Effects of Ethylene oxide resterilisation and In- Vitro degradation on mechanical properties of partially absorbable composite hernia meshes

Background: Prosthetic mesh repair for abdominal wall hernias is widely used because of its technical simplicity and low hernia recurrence rates. The most commonly used material is pure polypropylene mesh, however newer  composite materials are recommended by some centers because of their advantages. However, these meshes are more expensive than pure polypropylene meshes. Resterilisation of a pure polypropylene mesh has been  shown to be quite safe, and many centers prefer slicing a large mesh into smaller pieces that suitable for hernia type or defect size. Nevertheless there is no data about the safety after resterilisation of the composite meshes.Objective: To search the effects of resterilisation and In vitro degradation in phosphate buffered saline solution on the physical structure and the mechanical properties of partially absorbable lightweigth meshes.Design: Laboratory-based research.Subjects: Two composite meshes were used in the study: One mesh is consisted of monofilament polypropylene and monofilament polyglecaprone -a copolymer of glycolide and epsilon (ε)-caprolactone- (Ultrapro®, 28 g/m2, Ethicon, Hamburg, Germany), and the other one consisted of multifilament polypropylene and multifilament polyglactine (Vypro II®, 30 g/m2, Ethicon, Hamburg, Germany). Two large meshes were cut into rectangular specimens sized 50x20 mm for mechanical testing and 20x20 mm for In vitro degradation experiments. Meshes were divided into control group with no resterilisation and gas resterilisation. Ethylene oxide gas sterilisation was performed at 55°C for 4.5 hours. In vitro degradation in 0.01 M phosphate buffered saline (PBS, pH 7.4) solution at 37 ± 1°C for 8  weeks was applied to one subgroup in each mesh group. Tensiometric measurements and scanning electron microscopyic evaluations were completed for control and resterilisation specimens.Results: Regardless of resterilisation, when meshes were exposed to In vitro degradation, all mechanical parameters decreased significantly. Highest reduction in mechanical properties was observed for Ultrapro due to the degradation of absorbable polyglecaprone and polyglactin parts of these meshes. It was observed that resterilisation by ethylene oxide did not have significant difference on the degradation characteristics and almost similar physical structures  were observed for resterilised and non-resterilised meshes. For Vypro II meshes, no significant mechanical  difference was observed between resterilised and non-resterilised meshes after degradation while resterilised Ultrapro meshes exhibited stronger characteristics than non-resterilised counterparts, after degradation

Effects of Ethylene Oxide Resterilization and In-vitro Degradation on Mechanical Properties of Partially Absorbable Composite Hernia Meshes*

