Biofunctionalization of silicone rubber with microgroove-patterned surface and carbon-ion implantation to enhance biocompatibility and reduce capsule formation

In Situ Forming Hydrogel as a Tracer and Degradable Lacrimal Plug for Dry Eye Treatment

Lacrimal plug is an effective and widely therapeutic strategy to treat dry eye. However, almost all commercialized plugs are fixed in a certain design and associated with many complications, such as spontaneous plug extrusion, epiphora, and granuloma and cannot be traced in the long-term. Herein, a simple in situ forming hydrogel is developed as a tracer and degradable lacrimal plug to achieve the best match with the irregular lacrimal passages. In this strategy, methacrylate-modified silk fibroin (SFMA) is served as a network, and a self-assembled indocyanine green fluorescence tracer nanoparticle (FTN) is embedded as an indicator to develop the hydrogel plug using visible photo-crosslinking. This SFMA/FTN hydrogel plug has excellent biocompatibility and biodegradability, which can be noninvasively monitored by near-infrared light. In vivo tests based on dry eye rabbits show that the SFMA/FTN hydrogel plug can completely block the lacrimal passages and greatly improve the various clinical indicators of dry eye. These results demonstrate that the SFMA/FTN hydrogel is suitable as an injectable and degradable lacrimal plug with a long-term tracking function. The work offers a new approach to the development of absorbable plugs for the treatment of dry eye.

The influence of foreign textile bodies from military clothes on the healing process of experimental injuries of soft tissues

Background

The healing of combat wounds can be complicated by the presence of foreign bodies, including fragments of military clothing. The present work aims to study the morphological features of soft tissue injuries with textile fibers implanted into wounds, personnel military forms during wound healing, in the experiment.

Methods

By randomization, 54 rats were divided into 3 groups. Control group animals performed a layer-by-layer incision of soft tissues without implantation of foreign bodies. Animals of the experimental group 1 were made implantation of fibers of a fabric consisting of 100% cotton, and of the experimental group 2-of fibers of a fabric consisting of 65% cotton and 35% polyester. Removal of laboratory animals from the experiment was carried out on the 15th, 30th, and 60th day. Soft tissue samples were histologically examined.

Results

The least pronounced inflammation was observed in rats of the control group. Wound healing in the experimental groups was slowed down due to the presence of inflammatory foci. A more pronounced inflammatory reaction was characterized by a group of animals with implanted tissue fibers consisting of 100% cotton. In the group with implanted tissue fibers consisting of 65% cotton and 35% polyester, the inflammatory reactions were less pronounced.

Conclusions

The presence of textile foreign bodies hampers the healing process of wounds of soft tissues due to the developing processes of inflammation around foreign bodies. The uniform of servicemen (35% synthetic and 65% natural fiber) is less reactive, leaving a wound as a textile foreign body, and has a less pronounced inflammatory effect, apparently due to the presence of synthetic threads that are more inert compared to fabric containing 100% natural fiber. This confirms the need for thorough debridement of combat wounds during the primary surgical treatment.

Functionalization of Silicone Surface with Drugs and Polymers for Regulation of Capsular Contracture

Breast reconstruction is achieved using silicone implants, which are currently associated with major complications. Several strategies have been considered to overcome the existing limitations as well as to improve their performance. Recently, surface modification has proved to be an effective clinical approach to prevent bacterial adhesion, reduce capsular thickness, prevent foreign body reactions, and reduce other implant-associated problems. This review article summarizes the ongoing strategies for the surface modification of silicone implants in breast reconstruction applications. The article mostly discusses two broad categories of surface modification: drug-mediated and polymer-based. Different kinds of drugs have been applied with silicone that are associated with breast reconstruction. Initially, this article discusses studies related to drugs immobilized on silicone implants, focusing on drug-loading methods and their effects on capsule contracture. Moreover, the pharmacological action of drugs on fibroblast cells is considered in this section. Next, the polymeric modification of the silicone surface is introduced, and we discuss its role in reducing capsule thickness at the cellular and biological levels. The polymeric modification techniques, their chemistry, and their physical properties are described in detail. Notably, polymer activities on macrophages and inflammation are also briefly discussed. Each of the reviewed articles is summarized, highlighting their discussion of capsular thickness, foreign body reactions, and bacterial attachment. The aim of this review is to provide the main points of some research articles regarding the surface modification of silicon, which can lead to a decrease in capsular thickness and provides better patient compliance.

