Vascular Endothelial Growth Factor Overexpression Positively Modulates the Characteristics of Periprosthetic Tissue of Polyurethane-Coated Silicone Breast Implant in Rats

Biocompatibility of polyurethane-coated breast implants: A histological comparison of implant capsules

BACKGROUND

Biocompatibility describes the influence of materials on their biological environment. Implant material in the human body can cause a foreign body reaction and the formation of a capsule around the foreign material. Since capsular formation is the most frequent issue after breast-implant insertion, knowledge and awareness of biocompatibility is crucial, especially since worldwide, breast augmentation continues to be the most popular plastic surgery, with over 1.6 million procedures performed in 2020, according to surveys by the International Society of Aesthetic Plastic Surgery (ISAPS).

MATERIAL AND METHODS

This study includes 80 capsular samples of female patients who underwent revision surgery after breast-implant insertion at the University Hospital Regensburg. Capsules of breast implants with different surface structures (smooth, textured and polyurethane-coated) and shapes (round-shaped, anatomically-shaped) were analyzed histologically after hematoxylin-eosin-staining in respect to capsular thickness and layer formation.

RESULTS

Capsular thickness and layering showed a statistically significant difference between polyurethane-coated and smooth as well as polyurethane-coated and textured implants. Capsules around polyurethane-coated implants presented greater thickness. However, the difference between smooth and textured implants was not statistically significant. Furthermore, the shape of the implants also indicated a statistically significant difference in capsular thickness. Implants of anatomical shape resulted in a thinner capsule than round-shaped breast-implants.

CONCLUSION

In conclusion, this study demonstrated a thicker capsule around polyurethane-coated breast implants and no difference in capsular thickness between smooth and textured breast implants. Anatomically shaped breast-implants presented a thinner capsule than round shaped breast-implants.

CD248 Regulates Inflammation and Encapsulation in Silicone-Related Capsule Formation

BACKGROUND

Capsular contracture is the most common reason for having a secondary breast implant operation. The failure of the implanted device and discomfort are related to foreign body response, which involves a pathologic encapsulation. An up-regulated expression of CD248 was previously demonstrated to modulate inflammation and fibrosis. The authors hypothesized that CD248 contributes to foreign body reaction and contracture during silicone-stimulated capsule formation.

METHODS

A murine capsular contracture model was established to correlate CD248 with capsular contracture. The timing and site of CD248 expression were characterized by protein analysis and histologic examination. The capsules between wild-type mice and CD248 knockout mice were compared in this model to verify the possible role of CD248 in silicone-related capsule formation.

RESULTS

CD248 was expressed in the peri-silicone implant capsule by stromal fibroblast and perivascular fibroblast. CD248 was overexpressed on day 4 and down to a constant level, but it was still up-regulated through day 21 to day 56 after silicone implantation. The CD248 knockout mice showed a prolonged inflammation period, whereas the wild-type mice developed a thinner but more collagenous capsule.

CONCLUSIONS

In conclusion, an effective murine capsular contracture model was established to study the relationship between CD248 and capsular contracture. CD248 may play a role in inflammation and encapsulation during silicone implantation. CD248 deletion in mice contributed to a loose and irregular collagen bundle in a capsule area, implying a decrease in contracture. Therefore, CD248 could be a potential therapeutic target in capsular contracture.

CLINICAL RELEVANCE STATEMENT

CD248 may play a role in inflammation and encapsulation during silicone implantation. It could be a potential therapeutic target in clinical capsular contracture.

Biomarkers in Primary Focal Segmental Glomerulosclerosis in Optimal Diagnostic-Therapeutic Strategy

Focal segmental glomerulosclerosis (FSGS) involves podocyte injury. In patients with nephrotic syndrome, progression to end-stage renal disease often occurs over the course of 5 to 10 years. The diagnosis is based on a renal biopsy. It is presumed that primary FSGS is caused by an unknown plasma factor that might be responsible for the recurrence of FSGS after kidney transplantation. The nature of circulating permeability factors is not explained and particular biological molecules responsible for inducing FSGS are still unknown. Several substances have been proposed as potential circulating factors such as soluble urokinase-type plasminogen activator receptor (suPAR) and cardiolipin-like-cytokine 1 (CLC-1). Many studies have also attempted to establish which molecules are related to podocyte injury in the pathogenesis of FSGS such as plasminogen activator inhibitor type-1 (PAI-1), angiotensin II type 1 receptors (AT1R), dystroglycan(DG), microRNAs, metalloproteinases (MMPs), forkheadbox P3 (FOXP3), and poly-ADP-ribose polymerase-1 (PARP1). Some biomarkers have also been studied in the context of kidney tissue damage progression: transforming growth factor-beta (TGF-β), human neutrophil gelatinase-associated lipocalin (NGAL), malondialdehyde (MDA), and others. This paper describes molecules that could potentially be considered as circulating factors causing primary FSGS.

