Pirfenidone prevents capsular contracture after mammary implantation

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.

Novel, Blended Polymeric Microspheres for the Controlled Release of Methotrexate: Characterization and In Vivo Antifibrotic Studies

Low dose methotrexate (MTX) is known to effectively decrease type I collagen production in dermal fibroblasts, while increasing the matrix metalloproteinase-1 (MMP-1) production in vitro. For in vivo use as an antifibrotic agent on wounds, a linear and extended controlled release formulation of MTX is required. The objective of this study was to optimize the fabrication of MTX-loaded polymeric microspheres with such properties, and to test the efficacy for the prevention of fibrosis in vivo. Poly lactic-co-glycolic acid (PLGA), Poly (L-lactic acid) (PLLA) and the diblock copolymer, methoxypolyethylene glycol-block-poly (D, L-lactide) (MePEG-b-PDLLA), were used to fabricate microspheres, which were then characterized in terms of size, drug encapsulation efficiency, and in vitro release profiles. The optimized formulation (PLGA with diblock copolymer) showed high drug encapsulation efficiency (>80%), low burst release (~10%) and a gradual release of MTX. The amphipathic diblock copolymer is known to render the microsphere surface more biocompatible. In vivo, these microspheres were effective in reducing fibrotic tissue which was confirmed by quantitative measurement of type I collagen and α-smooth muscle actin expression, demonstrating that MTX can be efficiently encapsulated in PLGA microspheres to provide a delayed, gradual release in wound beds to reduce fibrosis in vivo.

Exploring the Overlooked Roles and Mechanisms of Fibroblasts in the Foreign Body Response

Significance: Foreign body response (FBR), wherein a fibrotic capsule forms around an implanted structure, is a common surgical complication that often leads to pain, discomfort, and eventual revision surgeries. Although believed to have some mechanistic overlap with normal wound healing, much remains to be discovered about the specific mechanism by which this occurs. Recent Advances: Current understanding of FBR has focused on the roles of the immune system and the biomaterial, both major contributors to FBR. However, another key player, the fibroblast, is often overlooked. This review summarizes key contributors of FBR, focusing on the roles of fibroblasts. As much remains to be discovered about fibroblasts' specific roles in FBR, we draw on current knowledge of fibroblast subpopulations and functions during wound healing. We also provide an overview on candidate biomaterials and signaling pathways involved in FBR. Critical Issues and Future Directions: While the global implantable medical devices market is considerable and continues to appreciate in value, FBR remains one of the most common surgical implant complications. In parallel with the continued development of candidate biomaterials, further exploration of potential fibroblast subpopulations at a transcriptional level would provide key insights into further understanding the underlying mechanisms by which fibrous encapsulation occurs, and unveil novel directions for antifibrotic and regenerative therapies in the future.

Pharmacological Approaches for the Prevention of Breast Implant Capsular Contracture

Capsular contracture is a common complication associated with breast implants following reconstructive or aesthetic surgery in which a tight or constricting scar tissue capsule forms around the implant, often distorting the breast shape and resulting in chronic pain. Capsulectomy (involving full removal of the capsule surrounding the implant) and capsulotomy (where the capsule is released and/or partly removed to create more space for the implant) are the most common surgical procedures used to treat capsular contracture. Various structural modifications of the implant device (including use of textured implants, submuscular placement of the implant, and the use of polyurethane-coated implants) and surgical strategies (including pre-operative skin washing and irrigation of the implant pocket with antibiotics) have been and/or are currently used to help reduce the incidence of capsular contracture. In this article, we review the pharmacological approaches-both commonly practiced in the clinic and experimental-reported in the scientific and clinical literature aimed at either preventing or treating capsular contracture, including (i) pre- and post-operative intravenous administration of drug substances, (ii) systemic (usually oral) administration of drugs before and after surgery, (iii) modification of the implant surface with grafted drug substances, (iv) irrigation of the implant or peri-implant tissue with drugs prior to implantation, and (v) incorporation of drugs into the implant shell or filler prior to surgery followed by drug release in situ after implantation.

Suppression of the fibrotic encapsulation of silicone implants by inhibiting the mechanical activation of pro-fibrotic TGF-β

The fibrotic encapsulation of implants involves the mechanical activation of myofibroblasts and of pro-fibrotic transforming growth factor beta 1 (TGF-β1). Here, we show that both softening of the implant surfaces and inhibition of the activation of TGF-β1 reduce the fibrotic encapsulation of subcutaneous silicone implants in mice. Conventionally stiff silicones (elastic modulus, ~2 MPa) coated with a soft silicone layer (elastic modulus, ~2 kPa) reduced collagen deposition as well as myofibroblast activation without affecting the numbers of macrophages and their polarization states. Instead, fibroblasts around stiff implants exhibited enhanced intracellular stress, increased the recruitment of α_v and β₁ integrins, and activated TGF-β1 signalling. In vitro, the recruitment of α_v integrin to focal adhesions and the activation of β₁ integrin and of TGF-β were higher in myofibroblasts grown on latency-associated peptide (LAP)-coated stiff silicones than on soft silicones. Antagonizing α_v integrin binding to LAP through the small-molecule inhibitor CWHM-12 suppressed active TGF-β signalling, myofibroblast activation and the fibrotic encapsulation of stiff subcutaneous implants in mice.

Effects of Oral Zafirlukast, Sildenafil, or Pirfenidone on the Formation of Postsurgical Intra-abdominal Adhesions in an Experimental Rat Model

INTRODUCTION

Intra-abdominal adhesions' main etiology is surgical procedures that commonly require reintervention. Oral treatments with Sildenafil, Zafirlukast, and Pirfenidone have yielded decreased severity of fibrotic phenomena secondary to the introduction of foreign material. This study aimed to evaluate the efficacy of oral Zafirlukast, Sildenafil or Pirfenidone treatment on reducing or preventing intra-abdominal adhesions in an experimental rat model.

METHODS

Four groups, each of 10 male Wistar rats weighing 250-300 g, were used. A midline laparotomy was used to excise an area of 1.5´1.5cm and reconstructed with polypropylene mesh fixed to the abdominal wall. After 12 h, oral doses of Zafirlukast (1.25 mg/kg, group B), Sildenafil (15 mg/kg, group C), or Pirfenidone (500 mg/kg, group D) were given every day for eight days. The control group, A, received no treatment. At day nine, animals were reoperated. The implant was resected after ethically approved euthanasia and specimens were fixed in 10% formaldehyde for histopathology.

