Reducing Peri-implant Capsule Thickness in Submuscular Rodent Model of Breast Reconstruction With Delayed Radiotherapy.

INTRODUCTION: Capsular contracture remains the most common complication following device-based breast reconstruction, occurring in up to 50% of women who also undergo adjuvant radiotherapy either before or after device-based reconstruction. While certain risk factors for capsular contracture have been identified, there remains no clinically effective method of prevention. The purpose of the present study is to determine the effect of coating the implant with the novel small molecule Met-Z2-Y12, with and without delayed, targeted radiotherapy, on capsule thickness and morphologic change around smooth silicone implants placed under the latissimus dorsi in a rodent model. METHODS: Twenty-four female Sprague Dawley rats each had 2 mL smooth round silicone breast implants implanted bilaterally under the latissimus dorsi muscle. Twelve received uncoated implants and twelve received implants coated with Met-Z2-Y12. Half of the animals from each group received targeted radiotherapy (20 Gray) on postoperative day ten. At three and 6 months after implantation, the tissue surrounding the implants was harvested for analysis of capsular histology including capsule thickness. Additionally, microCT scans were qualitatively analyzed for morphologic change. RESULTS: Capsules surrounding Met-Z2-Y12-coated implants were significantly thinner (P = 0.006). The greatest difference in capsule thickness was seen in the irradiated 6-month groups, where mean capsule thickness was 79.1 ± 27.3 µm for uncoated versus 50.9 ± 9.6 µm for Met-Z2-Y12-coated implants (P = 0.038). At the time of explant, there were no capsular morphologic differences between the groups either grossly or per microCT. CONCLUSIONS: Met-Z2-Y12 coating of smooth silicone breast implants significantly reduces capsule thickness in a rodent model of submuscular breast reconstruction with delayed radiotherapy.

Influence of Irradiation on Capsules of Silicone Implants Covered with Acellular Dermal Matrix in Mice.

BACKGROUND: In advanced breast cancer, radiotherapy is recommended as adjuvant therapy following breast reconstructive surgery. This inevitably led to growing concerns over possible complications of radiotherapy on implants. In this experimental animal study, we investigated the utility of acellular dermal matrix (ADM) wraps around implants as preventive management for radiotherapy complications. METHODS: Black mice (C57NL6; n = 32) were assigned to groups that either received radiation or did not: groups A and B underwent surgery using implants without radiotherapy; while groups C and D underwent surgery using implants with radiotherapy for one and three months, respectively. The hemispheric silicone implants with an 0.8-cm-diameter were inserted on the left back of each mouse, and implants wrapped by ADM were inserted on the right back. The Clinic 23EX LINAC model was used for irradiation at 10 Gy. The samples were evaluated by gross assessment, histological analysis, immunohistochemical analysis, and the Western blotting test. RESULTS: The H&E staining analysis showed that membrane thickness is smallest in group A, followed by groups C, D, and B. In a Masson trichrome histological analysis, collagen fibers became less dense and more widespread over time in the groups that received an ADM. Immunohistochemistry findings were similarly constant. However, the expression of TGF-ß1 was increased in the irradiated groups, whereas it was decreased in the non-irradiated groups as observed over time. CONCLUSIONS: Radiotherapy was shown to increase risk factors for capsular contracture, including inflammatory response, pseudoepithelium, thinning of membrane, and TGF-ß1 expression over time; however, the accompanying framework using an ADM as a barrier between implant and tissue was shown to be effective in alleviating these risks. 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 www.springer.com/00266 .

Angiotensin-Converting Enzyme Inhibitor Reduces Radiation-Induced Periprosthetic Capsular Fibrosis.

BACKGROUND: The capsular contracture is one of the main complications after radiotherapy in patients with implant-based reconstruction. The aim of this study is to evaluate the efficacy of ramipril for the prevention of radiation-induced fibrosis around the silicone implant. MATERIALS AND METHODS: Thirty Wistar rats in 5 groups were used. Group 1: implant; group 2: implant + radiation; group 3: ramipril + implant; group 4: ramipril + implant + radiation; group 5: sham. Ramipril treatment was started 5 d before surgery and continued for 12 wk after surgery. A mini silicone implant was placed in the back of the rats. A single fraction of 21.5 Gy radiation was applied. Tissues were examined histologically and immunohistochemically (TGF-ß1, MMP-2, and TIMP-2 expression). The alteration of plasma TGF-ß1 levels was examined before and after the experiment. RESULTS: After applying implant or implant + radiation, capsular thickness, percentage of fibrotic area, tissue and plasma TGF-ß1 levels significantly increased, and MMP-2/TIMP-2 ratio significantly decreased compared with the sham group. In ramipril-treated groups, the decrease in capsular thickness, fibrosis, TGF-ß1 positivity, and an increase in MMP-2/TIMP-2 ratio were found significant. In the ramipril + implant + radiation group, the alteration values of TGF-ß1 dramatically decreased. CONCLUSIONS: Our results show that ramipril reduces radiation-induced fibrosis and contracture. The results of our study may be important for the design of the clinical trials required to investigate the effective and safe doses of ramipril, which is an inexpensive and easily tolerated drug, on humans.

