Silicone Implants with Smooth Surfaces Induce Thinner but Denser Fibrotic Capsules Compared to Those with Textured Surfaces in a Rodent Model

Advances in Etiology and Prevention of Capsular Contracture After Breast Implantation

Capsular contracture (CC) is one of the most common complications of breast implant usage in breast augmentation or reconstruction. The CC approach can cause breast hardening, pain, and varying degrees of deformity, affecting the quality of life of patients. Considerably, it has become one of the most common reasons for frequent surgeries. Nonetheless, the etiology and pathogenesis of CC remain unclear. Moreover, there exist still a lot of uncertainties regarding prevention and treatment measures. In this article, we present discussions on the research status of the etiology, pathogenesis, prevention, and treatment measures of CC. In summary, this study provides a reference for further research on CC and clinical use.Level of Evidence V This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

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.

Development of a fish oil-nanoemulsion gel as a drug-delivery system to prevent capsular contracture

Capsular contracture, a significant complication of breast-implant surgery, causes pain and deformation following the formation of a tight capsule around an implant. Current surgical and non-surgical treatment options are invasive, expensive, and typically administered for prolonged periods, potentially leading to side effects. To address these challenges, we developed a novel fish oil-encapsulated, poloxamer-based nanoemulsion gel with omega-3 (ω3) as the primary active component (NE-ω3 gel; N3G). This formulation can be injected during surgery, reducing the need for prolonged administration of medications and minimizing associated side effects. N3G was prepared through a two-step process involving the emulsification of fish oil followed by gelation with poloxamer to create a thermoreversible gel. Dynamic light-scattering analysis confirmed a uniform distribution of nanoemulsion particles, which had a mean diameter of 287 ± 8.599 nm and a PDI of 0.29 ± 0.047. FTIR and DSC analyses validated the encapsulation of fish oil within poloxamer micelles. Drug-release analysis demonstrated that more than 96% of fish oil was released within 10 h. In in vivo experiments, rats (n = 30) were divided into three groups: a negative control group (G1), a positive control group receiving fish oil (G2), and an experimental group with implants coated with N3G (G3). G3 exhibited a 21.2% reduction in capsular thickness compared to G1 and a 5.6% reduction compared to G2. In addition, significant decreases in fibrosis and myofibroblast counts were observed in G3. These results, supported by histological and gene expression analyses, highlight the effectiveness of N3G in reducing inflammation and fibrosis. This study underscores the therapeutic potential of N3G for capsular contracture, based on its persistence, thermoreversibility, and improved dosing and storage characteristics.

Stem Cell-Enriched Hybrid Breast Reconstruction Reduces Risk for Capsular Contracture in a Hybrid Breast Model

BACKGROUND

Hybrid breast reconstruction (HBR) combines silicone implants with fat grafting to improve implant coverage, treating local tissue deficiencies and leading to a more natural breast appearance. Recent data also indicated less capsular contracture after HBR. The authors developed a novel technique and animal model of cell-assisted (CA) HBR to illuminate its effects on capsular contracture.

METHODS

Animals received silicone implants in a dorsal submuscular pocket. Although animals of the HBR group received fat grafting around the implant without stem cell enrichment, rats of the CA-HBR1 and the CA-HBR2 groups received stem cell-enriched fat grafting with 2 × 10 6 and 4 × 10 6 adipose-derived stem cells immediately after implant insertion. On day 60, animals underwent sonography and elastography imaging and were euthanized, and outcome analysis was performed by means of histology, immunohistochemistry, chemical collagen quantification, and gene expression analysis.

RESULTS

With this novel technique, long-term survival of adipose-derived stem cells within the implant pocket was demonstrated after 60 days after implant insertion. CA-HBR led to significantly reduced thickness and collagen density of capsular contractures. In addition, CA-HBR resulted in reduced fibrotic responses with less occurrence of collagen type I and transforming growth factor-β in capsule tissue. Moreover, the addition of stem cells suppressed fibrotic and inflammatory responses on a genetic level with significant underexpression of collagen type I and transforming growth factor-β1.

CONCLUSIONS

With this new technique and animal model, the authors observed a preventive effect on capsular contracture substantiating the basis of clinical outcomes of HBR. The authors propose that the addition of stem cells to HBR might booster its beneficial results.