Reducing Capsular Contracture Formation in Breast Augmentation with Silicone Implants: Experimental Study on Rats

Silicone implants are frequently used for breast augmentation and reconstruction. However, late complication, such as capsular contracture, remain the most important side effect. In this study we compare different methods for reducing the inflammatory reaction around the silicone implant by introducing one microtextured breast implant in wistar rats. The rats were dividing in 4 groups: the first one was the control group that received untreated implant; in the second we used silicone implants impregnated with rifampin solution, the third one had implant combined with intramuscular dexamethasone injection and the last one had silicone implant associated with autologous centrifuged fat introduced in the implant pocket. The implants and the capsular tissue surrounding were removed after eight weeks. Capsule samples were submitted to histological evaluations. The present study demonstrated that fat grafting may have a role in reducing and preventing capsular contractures after breast augmentation with silicone implants by decreasing the inflammatory process.

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.

Expression of NF-κB-p65 and α-SMA in the Study of Capsules formed by Surface Textured Implants Versus Foam Covered Silicone Implants in a Rat Model

BACKGROUND

We aimed to compare inflammatory and intercellular transcription responses induced by surface textured (ST) implants versus foam covered (FC) silicone implants placed on the dorsal aspect of rats.

METHODS

We utilized 80 female rats of the Wistar lineage. The rats were divided into four subgroups of 20 with one type of implant placed in the dorsum per rat. Analysis was carried out on peri-implant capsules at 90 d and at 180 d post-surgery with microscopic evaluation of inflammatory and immuno-histochemical response of NF-κB-p65 and α-SMA in fibroblasts. This study was carried out at the Evangelical Faculty of Parana and at the Ivo Pitanguy Institute, Brazil in 2015.

RESULTS

The FC exhibited higher levels of acute and chronic inflammation on evaluation in both time frames. The capsule surrounding the ST implants was significantly thicker with well-organized collagen fibres. NFκB-p65 expression in the capsule surrounding the FC implant was more pronounced. There was higher and more significant α-SMA expression in the capsules of the surface textured (ST) silicone implants compared to the foam-covered (FC) silicone implants.

CONCLUSION

Activation of NFκB-p65 plays a key role in the evolution of capsule formation and maintenance of inflammation by regulating the healing process. Similarly, higher and more prolonged levels of inflammation (increased NF-κB-p65 results in increased inflammation) and lower α-SMA (higher α-SMA is protective against capsular contracture) did not directly translate to a thicker capsule and ultimately, capsular contracture in foam covered silicone implants.

Silicone Implants Immobilized with Interleukin-4 Promote the M2 Polarization of Macrophages and Inhibit the Formation of Fibrous Capsules

Breast augmentations with silicone implants can have adverse effects on tissues that, in turn, lead to capsular contracture (CC). One of the potential ways of overcoming CC is to control the implant/host interaction using immunomodulatory agents. Recently, a high ratio of anti-inflammatory (M2) macrophages to pro-inflammatory (M1) macrophages has been reported to be an effective tissue regeneration approach at the implant site. In this study, a biofunctionalized implant was coated with interleukin (IL)-4 to inhibit an adverse immune reaction and promoted tissue regeneration by promoting polarization of macrophages into the M2 pro-healing phenotype in the long term. Surface wettability, nitrogen content, and atomic force microscopy data clearly showed the successful immobilization of IL-4 on the silicone implant. Furthermore, in vitro results revealed that IL-4-coated implants were able to decrease the secretion of inflammatory cytokines (IL-6 and tumor necrosis factor-α) and induced the production of IL-10 and the upregulation of arginase-1 (mannose receptor expressed by M2 macrophage). The efficacy of this immunomodulatory implant was further demonstrated in an in vivo rat model. The animal study showed that the presence of IL-4 diminished the capsule thickness, the amount of collagen, tissue inflammation, and the infiltration of fibroblasts and myofibroblasts. These results suggest that macrophage phenotype modulation can effectively reduce inflammation and fibrous CC on a silicone implant conjugated with IL-4.