The Effect of Omega-3 Fatty Acids on Capsular Tissue around the Breast Implants.

BACKGROUND: One of the most common complications of the use of foreign material, in both reconstructive and cosmetic breast surgery, is capsular contracture. Historically, research on capsular contracture has focused mainly on reducing bacterial contamination through antibiotic solutions. Only secondary studies have focused on pharmacological control of the inflammation process, with particular attention paid to the main inflammation pathway, the arachidonic acid cascade. An important role in the arachidonic acid cascade is played by the omega-3 fatty acids, which are found mainly in oily fish and food supplements. The goal of the present study was to investigate the effects of omega-3 supplements on capsule contraction. METHODS: Female C57BL/6 mice were implanted with custom-made silicone gel implants and divided into two groups. The treated group received omega-3 oil daily while the control group received water daily by gavage. After mice were euthanized, samples of capsules were collected to evaluate thickness and transforming growth factor (TGF)-ß expression. RESULTS: The results showed that capsules in the omega-3 group were thinner and more transparent than those found in the control group. In addition, a significant downregulation of the TGF-ß2 gene transcript was observed in the omega-3 group. CONCLUSIONS: Omega-3 supplementation seems to be effective in reducing the occurrence of capsular formation, mainly through inhibition of the TGF-ß pathway and impairment of collagen deposit. Omega-3 supplementation is a simple and promising method that could be used to prevent or at least reduce capsular contracture after silicone implant surgery.

Inhibition Mechanism of Acellular Dermal Matrix on Capsule Formation in Expander-Implant Breast Reconstruction After Postmastectomy Radiotherapy.

BACKGROUND: Capsular contracture is one of the most common complications of expander-implant breast reconstruction. Recently, clinical reports have shown that use of an acellular dermal matrix (ADM) to cover breast implants decreases incidence of capsular contracture, but the underlying mechanism is unclear. Here, we examine how ADM reduces capsular formation in expander-implant breast reconstruction and identify cellular and molecular mechanisms of ADM-mediated reduction of capsular contracture in nonirradiated and irradiated patients. METHODS: Thirty patients who underwent immediate two-stage implant-based breast reconstruction were included; 15 received radiotherapy. While the tissue expander was changed to permanent silicone implant, biopsies of the subpectoral capsule and ADM capsule were performed. Capsule thickness, immunohistochemistry of α-smooth muscle actin (αSMA), vimentin, CD31, F4/80 expression, αSMA and CD31 coexpression, and relative gene expression levels of transforming growth factor (TGF)-ß1 and platelet-derived growth factor (PDGF)-B were investigated. RESULTS: Irradiated submuscular capsules were thicker than nonirradiated submuscular capsules, but the thickness of ADM capsules did not significantly differ between nonirradiated and irradiated groups. Levels of myofibroblasts, fibroblasts, vascularity, EndoMT, and macrophages were significantly lower in ADM capsules than in submuscular capsules. With the exception of EndoMT, all others were increased in irradiated submuscular capsules compared with nonirradiated submuscular capsule, while none significantly differed between nonirradiated and irradiated ADM capsules. CONCLUSIONS: Use of ADM reduced myofibroblasts, vascularity, fibroblasts, and EndoMT in capsule tissues. Moreover, ADM use decreased macrophages, a key regulator of tissue fibrosis, as well as TGF-ß1 and PDGF-B expression. We hope that these results provide basic concepts important for prevention of capsular contracture.

A meta-analysis of implant-based breast reconstruction and timing of adjuvant radiation therapy.

