In situ detection of neoplastic transformation and chemopreventive effects in rat esophagus epithelium using angle-resolved low-coherence interferometry.

We present a quantitative study of the nuclear morphometry of epithelial cells in an animal model of esophageal carcinogenesis. Changes in the size and texture of cell nuclei as a result of neoplastic transformation and chemopreventive action are observed in situ using a new optical technique, angle-resolved low-coherence interferometry (a/LCI). The capabilities of a/LCI are demonstrated via quantitative in situ measurements of the nuclear morphometry of basal epithelial cells, approximately 50-100 microm beneath the tissue surface without the need for exogenous contrast agents or tissue fixation. The measurements quantify changes in nuclear size, characterized by average diameter, and nuclear texture, characterized by fractal dimension of the subcellular structures. Using this technique, we observed changes in the morphometry of rat esophageal epithelial cells in response to treatment with the carcinogen N-nitrosomethylbenzylamine. In addition, morphometric changes were observed in the esophagi of rats treated with N-nitrosomethylbenzylamine and two chemopreventive agents, difluoromethylornithine and perillyl alcohol. These agents induced either apoptosis in the basal epithelium (difluoromethylornithine) or both apoptosis and vacuolation of basal epithelial cells (perillyl alcohol). Vacuolation was associated with cellular toxicity. The light-scattering measurements were compared with histological images of the same tissues. The potential of a/LCI as a noninvasive means to investigate the development of epithelial neoplasia and for tracking the efficacy of chemopreventive agents appears high. This technique also may provide a new screening tool for intraepithelial neoplasia.