The effect of the angiogenesis inhibitor, angiostatin, on hypertrophic scarring

Abstract

Introduction: Hypertrophic scarring is commonly seen by plastic surgeons in China. Since the etiology of hypertrophic scarring is still unknown, the only reliable treatment is surgical excision. To understand if angiogenesis plays an important role in the formation of hypertrophic scars, we investigated the effect of angiostatin, a potent angiogenesis inhibitor, on hypertrophic scar formation. Our hypothesis is that angiogenesis is required for increased scar formation and angiogenesis inhibition may be one of the methods that can be used to prevent the formation of hypertrophic scars. Methods: We have developed a reliable model in rabbits that results in hypertrophic scarring by creating a 6mm x 6mm full thickness skin wound on both ears. The cDNA for angiostatin is cloned into the pcDNA 3.1 mammalian expression vector. After the wounds re-epithelialized but prior to excessive scarring, the angiostatin expression vector was injected with Lipofectin 2000 once every two days. The expression of angiostatin was confirmed by RT-PCR. The scar tissue was harvested 14 days after injection and processed for histology and total protein. Histology was examined with routine stains, the amount of collagen deposition in the scar tissue was detected by proline assay, and TGF-β1 and VEGF expression was detected by western blot. Results: Compared to the control injection scar, the injection of angiostatin led to a much more normal-looking of scar in the rabbit ear. The proline assay demonstrated that the injection of the angiostatin expression vector resulted in much less collagen in the scar tissue. Western blot analysis showed there was less TGF-β1 and VEGF protein expression in the treated ear compared to the control. Conclusion: The introduction of a vector over-expression angiostatin can result in the decreased formation of hypertrophic scars in a rabbit ear model. This is corroborated by evidence of decreased collagen deposition, the primary extracellular matrix component of scars. In addition, we demonstrate the decreased expression of τηε pro-fibrosis growth factor, TGF-1, and the potent angiogenic factor, VEGF. These data suggest that angiogenesis inhibitors may have a potential role in the treatment of hypertrophic scarring.