CLINICAL RELEVANCE STATEMENT

Stem cell-enriched fat grafting around silicone implants may reduce the risk for capsular contracture after silicone breast implantation. While fat grafting alone already shows beneficial effects, the addition of stem cells to the fat graft can potentiate this effect.

Study of the Effect of Different Breast Implant Surfaces on Capsule Formation and Host Inflammatory Response in an Animal Model

BACKGROUND

Breast implants are biomaterials eliciting a physiological and mandatory foreign body response.

OBJECTIVES

The authors designed an animal study to investigate the impact of different implant surfaces on the formation of the periprosthetic capsule, the inflammatory response, and the cellular composition.

METHODS

The authors implanted 1 scaled-down version of breast implants by different manufactures on 70 female Sprague Dawley rats. Animals were divided into 5 groups of 14 animals. Group A received a smooth implant (Ra ≈ 0.5 µm) according to the ISO 14607-2018 classification, Group B a smooth implant (Ra ≈ 3.2 µm), Group C a smooth implant (Ra ≈ 5 µm), Group D a macrotextured implant (Ra ≈ 62 µm), and Group E a macrotextured implant (Ra ≈ 75 µm). At 60 days, all animals received a magnetic resonance imaging (MRI), and 35 animals were killed and their capsules sent for histology (capsule thickness, inflammatory infiltrate) and immunohistochemistry analysis (cellular characterization). The remaining animals repeated the MRI at 120 days and were killed following the same protocol.

RESULTS

MRI showed a thinner capsule in the smooth implants (Groups A-C) at 60 days (P < .001) but not at 120 days (P = .039), confirmed with histology both at 60 days (P = .005) and 120 days (P < .001). Smooth implants (Groups A-C) presented a mild inflammatory response at 60 days that was maintained at 120 days and a high M2-Macrophage concentration (anti-inflammatory).

CONCLUSIONS

Our study confirms that smooth implants form a thinner capsule, inferior inflammatory infiltrate, and a cellular composition that indicates a mild host inflammatory response. A new host inflammatory response classification is elaborated classifying breast implants into mild, moderate, and high.

Implantation and tracing of green fluorescent protein-expressing adipose-derived stem cells in peri-implant capsular fibrosis

BACKGROUND

Adipose-derived stem cells (ASCs) have been reported to reduce fibrosis in various tissues. In this study, we investigated the inhibitory role of ASCs on capsule formation by analyzing the histologic, cellular, and molecular changes in a mouse model of peri-implant fibrosis. We also investigated the fate and distribution of ASCs in the peri-implant capsule.

METHODS

To establish a peri-implant fibrosis model, customized silicone implants were inserted into the dorsal site of C57BL/6 wild-type mice. ASCs were harvested from the fat tissues of transgenic mice that express a green fluorescent protein (GFP-ASCs) and then injected into the peri-implant space of recipient mice. The peri-implant tissues were harvested from postoperative week 2 to 8. We measured the capsule thickness, distribution, and differentiation of GFP-ASCs, as well as the cellular and molecular changes in capsular tissue following ASC treatment.

RESULTS

Injected GFP-ASCs were distributed within the peri-implant capsule and proliferated. Administration of ASCs reduced the capsule thickness, decreased the number of myofibroblasts and macrophages in the capsule, and decreased the mRNA level of fibrogenic genes within the peri-implant tissue. Angiogenesis was enhanced due to trans-differentiation of ASCs into vascular endothelial cells, and tissue hypoxia was relieved upon ASC treatment.

CONCLUSIONS

We uncovered that implanted ASCs inhibit capsule formation around the implant by characterizing a series of biological alterations upon ASC treatment and the fate of injected ASCs. These findings highlight the value of ASCs for future clinical applications in the prevention of capsular contracture after implant-based reconstruction surgery.