Evaluations for surrounding tissue incorporation after implantation of synthetic vascular prostheses in animal models

Incorporation of surrounding tissues after implantation of synthetic vascular prostheses potentially varies in accordance with implanted prostheses. To evaluate post-implant tissue incorporation, we examined surgical, histological and ultrastructural findings after implantation in animal models. Three types of commercially available prostheses were tested (Gelweave™; Group G, J Graft SHIELD NEO^®; Group J and Triplex^®; Group T). Prostheses were implanted into Sprague-Dawley rats subcutaneously or sutured on abdominal aorta of Japanese white rabbits. The tissues were surgically examined for adhesion and were subjected to histological evaluations for cellular and tissue infiltration and ultrastructural observations by scanning electron microscopy (SEM). Group G exhibited less tendency in adhesion formation in early phase (rat: G vs J, P < 0.0001; G vs T, P < 0.0001/rabbit: G vs J, P < 0.0001; G vs T, P = 0.059). In late phase, Group J showed highest adhesion (rat: G vs J, P = 0.0004; J vs T, P = 0.015/rabbit: G vs J, P = 0.0015; J vs T, P = 0.0044). In group G, a gap was observed between implants and surrounding tissues forming capsulation, whereas other groups exhibited tissue infiltration inside of the implants wall which were also confirmed by SEM. The tissue permeation toward the implants and adhesion was positively correlated (P < 0.0001). Surrounding tissue conformation varied in accordance with the type of prostheses. It is desirable to elucidate characteristics of each prosthesis to select suitable grafts for each patient to achieve a better surgical outcome.

Healing features of experimental injuries of soft tissues that contain foreign bodies in the form of fragments of military personnel uniforms

INTRODUCTION

The healing of combat wounds can be complicated by the presence of foreign bodies. The present research aimed to study the regeneration of soft tissue injuries complicated by foreign bodies in the form of fragments of military uniforms.

METHODS

60 rats were divided into four groups: intact (Int), control (Con) and two experimental (EG1, EG2). In Con, wounds were sutured without implantation of foreign bodies. A uniform consisting of 100% cotton was used as foreign bodies for EG1 and a uniform consisting of 65% cotton and 35% polyester for EG2. Histological studies were performed according to generally accepted methods. The growth factors wеre determined by ELISA.

RESULTS

In EG1, the inflammatory reaction proceeded protractedly, which complicated the development of granulation tissue. In EG2, considering the moderate inflammatory reactions, healing of the wounds became possible. The increase of the growth factors content in Con was maximal at the 15th day: basic fibroblast growth factor (bFGF)-2.2 times and vascular endothelial growth factor (VEGF)-1.6 times (p<0.001). In experimental groups, the bFGF content was maximal at the 60th day and exceeded the normal values by 1.7 times in EG1 and by 2.6 times in EG2 (p<0.001); the level of VEGF was slightly higher than that in healthy animals.

CONCLUSIONS

The study showed wound healing in all groups. The repair of injuries in rats of EG1 and EG2 was complicated by the textile implant and took longer. The dynamics of the content of growth factors reflected the impairment of wound healing processes. These violations were more pronounced in the EG1 group.

A multi-center, retrospective, preliminary observational study to assess the safety of BellaGel® after augmentation mammaplasty

Background

BellaGel® is the only cohesive silicone gel-filled breast implant from a Korean manufacturer, and it was first developed in 2005. It was approved by the CE in 2008, thus becoming the first Asian breast implant available in the EU. We conducted this study to assess the safety of BellaGel® in patients receiving augmentation mammaplasty.

Methods

We evaluated a consecutive series of 239 patients (478 breasts) who received esthetic augmentation mammaplasty using the BellaGel® (round smooth, round textured, round nanotextured, and anatomical textured types of implant) (HansBiomed Co. Ltd., Seoul, Korea) at three clinics in Korea (JW Plastic Surgery Center, BS The Body Plastic Surgery Clinic and Grace Plastic Surgery Clinic) during a period from December 1, 2015 to January 31, 2018.

Results

A total of 239 patients with a mean age of 33.1 ± 8.5 years old were followed up during a mean period of 399.58 ± 232.71 days, where there were no cases of capsular contracture in our clinical series of the patients. Other complications include one case (0.4%) of seroma, three cases (1.3%) of hematoma, and one case (0.4%) of infection. Moreover, there were no significant differences in the cumulative incidences of complications between the four types of the BellaGel® (χ2 = 2.322, df = 3, P = 0.508). Furthermore, the cumulative Kaplan-Meier survival rate was estimated at 0.979 (95% CI 0.961–0.997).

Conclusions

Our results indicate that the BellaGel® is such a safe breast implant that surgeons might consider using it for esthetic augmentation mammaplasty.

Level of evidence: Level III, risk/prognostic study.

