"Histological and Immunohistochemical Evaluation of Human Breast Capsules Formed Around Five Different Expander Surfaces"

Background: Polyurethane (PU) coating and implant texturization were designed to reduce the incidence of capsular contracture (CC), even if the link between surface type and CC remains unclear. To date the etiopathogenetic aspects have not been fully clarified. The aim of this study was to evaluate capsules formed around 5 different breast expanders. Methods: Thirty patients were divided into randomized groups implanted with 5 different expanders: Smooth, coated with PU foam (Poly), with a low-microtextured, high-microtextured, and macrotextured surface (L-Micro, H-Micro, Macro). Specimens of the capsules were removed at implant reconstruction and evaluated for morphology and immunohistochemistry expression of α-smooth muscle actin (α-SMA), collagen type I and III, CD68, CD34, and CD3. Remodeling combined index was also evaluated. Results: Expression of α-SMA was significantly increased in Smooth capsules versus Poly, L-Micro, and H-Micro groups (p=0.007; p=0.010; p=0.028), while the prevalence of collagen type I in Smooth capsules and collagen type III in Poly capsules identified a stable versus an unstable tissue. Remodeling combined index and α-SMA showed an inverted correlation. CD68 and CD34 cellular expression increased significantly in Poly capsules with respect to Smooth (p<0.001; p<0.001) and Macro groups (p<0.001; p<0.001). CD3 showed no significant difference among the groups. Conclusions: In this human study we observed that an increased tissue remodeling and a reduced myofibroblasts activation, along with the inflammatory infiltration and the neo-angiogenesis, especially in Poly and L-Micro groups, might promote the formation of an unstable and less fibrotic capsule, lowering the risk of CC.