Advances in surface modifications of the silicone breast implant and impact on its biocompatibility and biointegration

Silicone breast implants are commonly used for cosmetic and oncologic surgical indications owing to their inertness and being nontoxic. However, complications including capsular contracture and anaplastic large cell lymphoma have been associated with certain breast implant surfaces over time. Novel implant surfaces and modifications of existing ones can directly impact cell-surface interactions and enhance biocompatibility and integration. The extent of foreign body response induced by breast implants influence implant success and integration into the body. This review highlights recent advances in breast implant surface technologies including modifications of implant surface topography and chemistry and effects on protein adsorption, and cell adhesion. A comprehensive online literature search was performed for relevant articles using the following keywords silicone breast implants, foreign body response, cell adhesion, protein adsorption, and cell-surface interaction. Properties of silicone breast implants impacting cell-material interactions including surface roughness, wettability, and stiffness, are discussed. Recent studies highlighting both silicone implant surface activation strategies and modifications to enhance biocompatibility in order to prevent capsular contracture formation and development of anaplastic large cell lymphoma are presented. Overall, breast implant surface modifications are being extensively investigated in order to improve implant biocompatibility to cater for increased demand for both cosmetic and oncologic surgeries.

Tamoxifen reduces silicone implant capsule formation in a mouse model

Capsular contracture as a result of the foreign body response (FBR) is a common issue after implant-based breast reconstruction, affecting up to 20% of patients. New evidence suggests that tamoxifen may mitigate the FBR. C57BL/6 female mice were treated with daily tamoxifen or control injections and implanted with bilateral silicone implants in the submammary glandular plane. Implants were removed en bloc after 2 weeks and the implant capsules were evaluated histologically. Tamoxifen treatment decreased capsule thickness, decreased the number of αSMA+ cells (477 ± 156 cells/mm control vs 295 ± 121 cells/mm tamoxifen, p = 0.005 unpaired t test), and decreased CD31+ cells (173.9 ± 96.1 cells/mm2 control vs 106.3 ± 51.8 cells/mm2 tamoxifen, p = 0.043 unpaired t test). There were similar amounts of pro- and anti-inflammatory macrophages (iNOS 336.1 ± 226.3 cells/mm control vs 290.6 ± 104.2 cells/mm tamoxifen, p > 0.999 Mann-Whitney test and CD163 136.6 ± 76.4 cells/mm control vs 94.1 ± 45.9 cells/mm tamoxifen, p = 0.108 unpaired t test). Tamoxifen treatment in the mouse silicone breast implant model decreased capsule formation through modulation of myofibroblasts, neovascularization, and collagen deposition. Tamoxifen may be useful for reducing or preventing capsule formation in clinical breast implantations.

Oral doxycycline prevents skin-associated adverse effects induced by injectable collagenase in a rodent model of capsular contracture around silicone implants

Background

The collagenase of the bacterium Clostridium histolyticum (CCH) is already an established treatment for fibroproliferative diseases like M. Dupuytren and M. Peyronie Although results are comparable to surgical intervention, skin laceration is a severe and relevant side effect. Doxycycline (DOX) recently rose interest as an inhibitor of matrix-metalloproteinases alongside its capabilities of skin accumulation. It therefore might be a potential skin protective agent in the use of CCH.

Methods

For simulation of a fibroproliferative disease adjacent to the skin, we utilized a rodent model of capsular fibrosis involving silicone implants and subsequent fibrotic capsule formation. For in-vitro studies, fibrotic capsules were excised and incubated with 0.9 mg/ml CCH and four different doses of DOX. For in-vivo experiments, animals received 0.0, 0.3 or 0.9 mg/ml CCH injections into the fibrotic capsules with or without prior oral DOX administration. Outcome analysis included histology, immunohistochemistry, gene expression analysis, chemical collagen and DOX concentration measurements as well as μCT imaging.

Results

In-vitro, DOX showed a dose-dependent inhibition of CCH activity associated with increasing capsule thickness and collagen density and content. In-vivo, oral DOX administration did neither interfere with capsule formation nor in effectiveness of CCH dissolving fibrotic capsule tissue. However, skin thickness and especially collagen density was significantly higher compared to control groups. This led to a reduced rate of clinical skin lacerations after DOX administration.

Conclusion

DOX inhibits CCH and accumulates in the skin. Thereby, DOX can effectively reduce skin laceration after CCH treatment.

In Vivo and In Vitro Fibroblasts' Behavior and Capsular Formation in Correlation with Smooth and Textured Silicone Surfaces

BACKGROUND

As the most principal complication following breast augmentation with silicone breast implants, capsular contracture is greatly influenced by surface texture. However, there have long been widespread debates on the function of smooth or textured surface implants in reducing capsular contracture.

