Histological, Ultrastructural, and Genetic Investigatory Comparison between Different Types of Experimentally - Induced Antemortem Burns

Abstract

Background: Burn is a cutaneous injury that is caused by heat, electricity, chemicals, freezing, and radiation. Aims and Objectives: This study aimed to differentiate between dry heat burn injury and other common cutaneous burn injuries. Materials and Methods: For this, different types of dermal burns were created experimentally in four groups of rats, 5 rats for each, as the following: dry heat burn model, scalding model, chemical burn model, and electrical burn model. The burnt skin and hair samples were subjected to scanning electron microscopic examination, molecular assay of aquaporin-3 (AQP-3) gene expression, and histopathological investigation. Results: There were crakes, holes, and cuticular irregularity in hairs exposed to both dry heat and sulfuric acid (chemical burn), while the major lesion observed in hairs exposed to boiling water (scald injury) was cuticular cell loss. On the other hand, dry burnt skin showed empty orifices of the hair and sebaceous gland with overlapped smooth lamella, while scald induced irregularity of collagen fibers. The sulfuric acid produces separation of the epidermis from the dermis and irregularity in collagen fiber. Rat skin exposed to electric current appears with fissure, lacerated edges, and erected broken hairs. Despite AQP-3 gene expression was significantly upregulated in the burnt skin of all experimental models in comparing with control rats, dry heat burned skin showed the highest upregulated level. In addition, the coagulation of the dermoepidermal cells and vesicles formation were the most pronounced lesions observed in all types of burns, while scald was distinguished by appearance of elongated cellular nuclei. Conclusion: These observations suggest the possibility to differentiate between dry thermal burn, scald injury, chemical burn, and electrical burn using the combination between scanning electron microscopic examination, analysis of cutaneous AQP-3 gene expression, and histological investigation.