RESULTS

Control group A yielded adhesions with greater fibrovascular density and neighboring organ involvement than the other groups (P = 0.001), as well as intense inflammatory infiltrates and numerous granulomas (P = 0.04). Adhesions in group C had less fibrovascular density (P = 0.03) with decreased serosal injuries (P = 0.001) and less organ involvement. Group D had reduced adhesions without organ involvement (P < 0.01), and less inflammatory infiltrates, collagen fibers, and foreign body granulomas than groups B or C (P < 0.01).

CONCLUSIONS

Oral administration of these agents did not prevent adhesions but ameliorated them. Oral Pirfenidone offered the best performance and could be recommended for human use.

Local Delivery of Pirfenidone by PLA Implants Modifies Foreign Body Reaction and Prevents Fibrosis

Peri-implant fibrosis (PIF) increases the postsurgical risks after implantation and limits the efficacy of the implantable drug delivery systems (IDDS). Pirfenidone (PF) is an oral anti-fibrotic drug with a short (<3 h) circulation half-life and strong adverse side effects. In the current study, disk-shaped IDDS prototype combining polylactic acid (PLA) and PF, PLA@PF, with prolonged (~3 days) PF release (in vitro) was prepared. The effects of the PLA@PF implants on PIF were examined in the rabbit ear skin pocket model on postoperative days (POD) 30 and 60. Matching blank PLA implants (PLA⁰) and PLA⁰ with an equivalent single-dose PF injection performed on POD0 (PLA⁰+injPF) served as control. On POD30, the intergroup differences were observed in α-SMA, iNOS and arginase-1 expressions in PLA@PF and PLA⁰+injPF groups vs. PLA⁰. On POD60, PIF was significantly reduced in PLA@PF group. The peri-implant tissue thickness decreased (532 ± 98 μm vs. >1100 μm in control groups) approaching the intact derma thickness value (302 ± 15 μm). In PLA@PF group, the implant biodegradation developed faster, while arginase-1 expression was suppressed in comparison with other groups. This study proves the feasibility of the local control of fibrotic response on implants via modulation of foreign body reaction with slowly biodegradable PF-loaded IDDS.

Implant Fibrosis and the Underappreciated Role of Myofibroblasts in the Foreign Body Reaction

Body implants and implantable medical devices have dramatically improved and prolonged the life of countless patients. However, our body repair mechanisms have evolved to isolate, reject, or destroy any object that is recognized as foreign to the organism and inevitably mounts a foreign body reaction (FBR). Depending on its severity and chronicity, the FBR can impair implant performance or create severe clinical complications that will require surgical removal and/or replacement of the faulty device. The number of review articles discussing the FBR seems to be proportional to the number of different implant materials and clinical applications and one wonders, what else is there to tell? We will here take the position of a fibrosis researcher (which, coincidentally, we are) to elaborate similarities and differences between the FBR, normal wound healing, and chronic healing conditions that result in the development of peri-implant fibrosis. After giving credit to macrophages in the inflammatory phase of the FBR, we will mainly focus on the activation of fibroblastic cells into matrix-producing and highly contractile myofibroblasts. While fibrosis has been discussed to be a consequence of the disturbed and chronic inflammatory milieu in the FBR, direct activation of myofibroblasts at the implant surface is less commonly considered. Thus, we will provide a perspective how physical properties of the implant surface control myofibroblast actions and accumulation of stiff scar tissue. Because formation of scar tissue at the surface and around implant materials is a major reason for device failure and extraction surgeries, providing implant surfaces with myofibroblast-suppressing features is a first step to enhance implant acceptance and functional lifetime. Alternative therapeutic targets are elements of the myofibroblast mechanotransduction and contractile machinery and we will end with a brief overview on such targets that are considered for the treatment of other organ fibroses.

Silicone Breast Implant Coated with Triamcinolone Inhibited Breast-Implant-Induced Fibrosis in a Porcine Model

Cosmetic silicone implants for breast reconstruction often lead to medical complications, such as abnormally excessive fibrosis driven by foreign body granulomatous inflammation. The purpose of this study was to develop a silicone breast implant capable of local and controlled release of a glucocorticoid drug triamcinolone acetonide (TA) for the prevention of silicone-breast-implant-induced fibrosis in a Yorkshire pig model (in vivo). Implants were dip-coated in a TA solution to load 1.85 μg/cm² of TA in the implant shell, which could release the drug in a sustained manner for over 50 days. Immunohistochemical analysis for 12 weeks showed a decline in tumor necrosis factor-α expression, capsule thickness, and collagen density by 82.2%, 55.2%, and 32.3%, respectively. Furthermore, the counts of fibroblasts, macrophages, and myofibroblasts in the TA-coated implants were drastically reduced by 57.78%, 48.8%, and 64.02%, respectively. The TA-coated implants also lowered the expression of vimentin and α-smooth muscle actin proteins, the major profibrotic fibroblast and myofibroblast markers, respectively. Our findings suggest that TA-coated silicone breast implants can be a promising strategy for safely preventing fibrosis around the implants.

Dielectric Elastomer Actuators, Neuromuscular Interfaces, and Foreign Body Response in Artificial Neuromuscular Prostheses: A Review of the Literature for an In Vivo Application

The inability to replace human muscle in surgical practice is a significant challenge. An artificial muscle controlled by the nervous system is considered a potential solution for this. Here, this is defined as a neuromuscular prosthesis. Muscle loss and dysfunction related to musculoskeletal oncological impairments, neuromuscular diseases, trauma or spinal cord injuries can be treated through artificial muscle implantation. At present, the use of dielectric elastomer actuators working as capacitors appears a promising option. Acrylic or silicone elastomers with carbon nanotubes functioning as the electrode achieve mechanical performances similar to human muscle in vitro. However, mechanical, electrical, and biological issues have prevented clinical application to date. Here materials and mechatronic solutions are presented which can tackle current clinical problems associated with implanting an artificial muscle controlled by the nervous system. Progress depends on the improvement of the actuation properties of the elastomer, seamless or wireless integration between the nervous system and the artificial muscle, and on reducing the foreign body response. It is believed that by combining the mechanical, electrical, and biological solutions proposed here, an artificial neuromuscular prosthesis may be a reality in surgical practice in the near future.