MATERIALS AND METHODS

Three commercially available silicone breast implants with smooth and textured surfaces were subjected to surface characterization, and in vitro and in vivo assessments were then implemented to investigate the effect of these different surfaces on the biological behaviors of fibroblasts and capsular formation in rat models.

RESULTS

Surface characterization demonstrated that all three samples were hydrophobic with distinct roughness values. Comparing the interactions of fibroblasts or tissues with different surfaces, we observed that as surface roughness increased, the adhesion and cell spreading of fibroblasts, the level of echogenicity, the density of collagen and α-SMA-positive immunoreactivity decreased, while the proliferation of fibroblasts and capsule thickness increased.

CONCLUSIONS

Our findings elucidated that the effect of silicone implant surface texture on fibroblasts' behaviors and capsular formation was associated with variations in surface roughness, and the number of myofibroblasts may have a more significant influence on the process of contracture than capsule thickness in the early stage of capsular formation. These results highlight that targeting myofibroblasts may be wielded in the prevention and treatment strategies of capsular contracture clinically.

LEVEL OF EVIDENCE V

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

TGF-β1 and CD68 immunoexpression in capsules formed by textured implants with and without mesh coverage: a study on female rats

PURPOSE

To evaluate fibrosis formation and number of macrophages in capsules formed around textured implants without and with mesh coverage.

METHODS

Fibrosis was analyzed through transforming growth factor-beta 1 (TGF-β1) immunomarker expression and the number of macrophages through CD68 percentage of cells in magnified field. Sixty female Wistar rats were distributed into two groups of 30 rats (unmeshed and meshed). Each group was then subdivided into two subgroups for postoperative evaluation after 30 and 90 days. The p value was adjusted by Bonferroni lower than 0.012.

RESULTS

No difference was observed in fibrosis between meshed and unmeshed groups (30 days p = 0.436; 90 days p = 0.079) and from 30 to 90 days in the unmeshed group (p = 0.426). The meshed group showed higher fibrosis on the 90th day (p = 0.001). The number of macrophages was similar between groups without and with mesh coverage (30 days p = 0.218; 90 days p = 0.044), and similar between subgroups 30 and 90 days (unmeshed p = 0.085; meshed p = 0.059).

CONCLUSIONS

In the meshed group, fibrosis formation was higher at 90 days and the mesh-covered implants produced capsules similar to microtextured ones when analyzing macrophages. Due to these characteristics, mesh coating did not seem to significantly affect the local fibrosis formation.

The Treatment of Capsular Contracture Around Breast Implants Induced by Fractionated Irradiation: The Collagenase of the Bacterium Clostridium Histolyticum as a Novel Therapeutic Approach

BACKGROUND

Irradiation therapy limits the utilization of silicone implants for breast reconstruction due to a significant risk for capsular contracture. The injection of the collagenase of the bacterium Clostridium histolyticum (CCH) might trivialize this risk by providing a minimal-invasive treatment option by capsular contracture degradation. However, efficacy in degrading breast implant capsules induced by fractionated irradiation remains unclear.

METHODS

Twenty-four rats in three groups received miniature silicone implants in a submuscular pocket. After 3D dose calculation and treatment field definition, rats of two groups underwent fractionated radiotherapy (6 × 8 Gy) using a linear accelerator. A third group served as control. On day 120, one irradiated group received injections of 0.3 mg/ml collagenase. Administration of plain solvent solution served as control in the two other groups. Outcome parameters included CT-imaging, histology, vessel wall analysis, immunohistochemistry, chemical collagen quantification and gene expression analysis.

RESULTS

Fractioned irradiation leads to a significant increase in collagen deposition around silicone implants with higher capsule thickness and collagen density when comparing all groups. Additionally, significant alterations of collagen fiber deposition were evident. Vessel wall thickness was significantly increased after radiotherapy. The injection of collagenase led to a significant reduction of capsule thickness, collagen density and content. However, the collagenase application induced a significant overexpression of TGFβ1. No side effects were monitored.

CONCLUSIONS

The CCH proved to be a safe and effective approach to degrade capsule tissue induced by fractionated irradiation in an animal model. This may pave its way for clinical application in implant-based breast reconstruction patients.

