Heat Treatment Enhances Healing Process of Experimental Pseudomonas Corneal Ulcer

We investigated the effects of hyperthermia on the healing process of experimental Pseudomonas corneal ulceration (PCU). Hartley guinea pigs were used to develop animal models of PCU. As a heat source, disposable chemical pocket warmers were applied. The healing process of PCU was compared between the heat-treated corneas and the control corneas. The severity of infection and the degree of angiogenesis were classified by a clinical scoring system. The animals were euthanized 14 days after infection and the corneas were submitted for histopathological examination. The expression of vascular endothelial growth factor (VEGF) was examined immunohistochemically. Comparative reverse transcription polymerase chain reaction was performed to measure the expression level of VEGF in the cornea. Hyperthermia significantly promoted corneal epithelization and neovascularization in the PCU model. Heat treatment significantly decreased the number of viable Pseudomonas organisms present in PCU. On immunohistochemistry, the heated cornea demonstrated more intense staining for VEGF. Comparative reverse transcription polymerase chain reaction showed upregulation of the expression level of VEGF mRNA in the heat-treated cornea. Hyperthermia accelerated the healing process of PCU with increased corneal neovascularization. Angiogenesis may play an important role in the PCU healing process, which is enhanced by the heat treatment.