title: Combined impedance spectroscopy and Fourier domain optical coherence tomography to monitor cells in three-dimensional structures.
abstract: OBJECTIVE
  To assess non-invasively and in real time the three- dimensional organization of cells within porous matrices by combining Fourier Domain Optical Coherence Tomography (FDOCT) and Impedance Spectroscopy (IS).
  
  
  METHODS
  Broadband interferences resulting from the recombination of in-depth light scattering events within the sample and light from a reference arm are measured as a modulation of the spectrum generated by a superluminescent laser diode (lambdao = 930nm, FWHM 90nm). Fourier transform allows in-depth localization of the scatterers, and the 3D microstructure of the sample is reconstructed by raster scanning. Simultaneously impedance spectroscopy is performed with a dielectric probe connected to an impedance analyzer to gather additional cellular information, and synchronized with FDOCT measurements.
  
  
  RESULTS
  A combined IS-FDOCT system allowing an axial resolution of 5 micrometer in tissues and impedance measurements over the range 20MHz-1GHz has been developed. Alginate matrices have been characterized in terms of microstructure and impedance. Matrices seeded with adipose-derived stem cells have been monitored without the use of labeling agent.
  
  
  CONCLUSIONS
  We have developed a multimodality system that will be instrumental to non-invasively monitor changes in total cell volume fraction and infer cell-specific dielectric properties in 3D structure.
authors.affiliation: MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh - Scotland. Pierre.Bagnaninchi@ed.ac.uk
authors.forename: Pierre O
authors.initials: PO
authors.lastname: Bagnaninchi
mesh_terms: D048429:Cell Size; D005583:Fourier Analysis; D021621:Imaging, Three-Dimensional; D013057:Spectrum Analysis / Q000379:methods*; D023822:Tissue Engineering / Q000379:methods*; D041623:Tomography, Optical Coherence / Q000379:methods*