Histological evaluation of capsules formed by texturized silicone implants with and without polyester mesh coverage (Parietex®). A study on female rats

Purpose

To evaluate capsules formed by microtextured silicone implants with and without Parietex® mesh coverage histologically.

Methods

Sixty Wistar rats were divided in two groups (meshed and unmeshed). Each group was, then, divided into two subgroups for evaluation at 30 and 90 days. Capsules were analyzed based on hematoxylin and eosin (HE) and picrosirius staining.

Results

The number of fibroblasts, neutrophils and macrophages was similar among all subgroups. There was a higher lymphocyte reaction in the 30-day meshed group (p = 0.003). Giant cell reaction, granulation tissue and neoangiogenesis were similar among the subgroups. Synovial metaplasia was milder at 90-day in the unmeshed (p = 0.002) and meshed group (p < 0.001). Capsular thickness was significantly greater in the meshed samples (30-day p < 0.001 and 90-day p < 0.001). There was a similar amount of collagen types I and III in both groups.

Conclusions

The mesh-covered implants produced capsules similar to the microtextured ones when analyzing inflammatory variables. Synovial metaplasia was milder at 90 than at 30 days, and the capsular thickness was significantly greater in the meshed group. A similar amount of collagen types I and III was observed. Due to these characteristics, the mesh coverage did not seem to significantly affect the local inflammatory activity.

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.

Does methylene blue increases capsular contracture in immediate breast reconstruction with silicone implant? An experimental study

Recently, most of the immediate breast reconstructions following mastectomy are being carried out with the use of silicone implants. In these patients, methylene blue is being used for the detection of sentinel lymph nodes. This experimental study was performed to determine the effect of methylene blue on capsular contracture around breast implants. Thirty-two Sprague Dawley rats were divided into 4 groups. Custom made silicone blocks were placed on the back of animals. In group 1, the incision was closed without performing any additional procedure. In group 2 (control), 0.1 mL of 0.9% normal saline was instilled into the pocket. Group 3 and 4 (study groups) received 0.1 and 0.2 mL of 1% methylene blue, respectively. On postoperative day 60, implants and capsular tissue were extracted. Capsule formation was evaluated both macroscopically and microscopically. The histological evaluation included capsule thickness, inflammation, neovascularization, and fibrosis gradients. Regarding capsule thickness, there were statistically significant differences between groups 1-3, 1-4, 2-3, and 2-4. Although there were more moderate and severe inflammation gradients in groups III and IV, there was no significant difference regarding inflammation severity between control and study groups. In respect of vascular proliferation, there was a statistically significant difference between control and study groups. Similarly, fibrosis gradients were higher in both groups 3 and 4. The study showed that the injection of methylene blue around silicone implants enhanced the formation of capsular contracture. In this case, the degree of contracture was independent of the dose given. Abbreviations: CC: capsular contracture; MM: methylene blue; SLNB: sentinel lymph node biopsy; NS: normal saline; H&E: hematoxylin and eosin; D: dorsal; V: ventral; L: lateral; n: frequency.

Covalently Grafted 2-Methacryloyloxyethyl Phosphorylcholine Networks Inhibit Fibrous Capsule Formation around Silicone Breast Implants in a Porcine Model

The surface of human silicone breast implants is covalently grafted at a high density with a 2-methacryloyloxyethyl phosphorylcholine (MPC)-based polymer. Addition of cross-linkers is essential for enhancing the density and mechanical durability of the MPC graft. The MPC graft strongly inhibits not only adsorption but also the conformational deformation of fibrinogen, resulting in the exposure of a buried amino acid sequence, γ377-395, which is recognized by inflammatory cells. Furthermore, the numbers of adhered macrophages and the amounts of released cytokines (MIP-1α, MIP-1β, IL-8, TNFα, IL-1α, IL-1β, and IL-10) are dramatically decreased when the MPC network is introduced at a high density on the silicone surface (cross-linked PMPC-silicone). We insert the MPC-grafted human silicone breast implants into Yorkshire pigs to analyze the in vivo effect of the MPC graft on the capsular formation around the implants. After 6 month implantation, marked reductions of inflammatory cell recruitment, inflammatory-related proteins (TGF-β and myeloperoxidase), a myoblast marker (α-smooth muscle actin), vascularity-related factors (blood vessels and VEGF), and, most importantly, capsular thickness are observed on the cross-linked PMPC-silicone. We propose a mechanism of the MPC grafting effect on fibrous capsular formation around silicone implants on the basis of the in vitro and in vivo results.

