Application of Optical Coherence Tomography for Monitoring Changes in Cervicovaginal Epithelial Morphology in Macaques: Potential for Assessment of Microbicide Safety

Objectives: Safety is a primary concern in the development of topical microbicides. Optical coherence tomography (OCT), a high-resolution, in-depth cross-sectional imaging modality, was utilized in conjunction with colposcopy to assess induced cervicovaginal epithelial changes that may predict product safety. Study Design: OCT and colposcopic images of macaque vaginal and cervical tissues were obtained in excised tissue and in vivo under various conditions, including mechanical injury and nonoxynol-9 treatment. Results: A scoring system was developed to categorize and quantify the OCT images based on morphologic features that indicate the presence or absence of an intact epithelial layer and inflammation. Using 3 categories (normal, mild to moderately abnormal, and severely abnormal), differences between healthy and injured tissue were apparent on OCT images. Normal images (category 1) had a bilayered structure representative of the epithelium and submucosa. Mild to moderately abnormal images (category 2) had areas of normal and abnormal epithelium. Severely abnormal images (category 3) had complete loss of the epithelium and/or inflammation, with loss of the bilayered structure on OCT. Conclusions: OCT is a noninvasive imaging modality complementary to colposcopy. It distinguished between normal and abnormal (or injured) tissue and thus holds promise for safety evaluations of candidate microbicides and other vaginal products.