Evaluation of Ki-67 as a histological index of burn damage in a swine model

Histological diagnosis of burn depth lacks consensus. The purpose of this study was to determine whether Ki-67, a cell proliferation marker, provides an index of integument viability after burn injury. Induction of thermal burn injuries (3, 12, 20, 30, 75, 90, and 120 seconds) were made with a brass rod heated to 100°C on the dorsal trunk of the swine. Controls were created with a brass rod heated to 37.5°C. Four 6-mm biopsies were obtained from each site for histological analysis of Ki-67. Biopsies were taken at the following times postinjury: 1, 12, 24, 36, 48, 72, and 96 hours. The results illustrate a characteristic Ki-67 nuclear staining in the basal layer of the epidermis and in the hair follicle. With increasing thermal injury, the nuclei of the cells changed morphology: condensing, fragmenting, and elongating. The uniqueness of the labeling index was to include only morphologically intact nuclei as having capacity to proliferation. Quantitative analysis showed a reduction in the mean number of Ki-67-positive cells, suggesting a reduced regenerative capacity. This study supports using this index as a means of performing histology for burn depth analysis. In future studies, determining viability of partial-thickness burns will require multiple histological markers such as Ki-67 in addition to hematoxylin and eosin staining.