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

Osteopontin attenuates the foreign-body response to silicone implants

The inflammatory process resulting in the fibrotic encapsulation of implants has been well studied. However, how acellular dermal matrix (ADM) used in breast reconstruction elicits an attenuated foreign-body response (FBR) remains unclear. Here, by leveraging single-cell RNA-sequencing and proteomic data from pairs of fibrotically encapsulated specimens (bare silicone and silicone wrapped with ADM) collected from individuals undergoing breast reconstruction, we show that high levels of the extracellular-matrix protein osteopontin are associated with the use of ADM as a silicone wrapping. In mice with osteopontin knocked out, FBR attenuation by ADM-coated implants was abrogated. In wild-type mice, the sustained release of recombinant osteopontin from a hydrogel placed adjacent to a silicone implant attenuated the FBR in the absence of ADM. Our findings suggest strategies for the further minimization of the FBR.

Woxuanzhongzhou formula improves DHEAS and high-fat diet-induced IR and anovulatory mice via AMPK/PGC1- α/Irisin pathway

BACKGROUND

Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder in women of reproductive age. Anovulation is one of the most important clinical features of PCOS, and insulin resistance (IR) is one of the critical pathogenic factors. Woxuanzhongzhou (WXZZ) is a traditional herbal formulation that has shown efficacy in treating PCOS combined with IR, but the underlying mechanism is not clear. The aim of this study was to investigate the molecular mechanism of WXZZ on dehydroepiandrosterone sulfate and high fat diet induced PCOS with IR mice.

METHODS

40 female C57BL/6 mice were randomized to 4 groups: control group, model group, metformin group, and WXZZ group. Some mice is induced by dehydroepiandrosterone sulfate (DHEA) and high-fat diet (HFD) for 3 weeks. Following model induction, metformin and WXZZ were administered by gavage. Body weight, fasting blood glucose (FBG), fasting insulin (FINS) levels, the homeostatic model assessment of insulin resistance (HOMA-IR), and gonadal hormones were measured. Estrous cycles were monitored. The structure of the gastrocnemius muscle and subcutaneous fatty tissue were also evaluated. Additionally, serum irisin and non-esterified fatty acids (NEAF) levels and the protein and gene expression levels of AMPK, PGC1-α, FNDC5, irisin in the gastrocnemius muscle and CaMKK, AMPK, PGC1-α, UCP1 in fat were analyzed.

RESULTS

The DHEA + HFD + WXZZ group exhibited significant improvements in several key parameters compared to the DHEA + HFD group. WXZZ ameliorated endocrine and metabolic disorders, resumed estrous cycle in DHEAS and high-fat diet-induced IR and anovulatory mice. Significant reductions were observed in body weight, serum testosterone, luteinizing hormone, luteinizing hormone/ follicle-stimulating hormone ratio, FINS, and HOMA-IR. Additionally, WXZZ promoted irisin expression and secretion by up-regulating the protein and gene AMPK/PGC1-α/FNDC5 expression in gastrocnemius muscle and up-regulated the protein and gene CaMKK/AMPK/PGC1-α/UCP1 expression in fat. WXZZ inhibited the overproduction of serum NEFA, and reduced lipid accumulation. Structural analysis of the gastrocnemius muscle and adipose tissue revealed partial restoration.

CONCLUSION

WXZZ exhibits therapeutic effects in DHEAS and high-fat diet-induced IR and anovulatory mice. These effects may be mediated through the activation of AMPK/PGC1-α pathway in muscle to promote the secretion of irisin.

Capsular Contracture After Postmastectomy Radiation in Implant-Based Breast Reconstruction: Effect of Implant Pocket and Two-Stage Surgery

