Breast Implant Capsule: A Murine Model Comparing Capsular Contracture Susceptibility Among Six Breast Implants Available in the Market

Inflammatory response to various implant surfaces in murine models: A systematic analysis

Breast implants (BIs) are commonly used in cosmetic and reconstructive breast surgery but are linked to several complications such as capsular contracture, implant rupture, and potential malignancies. The key to mitigating these issues is the exploration of host-implant interactions, especially in response to the diverse BI surface textures, classified under ISO 14607:2018 standards. We aimed to systematically analyze the effects of different BI surface textures on inflammatory response and capsule formation in murine models, to improve BI design and clinical outcomes. A PRISMA-guided systematic review was conducted across 4 databases, focusing on murine model studies related to BI surface variations. Non-murine, human studies and those involving physical or pharmacological interventions were excluded. Implant surfaces were categorized per ISO 14607:2018, including smooth, microtextured, macrotextured, and polyurethane foam-coated (PU) BI, and compared with new ISO 14607:2018. Outcomes were assessed on capsule characteristics, inflammatory patterns, and biomechanical properties. Smooth-surfaced implants were linked to thinner, more orderly capsules, with a subdued inflammatory reaction. Microtextured implants elicited a moderate response with varying tissue integration and inflammation levels. Macrotextured implants showed pronounced tissue reaction. PU implants induced a robust inflammatory response, characterized by increased neoangiogenesis and thicker, more cellular capsules. Data inconsistencies across studies highlighted the complexity of biological responses to different implant surfaces. In conclusion, smooth implants developed thinner capsules and lower inflammation. Increasing surface texture resulted in denser capsules and more abundant inflammatory patterns, highlighting the significant role of BI surface texture in influencing host responses.

Smooth Operator: Nanotextured Breast Tissue Expanders Are Associated with Lower Rates of Capsular Contracture

Background: Continuous research on breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) has introduced a focus on surface texturizations and a shift towards smooth breast devices, yet outcomes comparing the complication profiles of differently textured tissue expanders (TEs) remain conflicting. The study aim was to compare the complication profile of a new nanotextured and MRI-compatible TE to micro- and macrotextured TEs and to identify possible predictors for complications. Methods: A retrospective analysis of women undergoing expander-based breast reconstruction after mastectomy between January 2016 and March 2022 was conducted. The primary endpoint was the development of capsular contracture. Possible predictors were analyzed in a mixed-effects model using the least absolute shrinkage and selection operator (LASSO). Moreover, a comparison of complications and an evaluation of predictors were carried out. Results: A total of 147 breasts, encompassing 82 nanotextured, 43 microtextured and 22 macrotextured TEs, were analyzed. Breasts with nanotextured TEs were less likely to develop capsular contracture overall (OR, 0.12; 95%CI 0.05-0.28, p < 0.001). Post-mastectomy radiotherapy (PMRT) was identified as a predictor for capsular contracture (OR, 4.67; 95%CI 1.86-11.71, p < 0.001). Breasts with nanotextured TEs showed a higher rate of seroma, but lower rates of malposition and pain. Predictors for developing postoperative complications included higher mastectomy weight (p = 0.008). Conclusions: Breasts with nanotextured TEs exhibited the lowest rate of capsular contracture compared to micro- and macrotextured TEs. Together with its MRI-compatibility and improved oncologic follow-up, the nanotextured TE seems to be a favorable device for expander-based breast reconstruction.

Impact of Hematoma on Capsular Contracture: A Comparative Study of Smooth and Textured Implants in a Miniature Pig Model

BACKGROUND

Capsular contracture is a significant complication following mammaplasty, with varying incidence rates and symptoms. The etiology of capsular contracture is multifactorial, with postoperative hematoma recognized as a potential contributing factor.

OBJECTIVES

In this study we aimed to investigate the impact of postoperative hematoma on capsular contracture following mammaplasty, utilizing pig models and modified biomechanical testing. We sought to compare the severity of capsular contracture between smooth and textured implants in the presence of hematoma, assess the biomechanical properties of the capsules, and explore the histological and molecular changes associated with the condition.

METHODS

The study involved 5 female miniature pigs, implanted with both smooth and textured implants. Hematoma models were established, and various methods were employed to evaluate the impact of the prosthesis surface and hematoma on capsular contracture, including ultrasound assessment, biomechanical tests, scanning electron microscopy, histological analysis, and transcriptome sequencing.

RESULTS

Capsules in hematoma groups were classified as Baker III/IV, with significantly unfavorable thickness, elastic modulus, and relaxation and creep amounts compared to nonhematoma groups. Smooth implants under hematoma conditions exhibited increased muscle content and biomechanical strength of the capsule. Transcriptomic analysis highlighted differential gene expression related to muscle development and contraction in smooth implants with hematomas.

CONCLUSIONS

Hematomas increase the risk of capsular contracture, with smooth implants exacerbating this effect by enhancing pathways related to muscle development and contraction. This underscores the importance of hematoma prevention and treatment strategies, particularly when placing smooth implants, to minimize the occurrence of capsular contracture. The study provides insights into the mechanisms underlying capsular contracture and offers evidence to guide surgical and postoperative management strategies.

An Update on Implant-Associated Malignancies and Their Biocompatibility

Implanted medical devices are widely used across various medical specialties for numerous applications, ranging from cardiovascular supports to orthopedic prostheses and cosmetic enhancements. However, recent observations have raised concerns about the potential of these implants to induce malignancies in the tissues surrounding them. There have been several case reports documenting the occurrence of cancers adjacent to these devices, prompting a closer examination of their safety. This review delves into the epidemiology, clinical presentations, pathological findings, and hypothesized mechanisms of carcinogenesis related to implanted devices. It also explores how the surgical domain and the intrinsic properties and biocompatibility of the implants might influence the development of these rare but serious malignancies. Understanding these associations is crucial for assessing the risks associated with the use of medical implants, and for developing strategies to mitigate potential adverse outcomes.

Omental coating attenuates implant-induced foreign body reaction in rats

The objective of this study is to clarify whether the omental coating can effectively attenuate foreign body reaction (FBR) induced by implanted materials. Male Sprague-Dawley rats were injected with polydextran particle slurry intraperitoneally to activate the omentum. 7 days later, polyether polyurethane sponge discs were implanted subcutaneously on each side of the rat's back as the foreign implants to induce FBR. The next day, omental transposition were performed. The disc on the left side of each rat's back was wrapped with omental flap (omental group); the disc on the right side was untreated (control group). All discs were removed 21 days after implantation and assessed by determining the components of the fibrovascular tissue (angiogenesis, inflammation, foreign body giant cells (FBGCs) aggregation and fibrogenesis). In implants in omental group, micro vessel density (MVD), Hemoglobin (Hb) content and VEGF levels (pro-angiogenic cytokine) were increased when compared with implants from control group. Inflammatory parameters (IL-1β; macrophage accumulation-NAG activity; neutrophil accumulation- MPO levels) were decreased in implants after omental coating. Also, collagen deposition, fibrous capsule thickness, and FBGCs decreased in implants from omental group. However, intra-implant levels of TNF-α and TGF-β1 were not different after omental coating. Our findings showed for the first time that the omental coating around the implants attenuate the adverse FBR, it may be critical in developing new strategies to control FBR and improve the function and performance of the implanted materials.