Imaging Abeta plaques in living transgenic mice with multiphoton microscopy and methoxy-X04, a systemically administered Congo red derivative

J Neuropathol Exp Neurol. 2002 Sep;61(9):797-805. doi: 10.1093/jnen/61.9.797.


The identification of amyloid deposits in living Alzheimer disease (AD) patients is important for both early diagnosis and for monitoring the efficacy of newly developed anti-amyloid therapies. Methoxy-X04 is a derivative of Congo red and Chrysamine-G that contains no acid groups and is therefore smaller and much more lipophilic than Congo red or Chrysamine-G. Methoxy-X04 retains in vitro binding affinity for amyloid beta (Abeta) fibrils (Ki = 26.8 nM) very similar to that of Chrysamine-G (Ki = 25.3 nM). Methoxy-X04 is fluorescent and stains plaques, tangles, and cerebrovascular amyloid in postmortem sections of AD brain with good specificity. Using multiphoton microscopy to obtain high-resolution (1 microm) fluorescent images from the brains of living PSI/APP mice, individual plaques could be distinguished within 30 to 60 min after a single i.v. injection of 5 to 10 mg/kg methoxy-X04. A single i.p. injection of 10 mg/kg methoxy-X04 also produced high contrast images of plaques and cerebrovascular amyloid in PSI/APP mouse brain. Complementary quantitative studies using tracer doses of carbon- 11-labeled methoxy-X04 show that it enters rat brain in amounts that suggest it is a viable candidate as a positron emission tomography (PET) amyloid-imaging agent for in vivo human studies.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alkenes / chemistry
  • Alkenes / pharmacokinetics*
  • Alzheimer Disease / diagnosis*
  • Alzheimer Disease / pathology
  • Amyloid beta-Peptides / analysis*
  • Amyloid beta-Peptides / chemistry
  • Amyloid beta-Peptides / metabolism
  • Animals
  • Benzene / chemistry
  • Benzene / pharmacokinetics*
  • Benzene Derivatives
  • Binding, Competitive / drug effects
  • Blood-Brain Barrier
  • Carbon Radioisotopes
  • Coloring Agents / chemistry
  • Coloring Agents / pharmacokinetics
  • Congo Red / analogs & derivatives*
  • Congo Red / chemistry
  • Disease Models, Animal
  • Imaging, Three-Dimensional
  • Male
  • Mice
  • Mice, Transgenic
  • Microscopy / methods*
  • Peptide Fragments / chemistry
  • Plaque, Amyloid / metabolism
  • Plaque, Amyloid / pathology*
  • Rats
  • Rats, Sprague-Dawley
  • Sensitivity and Specificity
  • Stilbenes


  • 1,4-bis(4'-hydroxystyryl)-2-methoxybenzene
  • Alkenes
  • Amyloid beta-Peptides
  • Benzene Derivatives
  • Carbon Radioisotopes
  • Coloring Agents
  • Peptide Fragments
  • Stilbenes
  • amyloid beta-protein (1-40)
  • Congo Red
  • Benzene