Effects of topical copper tripeptide complex on wound healing in an irradiated rat model

Objectives. To evaluate clinical and immunohistopathological effects of topical glycyl-histidyl-lysine-copper (GHK-Cu) on in vivo irradiated rat wounds. Design. Animal model. Setting. Academic institution. Subjects and Methods. After dorsal irradiation and a 28-day recovery period, 2 × 8 cm cranially based dorsal flaps were created in Sprague-Dawley rats. Twice daily GHK-Cu gel (test) or aquaphilic ointment (control) was applied for 10 days. Animals were euthanized, digital images of flaps were taken, and harvested tissues were immunohistochemically stained for a vascular endothelium marker, caveolin-1, and vascular endothelial growth factor (VEGF). Digital image analysis was used for outcome measures. Unpaired t-tests were used for statistical analyses; significance of P < .01 accounted for multiple comparisons. Results. By digital analysis of clinical images, 13 test and 10 control animals showed mean ischemic areas of 5.0 cm² (SD = 0.9) for tests and 3.8 cm² (SD = 1.1; P = .011) for controls. Whole slide digitized images allowed quantification of caveolin-1-stained blood vessels and VEGF expression in fibroblasts at the interface of healing flaps. Caveolin-1 analyses showed a mean of 209.0 vessels (SD = 111.1) and a mean vessel luminal area of 525.7 um ² (SD = 191.0) in tests and 207.4 vessels (SD = 109.4; P = .973) and 422.8 um² (SD = 109.7; P = .118) in controls. VEGF quantified as the percentage of pixels exceeding a colorimetric threshold, with higher fractions of positive pixels indicating more intense staining, showed a mean intensity score of 0.34 (SD = 0.19) in tests and 0.54 (SD = 0.41; P = .169) in controls. Conclusions. Irradiated dorsal rat flaps treated with topical GHK-Cu gel demonstrated no difference in flap ischemia, blood vessel number or area, or VEGF expression compared to controls.