Vascular Endothelial Growth Factor Overexpression Positively Modulates the Characteristics of Periprosthetic Tissue of Polyurethane-Coated Silicone Breast Implant in Rats

Abstract

Capsular contracture is one of the most common complications associated with silicone breast implants. The surface of the implant is one of the factors often associated with the occurrence of capsular contracture. In this study, the authors evaluated the differences in morphologic and molecular characteristics of the capsule formed around polyurethane-coated versus textured-surface silicone implants in rats, mainly the modifications in angiogenesis and the expression of vascular endothelial growth factor (VEGF). A pocket was performed on the animal's back, where the silicone implants were introduced. Two groups of animals received a polyurethane-coated silicone implant and the other groups received a textured-surface silicone implant, and the capsules around the prostheses were submitted to histologic and immunohistochemistry analysis, 30 or 90 days after surgery. The capsules around the polyurethane-coated silicone prostheses were significantly thicker than the textured-surface silicone implants. Furthermore, the layer adjacent to the polyurethane-coated silicone implants was more cellular and irregular than the layer around the textured-surface silicone implants. Textured implant periprosthetic capsules presented fewer inflammatory cells and less vascularization than the polyurethane-coated silicone implants. The collagen layer of periprosthetic tissue of textured implants appears to be more continuous and aligned in parallel fashion than polyurethane-coated implants. Immunohistochemical analysis revealed high levels of transforming growth factor-β and VEGF in the capsules around the polyurethane-coated silicone implants when compared with the textured-surface silicone implants. These findings suggest that the intense VEGF expression in capsules around the polyurethane-coated silicone implant is able to improve the tissue vascularization, resulting in a softer capsule compared with the textured-surface silicone implant.