Efficient reduction of fibrous capsule formation around silicone breast implants densely grafted with 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers by heat-induced polymerization

This article presents the efficacy of heat-induced MPC-grafting against excessive fibrous capsule formation and related inflammation in tissues surrounding silicone breast implants inserted in a pig model.

Smooth Muscle Alpha Actin Immunoexpression (α-Sma) and CD-117 Antibody (C-Kit) in Capsules Formed by Polyurethane Foam-Coated Silicone Implants and with Textured Surface: A Study on Rats

BACKGROUND

One of the undesirable complications that might occur after breast augmentation with silicone implants is capsular contracture. In its etiology, the relations between mast cells and myofibroblasts play an important role in collagen synthesis. Mast cells are able to activate fibroblasts into myofibroblasts, through paracrine secretions, inducing collagen production. The objectives of this study were to analyze the myofibroblast concentration through the α-SMA immunomarker and evaluate the intensity of mast cell expression against the C-Kit immunomarker.

MATERIAL AND METHOD

Sixty-four Wistar rats were used, divided into two groups (polyurethane foam and textured surface) with 32 animals in each. The animals received silicone implants on the back, below the panniculus carnosus, and after the determined period, they were killed and the capsules formed around the implants were studied. The capsules were analyzed employing the immunohistochemical technique, with the α-SMA and C-Kit immunomarkers in subgroups of 30, 50, 70 and 90 days.

RESULTS

The myofibroblast concentration was higher in the polyurethane group when compared to the textured group (30 days p = 0.105; 50 days p = 0.247; 70 days p = 0.014 and 90 days p = 0.536). The intensity of mast cell expression was more pronounced in the polyurethane group when compared to the textured group (30 days p = 0.798; 50 days p = 0.537; 70 days p = 0.094 and 90 days p = 0.536).

CONCLUSIONS

Polyurethane-coated implants induced higher concentrations of myofibroblasts and higher expression of mast cells, when compared to the textured surface implants.

NO LEVEL ASSIGNED

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 .

Thermogel Loaded with Low-Dose Paclitaxel as a Facile Coating to Alleviate Periprosthetic Fibrous Capsule Formation

Medical-grade silicones as implants have been utilized for decades. However, the postoperative complications, such as capsular formation and contracture, have not yet been fully controlled and resolved. The aim of the present study is to elucidate whether the capsular formation can be alleviated by local and sustained delivery of low-dose paclitaxel (PTX) during the critical phase after the insertion of silicone implants. A biocompatible and thermogelling poly(lactic acid- co-glycolic acid)- b-poly(ethylene glycol)- b-poly(lactic acid- co-glycolic acid) triblock copolymer was synthesized by us. The micelles formed by the amphiphilic polymers in water could act as a reservoir for the solubilization of PTX, a very hydrophobic drug. The concentrated polymer aqueous solution containing PTX exhibited a sol-gel transition upon heating and formed a thermogel depot at body temperature. In vitro release tests demonstrated that the entrapped microgram-level PTX displayed a sustained release manner up to 57 days without a significant initial burst effect. Customized silicone implants coated with the PTX-loaded thermogels at various drug concentrations were inserted into the pockets of the subpanniculus carnosus plane of rats. The histological observations performed 1 month postoperation showed that the sustained release of PTX with an appropriate dose significantly reduced the peri-implant capsule thickness, production and deposition of collagen, and expression of contracture-mediating factors compared with bare silicone implants. More importantly, such an optimum dose had an excellent repeatability for the suppression of the capsular formation. Therefore, this study provides a strategic foothold regarding the sustained release of low-dose PTX to alleviate fibrotic capsule formation after implantation, and the microgram-level PTX-loaded thermogel holds great potential as an "all-purpose antifibrosis coating" for veiling the surfaces of various implantable medical devices.