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.

Size matters-in vitro behaviour of human fibroblasts on textured silicone surfaces with different pore sizes

Capsular contracture remains a challenge in plastic surgery and represents one of the most common postoperative complications following alloplastic breast reconstruction. The impact of the surface structure of silicone implants on the foreign body reaction and the behaviour of connective tissue-producing cells has already been discussed. The aim of this study was to investigate different pore sizes of silicone surfaces and their influence on human fibroblasts in an in vitro model. Four different textures (no, fine, medium and coarse texture) produced with the salt-loss technique, have been assessed in an in vitro model. Human fibroblasts were seeded onto silicone sheets and evaluated after 1, 4 and 7 days microscopically, with viability assay and gene expression analysis. Comparing the growth behaviour and adhesion of the fibroblasts on the four different textures, a dense cell layer, good adhesion and bridge-building ability of the cells could be observed for the fine and medium texture. Cell number and viability of the cells were increasing during the time course of experiments on every texture. TGFß1 was lowest expressed on the fine and medium texture indicating a trend for decreased fibrotic activity. For silicone surfaces produced with the salt-loss technique, we were able to show an antifibrotic effect of smaller sized pores. These findings underline the hypothesis of a key role of the implant surface and the pore size and pore structure in preventing capsular contracture.

Domesticating the foreign body response: Recent advances and applications

The foreign body response is an immunological process that leads to the rejection of implanted devices and presents a fundamental challenge to their performance, durability, and therapeutic utility. Recent advances in materials development and device design are now providing strategies to overcome this immune-mediated reaction. Here, we briefly review our current mechanistic understanding of the foreign body response and highlight new anti-FBR technologies from this decade that have been applied successfully in biomedical applications relevant to implants, devices, and cell-based therapies. Further development of these important technologies promises to enable new therapies, diagnostics, and revolutionize the management of patient care for many intractable diseases.

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 .

Botulinum Toxin A Plays an Important Role in the Placement of Implants Deep Within the Pectoralis Major Muscle for Mammaplasty: A Systematic Review and Meta-analysis

BACKGROUND

Breast prosthesis implants have been safely and efficiently used in the plastic surgery department. With the increasing demand for aesthetics, these silicon implants were not only used in breast augmentation surgery but also in breast reconstruction after mastectomy. Nevertheless, breast prosthesis implantation brings a lot of complications, such as: postoperative chronic pain, capsule contracture, prosthesis displacement and prosthesis rupture and infection in severe cases. From the year 1998, botulinum toxin A (BTX-A), a neurotoxin, has been reported to be effective for pain control, capsule contracture lessening, expander enlargement and so on. However, those articles included all kinds of study types: randomized, double-blinded controlled trial (RCT), nonrandomized trial, retrospective analysis and case series, besides the outcomes were varied. To clarify how BTX-A acts at the mammaplasty field, we made this systematic review and meta-analysis.

PURPOSE

To review how BTX-A acts in the field of mammaplasty as well as discuss the relative mechanisms of BTX-A and the related research progress.

METHODS

We searched Pubmed, Embase, Cochrane, Web of science, Clinical trials, Wanfang Database and VIP from inception until March 2018 for papers reporting the use of BTX-A in the breast surgery using implants deep within the pectoralis major muscle. System review, viewpoints and case reports were excluded.

RESULTS

Ten articles met the criteria for inclusion including six prospective controlled (2 RCT; 4 other trails), three retrospective cohorts and one case series. These studies were all about patients using BTX-A during or after breast surgery with expanders or prostheses. A total of 682 patients were enrolled, 543 (79.61%) accepted BTX-A injection, 185 underwent mastectomies with immediate reconstruction, 13 with delayed reconstruction, 295 mastectomies with either immediate or delayed reconstruction and 189 with breast augmentation using silicone prostheses. The study time ranging from 4 months to 13 years, 15 patients (2.76%) received BTX-A injection more than two times, 9.2% received less than 75 U BTX-A, 34.3% 75-100 U, 0.18% 250 U, and in 56.4% the dosage was not stated. No complications associated with BTX-A were mentioned, almost all the studies reported efficacy for pain control. Other assessments included increased speed of expander enlargement and volume were mentioned in four papers, two articles analyzed the visual analogue scores, three suggested relief of capsular contracture, two reported lower narcotic use, three mentioned shorter hospital stays and one proved lowering the rate of unplanned expander. It seems all the studies demonstrate the valid usage of BTX-A, but the quality of this evidence still under the line.

CONCLUSION

We could try to use BTX-A as a new method in the field of mammaplasty. There are so many advantages such as postoperative pain relief, reducing the hospital stay, and increasing operation success rate, but rigorous methodological evidence is still lacking. A lot of studies were retrospective, only two studies used the RCT method. Therefore, to obtain strong evidence to clarify the usage of BTX-A, more randomized double-blinded controlled trials will be required, meanwhile the mechanism study adds to the evidence.

LEVEL OF EVIDENCE III

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 .

Current Approaches Including Novel Nano/Microtechniques to Reduce Silicone Implant-Induced Contracture with Adverse Immune Responses

Capsular contracture, which is the pathologic development of fibrous capsules around implants, is a major complication of reconstructive and aesthetic breast surgeries. Capsular contracture can cause implant failure with breast hardening, deformity, and severe pain. The exact mechanisms underlying this complication remain unclear. In addition, anaplastic large cell lymphoma is now widely recognized as a very rare disease associated with breast implants. Foreign body reactions are an inevitable common denominator of capsular contracture. A number of studies have focused on the associated immune responses and their regulation. The present article provides an overview of the currently available techniques, including novel nano/microtechniques, to reduce silicone implant-induced contracture and associated foreign body responses.

