Effect of tissue inhibitors of metalloproteinases and matrix metalloproteinases on capsular formation around smooth and textured silicone gel implants.

BACKGROUND: Capsular contracture is one of the most distressing complications after cosmetic breast augmentation. Evidence suggests that matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) may play a key role in the onset or progression of several fibrotic disorders. In this study we used quantitative reverse-transcription PCR methodology to profile the expression of TIMP-1, TIMP-2, MMP-2, and MMP-9 in the tissue of patients with capsular contracture after breast augmentation with smooth and textured silicone breast implants.

METHODS: The study included 20 female patients (average age = 37 +/- 15 years) with capsular contracture after bilateral subglandular cosmetic breast augmentation with smooth silicone implants. Ten patients developed grade II capsule contracture, 8 grade III contracture, and 1 grade IV contracture. Twenty other female patients (average age = 41 +/- 9 years) with capsular contracture after breast augmentation with textured silicone implants were also included (Baker grade II = 10 patients, grade III = 8, grade IV = 2). Expression of mRNA in capsular tissue was calculated using a relative quantification method (Pfaffl). Statistical analysis was performed using the Mann-Whitney test. The level of significance was considered to be p < 0.05.

RESULTS: The expression of MMP-2 was significantly increased in tissue of patients with textured implants and capsular contracture grades II and III/IV in comparison to grade I (p < 0.05). In comparison to grade I, the capsular tissue from patients with Baker II and III/IV fibrosis showed a significant increase for TIMP-1 and TIMP-2 (p < 0.05) in both smooth and textured silicone implants. The expression was significantly higher in tissue from patients with severe contracture (Baker III/IV) and smooth silicone implants compared with that in tissue from patients with textured implants (p < 0.05).

CONCLUSION: The decrease in MMP-to-TIMP expression can cause increased synthesis and deposition of collagen surrounding alloplastic breast implants, leading to a profibrotic state. The higher expression of TIMPs in capsular tissue of patients with smooth silicone gel implants might be a reason for the observed higher rates of capsular contracture. In the future, a nonoperative treatment that decreases TIMPs but increases the activity of MMPs may be an appropriate therapy for patients with capsular contracture.