BackgroundSilicone implants are biomaterials that are frequently used in the medical industry due to their physiological inertness and low toxicity. However, capsular contracture remains a concern in long-term transplantation. To date, several studies have been conducted to overcome this problem. This review summarizes and explores these trends.Main bodyFirst, we examined the overall foreign body response from initial inflammation to fibrosis capsule formation in detail and introduced various studies to overcome capsular contracture. Secondly, we introduced that the main research approaches are to inhibit fibrosis with anti-inflammatory drugs or antibiotics, to control the topography of the surface of silicone implants, and to administer plasma treatment. Each study examined aspects of the various mechanisms by which capsular contracture could occur, and addressed the effects of inhibiting fibrosis.ConclusionThis review introduces various silicone surface modification methods to date and examines their limitations. This review will help identify new directions in inhibiting the fibrosis of silicone implants.

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The number of breast reconstruction surgeries has been increasing due to the increase in mastectomies. Surgical implants (the standard polydimethylsiloxane (PDMS) implants) are widely used to reconstruct breast tissues, however, it can cause problems such as adverse immune reactions, fibrosis, rupture, and additional surgery. Hence, polymeric fillers have recently garnered increasing attention as strong alternatives for breast reconstruction materials. Polymeric fillers offer noninvasive methods of reconstruction, thereby reducing the possible adverse effects and simplifying the treatment. In this study, we synthesized a 2-hydroxylethylmethacrylate (HEMA) and acrylamide (Am) copolymer (Poly(HEMA-Am)) by redox polymerization to be used as a biocompatible filler material for breast reconstruction. The synthesized hydrogel swelled in phosphate buffered saline (PBS) shows an average modulus of 50 Pa, which is a characteristic similar to that of the standard dermal acrylamide filler. To investigate the biocompatibility and cytotoxicity of the Poly(HEMA-Am) hydrogel, we evaluated an in vitro cytotoxicity assay on human fibroblasts (hFBs) and human adipose-derived stem cells (hADSCs) with the hydrogel eluate, and confirmed a cell viability of over 80% of the cell viability with the Poly(HEMA-Am) hydrogel. These results suggest our polymeric hydrogel is a promising filler material in soft tissue augmentation including breast reconstruction.

BellaGel SmoothFine® implant is a novel nanotextured silicone breast implant. The objective of this study was to characterize differences of BellaGel SmoothFine® surfaces with commercial available implant surfaces in terms of texture, topography, and wettability as well as the behavior of capsular contracture. The surface textures of breast implants from two different manufacturers (Hans Biomed and Motiva) were evaluated. The implants utilized in this study were BellaGel Smooth®, BellaGel Textured®, BellaGel SmoothFine® or Motiva SilkSurface®. The shell textures of these implants were characterized using a scanning electron microscopy, three dimensional confocal laser scanning microscope, and contact angle goniometer. Silicone breast implants were emplaced beneath the panniculus carnosus muscle on the dorsum of Sprague Dawley rats and observed for up to 8 weeks postoperative days. The fibrous capsules around silicone implants were explanted for histological examination. BellaGel SmoothFine® exhibits a relatively flat, with little or no depth in the texturing, 5.96 ± 0.41 μm surface roughness, and a contact angle of 103.14 ± 2.06 BellGel SmoothFine® implant resulted in significant decreases in capsule thickness (P < 0.05) and collagen production (P < 0.05) at 8 weeks with respect to the BellaGel Smooth® and BellaGel Textured® implant groups. Significant (P < 0.05) decreases in inducible nitric oxide synthase, an inflammation marker, were observed in the BellGel SmoothFine®. Fibrous tissue formation markers (Vimentin and alpha-smooth muscle actin) were significantly reduced in BellaGel SmoothFine® surfaces versus BellaGel Smooth® surfaces (P < 0.05) or BellaGel Textured® groups (P < 0.05). Overall, these findings suggest that the nanotextured BellaGel SmoothFine® implant is associated with less breast implant derived capsular contracture than other surfaces.

Background Polydioxanone (PDO) threads, poly‐L‐lactic acid (PLLA) threads, and polycaprolactone (PCL) threads have been used for lifting and antiaging purposes. The new PCL threads that have less residual monomer compared to the previous PCL are developed. Aims The efficacy of threads regarding collagen synthesis and wrinkle improvement was evaluated in vivo model. Methods In this study, threads were inserted into 30 six‐week‐old male SKH‐1 hairless mice. One of four threads was implanted at either side of the spine of each mouse. Biopsy specimens obtained at 1, 4, and 8 weeks were examined using hematoxylin and eosin (H&E) and Herovici's stain. Additionally, immunoblot analysis was performed using primary antibody for collagen type III and transforming growth factor‐β (TGF‐β) and visualized by chemiluminescence and densitometric quantification. Finally, skin replicas were used to calculate total wrinkle area (mm2). Results Neocollagenesis was significantly increased by 50% in the new PCL and pre‐existing PCL groups at 8 weeks (p value < 0.001). Additionally, new‐PCL‐implanted mice showed a significant increase in collagen type III and TGF‐β expressions at 8 weeks (p value < 0.001). The number of inflammatory cells was also increased in the skin of PCL‐implanted mice at 8 weeks. Finally, wrinkles were reduced about 20% in the new PCL group at 8 weeks. Conclusions The new PCL thread exhibited a superior skin rejuvenation effect. This suggests that the material processing technology can be applied not only to the thread but also to various products such as dermal filler and cosmetics.

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The surface of poly(dimethylsiloxane) (PDMS) is grafted with poly(acrylic acid) (PAA) layers via surface‐initiated photopolymerization to suppress the capsular contracture resulting from a foreign body reaction. Owing to the nature of photo‐induced polymerization, various PAA micropatterns can be fabricated using photolithography. Hole and stripe micropatterns ≈100‐µm wide and 3‐µm thick are grafted onto the PDMS surface without delamination. The incorporation of PAA micropatterns provides not only chemical cues by hydrophilic PAA microdomains but also topographical cues by hole or stripe micropatterns. In vitro studies reveal that a PAA‐grafted PDMS surface has a lower proliferation of both macrophages (Raw 264.7) and fibroblasts (NIH 3T3) regardless of the pattern presence. However, PDMS with PAA micropatterns, especially stripe micropatterns, minimizes the aggregation of fibroblasts and their subsequent differentiation into myofibroblasts. An in vivo study also shows that PDMS samples with stripe micropatterns polarized macrophages into anti‐inflammatory M2 macrophages and most effectively inhibits capsular contracture, which is demonstrated by investigation of inflammation score, transforming‐growth‐factor‐β expression, number of macrophages, and myofibroblasts as well as the collagen density and capsule thickness.

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