LEVEL OF EVIDENCE

This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Reduced Remodeling Biomarkers Tissue Expression in Nanotextured Compared With Polyurethane Implants Capsules: A Study in Rats

BACKGROUND

In the biological response to biomaterials, the implant shell plays a key role in immune and inflammatory reactions. We hypothesized that the capsules formed around nanotextured implants exhibit an immunohistochemical behavior different to those formed around polyurethane implants.

OBJECTIVES

The aim of this study was to evaluate through immunohistochemistry markers the capsules formed around nanotextured and polyurethane implants.

METHODS

Sixty albino female Wistar rats were divided into 2 groups (nanotextured and polyurethane), with 30 animals in each group. A mini silicone implant was inserted on the back of the animals. After a predetermined period, the animals were killed, and the capsules formed around the implants were studied. The capsules in the 30-, 60-, and 90-day subgroups were analyzed via immunohistochemistry to detect markers for fibroblast α smooth muscle actin (α-SMA), transforming growth factor β (TGF-β), cluster of differentiation 34 (CD34), and CD68, via picrosirius staining to determine the density of type I and III collagen fibers and via hematoxylin and eosin staining to assess capsule thickness. A Wilcoxon-Mann-Whitney test was used to compare the groups, and a Kruskal-Wallis test was used to compare the subgroups.

RESULTS

Lower α-SMA, TGF-β, CD34 and CD68 immunoexpression was observed in the nanotextured 30- and 60-day subgroups than in the corresponding polyurethane subgroups. In the 90-day subgroup, more pronounced α-SMA and CD34 immunoexpression was observed in the nanotextured group; however, TGF-β and CD68 immunoexpression remained lower. The nanotextured implants showed reduced capsular thickness and greater formation of type I collagen in all the analyzed subgroups.

CONCLUSIONS

Nanotextured implants led to reduced immune and inflammatory reactions compared with polyurethane implants according to all analyzed variables.

Review of silicone surface modification techniques and coatings for antibacterial/antimicrobial applications to improve breast implant surfaces

Silicone implants are widely used in the medical field for plastic or reconstructive surgeries for the purpose of soft tissue issues. However, as with any implanted object, healthcare-associated infections are not completely avoidable. The material suffers from a lack of biocompatibility and is often subject to bacterial/microbial infections characterized by biofilm growth. Numerous strategies have been developed to either prevent, reduce, or fight bacterial adhesion by providing an antibacterial property. The present review summarizes the diverse approaches to deal with bacterial infections on silicone surfaces along with the different methods to activate/oxidize the surface before any surface modifications. It includes antibacterial coatings with antibiotics or nanoparticles, covalent attachment of active bacterial molecules like peptides or polymers. Regarding silicone surfaces, the activation step is essential to render the surface reactive for any further modifications using energy sources (plasma, UV, ozone) or chemicals (acid solutions, sol-gel strategies, chemical vapor deposition). Meanwhile, corresponding work on breast silicone prosthesis is discussed. The latter is currently in the line of sight for causing severe capsular contractures. Specifically, to that end, besides chemical modifications, the antibacterial effect can also be achieved by physical surface modifications by adjusting the surface roughness and topography for instance.

Interactions at engineered graft-tissue interfaces: A review

The interactions at the graft-tissue interfaces are critical for the results of engraftments post-implantation. To improve the success rate of the implantations, as well as the quality of the patients' life, understanding the possible reactions between artificial materials and the host tissues is helpful in designing new generations of material-based grafts aiming at inducing specific responses from surrounding tissues for their own reparation and regeneration. To help researchers understand the complicated interactions that occur after implantations and to promote the development of better-designed grafts with improved biocompatibility and patient responses, in this review, the topics will be discussed from the basic reactions that occur chronologically at the graft-tissue interfaces after implantations to the existing and potential applications of the mechanisms of such reactions in designing of grafts. It offers a chance to bring up-to-date advances in the field and new strategies of controlling the graft-tissue interfaces.

Pro-Fibrotic CD26-Positive Fibroblasts Are Present in Greater Abundance in Breast Capsule Tissue of Irradiated Breasts

BACKGROUND

Breast capsular contracture is a major problem following implant-based breast reconstruction, particularly in the setting of radiation therapy. Recent work has identified a fibrogenic fibroblast subpopulation characterized by CD26 surface marker expression.

