SP33. Nanoparticulate Shedding of Silicone Breast Implant Shells

PURPOSE: The pathophysiology of multiple breast implant-associated illnesses including capsular contracture and breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) are still poorly understood. Particulate shedding is a known phenomenon of silicone breast implants, documented both in vitro and in vivo, and hypothesized to play a role in chronic peri-implant inflammation linked to adverse outcomes. Prior research quantifying shed particles have focused on the microparticle range (size >1μm). As recent technological advancements permit exploration of the nanoparticle (NP) range (size &lt1;μm), the field of nanometer-range sized particle analysis has garnered interest across multiple medical implant materials, but remains underexplored in breast prostheses. Thus, we sought to investigate the presence and degree of nanoparticulate shedding from both textured and smooth surface implants. METHODS: Silicone textured and smooth implant shells from Allergan and Mentor were thoroughly cleaned of their gel interior, sterilized, cut into 9x19mm samples and used to line individual wells within a 96-well plate such that the outer shell surface faced into the well. Serum-free cell culture media (i.e., no added growth factors or nutrients) was added and incubated for 48 hours, after which the shell ‘conditioned’ media (CM) was collected from both textured and smooth implant shells, referred to as textured conditioned media (TCM) and smooth conditioned media (SCM) respectively. Samples were diluted 10x with phosphate-buffered saline (PBS) and analyzed via the NanoSight Pro Nanoparticle Tracking Analyzer (Malvern Panalytical, Malvern, UK). Fresh serum-free media was included as a control. Five consecutive measurements of NP size distribution and concentration were recorded per sample. RESULTS: No NPs were detected in serum-free media. NP signals were evident from all implant-conditioned media samples. Mean NP concentration was greater in Allergan TCM (2.09x109 particles/mL) and Mentor TCM (2.69x109) by one order of magnitude compared to Allegan SCM (1.19x108) and by two orders of magnitude compared to Mentor SCM (4.18x107). Median NP size was greater in Allergan and Mentor SCM (152 and 185nm, respectively) compared to each manufacturer’s TCM counterparts (126 and 141nm, respectively). TCM particle concentration versus size histograms appeared focused around the 100-200nm range, while SCM histograms ranged more broadly across smaller size ranges, with additional particle concentration peaks seen between 600-1,000nm. CONCLUSION: We report the identification and size characterization of nano-particulates released from breast implants when incubated in media, a simplistic recreation of the clinical peri-implant breast environment. Results from our in vitro model implicate nanoscale shedding as a potential mechanism in vivo. Such debris, as with well-recognized larger shed silicone particles, carries the potential to illicit a foreign body immune response and induce a state of chronic inflammation. Higher NP concentration from textured surface implants may correlate with their specific risk for BIA-ALCL. Follow-on in vivo studies of these novel in vitro findings are planned.