A matter of age: Investigation of the ability to classify epithelial cells of different anatomical origin in aged samples using imaging flow cytometry

The evolution of forensic biological analysis from identity-focused inquiries to activity-level investigations has necessitated a more nuanced evaluation of biological material sources. In this context, imaging flow cytometry (IFC) has emerged as a promising novel technique for differentiating various epithelial cell types, offering potential advancements in the interpretation of forensic evidence. This project investigates if storage conditions of three and six months had a significant effect on the morphology of four different types of epithelial cells (penile, vaginal, buccal and epidermal) collected from 30 participants (15 males and 15 females) of three different age groups: 18-39, 40-59, and 60 + years. The data collected included 234 morphological measurements collected from over 635 thousand cells that were compared to the fresh samples collected from the same individuals. Our findings show that samples stored for three months, in conditions similar to those expected in forensic casework circumstances, generated similar cell counts (indicating minimal cell loss due to storage and aging) and classification accuracy to samples that were collected and processed immediately. However, the capacity of IFC in sample age identification remains unclear due to the confounding effects of instrument run and sample preparation differences.