Current advanced therapy cell-based medicinal products for type-1-diabetes treatment

In the XXI century diabetes mellitus has become one of the main threats to human health with higher incidence in regions such as Europe and North America. Type 1 diabetes mellitus (T1DM) occurs as a consequence of the immune-mediated destruction of insulin producing β-cells located in the endocrine part of the pancreas, the islets of Langerhans. The administration of exogenous insulin through daily injections is the most prominent treatment for T1DM but its administration is frequently associated to failure in glucose metabolism control, finally leading to hyperglycemia episodes. Other approaches have been developed in the past decades, such as whole pancreas and islet allotransplantation, but they are restricted to patients who exhibit frequent episodes of hypoglycemia or renal failure because the lack of donors and islet survival. Moreover, patients transplanted with either whole pancreas or islets require of immune suppression to avoid the rejection of the transplant. Currently, advanced therapy medicinal products (ATMP), such as implantable devices, have been developed in order to reduce immune rejection response while increasing cell survival. To overcome these issues, ATMPs must promote vascularization, guaranteeing the nutritional contribution, while providing O₂ until vasculature can surround the device. Moreover, it should help in the immune-protection to avoid acute and chronic rejection. The transplanted cells or islets should be embedded within biomaterials with tunable properties like injectability, stiffness and porosity mimicking natural ECM structural characteristics. And finally, an infinitive cell source that solves the donor scarcity should be found such as insulin producing cells derived from mesenchymal stem cells (MSCs), embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Several companies have registered their ATMPs and future studies envision new prototypes. In this review, we will discuss the mechanisms and etiology of diabetes, comparing the clinical trials in the last decades in order to define the main characteristics for future ATMPs.

The aetiopathogenesis of capsular contracture: A systematic review of the literature

BACKGROUND

Capsular contracture is the most frequent complication after breast augmentation or reconstruction with breast implants. The immune system plays a prominent role in capsular contracture formation, albeit to an unknown extent. Bacterial contamination in situ has been hypothesized to be causative for capsular contracture. How this relates to the immunological processes involved is unknown. This article aims to provide an overview of immunological and bacterial factors involved in development of capsular contracture.

MATERIALS AND METHODS

We undertook a systematic literature review focused on immunological factors and microbiota in relation to capsular contraction around implants. This systematic review was performed in accordance with the PRISMA guidelines. PubMed, EMBASE, and the Cochrane databases were searched from inception up to October 2016. Included studies were assessed for the following variables: subject characteristics, number of capsules, primary indication for surgery, surgical procedure, follow-up or implant duration, study methods, type of antibiotics or medical therapies and outcomes related to microbiota and immunological factors.

RESULTS

Data on immunological factors and bacterial contamination were retrieved from 64 included studies. Notably the presence of macrophages and Staphylococcus epidermidis within capsules was often associated with capsular contracture.

CONCLUSION

This review provides a clear overview of the immunological factors associated with capsular contracture and provides a hypothetical immunological model for development of the disease. Furthermore, an overview of bacterial contamination and associations with capsular contracture has been provided. Follow-up research may result in clinical recommendations to prevent capsular contracture.

Multicompartment Drug Release System for Dynamic Modulation of Tissue Responses

Pharmacological modulation of responses to injury is complicated by the need to deliver multiple drugs with spatiotemporal resolution. Here, a novel controlled delivery system containing three separate compartments with each releasing its contents over different timescales is fabricated. Core-shell electrospun fibers create two of the compartments in the system, while electrosprayed spheres create the third. Utility is demonstrated by targeting the foreign body response to implants because it is a dynamic process resulting in implant failure. Sequential delivery of a drug targeting nuclear factor-κB (NF-κB) and an antifibrotic is characterized in in vitro experiments. Specifically, macrophage fusion and p65 nuclear translocation in the presence of releasate or with macrophages cultured on the surfaces of the constructs are evaluated. In addition, releasate from pirfenidone scaffolds is shown to reduce transforming growth factor-β (TGF-β)-induced pSMAD3 nuclear localization in fibroblasts. In vivo, drug eluting constructs successfully mitigate macrophage fusion at one week and fibrotic encapsulation in a dose-dependent manner at four weeks, demonstrating effective release of both drugs over different timescales. Future studies can employ this system to improve and prolong implant lifetimes, or load it with other drugs to modulate other dynamic processes.

Follistatin and the Breast Implant Capsule

Supplemental Digital Content is available in the text.

Background:

Breast capsular contracture remains an elusive problem faced by plastic surgeons and is the leading long-term complication after breast implantation. Follistatin (Fst) is a protein with known anti-inflammatory and antifibrotic properties and has the potential to limit the severity of diseases associated with inflammation and fibrosis such as capsular contracture. The aim of this study was to examine the effect of Fst288 on capsular fibrosis around silicone implants in a mouse model.

Methods:

BALB/c mice were implanted subcutaneously with untreated silicone implants (baseline control). In the experimental group, immediately after silicone implant insertion, the implant pocket received either a single injection of 1 µg Fst288 or normal saline (internal control). The animals were killed at 3, 5, 7, 14, 28, and 90 days after surgery, and serum, implants, and the surrounding tissue were removed for histological and immunohistochemical analyses.

Results:

Fst288 treatment resulted in significant decreases in capsule thickness at 28 days (P < 0.05) and 3 months (P < 0.001), decreased collagen production at 14 days (P < 0.05) and 3 months (P < 0.01), decreased angiogenesis at 3 months (P < 0.001), decreased α-smooth muscle actin levels at 3 months (P < 0.05), and a decrease in the number of CD45+ cells at days 5 (P < 0.05) and 7 (P < 0.01), respectively, when compared with control implants.

Conclusions:

A single injection of Fst288 at the time of silicone implant insertion into the mice results in a significant reduction in pericapsular inflammation and capsular fibrosis.

The Effect of Hyaluronic Acid Application on the Perisilicon Capsule Structure

BACKGROUND

Silicon implants constitute a major part of plastic surgery practice. Although materials with high biocompatibility have been used around the implants, capsule formation still develops and progressive nature of this process results in capsule contraction. The aim of this study is to evaluate the effects of hyaluronic acid injected around the silicon block on the capsule structure.

METHODS

Twenty Wistar albino rats were used in the study. Rats were divided into two main groups (group 1 and group 2) and two subgroups. Rats in group 1 were sacrificed in week 4 and rats in group 2 were sacrificed in week 8. A subcutaneous pouch was created in the dorsum of the rats and a silicon block was placed into the pouch in groups 1A and 2A. 0.2 ml of hyaluronic acid was injected around the silicon block in group 1B and group 2B. Rats were sacrificed and capsule structure and thickness were analyzed following macroscopic evaluation. Concentrations of transforming growth factor-β1 (TGF-β1) and heat shock protein-47 (HSP-47) were evaluated immunohistochemically, and statistical comparisons were made.

