threshold analysis identified rims of signal at low + narrow threshold ranges. The integrated signals from a treatment group known to preserve the BBB were significantly less than the groups with CCI injury alone. There was no significant difference at high + wide signal intensity threshold ranges.
  
  
  CONCLUSIONS
  Alexa Fluor 680 infrared photodetection and image analysis can aid in detecting differential degrees of BBB permeability after traumatic brain injury and maybe particularly useful in demonstrating BBB preservation of at-risk regions in response to therapeutic agents.
authors.affiliation: Department of Pediatric Surgery, University of Texas Health Science Center at Houston, Houston, Texas. Electronic address: George.P.Liao@uth.tmc.edu.
authors.forename: George P
authors.initials: GP
authors.lastname: Liao
authors.affiliation: Department of Pediatric Surgery, University of Texas Health Science Center at Houston, Houston, Texas.
authors.forename: Scott D
authors.initials: SD
authors.lastname: Olson
authors.affiliation: Department of Pediatric Surgery, University of Texas Health Science Center at Houston, Houston, Texas.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Kota
authors.affiliation: Department of Pediatric Surgery, University of Texas Health Science Center at Houston, Houston, Texas.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Hetz
authors.affiliation: Department of Pediatric Surgery, University of Texas Health Science Center at Houston, Houston, Texas.
authors.forename: Philippa
authors.initials: P
authors.lastname: Smith
authors.affiliation: Department of Pediatric Surgery, University of Texas Health Science Center at Houston, Houston, Texas.
authors.forename: Supinder
authors.initials: S
authors.lastname: Bedi
authors.affiliation: Department of Pediatric Surgery, University of Texas Health Science Center at Houston, Houston, Texas.
authors.forename: Charles S
authors.initials: CS
authors.lastname: Cox
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier; D001930:Brain Injuries / Q000503:physiopathology* / Q000628:therapy; D002199:Capillary Permeability; D002560:Cerebrovascular Circulation / Q000502:physiology; D003911:Dextrans; D005456:Fluorescent Dyes; D006801:Humans; D008297:Male; D045164:Mesenchymal Stem Cell Transplantation / Q000379:methods; D051381:Rats
chemical_list: D003911:Dextrans; D005456:Fluorescent Dyes
keywords: Blood brain barrier; Edema; Fluorescence; Permeability; Traumatic brain injury