Reduced fibrous capsule formation at nano-engineered silicone surfaces via tantalum ion implantation

Nano-engineered surface of silicone implant improves the biocompatibility and suppresses the fibrous capsule formation which is the most common side effect of polymeric implants.

Promoted Angiogenesis and Osteogenesis by Dexamethasone-loaded Calcium Phosphate Nanoparticles/Collagen Composite Scaffolds with Microgroove Networks

Reconstruction of large bone defects remains a clinical challenge because current approaches involving surgery and bone grafting often do not yield satisfactory outcomes. For artificial bone substitutes, angiogenesis plays a pivotal role to achieve the final success of newly regenerated bone. In this study, dexamethasone-loaded biphasic calcium phosphate nanoparticles/collagen composite scaffolds with several types of concave microgrooves were prepared for simultaneous promotion of angiogenesis and osteogenesis. Microgrooves in the scaffolds were supposed to guide the assembly of human umbilical vascular endothelial cells (HUVECs) into well aligned tubular structures, thus promoting rapid angiogenesis. The scaffolds were used for co-culture of HUVECs and human bone marrow-derived mesenchymal stem cells. Subcutaneous implantation in mice showed that more blood vessels and newly formed bone were observed in the microgrooved composite scaffolds than in the control scaffold. Scaffold bearing parallel microgrooves with a concave width of 290 µm and a convex ridge width of 352 µm showed the highest promotion effect on angiogenesis and osteogenesis among the parallelly microgrooved composite scaffolds. The scaffolds bearing a grid network had further superior promotion effect to the scaffolds bearing parallel microgrooves. The results indicated that microgrooves in the composite scaffolds facilitated angiogenesis and stimulated new bone formation. The microgrooved composite scaffolds should be useful for repairing of large bone defects.

Surface changes of nanotopography by carbon ion implantation to enhance the biocompatibility of silicone rubber: an in vitro study of the optimum ion fluence and adsorbed protein

Lower cellular adhesion and dense fibrous capsule formation around silicone breast implants caused by lower biocompatibility is a serious clinical problem. Preliminary work has shown that ion implantation enhances cell adhesion. Whether the biocompatibility is further enhanced by higher doses of carbon ion implantation and the mechanism by which ion implantation enhances biocompatibility remain unclear. In this study, five doses of carbon ions, which gradually increase, were implanted on the surface of silicone rubber and then the surface characteristics were surveyed. Then, cell adhesion, proliferation and migration were investigated. Furthermore, the vitronectin (VN) protein was used as a model protein to investigate whether the ion implantation affected the adsorbed protein on the surface. The obtained results indicate that enhanced cytocompatibility is dose dependent when the doses of ion implantation are less than 1 × 10¹⁶ ions/cm². However, when the doses of ion implantation are more than 1 × 10¹⁶ ions/cm², enhanced cytocompatibility is not significant. In addition, surface physicochemical changes by ion implantation induced a conformational change of the adsorbed vitronectin protein that enhanced cytocompatibility. Together, these results suggest that the optimum value of carbon ion implantation in silicone rubber to enhance biocompatibility is 1 × 10¹⁶ ions/cm², and ion implantation regulates conformational changes of adsorbed ECM proteins, such as VN, and mediates the expression of intracellular signals that enhance the biocompatibility of silicone rubber. The results herein provide new insights into the surface modification of implant polymer materials to enhance biocompatibility. It has potentially broad applications in the biomedical field.

A polydopamine peptide coating enables adipose-derived stem cell growth on the silicone surface of cochlear implant electrode arrays

The simultaneous application of neurotrophic factors with cochlear implantation is proposed to enhance the bioelectrical interface between electrodes and auditory neurons, and thus improve speech intelligibility in patients with cochlear implants (CIs). In cell-based approaches, the goal is to colonize CIs with cells producing neurotrophic factors. This study aims to evaluate whether a polydopamine (PD) functionalization of the hydrophobic silicone surface of the electrode carrier enables colonization of adipose-derived stem cells known to deliver neurotrophic factors. Surface characteristics of PD-coated silicone samples and electrode carriers were determined, and the proliferation and viability of adipose-derived stem cells (ASCs) on these surfaces were subsequently analyzed. A homogenous PD coating and cell growth with regular morphology was observed on coated silicone samples and electrode arrays. Hydrophilicity and cell viability was significantly enhanced by PD surface modification. Insertion forces of coated electrode arrays did not increase compared with untreated CIs. Hence, PD coating of the silicone surface of CIs might allow for sufficient colonization with ASCs as a continuous source of neurotrophic factors. © 2017 Wiley Periodicals, Inc. J Biomater Res Part A: 106B: 1431-1438, 2018.