RESULT

Capsule structure consisted of three layers in all the groups. A more intense collagen structure was observed in the middle layer. The capsule was thinnest in group 1A and thickest in group 2B; the difference between the groups was statistically significant. TGF-β1 was most intense in group 2B and it was correlated with the amount of collagen. Involvement of HSP-47 was observed mainly in collagen and also in fibroblasts and vascular structures, and its concentration was found to be lower in groups 2A and 2B.

CONCLUSION

Exogenously added cross-linked hyaluronic acid increased the capsular thickness and may increase the risk of developing capsular contracture around silicone implants.

LEVEL OF EVIDENCE II

Evidence was obtained from the well-designed controlled trials without randomization.

Stealthy role of size-driven stresses in biomechanics of breast implants capsular contracture

Breast Capsular Contracture (BCC) is one of the adverse complications occurring with greater incidence in breast augmentation surgical procedures. Its formation can be interpreted as the conclusive result of the physiological process known as response to a foreign body. From a biochemical standpoint, the formation of the peri-prosthetic capsule is certainly a multifactorial process: many hypotheses concerning its etiology have been suggested in the literature and a number of related pharmacological protocols have been consequently proposed to clinically treat this pathology with the aim to prevent further complications and avoid future re-interventions. However, the vast majority of these theories seems to be only partially supported by clinical outcomes and thus a shared opinion on this matter is still absent among specialists. Within this framework, by starting from clinical observations which highlighted an unexpected correlation between histo-morphological features of fibrotic capsules and overall size of breast implants, the present study investigates the hypothesis that the biomechanical interaction between prosthesis and host tissue may play a crucial role in the biological processes governing the pathological phenomenon at hand. Therefore, to shed light on the underlying mechanisms which could trigger the breast capsular contracture, both simple analytical solutions, in which elasticity and growth are simultaneously taken into account, and more accurate geometrically faithful Finite Element-based numerical simulations have been exploited. The theoretical findings demonstrate that somehow counter-intuitive radial and hoop stress fields occur at the capsula-implant interface in a way such that their combined action, independently from other possible concurrent factors, results significantly amplified for small-size breast prostheses, localized stress peaks in these cases promoting detaching and rippling phenomena actually observed in BCC clinical complications.

Effects of Different Concentrations of Injectable Collagenase Enzyme on Capsular Tissue Around Silicone Implants: A Preliminary Experimental Study for the Development of a New Treatment Strategy

OBJECTIVES

In recent studies, collagen organization was blamed for the formation of capsular contracture which is still a challenging problem after silicone implant-based breast operations. In this study, effects of different concentrations of collagenase enzyme derived from Clostridium histolyticum on the capsular tissue formation around the silicone implants were investigated. The injectable form of collagenase has a routine clinical use in the treatment of both Dupuytren's and Peyronie's diseases.

MATERIALS AND METHODS

Thirty-two Wistar albino rats were randomized into four groups. A 2 × 1 × 0.3-cm-sized silicone block was inserted inside a dorsal subcutaneous pocket in all groups. After 2 months of insertion, capsule thicknesses around the implants were detected under ultrasonography. This was followed by injection of isotonic saline, 150, 300, and 600 IU in Gr-1, 2, 3, and 4, respectively. All the animals were sacrificed at the end of the first week for histologic sampling to determine fibroblast proliferation, vessel density of the tissue, necrosis, edema, inflammation, and capsule thickness. All the data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests and compared for significance of the results.

RESULTS

There was no significant difference in terms of capsule thinning between the 300 and 600 IU groups but in both groups thinning was significantly higher than the sham group. In the 150 IU group there was no significant thinning as compared to the sham group (p > 0.05). However, complications such as skin necrosis, infection, and seroma formation were seen only in the 600 IU injection group. The optimal safe and effective dose of the enzyme was accepted as 300 IU. The 300 IU injection provided up to 89 % thinning in the capsule tissue. There was thinning of the collagen bundles parallel to capsule thickness. In the 600 IU group, micro-pores were encountered at the thinnest points.

CONCLUSION

However, the late results and recurrence rates of capsular contracture were not included in this study; collagenase seemed effective for the reduction of capsular tissue around the implants.

NO LEVEL ASSIGNED

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Pirfenidone vs. sodium hyaluronate/carboxymethylcellulose as prevention of the formation of intra-abdominal adhesions after colonic surgery. A randomized study in an experimental model

INTRODUCTION

Up to 93% of patients undergoing abdominal surgery will develop intra-abdominal adhesions with the subsequent morbidity that they represent. Various substances have been tested for the prevention of adhesions with controversial results; the aim of our study is to compare the capability of pirfenidone in adhesion prevention against sodium hyaluronate/carboxymethylcellulose.

METHODS

A randomized, prospective, longitudinal experimental study with Winstar rats. They were divided into 3 groups. The subjects underwent an exploratory laparotomy and they had a 4cm(2) cecal abrasion. The first group received saline on the cecal abrasion, and groups 2 and 3 received pirfenidone and sodium hyaluronate/carboxymethylcellulose respectively. All rats were sacrificed on the 21st day after surgery and the presence of adhesions was evaluated with the modified Granat scale. Simple frequency, central tendency and dispersion measures were recorded. For the statistical analysis we used Fisher's test.

RESULTS

To evaluate adhesions we used the Granat's modified scale. The control group had a median adhesion formation of 3 (range 0-4). The pirfenidone group had 1.5 (range 0-3), and the sodium hyaluronate/carboxymethylcellulose group had 0 (range 0-1). There was a statistically significant difference to favor sodium hyaluronate/carboxymethylcellulose against saline and pirfenidone (P<0.009 and P<.022 respectively).

CONCLUSIONS

The use of sodium hyaluronate/carboxymethylcellulose is effective for the prevention of intra-abdominal adhesions. More experimental studies are needed in search for the optimal adhesion prevention drug.

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.

Treatment with pirfenidone for two years decreases fibrosis, cytokine levels and enhances CB2 gene expression in patients with chronic hepatitis C

BACKGROUND

The aim of this study was to assess whether two-years treatment with Pirfenidone influences necroinflammation, fibrosis and steatosis, serum levels of TGF-β1, IL-6, TNF-α and CB1 and CB2 gene expression, in patients with chronic hepatitis C (CHC).