Capsular contracture (CC) is a concerning issue for individuals undergoing postmastectomy radiation therapy (PMRT) with implant-based breast reconstruction. This study investigated whether the extent of CC and implant migration differs based on implant placement and the reconstruction stage. Insertion plane and stage of breast implants were investigated, and the presence and severe cases of CC and implant migration were analyzed. Among 195 participants, 83 were in the pre-pectoral group, and 112 were in the sub-pectoral group. Two-staged surgery was performed on 116 patients, while 79 underwent direct-to-implant (DTI). Notably, The occurrence of CC (prepectoral, 17 [20.48%] and subpectoral, 42 [37.50%]; p = 0.011), CC severity (prepectoral, 4 [4.82%] and subpectoral, 17 [15.17%]; p = 0.021), and implant upward migration (prepectoral, 15 [18.07%] and subpectoral, 38 [33.92%]; p = 0.014) significantly varied between the two groups. The incidence of CC was more common in the DTI group (odds ratio [OR], 2.283; 95% confidence interval [CI], 1.164-4.478). Furthermore, subpectoral placement was an independent risk factor for occurrence (OR, 2.989; 95% CI, 1.476-6.054) and severity of CC (OR, 38.552; 95% CI, 1.855-801.186) and upward implant migration (OR, 2.531; 95% CI, 1.263-5.071). Our findings suggest that pre-pectoral reconstruction and the two-stage operation benefit patients who may undergo PMRT. These approaches can help reduce the incidence of CC and abnormal implant migration following radiation, leading to improved aesthetic outcomes and greater patient satisfaction.

Protective role of transforming growth factor-Β3 (TGF-Β3) in the formation of radiation-induced capsular contracture around a breast implant: In vivo experimental study

Postmastectomy radiotherapy causes capsular contracture due to fibroproliferation of the capsular tissue around the implant. In fibrosis, unlike normal wound healing, structural and functional disorders are observed in the tissues caused by excessive/irregular accumulation of extracellular matrix proteins. It has been reported that transforming growth factor-β3 (TGF-β3) prevents and reverses fibrosis in various tissues or provides scarless healing with its antifibrotic effect. Additionally, TGF-β3 has been shown to reduce fibrosis in radiotherapy-induced fibrosis syndrome. However, no study in the literature investigates the effects of exogenously applied TGF-β3 on capsular contracture in aesthetic or reconstructive breast implant application. TGF-β3, which has a very short half-life, has low bioavailability with parenteral administration. Within the scope of this study, free TGF-β3 was loaded into the nanoparticles to increase its low bioavailability and extend its duration of action by providing controlled release. The aim of this study is to investigate the preventive/improving effects of radiation induced capsular contracture using chitosan film formulations containing TGF-β3 loaded poly(lactic-co-glycolic acid)-b-poly(ethylene glycol) (PLGA-b-PEG) nanoparticles in implant-based breast reconstruction. In the characterization studies of nanoparticles, the particle size and zeta potential of the TGF-β3-loaded PLGA-b-PEG nanoparticle formulation selected to be used in the treatment group were found to be 123.60 ± 2.09 nm and -34.87 ± 1.42 mV, respectively. The encapsulation efficiency of the formulation was calculated as 99.91 %. A controlled release profile was obtained in in vitro release studies. Chitosan film formulations containing free TGF-β3 or TGF-β3-loaded PLGA-b-PEG nanoparticles were used in in vivo studies. In animal studies, rats were randomly distributed into 6 groups (n = 8) as sham, implant, implant + radiotherapy, implant + radiotherapy + chitosan film containing unloaded nanoparticles, implant + radiotherapy + chitosan film containing free TGF-β3, implant + radiotherapy + chitosan film containing TGF-β3 loaded nanoparticle. In all study groups, a 2 cm incision was made along the posterior axillary line at the thoracic vertebral level in rats to reach the lateral edge of the latissimus dorsi. The fascial attachment to the chest wall was then bluntly dissected to create a pocket for the implants. In the treatment groups, the wound was closed after films were placed on the outer surface of the implants. After administering prophylactic antibiotics, rats were subjected to irradiation with 10 Gy photon beams targeted to each implant site. Each implant and the surrounding excised tissue were subjected to the necessary procedures for histological (capsule thickness, cell density), immunohistochemical, and biochemical (α-SMA, vimentin, collagen type I and type III, TGF-β1 and TGF-β3: expression level/protein level) examinations. It was determined that the levels of TGF-β1 and TGF-β3 collagen type III, which decreased as a result of radiotherapy, were brought to the control level with free TGF-β3 film and TGF-β3 nanoparticle film formulations. Histological analyses, consistent with biochemical analyses, showed that thick collagen and fibrosis, which increased with radiotherapy, were brought to the control level with free TGF-β3 film and TGF-β3 nanoparticle film treatments. In biochemical analyses, the decrease in thick collagen was compatible with the decrease in the collagen type I/type III ratio in the free TGF-β3 film and TGF-β3 nanoparticle film groups. Changes in protein expression show that TGF-β3 loaded nanoparticles are more successful than free TGF-β3 in wound healing. In line with these results and the literature, it is thought that the balance of TGF-β1 and TGF-β3 should be maintained to ensure scarless wound healing with no capsule contracture.

