The Effect Of The Surface Texture Of Silicone Rubber On Biological Behaviors Of Fibroblasts And Capsular Formation

Background: Breast augmentation is currently the most common plastic surgery,mainly applied for aesthetics and reconstruction of the breast.Silicone breast implant,consisting of an external shell formed by silicone rubber and an internal silicone gel,is the most common material utilized in breast augmentation.It can be divided into the smooth surface implant and the textured surface implant based on the surface texture of silicone shells.Implantation of a prosthesis usually provokes a foreign body reaction(FBR),which results in the deposition of collagen around the implant.Excessive FBR can trigger capsular contracture(CC),which causes breast stiffness,pain,obvious deformities and reoperation.CC remains the primary complication following breast augmentation with silicone breast implants.It is considered that the surface texture of implants plays a crucial role in the interaction between the implant and breast tissue,and affects the development of CC.However,there have long been widespread debates on the benefits of smooth and textured surface implants in reducing CC.Based on the contexts described above,we designed this study.Firstly,shells of three kind of commercially available silicone breast implants with identical ontological features and different surface textures were purchased from the same company,several physical properties of these shells were detected to clarify the distinction of the surface characteristics among them.We then assessed the effect of the surface texture from these silicone rubbers on the biological behaviors of fibroblasts.Finally,imaging,histological and immunohistochemical evaluations were performed to investigate the effect of the surface texture from these silicone rubbers on the capsular formation in animal models.These findings will provide a unique insight into the correlation between surface textures and clinical outcomes,facilitating a better comprehension of the function of surface textures in the clinical performance of prostheses,and meanwhile afford referential significances for clinical practices.Objectives: This study primarily aimed to investigate the effect of the surface texture from different silicone rubbers on biological behaviors of fibroblasts and capsular formation.Methods: 1.Preparation and grouping of materials(1)Cutting: disks equivalent to the bottom area of 96-well plate,24-well plate and 6-well plate were cut respectively from the shells of three silicone breast implants for cell experiments,and 1-cm-diameter disks were prepared for surface characterization and animal models.(2)Disinfection: silicone disks were sterilized with 75% alcohol overnight,followed by immersion in phosphate-buffered saline(PBS)for 2 h,airing was carried out before subsequent experiments.(3)Grouping: the smooth surface group,the textured surface 1 group as well as the textured surface 2 group.2.Surface characteristics detection of different silicone rubbers(1)Surface topography: the microscopic topography of surfaces was scrutinized by utilizing cyro-focused ion beam scanning electron microscopy(FIB-SEM).(2)Surface roughness: the average roughness(Ra)was taken as the evaluation indicator and detected using a confocal laser scanning microscopy.(3)The wettability: the water contact angle(CA)was taken as the evaluation indicator and obtained applying an optical contact angle meter.3.Evaluation of biological behaviors of human-derived fibroblasts cultured on the surface of different silicone rubbers(1)The proliferation and activity of cells: fibroblasts were seeded onto different silicone rubbers,and the cell activity at 24 h and 48 h were measured respectively using CCK-8.(2)The adhesive ability of cells: fibroblasts were cultured on different silicone rubbers for 48 h,and the expressions of the focal adhesion kinase(FAK)and adhesion-associated proteins(Talin,Zyxin,Vinculin and Paxillin)were then detected by wielding Western Blotting(WB).(3)Morphology of cells: FIB-SEM was implemented to scrutinize the morphology of fibroblasts which were incubated on the surface of different silicone rubbers for 48 h.(4)The cytoskeletal organization: fibroblasts,cultured on different silicone rubbers for 48 h,were stained with immunofluorescence,and then the cytoskeletal organization was observed by using a confocal laser scanning microscopy.4.The effect of different silicone rubber surfaces on the capsular formation in rats(1)Experimental grouping: A total of five female Sprague-Dawley rats were used for animal experiments,each rat was implanted with three groups of silicone rubbers,and each group possessed five specimens.(2)Operation: three silicone disks were inserted subcutaneously in the back region of each rat,and capsules were dissected after six weeks.(3)Imaging observation: before dissection,the level of echogenicity of capsules was examined by employing high-resolution ultrasound(HR-US)and quantified by calculating their gray values.(4)Histological measurements: hematoxylin-eosin staining was carried out to detect the thickness of capsules,and the arrangement and density of collagen fibers were evaluated through Masson trichrome staining.(5)Immunohistochemical assessment: immunohistochemical staining was performed on the capsule tissues to assess the expression of a-smooth muscle actin(a-SMA).Results: 1.The results of surface characteristics detection showed that the smooth surface possessed the minimum Ra(1.35 ± 0.13 μm),the value of CA was 110.20 ± 2.53°,and its surface was smooth and flat;textured surface 1 possessed the medium Ra(18.81 ± 0.57 μm)and the value of CA was 134.60 ± 0.82°,an extraordinarily irregular topography imaging was observed on it;textured surface 2 possessed the maximum Ra(43.66 ± 0.72 μm)and the value of CA was 119.80 ± 2.36°,it had two orders of morphological features,the first-order was hemispherical convex structure regularly distributed on the surface,and the second-order was the irregular ridge.There were significant differences in the value of Ra or CA among these silicone rubbers(P < 0.01).2.The data of CCK-8 revealed that there was no significant distinction in the viability of fibroblasts among all groups after 24-h incubation(P > 0.05).Either of the two textured surfaces presented observably higher viability than the smooth surface at 48 h(P < 0.01),while no obvious difference was obtained between the textured surfaces(P > 0.05).3.Results from WB and the quantification of gray values demonstrated that the expression of FAK and the adhesion-associated proteins gradually decreased with increasing surface Ra.4.The images of FIB-SEM illuminated that the morphology of fibroblasts gradually expanded with the decrease of surface Ra.5 The images of the confocal laser scanning microscopy elucidated that the cytoskeletal arrangement of fibroblasts became compact and parallel with the increase of surface Ra.6.The results from animal experiments explicated that as the value of Ra increased,the level of echogenicity of capsules got weaker,capsules became thicker,the collagen fiber arrangement became more disorganized and sparser,and the expression of a-SMA decreased gradually.Conclusions: 1.There were significant differences in surface properties,such as the topography,the value of Ra and the value of CA,among these silicone rubbers.2.The effect of the surface texture from distinct silicone rubbers on the proliferation,the adhesion,the morphology as well as the cytoskeletal organization of fibroblasts and capsular formation in rats was closely associated with the value of Ra.3.Overall,textured surface 2,with regular distribution and two orders of morphological features,the maximum value of Ra as well as the moderate hydrophobicity,may be more propitious to reduce the contraction of capsules.