METHODS

Twenty-eight patients out of 34 with CHC virus infection were enrolled in the study and received Pirfenidone (1200 mg/day) for 24 months. Six patients dropped out after 12 months of PFD. Liver biopsies and serum samples were obtained at the beginning and end of treatment. Modified HAI was calculated. CB1 and CB2 gene expression was correlated with fibrosis progression alongside with necroinflammation and steatosis. TGF-β1, IL-6, TNF-α and liver transaminases were measured in serum at two-months intervals. HCV genotype and viral load were also assessed. Quality of life was evaluated by SF36 questionnaires and the prognosis of disease was assessed with Child-Pugh score. The Wilcoxon test matched-pair signed ranks were used to analyze the outcomes.

RESULTS

Intention to treat analyses were performed for biochemistry and clinical parameters. At the end of treatment, necroinflammation grading was reduced in an average of 3.2 points in 82% of patients (p < 0.05) and Ishak's fibrosis stage decreased 2-points average in 67% of patients (p < 0.05). Steatosis decreased in 61% of patients. IL-6 and TGF-β1 serum levels decreased significantly in 93% and 67% of patients (p < 0.05), respectively, while TNF-α diminished in 47% of patients. ALT and AST tended to normalize in 81% of patients; CB2 mRNA levels increased in 86% and CB1 expression diminished in 29% of patients. Both, quality of life and Child-Pugh score improvements were reported in all patients.

CONCLUSIONS

Pirfenidone for two years benefits CHC patients and improves inflammation, fibrosis and steatosis in higher number of patients as previously shown for 12-months treatment with PFD. Additionally, PFD improved TGFβ1 and IL-6 levels and diminished liver expression of anti-fibrogenic receptor CB2.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02161952. Protocol Registration Date: 06/11/2014.

An innovative procedure for the treatment of primary and recurrent capsular contracture (CC) following breast augmentation

BACKGROUND

Capsular contracture (CC) is the most frequently reported complication following alloplastic breast augmentation. At present, none of the available preventive measures are effective, and various treatment modalities have been advocated. Reduction of the inflammatory process is critical for successful treatment. Late intracapsular glucocorticosteroid (GC) injections have been somewhat effective for the treatment, but the fine balance between the effectiveness of therapeutic GC dosages and their potential serious side effects is of utmost importance.

OBJECTIVES

The authors investigate whether instillation of a rapid-acting water-soluble GC in the implant pocket during the early proliferative phase of wound healing is more effective than delayed instillation during the remodeling phase.

METHODS

Between 2003 and 2009, 33 consecutive patients presenting with CC (Baker grades III and IV) were managed by capsulectomy with implant replacement and corticosteroid therapy immediately as well as 2 to 3 days later through an indwelling catheter left in place for that period. This delayed but early administration is a novel technique for GC injection.

RESULTS

Complete correction of the contracture with no recurrence was achieved in all patients with a follow-up range of 2 to 10 years.

CONCLUSIONS

This GC administration technique avoids the potential complications of long-term, slow corticosteroid release. It has a targeted anti-inflammatory effect, probably at a critical stage of the healing process, and could effectively prevent CC following alloplastic breast augmentation.

Pharmacological treatment for keloids

INTRODUCTION

Keloids are fibroproliferative disorders that are characterized by histological accumulation of collagens and fibroblasts, refractory clinical symptoms such as itching, topical invasiveness, and frequent postsurgical recurrence. At present, to treat or prevent keloids, new drugs are currently being designed and the pharmaceutical indications of known drugs are being expanded.

AREAS COVERED

The current pharmacological interventions for keloids are mainly described on the basis of the various hypotheses on keloid etiology and the keloid ingredients that are targeted. These interventions include angiotension-converting enzyme inhibitors and calcium-channel blockers (based on hypertension hypothesis), selective estrogen receptor modulator (based on endocrinological hypothesis), vitamins and essential fatty acids (based on immunonutritional hypothesis), and transglutaminase inhibitor (based on metabolic hypothesis). Drugs that directly target the reduction or destruction of the major extracellular matrix or cellular constituents of keloids are also included. Besides, drugs that indirectly modulate the biochemical microenvironment are described. These include growth factors, immunomodulators, and anti-inflammation and anti-allergy drugs.

EXPERT OPINION

Due to the unclear etiology of keloids and the lack of animal models, efficient, reliable, and specific pharmaceutical interventions for keloids continue to be lacking. The reliability of current data and clinical observations must be strengthened by large-scale, randomized, controlled clinical trials.

Controlled clinical trial with pirfenidone in the treatment of breast capsular contracture: association of TGF-β polymorphisms

BACKGROUND

Breast capsular contracture (BCC) is a commonly adverse event postmammoplastly characterized by an immune response mediated by cytokines and transforming growth factor (TGF)-β1 resulting in excessive synthesis and deposit of extracellular matrix around the breast implant. Presence of TGF-β1 polymorphisms has been associated as a risk factor to develop fibroproliferative diseases.

METHODS

This open, controlled, prospective, and pilot clinical trial with 6 months duration was carried out to evaluate the efficacy of 1800 mg a day, of oral Pirfenidone (PFD) in the treatment of BCC (Baker Score III/IV) postmammoplasty. Twenty BCC cases received PFD and 14 BCC control cases underwent capsulectomy after 6 months of enrollment. Both groups were followed up for 6 more months up to 12 months to determine the relapse in the absence of PFD. Determination of TGF-β1 polymorphisms was performed to establish a correlation with capsular contracture.

RESULTS

PFD group experienced BCC-reduction in all breasts 6 months after enrollment. Only 1 of 20 cases relapsed after follow-up. In capsulectomy group, 2 of 14 cases presented progression to grade IV during presurgical period. All capsulectomy cases relapsed at end of follow-up. Nearly hundred percent of all patients studied in this protocol had a profibrogenic homozygous TGF-β1 polymorphism (codon 25; genotype Arg25Arg).

CONCLUSIONS

PFD is useful to improve BCC (Baker Score III/IV) postmammoplasty with no relapse after drug administration. There is also an association between capsular contracture and the presence of homozygous G/G TGF-β1 genotype.

