Past

Capsular contracture is a major complication of implant-based breast reconstruction. Recent studies have shown that use of acellular dermal matrices (ADM) for coverage of breast implants decreased or prevented capsular contractures. Moyer et al.1 performed histopathological analysis of native capsules and ADM capsules in both nonirradiated and irradiated patients. They observed significant differences in cellular infiltration and elastin distribution only. Other researchers have also investigated the histological differences between subpectoral and ADM capsules and the mechanism by which the ADM reduces capsule formation around the breast implant. However, the mechanism remains unclear.

Present

Although it is established that postmastectomy radiotherapy (PMRT) promotes capsular contracture, the effect of radiation on ADM capsule thickness has not been elucidated. In this study, there was no significant difference between the thickness of nonirradiated and irradiated ADM capsules.2 Myofibroblasts and macrophages, which play central roles in tissue fibrosis, were significantly reduced in the ADM capsules compared with the subpectoral capsules. We first investigated the number of endothelial–mesenchymal transition (EndoMT) cells and vimentin positive fibroblasts, and the TGF-β1 and PDGF-B transcript levels in the capsular tissues. The number of these cells and transcript levels were also reduced in the ADM capsules. This study provides insight into capsule formation around a breast implant and how ADM inhibits capsular contracture in nonirradiated and irradiated tissues.

Future

Various analyses using hematoxylin and eosin, α-smooth muscle actin (αSMA), vimentin, CD31, F4/80 expression, αSMA and CD31 coexpression, and relative gene expression levels of TGF-β1 and PDGF-B were conducted in this study. It was difficult to include a large number of patients; therefore, only a small subset of the population was enrolled. A large-scale study on the mechanism of peri-implant capsule formation is needed. To confirm the suggested mechanism of capsule formation and its inhibition by ADM, well-controlled animal experiments are essential.