Ex vivo optical metabolic measurements from cultured tissue reflect in vivo tissue status

Alex J. Walsh, Kristin M. Poole, Craig L. Duvall, Melissa C. Skala

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Optical measurements of metabolism are ideally acquired in vivo; however, intravital measurements are often impractical. Accurate ex vivo assessments would greatly broaden the applicability of optical measurements of metabolism. We investigate the use of live tissue culture experiments to serve as a surrogate for in vivo metabolic measurements. To validate this approach, NADH and FAD fluorescence intensity and lifetime images were acquired with a two-photon microscope from hamster cheek pouch epithelia in vivo, from biopsies maintained in live tissue culture up to 48 h, and from flash-frozen and thawed biopsies. We found that the optical redox ratio (fluorescence intensity of NADH/FAD) of the cultured biopsy was statistically identical to the in vivo measurement until 24 h, while the redox ratio of the frozen-thawed samples decreased by 15% (p < 0.01). The NADH mean fluorescence lifetime (τm) remained unchanged (p > 0.05) during the first 8 h of tissue culture, while the NADH τm of frozen-thawed samples increased by 13% (p < 0.001). Cellular morphology did not significantly change between in vivo, cultured, and frozen-thawed tissues (p > 0.05). All results were consistent across multiple depth layers in this stratified squamous epithelial tissue. Histological markers for proliferation and apoptosis also confirm the viability of tissues maintained in culture. This study suggests that short-term ex vivo tissue culture may be more appropriate than frozen-thawed tissue for optical metabolic and morphologic measurements that approximate in vivo status.

Original languageEnglish (US)
Article number116015
JournalJournal of Biomedical Optics
Volume17
Issue number11
DOIs
StatePublished - Nov 2012

Keywords

  • FAD
  • fluorescence lifetime
  • NADH
  • optical redox ratio
  • tissue viability
  • two-photon fluorescence

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Biomedical Engineering

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