Silicone Breast Implant Surface Texture Impacts Gene Expression in Periprosthetic Fibrous Capsules

Purpose: Silicone breast implants with smooth outer shells are associated with higher rates of capsular contracture, while textured implants have been linked to the development of breast implant-associated ALCL. By assessing the gene expression profile of fibrous capsules formed in response to smooth and textured implants, we can gain insight into the development of breast implant-associated pathologies. Methods: Miniature smooth or textured silicone implants were surgically inserted into female rats (n=10) and harvested for the surrounding capsules on postoperative week 6. RNA sequencing and quantitative polymerase chain reaction were performed to identify genes differentially expressed between smooth and textured capsules. For clinical correlation, the expression of candidate genes was assayed in implant capsules harvested from human patients with and without capsular contracture. Results: Out of 18,555 differentially expressed transcripts identified, three candidate genes were selected: matrix metalloproteinase-3 (MMP3), troponin-T3 (TNNT3) and neuregulin-1 (NRG1). In textured capsules, relative gene expression and immunostaining of MMP3 and TNNT3 was upregulated while NRG1 was downregulated compared to smooth capsules (mean relative fold change: 8.79, p=0.0059; 4.81, p=0.0056; 0.40, p<0.0001, respectively). Immunostaining of human specimens with capsular contracture revealed similar gene expression patterns to those of animal-derived smooth capsules. Conclusion: An expression pattern of low MMP3/low TNNT3/high NRG1 is specifically associated with smooth implant capsules and human implant capsules with capsular contracture. Our clinically relevant breast implant rat model provides a strong foundation to further explore the molecular genetics of implant texture and its effect on breast implant-associated pathologies.