BACKGROUND: Implant-based breast reconstruction is the most common type of reconstruction after postmastectomy radiation therapy (PMRT). The impact of the timing of PMRT to a tissue expander or permanent implant is not well understood. The purpose of this systematic review was to evaluate outcomes in implant-based reconstruction and the timing of PMRT. METHODS: A review of the English literature in the PubMed/MEDLINE database (2000-2016) was performed to identify all articles on implant-based breast reconstruction and PMRT. Cases from each study were grouped by PMRT to a tissue expander or PMRT to a permanent implant. Outcomes of interest included reconstructive failure and capsular contracture as overall rates and associations were pooled. Effect sizes (z values), risk ratios (RRs), and heterogeneity scores (I2) were calculated on meta-analysis. RESULTS: There were 20 studies meeting inclusion criteria with 2348 patients identified. Pooled analysis revealed an overall rate of reconstructive failure of 17.6% and Baker grade III/IV capsular contracture of 37.5%. PMRT applied to tissue expanders resulted in higher rates of reconstructive failure compared with PMRT applied to permanent silicone implants (20% versus 13.4%, RR = 2.33, P = 0.0083, 95% confidence interval 1.24-4.35), but lower rates of capsular contracture (24.5% versus 49.4%, RR = 0.53, P = 0.083, 95% confidence interval 0.26-1.09). CONCLUSIONS: Regardless of timing, PMRT applied to implant-based breast reconstruction was associated with high risk of reconstructive failure and capsular contracture. Surgeons should consider alternative strategies, such as autologous tissue reconstructions, in patients requiring PMRT.

Effect of zafirlukast on capsular contracture around silicone implants in rats / Efeito do zafirlukast na contratura capsular ao redor de implantes de silicone em ratos

PURPOSE: To evaluate the effect of zafirlukast on capsular contracture around silicone implants by measuring the pressure within the implant, using a rat experimental model. METHODS: Forty adult female Wistar rats were used. Each one received two silicone implants, one with smooth-surface and the other with textured-surface. They were randomly divided into four groups (n=10). The rats of control group I were sacrificed after the implants. The remaining animals were subjected to a daily regimen of intra-peritoneal injection for a period of 90 days and they were distributed as follows: control group II received 0.9 percent physiological saline solution; experimental group I received zafirlukast 1.25 mg/kg; and experimental group II received zafirlukast 5 mg/kg. The measurement of intra-implant pressure of control group I was determined on the surgery day and in other groups on the ninetieth day, after being sacrificed. RESULTS: In the evaluation of textured implants there was an increase of internal pressure in the control group II, and there was no increase in the experimental groups. Compared to the controls there were not significant differences in smooth implants. CONCLUSION: Zafirlukast reduced the risk of developing capsular contracture around silicone implants with textured surface.

OBJETIVO: Avaliar o efeito do zafirlukast na contratura capsular ao redor de implantes de silicone, através da aferição da pressão intra-implante, utilizando-se um modelo experimental de ratos. MÉTODOS: Quarenta ratos fêmeas Wistar foram utilizados. Cada um recebeu dois implantes de silicone, sendo um com superfície lisa e outro texturizada. Foram divididos aleatoriamente em quatro grupos (n=10). Os ratos do grupo controle I foram sacrificados após o implante. O restante dos animais foi submetido a um regime diário de injeção intraperitoneal por um período de 90 dias e foram distribuídos: grupo controle II recebeu solução salina fisiológica 0,9 por cento, grupo experimental I recebeu zafirlukast 1,25 mg/kg, e grupo experimental II recebeu zafirlukast 5 mg/kg. O grupo controle II recebeu solução salina; grupo experimental I, 1,25 mg/kg/dia de zafirlukast; grupo experimental II, 5mg/kg/dia de zafirlukast. A aferição da pressão intra-implante do grupo controle I foi averiguada no dia do ato operatório, e nos outros grupos no nonagésimo dia, após serem sacrificados. RESULTADOS: Na avaliação dos implantes texturizados houve aumento da pressão interna no grupo controle II e, não se observou aumento nos grupos experimentais. Na comparação com os controles não foram observadas diferenças significativas nos implantes lisos. CONCLUSÃO: O Zafirlukast reduziu o risco de desenvolver contratura capsular em torno de implantes de silicone com superfície texturizada.

Effect of zafirlukast on capsular contracture around silicone implants in rats.

PURPOSE: To evaluate the effect of zafirlukast on capsular contracture around silicone implants by measuring the pressure within the implant, using a rat experimental model. METHODS: Forty adult female Wistar rats were used. Each one received two silicone implants, one with smooth-surface and the other with textured-surface. They were randomly divided into four groups (n=10). The rats of control group I were sacrificed after the implants. The remaining animals were subjected to a daily regimen of intra-peritoneal injection for a period of 90 days and they were distributed as follows: control group II received 0.9% physiological saline solution; experimental group I received zafirlukast 1.25 mg/kg; and experimental group II received zafirlukast 5 mg/kg. The measurement of intra-implant pressure of control group I was determined on the surgery day and in other groups on the ninetieth day, after being sacrificed. RESULTS: In the evaluation of textured implants there was an increase of internal pressure in the control group II, and there was no increase in the experimental groups. Compared to the controls there were not significant differences in smooth implants. CONCLUSION: Zafirlukast reduced the risk of developing capsular contracture around silicone implants with textured surface.