OBJECTIVES

This work aimed to investigate the role of CD26-positive fibroblasts in the formation of breast implant capsules following radiation therapy.

METHODS

Breast capsule specimens were obtained from irradiated and nonirradiated breasts of 10 patients following bilateral mastectomy and unilateral irradiation at the time of expander-implant exchange, under institutional review board approval. Specimens were processed for hematoxylin and eosin staining as well as for immunohistochemistry and fluorescence activated cell sorting for CD26-positive fibroblasts. Expression of fibrotic genes and production of collagen were compared between CD26-positive, CD26-negative, and unsorted fibroblasts.

RESULTS

Capsule specimens from irradiated breast tissue were thicker and had greater CD26-postive cells on immunofluorescence imaging and on fluorescence activated cell sorting analysis than did capsule specimens from the nonirradiated breast. Compared with CD26-negative fibroblasts, CD26-positive fibroblasts produced more collagen and had increased expression of the profibrotic genes IL8, TGF-β1, COL1A1, and TIMP4.

CONCLUSIONS

CD26-positive fibroblasts were found in a significantly greater abundance in capsules of irradiated compared with nonirradiated breasts and demonstrated greater fibrotic potential. This fibrogenic fibroblast subpopulation may play an important role in the development of capsular contracture following irradiation, and its targeted depletion or moderation may represent a potential therapeutic option.

LEVEL OF EVIDENCE: 2

Improvement of biohistological response of facial implant materials by tantalum surface treatment

Background

A compact passive oxide layer can grow on tantalum (Ta). It has been reported that this oxide layer can facilitate bone ingrowth in vivo though the development of bone-like apatite, which promotes hard and soft tissue adhesion. Thus, Ta surface treatment on facial implant materials may improve the tissue response, which could result in less fibrotic encapsulation and make the implant more stable on the bone surface. The purposes of this study were to verify whether surface treatment of facial implant materials using Ta can improve the biohistobiological response and to determine the possibility of potential clinical applications.

Methods

Two different and commonly used implant materials, silicone and expanded polytetrafluoroethylene (ePTFE), were treated via Ta ion implantation using a Ta sputtering gun. Ta-treated samples were compared with untreated samples using in vitro and in vivo evaluations. Osteoblast (MG-63) and fibroblast (NIH3T3) cell viability with the Ta-treated implant material was assessed, and the tissue response was observed by placing the implants over the rat calvarium (n = 48) for two different lengths of time. Foreign body and inflammatory reactions were observed, and soft tissue thickness between the calvarium and the implant as well as the bone response was measured.

Results

The treatment of facial implant materials using Ta showed a tendency toward increased fibroblast and osteoblast viability, although this result was not statistically significant. During the in vivo study, both Ta-treated and untreated implants showed similar foreign body reactions. However, the Ta-treated implant materials (silicone and ePTFE) showed a tendency toward better histological features: lower soft tissue thickness between the implant and the underlying calvarium as well as an increase in new bone activity.

Conclusion

Ta surface treatment using ion implantation on silicone and ePTFE facial implant materials showed the possibility of reducing soft tissue intervention between the calvarium and the implant to make the implant more stable on the bone surface. Although no statistically significant improvement was observed, Ta treatment revealed a tendency toward an improved biohistological response of silicone and ePTFE facial implants. Conclusively, tantalum treatment is beneficial and has the potential for clinical applications.

Smooth Prosthesis: Our Experience and Current State of Art in the Use of Smooth Sub-muscular Silicone Gel Breast Implants

BACKGROUND

The objective of this clinical review is to provide an overview of the use of silicone gel-filled breast implants placed in the sub-muscular position, with a focus on complication rates reported for both smooth and textured implants. Furthermore, our experience in this field is also reviewed.

METHODS

MEDLINE, EMBASE, Web of Science, Scopus, the Cochrane Central and Google Scholar databases were reviewed to identify the literature related to smooth breast implants. Each article was reviewed by two independent reviewers to ensure all relevant publications were identified. The literature search identified 98 applicable articles. Of these, just a few articles were found to have a therapeutic level of evidence. The reference lists in each relevant paper were screened manually to include relevant papers not found through the initial search.