Early fragmentation of polyester urethane sheet neither causes persistent oxidative stress nor alters the outcome of normal tissue healing in rat skin

Silicone breast implant is associated with complications inherent to the surgical procedure. Prosthesis coating with polyurethane, however, commonly reduces the incidence of such complications. In this paper, the authors evaluated the inflammatory histomorphometric profile and oxidative damage associated to the implant of polyester urethane sheets. Forty-eight Wistar rats were divided into Sham or polyester urethane groups (n = 8/group) and underwent a polyester urethane implant in the dorsal skinfold. Tissue samples were collected on days seven, 30, and 90 after surgery and subjected to histomorphometric analysis and biochemical tests. Results were analyzed by one-way ANOVA (p ≤ 0.05). Peri-implant tissue samples exhibited characteristic inflammatory response associated with the biomaterial, with increased vascularization on day seven and augmented levels of IL1-b and TNF-a after 30 days. Peri-implant fibrocystic population was small on day seven, but increased considerably after 90 days. A rise in the carbonyl group levels of skin samples in the polyester urethane group was observed on day seven. Findings suggest that polyester urethane sheets undergo biodegradation at an early stage after implantation, followed by increased vascularity and microencapsulation of biomaterial fragments, without persistent oxidative damage. Fiber arrangement inside the collagen matrix results in a fibrotic scar because of polyester urethane degradation.

The Role of Periostin in Capsule Formation on Silicone Implants

Although silicone implants are widely used in breast and other reconstructive surgeries, the limited biocompatibility of these materials leads to severe complications, including capsular contracture. Here, we aimed to clarify the relationship between periostin and the process of capsule formation after in vivo implantation. Seven-week-old wild-type (WT) C57BL/6 mice and periostin-deficient mice were used. Round silicone implants were inserted into a subcutaneous pocket on the dorsum of the mice. After 8 weeks, the fibrous capsule around the implant was harvested and histologically examined to estimate capsular thickness and the number of inflammatory cells. Additionally, immunohistochemical analysis (periostin, α-SMA, and collagen type I) and western blotting (CTGF, TGF-β, VEGF, and MPO) were performed for a more detailed analysis of capsule formation. The capsules in periostin-knockout mice (PN-KO) were significantly thinner than those in WT mice. PN-KO mice showed significantly lower numbers of inflammatory cells than WT mice. Fibrous tissue formation markers (α-SMA, periostin, collagen type I, and CTGF) were significantly reduced in PN-KO mice. We also confirmed that inflammatory reaction and angiogenesis indicators (TGF-β, MPO, and VEGF) had lower expression in PN-KO mice. Inhibition of periostin could be important for suppressing capsule formation on silicone implants after in vivo implantation.

Histological evaluation of capsules formed by silicon implants coated with polyurethane foam and with a textured surface in rats

PURPOSE:

To assess the capsules formed by silicone implants coated with polyurethane foam and with a textured surface.

METHODS:

Sixty-four Wistar albinus rats were divided into two groups of 32 each using polyurethane foam and textured surface. The capsules around the implants were analyzed for 30, 50, 70 and 90 days. Were analyzed the following parameters: foreign body reaction, granulation tissue, presence of myofibroblasts, neoangiogenesis, presence of synovial metaplasia, capsular thickness, total area and collagen percentage of type I and III, in capsules formed around silicone implants in both groups.

RESULTS:

The foreign body reaction was only present in the four polyurethane subgroups. The formation of granulation tissue and the presence of myofibroblasts were higher in the four polyurethane subgroups. Regarding to neoangiogenesis and synovial metaplasia, there was no statistical difference between the groups. Polyurethane group presented (all subgroups) a greater capsule thickness, a smaller total area and collagen percentage of type I and a higher percentage area of type III, with statistical difference.

CONCLUSION:

The use of polyurethane-coated implants should be stimulated by the long-term results in a more stable capsule and a lower incidence of capsular contracture, despite developing a more intense and delayed inflammatory reaction in relation to implants with textured surface.

Alloplastic Augmentation of the Asian Face: A Review of 215 Patients

BACKGROUND

Asian aesthetic surgery has become increasingly popular over the last decade, especially augmentation of characteristically flattened facial features. Alloplastic implants are an option for facial augmentation, however many avoid their use due to concerns for morbidity associated with their use.

OBJECTIVES

To validate our hypothesis that when used properly, alloplastic implants have a low complication profile and provides excellent aesthetic results.