Attenuating Chronic Fibrosis: Decreasing Foreign Body Response with Acellular Dermal Matrix

Surgical implants are increasingly used across multiple medical disciplines, with applications ranging from tissue reconstruction to improving compromised organ and limb function. Despite their significant potential for improving health and quality of life, biomaterial implant function is severely limited by the body's immune response to its presence: this is known as the foreign body response (FBR) and is characterized by chronic inflammation and fibrotic capsule formation. This response can result in life-threatening sequelae such as implant malfunction, superimposed infection, and associated vessel thrombosis, in addition to soft tissue disfigurement. Patients may require frequent medical visits, as well as repeated invasive procedures, increasing the burden on an already strained health care system. Currently, the FBR and the cells and molecular mechanisms that mediate it are poorly understood. With applications across a wide array of surgical specialties, acellular dermal matrix (ADM) has emerged as a potential solution to the fibrotic reaction seen with FBR. Although the mechanisms by which ADM decreases chronic fibrosis remain to be clearly characterized, animal studies across diverse surgical models point to its biomimetic properties that facilitate decreased periprosthetic inflammation and improved host cell incorporation. Impact Statement Foreign body response (FBR) is a significant limitation to the use of implantable biomaterials. Acellular dermal matrix (ADM) has been observed to decrease the fibrotic reaction seen with FBR, although its mechanistic details are poorly understood. This review is dedicated to summarizing the primary literature on the biology of FBR in the context of ADM use, using surgical models in breast reconstruction, abdominal and chest wall repair, and pelvic reconstruction. This article will provide readers with an overarching review of shared mechanisms for ADM across multiple surgical models and diverse anatomical applications.

Acellular dermal matrix in reconstructive surgery: Applications, benefits, and cost

Modern tissue engineering has made substantial advancements that have revolutionized plastic surgery. Acellular dermal matrix (ADM) is an example that has gained considerable attention recently. ADM can be made from humans, bovines, or porcine tissues. ADM acts as a scaffold that incorporates into the recipient tissue. It is gradually infiltrated by fibroblasts and vascularized. Fortunately, many techniques have been used to remove cellular and antigenic components from ADM to minimize immune system rejection. ADM is made of collagen, fibronectin, elastin, laminin, glycosaminoglycans, and hyaluronic acid. It is used in critical wounds (e.g., diabetic wounds) to protect soft tissue and accelerate wound healing. It is also used in implant-based breast reconstruction surgery to improve aesthetic outcomes and reduce capsule contracture risk. ADM has also gained attention in abdominal and chest wall defects. Some studies have shown that ADM is associated with less erosion and infection in abdominal hernias than synthetic meshes. However, its higher cost prevents it from being commonly used in hernia repair. Also, using ADM in tendon repair (e.g., Achilles tendon) has been associated with increased stability and reduced rejection rate. Despite its advantages, ADM might result in complications such as hematoma, seroma, necrosis, and infection. Moreover, ADM is expensive, making it an unsuitable option for many patients. Finally, the literature on ADM is insufficient, and more research on the results of ADM usage in surgeries is needed. This article aims to review the literature regarding the application, Benefits, and costs of ADM in reconstructive surgery.

Implant-Based Breast Reconstruction after Mastectomy, from the Subpectoral to the Prepectoral Approach: An Evidence-Based Change of Mind?

Over the last years, prepectoral implant-based breast reconstruction has undergone a renaissance due to several technical advancements regarding mastectomy techniques and surgical approaches for the placement and soft tissue coverage of silicone implants. Initially abandoned due to the high incidence of complications, such as capsular contraction, implant extrusion, and poor aesthetic outcome, the effective prevention of these types of complications led to the prepectoral technique coming back in style for the ease of implant placement and the conservation of the pectoralis muscle function. Additional advantages such as a decrease of postoperative pain, animation deformity, and operative time contribute to the steady gain in popularity. This review aims to summarize the factors influencing the trend towards prepectoral implant-based breast reconstruction and to discuss the challenges and prospects related to this operative approach.