RESULTS

Eight articles report the risk of capsular contracture when the breast implants were placed in the sub-muscular position. Six of these articles report a similar rate of capsular contracture in smooth and textured implants. Local complications such as wrinkling, late seroma and double capsules were found to be associated with the use of textured breast implants (4 articles). All articles concerning BIA-ALCL reported a total absence occurring in smooth breast implants. All cases have been associated with textured mammary prostheses.

CONCLUSION

With our expertise in the field and the results of this up-to-date literature review, it can be concluded that there are no significant advantages of using one type of implant surface over the other when placed in the sub-pectoral position.

LEVEL OF EVIDENCE V

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Modulation of Foreign Body Reaction against PDMS Implant by Grafting Topographically Different Poly(acrylic acid) Micropatterns

The surface of poly(dimethylsiloxane) (PDMS) is grafted with poly(acrylic acid) (PAA) layers via surface-initiated photopolymerization to suppress the capsular contracture resulting from a foreign body reaction. Owing to the nature of photo-induced polymerization, various PAA micropatterns can be fabricated using photolithography. Hole and stripe micropatterns ≈100-µm wide and 3-µm thick are grafted onto the PDMS surface without delamination. The incorporation of PAA micropatterns provides not only chemical cues by hydrophilic PAA microdomains but also topographical cues by hole or stripe micropatterns. In vitro studies reveal that a PAA-grafted PDMS surface has a lower proliferation of both macrophages (Raw 264.7) and fibroblasts (NIH 3T3) regardless of the pattern presence. However, PDMS with PAA micropatterns, especially stripe micropatterns, minimizes the aggregation of fibroblasts and their subsequent differentiation into myofibroblasts. An in vivo study also shows that PDMS samples with stripe micropatterns polarized macrophages into anti-inflammatory M2 macrophages and most effectively inhibits capsular contracture, which is demonstrated by investigation of inflammation score, transforming-growth-factor-β expression, number of macrophages, and myofibroblasts as well as the collagen density and capsule thickness.

The Collagenase of the Bacterium Clostridium histolyticum in the Treatment of Irradiation-Induced Capsular Contracture

BACKGROUND

Irradiation therapy is an important pillar in the treatment of breast cancer. However, it can trigger capsular fibrosis, the most significant complication of implant-based breast reconstruction. As collagen is the main component of fibrotic capsules, the collagenase of the bacterium Clostridium histolyticum poses a potential treatment option for this pathological condition.

METHODS

Thirty-six rats received miniature silicone implants on their backs. On day 1, the implant sites of two groups were irradiated with 10 Gy. On day 120, one irradiated group received collagenase injections into the implant pockets (n = 12). Non-irradiated (n = 12) and irradiated capsules (n = 12) were injected with plain solvent solution serving as controls. Data were analyzed by means of in vivo imaging, histology, immunohistochemistry and gene expression analysis.

RESULTS

Compared with both controls, the injection of collagenase led to significantly thinner capsules. This was verified by in vivo imaging and histology. Although irradiation provoked alterations in capsule collagen structure and vessel wall thickness, the application of collagenase resulted in a significant reduction of collagen density. This was accompanied by an up-regulation of VEGF-A gene expression. Of note, hematoma formation inside the implant pocket occurred in two cases after collagenase injection.

CONCLUSIONS

The collagenase of the bacterium Clostridium histolyticum is effective in degrading irradiation-induced capsular fibrosis around silicone implants. Hematoma formation occurred most likely because of irradiation-induced alterations in vessel wall architecture and capsule vascularization. Further studies need to be performed to address the clinical safety of this novel treatment option.

A review of data in medical request and the patient questionnaire for magnetic resonance evaluation of silicone breast implants

Objective

To analyze the quality and quantity of data in the questionnaires and in request forms for magnetic resonance imaging.

Methods

This retrospective study was conducted with data from 300 medical records. The research used the following data from the questionnaires: patient age, reason for the magnetic resonance imaging, reason for placing the breast implant, report of any signs or symptoms, time elapsed since surgery to place the current breast implant, replacement implant surgery, chemotherapy, and/or radiation therapy treatments. From the magnetic resonance imaging request forms, information about the breast implant, the implant placement surgery, patient clinical information and ordering physician specialty were verified.

Results

The mean age of patients was 48.8 years, and the mean time elapsed since breast implant surgery was 5 years. A total of 60% of women in the sample were submitted to aesthetic surgery, while 23.7% were submitted to chemotherapy and/or radiation therapy. In the request forms, 23.7% of physicians added some piece of information about the patient, whereas 2.3% of them informed the type of implant and 5.2% informed about the surgery.