METHODS

A retrospective review was performed of all Asian patients undergoing alloplastic facial augmentation between 2009 and 2013 by a single surgeon. Procedures included augmentation of the forehead, nasal dorsum, midface, and chin. Charts were reviewed for outcomes including infection, extrusion, malposition, and operative revision.

RESULTS

Two hundred and fifteen patients had 243 implants placed. Of 141 nasal augmentations, there were 2 infections (1.4%), 1 extrusion (0.7%), 7 malpositions (4.9%), and 16 revisions (11.3%), 5 for malposition, 2 for contour irregularity, and 9 for aesthetic change. Augmentation genioplasty was performed in 40 patients with 1 malposition (2.5%) and 6 revisions (15%), 4 for under-correction and 2 for aesthetic change. Thirty-one midface and 31 forehead augmentations were performed without complications. One patient (3.2%) had forehead implant removal for aesthetic change. Overall infection and extrusion rates were 0.8% and 0.4%, respectively.

CONCLUSIONS

By utilizing surgical techniques such as creation of a precise sub-periosteal pocket, placing the implant away from the incision site, and leaving well-vascularized soft tissue coverage under minimal tension, alloplastic implants can safely be used as a first-line option for Asian facial augmentation.

LEVEL OF EVIDENCE

4 Therapeutic.

Comparative study of membranes induced by PMMA or silicone in rats, and influence of external radiotherapy

The induced membrane technique has been used for long bone defect reconstruction after traumatism. One of the major drawbacks of this method is the difficult removal of the polymethyl methacrylate spacer after membrane formation. We therefore replaced the stiff PMMA spacer with a semi-flexible medical grade silicone spacer. This study aimed to compare subcutaneously formed membranes, induced by PMMA and silicone, in the irradiated or not irradiated areas within 28 rats that received the spacers. Histological analysis was performed to evaluate the composition of the membrane and to quantify the amount of vessels. Histomorphometric measurements were used to evaluate membranes' thickness, while fibrosis and inflammation were scored. The expression of VEGF and BMP-2 in lysates of the crushed membranes was determined by Western blotting. ALP expression was analyzed in HBMSC cultures in contact with the same lysates. Non-irradiated membranes induced by the two spacer types were non-inflammatory, fibrous and organized in layers. Irradiation did not change the macroscopic properties of membranes that were induced by silicone, while PMMA induced membranes were sensitive to the radiotherapy, resulting in thicker, strongly inflammatory membranes. Irradiated membranes showed an overall reduced osteogenic potential. Medical grade silicone is safe for the use in radiotherapy and might therefore be of great advantage for patients in need of cancer treatment.

Biomedical implant capsule formation: lessons learned and the road ahead

Clinicians and investigators have been implanting biomedical devices into patients and experimental animals for centuries. There is a characteristic complex inflammatory response to the presence of the biomedical device with diverse cell signaling, followed by migration of fibroblasts to the implant surface and the eventual walling off of the implant in a collagen capsule. If the device is to interact with the surrounding tissues, the collagen envelope will eventually incapacitate the device or myofibroblasts can cause capsular contracture with resulting distortion, migration, or firmness. This review analyzes the various tactics used in the past to modify or control capsule formation with suggestions for future investigative approaches.

Alleviation of capsular formations on silicone implants in rats using biomembrane-mimicking coatings

Despite their popular use in breast augmentation and reconstruction surgeries, the limited biocompatibility of silicone implants can induce severe side effects, including capsular contracture - an excessive foreign body reaction that forms a tight and hard fibrous capsule around the implant. This study examines the effects of using biomembrane-mimicking surface coatings to prevent capsular formations on silicone implants. The covalently attached biomembrane-mimicking polymer, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), prevented nonspecific protein adsorption and fibroblast adhesion on the silicone surface. More importantly, in vivo capsule formations around PMPC-grafted silicone implants in rats were significantly thinner and exhibited lower collagen densities and more regular collagen alignments than bare silicone implants. The observed decrease in α-smooth muscle actin also supported the alleviation of capsular formations by the biomembrane-mimicking coating. Decreases in inflammation-related cells, myeloperoxidase and transforming growth factor-β resulted in reduced inflammation in the capsular tissue. The biomembrane-mimicking coatings used on these silicone implants demonstrate great potential for preventing capsular contracture and developing biocompatible materials for various biomedical applications.