Effects of zafirlukast on capsular contracture: long-term results

Capsular contracture is a distressing complication after breast augmentation for both the patient and surgeon. Although capsular contracture is a multifactorial process, one common denominator in the successful treatment of this complication is believed to be the abatement of inflammation. Leukotriene antagonists have recently emerged as effective prophylactic agents in reactive airway diseases. A prospective study was carried out on 60 female patients (120 prostheses implanted) with mild/severe capsular contracture in at least one breast. The hardness of capsular contracture was assessed by means of the mammary compliance method. Patients received zafirlukast (Accolate&#174;) for a 6-month period. Mammary compliance was assessed at the start of the study and thereafter monthly, during drug intake and for one year after drug withdrawal. The results show a significant decrease in breast compliance values in the first 6 months, followed by a significant increase one year after the end of drug intake. Indeed, zafirlukast-treated patients displayed a 6.93 percent reduction in mammary compliance after 1 month, 14.42 percent after 3 months, 22.05 percent after 6 months and 22.52 percent after 7 months (1 month after the withdrawal of the drug). Thereafter, mammary compliance values gradually increased. A 5.47 percent reduction in mammary compliance was observed 1 year after drug withdrawal. The present study suggests that zafirlukast may be effective in reducing breast capsule distortion in patients with long-standing contracture, though reduced capsular contracture values are strictly related to the duration of drug intake.

The impact of triamcinolone acetonide in early breast capsule formation in a rabbit model

BACKGROUND

The etiology and clinical treatment of capsular contracture remain unresolved as the causes may be multifactorial. Triamcinolone acetonide applied in the pocket during surgery was reported to be ineffective in prevention of capsular contracture. However, if injected 4-6 weeks after surgery or as a treatment for capsular contracture, decreased applanation tonometry measurements and pain were observed. It was assumed that intraoperative application of triamcinolone was not effective because its effect does not last long enough. However, betadine, antibiotics, and fibrin were found to be effective in preventing capsular contracture with intraoperative applications and are more effective in the early phases of wound healing than in later stages. The role of triamcinolone acetonide in capsule formation is unknown. The purpose of this study was to determine if triamcinolone acetonide modulates breast capsule formation or capsular contracture in the early phases of wound healing in a rabbit model.

METHODS

Rabbits (n=19) were implanted with one tissue expander and two breast implants and were killed at 4 weeks. Implant pocket groups were (1) Control (n=10) and (2) Triamcinolone (n=9). Pressure/volume curves and histological, immunological, and microbiological evaluations were performed. Operating room air samples and contact skin samples were collected for microbiological evaluation.

RESULTS

In the triamcinolone group, a decreased capsular thickness, mild and mononuclear inflammation, and negative or mild angiogenesis were observed. There were no significant differences in intracapsular pressure, fusiform cell density, connective tissue, organization of collagen fibers, and microbiological results between the groups. There was no significant difference in the dialysate levels of IL-8 and TNF-α, but correlation between IL-8 and TNF-α was observed.

CONCLUSION

Triamcinolone acetonide during breast implantation influences early capsule formation and may reduce capsular contracture.

LEVEL OF EVIDENCE III

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Acellular dermal matrix in aesthetic revisionary breast surgery

Breast augmentation is one of the most commonly-performed cosmetic procedures worldwide. Unfortunately, many women require revisionary surgery related to unsatisfactory results or complications such as capsular contracture, implant malposition, and ptosis. While, historically, surgeons have relied on often-imperfect native tissue to correct these deformities, acellular dermal matrix (ADM) offers a new option for solving these difficult aesthetic problems. In this article, the authors provide background information about the role of ADM in providing excellent and lasting results to cosmetic breast augmentation patients, and they describe their method of subpectoral revisionary augmentation with ADM.

Effects of fibrin, thrombin, and blood on breast capsule formation in a preclinical model

BACKGROUND

The root cause of capsular contracture (CC) associated with breast implants is unknown. Recent evidence points to the possible role of fibrin and bacteria in CC formation.

OBJECTIVES

The authors sought to determine whether fibrin, thrombin, and blood modulated the histological and microbiological outcomes of breast implant capsule formation in a rabbit model.

METHODS

The authors carried out a case-control study to assess the influence of fibrin, thrombin, and blood on capsule wound healing in a rabbit model. Eighteen New Zealand white rabbits received four tissue expanders. One expander acted as a control, whereas the other expander pockets received one of the following: fibrin glue, rabbit blood, or thrombin sealant. Intracapsular pressure/volume curves were compared among the groups, and histological and microbiological evaluations were performed (capsules, tissue expanders, rabbit skin, and air). The rabbits were euthanized at two or four weeks.

RESULTS

At four weeks, the fibrin and thrombin expanders demonstrated significantly decreased intracapsular pressure compared to the control group. In the control and fibrin groups, mixed inflammation correlated with decreased intracapsular pressure, whereas mononuclear inflammation correlated with increased intracapsular pressure. The predominant isolate in the capsules, tissue expanders, and rabbit skin was coagulase-negative staphylococci. For fibrin and thrombin, both cultures that showed an organism other than staphylococci and cultures that were negative were associated with decreased intracapsular pressure, whereas cultures positive for staphylococci were associated with increased intracapsular pressure.

CONCLUSIONS

Fibrin application during breast implantation may reduce rates of CC, but the presence of staphylococci is associated with increased capsule pressure even in the presence of fibrin, so care should be taken to avoid bacterial contamination.

The multifaceted role of pirfenidone and its novel targets

BACKGROUND

Pirfenidone (PFD) is a molecule that exhibits antifibrotic properties in a variety of in vitro and animal models of lung, liver and renal fibrosis. These pathologies share many fibrogenic pathways with an abnormal fibrous wound-healing process; consequently, tissue repair and tissue regeneration-regulating mechanisms are altered.

OBJECTIVE

To investigate the usefulness of PFD as an antifibrotic agent in clinical and experimental models of fibrotic disease.

CONCLUSIONS

There is a growing understanding of the molecular effects of PFD on the wound healing mechanism, leading to novel approaches for the management of fibrosis in lung, liver and renal tissues. Although the optimum treatment for fibrosis remains undefined, it is possible that combined therapeutic regimens that include this wide-application molecule, pirfenidone, could offer a useful treatment for fibrotic disease.

