An in vivo Insect-based Platform for Preclinical Endoscopic Imaging

Background and Study Aim Advanced endoscopic imaging technologies are routinely optimized and validated using vertebrate animal models. We present a novel, high-throughput insect model that provides a biologically realistic, reproducible, and ethically unproblematic alternative for evaluating endoscopic imaging modalities. Methods Manduca sexta larvae (fifth instar, 6.6 ± 0.23 g) were used for the demonstration of endoscopic imaging. Healthy controls (n = 27) were compared with chemically (5% dextran sodium sulfate, n = 20) and bacterially (Bacillus thuringiensis, n = 33) induced gut inflammation. Results Small-animal endoscopic imaging was readily feasible and revealed distinct anatomical features of M. sexta larvae. Animals with chemical-induced inflammation exhibited rectal swelling, melanization throughout the intestine, and increased transparency of the midgut epithelium. In comparison, bacterially induced inflammation resulted in intestinal swelling, a less extensive transparent membrane, melanization, and lesions in the hindgut and posterior midgut. Conclusion Endoscopic imaging of the intestinal tract of M. sexta larvae enabled a comprehensive examination of the internal anatomy under different inflammatory conditions. M. sexta larvae provide a suitable in vivo platform for studying intestinal inflammation over time. The model offers high survival rates, strong reproducibility, and cost-effectiveness, supporting the reduction of vertebrate animal experiments in accordance with the Replacement, Reduction, and Refinement principles.