The effect of a bacterial contamination on the formation of capsular contracture with polyurethane breast implants in comparison with textured silicone implants: an animal study

INTRODUCTION

One of the most common complications following breast augmentation is capsular contracture. The subclinical infection of the implant is often considered to be one of the main risk factors. It is believed that polyurethane (PU) implants, because of their larger foam-like surface, have lower capsular contracture rates due to better tissue integration. It remains unclear if bacterial contamination and biofilm formation result in higher capsular contracture rates under the condition of the increased surface of PU implants compared to textured silicone-gel implants. The effect of this bacterial contamination was examined in an animal-based study.

METHODS

A total of 80 mini implants (40 textured silicone-gel implants and 40 PU implants) were implanted in the dorsum of female Wistar rats. In each group, 20 implants were inoculated before implantation with a standard amount of Staphylococcus epidermidis. Capsules and implants were explanted after 60 days, followed by double-blind histological, immunohistochemical, and microbiological examinations.

RESULTS

Macroscopic separation of the total capsule in the textured implant group was possible whereas the growth of surrounding tissue into the foam structure of PU implants made separation in that group difficult. After contamination, a thicker capsule could be observed in both groups without significant differences. Histologically, capsules around PU implants showed significantly lower expression of parallel myofibrils. We were able to describe a significant higher infiltration with inflammatory cells in capsules around PU implants both with and without contamination. Microbiological investigations revealed positive growth of S. epidermidis around one PU implant without related signs of capsular contracture.

DISCUSSION

This study demonstrates that aside from the surface of silicone implants, bacterial contamination has major impact on the architecture of capsule formation. In our study, we were able to demonstrate that bacterial contamination leads to a thicker capsule and an increased tissue reaction with a higher amount of inflammatory cells. However, a resulting bacterial infection was only demonstrated in one case and had an insignificant influence on capsule architecture. The observed inflammatory reaction around PU implants was observed as a nonbacterial, granulomatose foreign body reaction.

EBM RATING

Level I: Evidence obtained from at least one properly designed randomized controlled trial.

Breast implant capsule flaps and grafts: a review of the literature

BACKGROUND

A breast implant capsule forms as a physiological response to the foreign material. Over the past decades, authors started to consider the breast implant capsule as a new source of tissue, thus describing several capsular flaps and grafts. The aim of this article is to provide an overview of the applications and indications for the use of capsular tissue flaps and grafts in reconstructive and aesthetic surgery.

METHODS

A review of the literature on breast implant capsule grafts and flaps was conducted. The reported surgical techniques were described and compared for indications and complications. The studies were evaluated and compared for number of patients and follow-up.

RESULTS

The search yielded a total of 21 citations. Patient population was reported in 11 studies for capsular flaps and 2 articles for capsular grafts. Between 1997 and 2012, a total of 74 patients underwent surgery with the use of capsular tissue. Among these, 60 patients had a capsular flap (81 %) and 14 (19 %) had a capsular graft. Complications were experienced in 5 patients (6.7 %).

CONCLUSIONS

Capsular flaps and grafts are indicated mainly to address breast implant-related problems. The breast implant capsule represents a versatile and reliable source of tissue for both aesthetic and reconstructive surgery.

NO LEVEL ASSIGNED

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 http://www.springer.com/00266.

The effect of botulinum neurotoxin type A on capsule formation around silicone implants: the in vivo and in vitro study

This study confirms that botulinum neurotoxin type A (BoNT-A) decreases capsular contracture and elucidates a possible mechanism. Silicone blocks were implanted subcutaneously in 20 mice. The experimental groups received BoNT-A (1, 2·5 or 5 U) instilled into the subcutaneous pocket. After 30 days, periprosthetic capsules were harvested and evaluated. The effect of BoNT-A on the differentiation of human dermal fibroblasts to myofibroblasts in culture was examined by Western blot analysis. Changes in transforming growth factor-beta1 (TGF-β1) expression in cultured fibroblasts were determined by enzyme-linked immunosorbent assay (ELISA). In in vivo study, the thickness of capsules (P < 0·05) and the number of alpha-smooth muscle actin (α-SMA)(+) cells in capsules (P < 0·05) were significantly decreased in the experimental groups. TGF-β1 was significantly underexpressed in the experimental groups (P < 0·05). In in vitro study, BoNT-A did not significantly affect fibroblast viability. Western blot analysis showed that α-SMA protein levels were significantly decreased in the experimental groups (P < 0·05). Based on ELISA, the amount of TGF-β1 was significantly decreased in the experimental groups (P < 0·05), especially cells treated with a high dose of BoNT-A (P < 0·001). This study confirms that BoNT-A prevents capsular formation around silicone implants, possibly by blocking TGF-β1 signalling and interrupting the differentiation of fibroblasts to myofibroblasts.

