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Published February 18, 2011 | Published
Book Section - Chapter Open

Chronic label-free volumetric photoacoustic microscopy of melanoma cells in scaffolds in vitro


Visualizing cells in three-dimensional (3D) scaffolds has been one of the major challenges in tissue engineering. Current imaging modalities have limitations. Microscopy, including confocal microscopy, cannot penetrate deeply (> 300 μm) into the scaffolds; X-ray micro-computed tomography (micro-CT) requires staining of the structure with a toxic agent such as osmium tetroxide. Here, we demonstrate photoacoustic microscopy (PAM) of the spatial distribution and temporal proliferation of melanoma cells inside three-dimensionally porous scaffolds with thicknesses over 1 mm. Melanoma cells have a strong intrinsic contrast which is easily imaged by label-free PAM with high sensitivity. Spatial distributions of the cells in the scaffold were well-resolved in PAM images. Moreover, we chronically imaged the same cell/scaffold constructs at different time points over 2 weeks. The number of cells in the scaffold was quantitatively measured from the PAM volumetric information. The cell proliferation profile obtained from PAM correlated well with that obtained using the traditional 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. We believe that PAM will become a useful imaging modality for tissue engineering applications, especially when thick scaffold constructs are involved, and that this modality can also be extended to image other cell types labeled with contrast agents.

Additional Information

© 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). This work was supported in part by an NIH Director's Pioneer Award (DP1 OD000798) and startup funds from Washington University in St. Louis (to X.Y.). This work was also sponsored by NIH grants (R01 EB000712, R01 NS46214, R01 EB008085, and U54 CA136398, to L.V.W.). Part of the work was performed at the Nano Research Facility (NRF), a member of the National Nanotechnology Infrastructure Network (NNIN), which is supported by the NSF under award ECS-0335765. L.V.W. has a financial interest in Microphotoacoustics, Inc. and Endra, Inc., which, however, did not support this work.

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