Conclusion

The amount of information in the magnetic resonance imaging request forms is very limited, and this may hinder quality of radiological reports. Institutional and technological measures should be implemented to encourage the requesting physicians and radiologists to share information.

Long-Term Effects of the Collagenase of the Bacterium Clostridium histolyticum for the Treatment of Capsular Fibrosis After Silicone Implants

BACKGROUND

Capsular contracture remains the most frequent long-term complication after augmentation mammoplasty with silicone implants. Thereby, the main part of the fibrotic capsule is collagen. The collagenase of the bacterium Clostridium histolyticum is approved for the treatment of fibrotic diseases and has been demonstrated to be effective for capsular fibrosis treatment in the short term. However, long-term effectiveness is currently unknown but mandatory for clinical utilization.

MATERIALS AND METHODS

Forty-eight rats received miniature silicone implants and an injection with either collagenase (treatment group) or plain solvent solution (control group) 120 days post insertion. Ten and 60 days after the injections, the rats underwent 7-Tesla magnetic resonance imaging (MRI) and high-resolution ultrasound (HR-US). Capsule tissue was harvested, and capsule thickness and collagen density were evaluated through histology. Furthermore, the expression levels of inflammatory (CD68, IL4, IL10, IL12, IL13), pro-, and anti-fibrotic (TGFb1, TGFb3, Smad3, Col1-4) genes were analyzed using qRT-PCR.

RESULTS

On days 10 and 60 after injection of collagenase, histology showed that capsule thickness was significantly reduced in the treatment group when compared with the control (p < 0.05). Thickness measurements were verified by MRI and HR-US analysis. Skin perforation occurred in two cases after collagenase injection. The initial up-regulation of pro-fibrotic and inflammatory genes 10 days after collagenase injection did not persist in the long term. Contrarily, on day 60, a slight trend towards lower expression levels with a significant down-regulation of TGFb3 was detected in the treatment group.

CONCLUSION

The collagenase of the bacterium C. histolyticum effectively degrades capsular fibrosis around silicone implants with stable outcomes throughout 60 days post injection. Skin perforation and adequate and uniform drug distribution within the implant pocket are issues that need to be addressed. Further studies are warranted to clarify whether collagenase injections have the potential to become a viable treatment option for capsular contracture.

NO LEVEL ASSIGNED

This journal requires that authors 46 assign a level of evidence to each article. For a full 47 description of these Evidence-Based Medicine ratings, 48 please refer to the Table of Contents or the online 49 Instructions to Authors. www.springer.com/00266 .

Simvastatin Reduces Capsular Fibrosis around Silicone Implants

Capsular fibrosis and contracture occurs in most breast reconstruction patients who undergo radiotherapy, and there is no definitive solution for its prevention. Simvastatin was effective at reducing fibrosis in various models. Peri-implant capsular formation is the result of tissue fibrosis development in irradiated breasts. The purpose of this study was to examine the effect of simvastatin on peri-implant fibrosis in rats. Eighteen male Sprague-Dawley rats were allocated to an experimental group (9 rats, 18 implants) or a control group (9 rats, 18 implants). Two hemispherical silicone implants, 10 mm in diameter, were inserted in subpanniculus pockets in each rat. The next day, 10-Gy of radiation from a clinical accelerator was targeted at the implants. Simvastatin (15 mg/kg/day) was administered by oral gavage in the experimental group, while animals in the control group received water. At 12 weeks post-implantation, peri-implant capsules were harvested and examined histologically and by real-time polymerase chain reaction. The average capsular thickness was 371.2 μm in the simvastatin group and 491.2 μm in the control group. The fibrosis ratio was significantly different, with 32.33% in the simvastatin group and 58.44% in the control group (P < 0.001). Connective tissue growth factor (CTGF) and transforming growth factor (TGF)-β1 gene expression decreased significantly in the simvastatin group compared to the control group (P < 0.001). This study shows that simvastatin reduces radiation-induced capsular fibrosis around silicone implants in rats. This finding offers an alternative therapeutic strategy for reducing capsular fibrosis and contracture after implant-based breast reconstruction.