Renal biopsy: use of biomarkers as a tool for the diagnosis of focal segmental glomerulosclerosis

Focal segmental glomerulosclerosis (FSGS) is a glomerulopathy associated with nephrotic syndrome and podocyte injury. FSGS occurs both in children and adults and it is considered the main idiopathic nephrotic syndrome nowadays. It is extremely difficult to establish a morphological diagnosis, since some biopsies lack a considerable quantifiable number of sclerotic glomeruli, given their focal aspect and the fact that FSGS occurs in less than half of the glomeruli. Therefore, many biological molecules have been evaluated as potential markers that would enhance the diagnosis of FSGS. Some of these molecules and receptors are associated with the pathogenesis of FSGS and have potential use in diagnosis.

A novel vascular clip design for the reliable induction of 2-kidney, 1-clip hypertension in the rat

The 2-kidney, 1-clip (2K1C) model has provided many insights into the pathogenesis of renovascular hypertension. However, studies using the 2K1C model often report low success rates of hypertension, with typical success rates of just 40-60%. We hypothesized that these low success rates are due to fundamental design flaws in the clips traditionally used in 2K1C models. Specifically, the gap widths of traditional silver clips may not be maintained during investigator handling and these clips may also be easily dislodged from the renal artery following placement. Therefore, we designed and tested a novel vascular clip possessing design features to maintain both gap width and position around the renal artery. In this initial study, application of these new clips to the left renal artery produced reliable and consistent levels of hypertension in rats. Nine-day application of clips with gap widths of 0.27, 0.25, and 0.23 mm elicited higher mean arterial blood pressures of 112 ± 4, 121 ± 6, and 135 ± 7 mmHg, respectively (n = 8 for each group), than those of sham-operated controls (95 ± 2 mmHg, n = 8). Moreover, 8 out of 8 rats in each of the 0.23 and 0.25 mm 2K1C groups were hypertensive, whereas 7 out of 8 rats in the 0.27 mm 2K1C group were hypertensive. Plasma renin concentrations were also increased in all 2K1C groups compared with sham-operated controls. In summary, this novel clip design may help eliminate the large degree of unreliability commonly encountered with the 2K1C model.

Maximizing the use of precapsular space and the choice of implant type in breast augmentation mammaplasty revisions: review of 49 consecutive procedures and patient satisfaction assessment

BACKGROUND

Capsular contracture, implant malposition and displacement, breast asymmetry, improper contour, and symmastia may compromise the aesthetic outcome of breast augmentation and usually require surgical correction. Correction of these deformities may be achieved by accommodating a new implant in a novel pocket created in the precapsular space in either the subpectoral or subglandular plane. This article describes a modality to correct adverse results of augmentation mammaplasty and evaluates patient satisfaction.

METHODS

Precapsular reaugmentation was performed in 49 patients who underwent cosmetic breast surgery revisions from 2004 to 2009. All patients had previously received breast implants but complained of implant malposition and dislocation, implant size change, capsular contracture, and symmastia. A precise neoprecapsular pocket was developed above the old anterior implant capsule wall, with dissection limited to create only the space necessary for proper placement of the implant. Patients were evaluated for resolution of symptoms, satisfaction, and complications.

RESULTS

Implant malposition and rippling, capsular contracture, breast asymmetry, and symmastia were the most common complaints from the first augmentation. Nineteen women had subpectoral implant placement, 12 had subglandular, and the rest (n = 18) had "dual-plane" location of their implants. We used textured silicone implants in 17 cases and polyurethane-coated prostheses in the remaining 32 cases. The average follow-up time was 24.1 months. Breast augmentation-related complications had resolved in all patients without any recurrence to date. The overall complication rate was very low and patient satisfaction with this procedure was extremely high.

CONCLUSION

The creation of a neoprecapsular pocket combined in peculiar cases with the placement of polyurethane-coated implants is a versatile option that offers an effective one-stage solution for the correction of cosmetic mammaplasty-induced deformities.