X-ray microcomputed tomography for the measurement of cell adhesionand proliferation in polymer scaffolds

We have explored the use of X-ray microcomputed tomography (μCT) for assessing cell adhesion and proliferation in polymer scaffolds. Common methods for examining cells in scaffolds include fluorescence microscopy and soluble assays for cell components such as enzymes, protein or DNA. Fluorescence microscopy is generally qualitative and cannot visualize the scaffold interior. Soluble assays quantitatively measure cell number but do not yield information on cell spatial distribution. Herein, the ability of μCT to detect cells in scaffolds was compared with fluorescence microscopy and a soluble DNA assay. Comparisons were performed using polymer scaffolds that were seeded with cells at different densities and cultured for different times. The results showed that fluorescence microscopy had better resolution than μCT and that the soluble DNA assay was approximately 5× more sensitive than μCT under the conditions tested. However, μCT was able to image through opaque scaffolds to yield quantitative 3D imaging and analysis via a single, non-invasive modality. Quantitative μCT analysis of cell penetration into scaffolds was demonstrated. Further, quantitative μCT volume analysis required that the cell density in the scaffolds be greater than 1 million cells per mL indicating that μCT is best suited for quantifying cells at relatively high density during culture in scaffolds. In sum, the results demonstrate the benefits and limitations of using μCT for 3D imaging and analysis of cell adhesion and proliferation in polymer scaffolds.