Effect of the inhibitor peptide of the transforming growth factor beta (p144) in a new silicone pericapsular fibrotic model in pigs

BACKGROUND

Capsular contracture is the most common complication associated with silicone prostheses. It may take the form of anything from slight hardening to obvious deformity. The role of transforming growth factor beta (TGF-beta) in the scar physiopathology of any fibrotic process has been demonstrated. The effects of inhibition of TGF-beta have also been demonstrated in experimental models of fibrosis, which opens the way for new therapeutic alternatives in the treatment of capsular contracture. The aim of this study was to evaluate periprosthetic fibrosis with a newly synthesized TGF-beta peptide inhibitor (p144).

METHODS

Three experimental groups were formed: Group I, subcutaneous and submuscular textured silicone prostheses were left untreated; Group 2, the prostheses were left after being immersed in the vehicle; Group 3, the same protocol was followed as in Group 2, but the solution contained the vehicle with the inhibitor peptide of TGF-beta, p144 (15 mg/prosthesis). The animals were sacrificed 24 weeks after implantation, and the capsules were assessed both macroscopically and histologically.

RESULTS

The results obtained showed that the inhibition of capsular thickness and soluble collagen content in pericapsular fibrosis did not significantly decrease in the group of animals treated with the TGF-beta inhibitor peptide in comparison with control cases.

CONCLUSIONS

We detected no statistically significant reduction in fibrosis in the periprosthetic capsule after treating the implants with the inhibitor peptide p144, but we feel that the influence of trauma around the prosthesis is critical in impeding the antifibrotic activity of the inhibitor peptide.

Local Delivery of Nicotine does not Mitigate Fibrosis but may Lead to Angiogenesis

As with most implanted biomaterials, the wound healing response following implantation of a silicone breast implant leads to the formation of a fibrotic capsule. This can result in capsular contracture, a painful complication that often necessitates the removal of implant. It is well established that nicotine and nicotinic agonists inhibit inflammatory signaling. Based on the link between the inflammatory response and capsule formation, we hypothesized that local delivery of nicotine from the implant may lead to the reduction in inflammation and capsule thickness, which may ultimately reduce the incidence of capsular contracture. Nicotine was loaded into PDMS membranes using a previously established method. The loaded materials were implanted into the submammary pockets between the third and fourth mammary glands of rats. To confirm that the nicotine was acting locally and not systemically, serum cotinine, the primary metabolite of nicotine, was measured by ELISA at 3 days. Thirty days post implantation, the animals were euthanized and the tissue samples were fixed for histological analysis. Blood vessel density was measured immunohistochemically, while the capsule thickness was evaluated microscopically. While the presence of the nicotine metabolite, cotinine, in the serum at the early time points demonstrated that the nicotine was released locally from the devices, there were no significant differences in the capsule thickness between the control and experimental implants. However, the results indicated that there were differences in angiogenesis with the local delivery of nicotine, which may have other implications for the development of biomaterials.

Zafirlukast pocket delivery impairs the capsule healing around textured implants in rats

BACKGROUND

The aim of this study was to investigate the effects of zafirlukast on capsule thickness, collagen fiber density, and myofibroblast cell count of the healing tissue around silicone textured implants in rats.

METHODS

Thirty-six male Wistar rats were divided (n = 18) into two groups. In one group, two parallel incisions (1.5 cm long) were made into the right and left sides of the spine. Two pockets were then created in which shell-shaped textured implants were inserted. The left-side pocket was injected with 0.2 ml of saline solution (SSG) and the right-side pocket with a dose of 1.25 mg/kg of zafirlukast (ZLG). The other 18 rats (sham, SG) had only one pocket created, followed by the placement of an implant and injection of 0.2 ml of saline solution. The rats were euthanized on the 7th, 35th, or 90th days followed by careful dissection of the implant. The capsules and peri-implant tissues were prepared for histologic analysis. An ANOVA test and Tukey test were applied (p < 0.05).

RESULTS

ZL was effective in impairing the capsule thickness on the 35th and 90th days compared to the other two groups (sham and saline). Not only was it effective in impairing the collagen density on the 35th and 90th days, but it also showed the same effect in the SSG (systemic); fewer myofibroblasts were counted on the 90th day in the ZLG compared to the SG group; the number of myofibroblasts was significantly lower in the ZLG than in the SSG.

CONCLUSIONS

Pocket delivery of one dose of Zafirlukast was effective in impairing capsule formation around the textured implant.

Potent antioxidant role of pirfenidone in experimental cirrhosis

Three important features must be considered when proposing therapeutic strategies in liver cirrhosis: inflammation, oxidative stress and fibrogenesis. Pirfenidone is a synthetic molecule which oxidative action has not been tested in cirrhosis. Cirrhosis was induced in rats by ligation of the common bile duct or carbon tetrachloride (CCl(4)) chronic intoxication and treated with pirfenidone or diphenyleneiodonium (a potent known antioxidant) for the last two weeks for bile duct ligation model or for the last three weeks for CCl(4) chronic intoxication. A 60% reduction in fibrosis index for bile duct ligation model and 42% for CCl(4) along with reduced inflammation was observed. Considerable reduction on hepatic enzymes and total and direct bilirubins were detected with pirfenidone in both models. Pirfenidone antioxidant capacity rendered a 28% and 30% reduction in nitrites and malonyldealdehide concentration in bile duct ligation and 52% and 38% in CCl(4). With respect to gene expression, fibrotic genes like transforming growth factor-beta (TGF-beta) and collagen Ialpha (Col-1alpha) were down-regulated by pirfenidone and increased expression of regenerative genes like hepatocyte growth factor (HGF) and c-met . Superoxide dismutase (SOD), catalase (CAT) and inducible nitric oxide synthase (iNOS) gene expression were importantly down-regulated where nuclear factor kappa B (NF-kappaB) binding activity also decreased with pirfenidone treatment. Also, SOD and CAT functional activity decreased after pirfenidone action. On the other hand, diphenyleneiodonium induced a drop in oxidative stress similar in extent to pirfenidone, but it was not as effective as pirfenidone in reducing fibrosis. In this work, we showed antioxidant properties of pirfenidone beyond its well-known antifibrotic effect. These features make pirfenidone an attractive drug for trying fibrotic diseases accompanied by oxidative stress processes.