Measurement of drug distribution in vascular tissue using quantitative fluorescence microscopy

Wade K. Wan, Mark A. Lovich, Chao-Wei Hwang, Elazer R. Edelman

Research output: Contribution to journalArticle

Abstract

Quantitative tools to assess vascular macromolecular distributions have been limited by low signal-to-noise ratios, reduced spatial resolution, postexperimental motion artifact, and the inability to provide multidimensional drug distribution profiles. Fluorescence microscopy offers the potential of identifying exogenous compounds within intact tissue by reducing autofluorescence, the process by which endogenous compounds emit energy at the same wavelength as fluorescent labels. A new technique combining fluorescence microscopy with digital postprocessing has been developed to address these limitations and is now described in detail. As a demonstration, histologic cross-sections of calf carotid arteries that had been loaded endovascularly with FITC-Dextran (20 kD) ex vivo were imaged at two different locations of the electromagnetic spectrum, one exciting only autofluorescent structures and the other exciting both autofluorescent elements and exogenous fluorescent labels. The former image was used to estimate the autofluorescence in the latter. Subtraction of the estimated autofluorescence resulted in an autofluorescence-corrected image. A standard curve, constructed from arteries that were incubated until equilibrium in different bulk phase concentrations of FITC-Dextran, was used to convert fluorescent intensities to tissue concentrations. This resulted in a concentration map with spatial resolution superior to many of the previous methods used to quantify macromolecular distributions. The transvascular concentration profiles measured by quantitative fluorescence microscopy compared favorably with those generated from the proven en face serial sectioning technique, validating the former. In addition, the fluorescence method demonstrated markedly increased spatial resolution. This new technique may well prove to be a valuable tool for elucidating the mechanisms of macromolecular transport, and for the rational design of drug delivery systems.

Original languageEnglish (US)
Pages (from-to)822-829
Number of pages8
JournalJournal of Pharmaceutical Sciences
Volume88
Issue number8
DOIs
StatePublished - Aug 1999
Externally publishedYes

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Fluorescence microscopy
Fluorescence Microscopy
Blood Vessels
Tissue
Labels
Pharmaceutical Preparations
Electromagnetic Phenomena
Signal-To-Noise Ratio
Drug Delivery Systems
Carotid Arteries
Artifacts
Signal to noise ratio
Demonstrations
Arteries
Fluorescence
Wavelength
fluorescein isothiocyanate dextran

ASJC Scopus subject areas

  • Drug Discovery
  • Organic Chemistry
  • Chemistry(all)
  • Molecular Medicine
  • Pharmacology
  • Pharmaceutical Science

Cite this

Measurement of drug distribution in vascular tissue using quantitative fluorescence microscopy. / Wan, Wade K.; Lovich, Mark A.; Hwang, Chao-Wei; Edelman, Elazer R.

In: Journal of Pharmaceutical Sciences, Vol. 88, No. 8, 08.1999, p. 822-829.

Research output: Contribution to journalArticle

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