Rezumat Efectele resterilizãrii cu oxid de etilen aei degradãrii in-vitro asupra proprietãåilor mecanice ale plaselor chirurgicale din material mixt paråial absorbabile Principiul aei scopul lucrãrii: Protezarea cu plase chirurgicale a herniilor de perete abdominal este o tehnicã extensiv utilizatã datoritã simplitãåii sale aei ratelor scãzute de recurenåã aferente. Cele mai utilizate materiale sunt plasele din polipropilenã, însã noi materiale mixte sunt recomandate de unele centre datoritã avantajelor pe care le prezintã. Aceste plase sunt, însã, mai costisitoare decât cele realizate exclusiv din polipropilenã. Resterilizarea unei plase de polipropilenã purã s-a dovedit a fi o procedurã destul de sigurã, iar multe centre preferã sã taie o plasã de dimensiuni mari în mai multe plase mai mici, ce pot fi folosite pentru orice tip de hernie sau orice dimensiune a defectului. Cu toate acestea, nu existã date privind gradul de siguranåã al resterilizãrii plaselor din material mixt. Studiul curent a fost desfãaeurat în vederea evaluãrii efectelor resterilizãrii aei degradãrii in-vitro cu fosfat tamponat cu soluåie salinã asupra structurii fizice aei a proprietãåilor mecanice ale plaselor chirurgicale uaeoare paråial absorbabile. Materiale aei metode: Douã tipuri de plase din material mixt au fost utilizate în acest studiu: o plasã alcãtuitã din monofilamente de polipropilenã aei monofilamente de poliglecapronã -un copolimer din glicolid aei epsilon (ε)-caprolactonã (Ultrapro®, 28 g/m 2 , Ethicon, Hamburg, Germania), iar cealaltã din multifilamente de polipropilenã aei multifilamente de poliglactinã (Vypro II®, 30 g/m 2 , Ethicon, Hamburg, Germania). Douã plase de dimensiuni mari au fost tãiate în probe rectangulare de 50x20 mm pentru testarea mecanicã aei de 20x20 mm pentru experimentele de degradare in-vitro. Plasele au fost distribuite în grupuri de control, fãrã sterilizare, aei de resterilizare cu gaz. Sterilizarea gazoasã cu oxid de etilen a fost efectiatã la 55°C timp de 4,5 ore. Câte un subgrup din fiecare grup de plase a fost supus degradãrii in-vitro cu 0,01 M fosfat tamponat cu soluåie salinã (PBS, pH 7,4) la 37 ± 1°C timp de 8 sãptãmâni. Mãsurãtorile tensiometrice aei de microscopie electronicã au fost efectuate pentru probele de control aei cele resterilizate. Rezultate: Indiferent de resterilizare, la expunerea plaselor la degradarea in-vitro, toåi parametrii mecanici au scãzut semnificativ. Cea mai mare scãdere în termeni de proprietãåi mecanice a fost observatã la plasele Ultrapro, din cauza degradãrii componentelor de poliglecapronã aei poliglactinã absorbabile ale acestor plase. S-a observat cã resterilizarea cu oxid de etilen nu a determinat diferenåe semnificative în ce Cuvinte cheie: plasã chirurgicalã, hernie, plasã din material mixt, resterilizare, degradare, proprietãåi mecanice, tensiometrie, rezistenåã la tracåiune, polipropilenã, poliglecapronã, poliglactinã Abstract Background and Aim: Prosthetic mesh repair for abdominal wall hernias is widely used because of its technical simplicity and low hernia recurrence rates. The most commonly used material is pure polypropylene mesh, although newer composite materials are recommended by some centers due to their advantages. However, these meshes are more expensive than pure polypropylene meshes. Resterilization of a pure polypropylene mesh has been shown to be quite safe, and many centers prefer slicing a large mesh into smaller pieces, suitable for any hernia type or defect size. Nevertheless there is no data about the safety after resterilization of the composite meshes. The present study was carried out to investigate the effects of resterilization and in vitro degradation in phosphate buffered saline solution on the physical structure and the mechanical properties of partially absorbable lightweight meshes. Methods: Two composite meshes were used in the study: One mesh consists of monofilament polypropylene and monofilament polyglecaprone -a copolymer of glycolide and epsilon (ε) -caprolactone -(Ultrapro®, 28 g/m 2 , Ethicon, Hamburg, Germany), and the other one consisted of multifilament polypropylene and multifilament polyglactine (Vypro II®, 30 g/m 2 , Ethicon, Hamburg, Germany). Two large meshes were cut into rectangular specimens sized 50 x 20 mm for mechanical testing and 20 x 20 mm for in vitro degradation experiments. Meshes were divided into control group with no resterilization and gas resterilization. Ethylene oxide gas sterilization was performed at 55°C for 4.5 hours. In vitro degradation in 0.01 M phosphate buffered saline (PBS, pH 7.4) solution at 37 ± 1°C for 8 weeks was applied to one subgroup in each mesh group. Tensiometric measurements and scanning electron microscopic evaluations were completed for control and resterilization specimens. Results: Regardless of resterilization, when the meshes were exposed to in vitro degradation, all mechanical parameters decreased significantly. Highest reduction in mechanical properties was observed for Ultrapro due to the degradation of absorbable polyglecaprone and polyglactin parts of these meshes. It was observed that resterilization by ethylene oxide did not determine significant difference on the degradation characteristics and almost similar physical structures were observed for resterilized and non-resterilized meshes. For Vypro II meshes, no significant mechanical difference was observed between resterilized and non-resterilized meshes after degradation while resterilized Ultrapro meshes exhibited stronger characteristics than non-resterilized counterparts, after degradation. Conclusion: Resterilization with ethylene oxide did not affect the mechanical properties of partially absorbable composite meshes. No important surface changes were observed in scanning electron microscopy after resterilization

In vitro cytotoxicity and genotoxicity of metallic and polymeric materials

31st Congress of the Federation-of-European-Biochemical-Societies (FEBS) -- JUN 24-29, 2006 -- Istanbul, TURKEYWOS: 000238914002084Federat European Biochem So

Blood compatibility of polymers derived from natural materials

Several polymers derived from natural materials are effective for tissue engineering or drug delivery applications, due to specific properties, such as biocompatibility, biodegradability, and structural activity. Their blood compatibility needs to be carefully evaluated to avoid thrombosis and other material-related adverse events in the hematic environment. We compared the surface properties and blood compatibility of protein and polysaccharide polymers, including fibroin, gelatin, and chitosan. Both fibroin and chitosan showed good hemocompatibility, with low platelet adhesion and spreading. Chitosan induced strong interactions with plasma proteins, especially with albumin. It was hypothesized that surface passivation by albumin inhibited the adsorption of other procoagulant and proadhesive proteins on chitosan and fibroin films, which limited platelet spreading. However, the significant and rapid polymer swelling encouraged protein entrapment within the soft, gelatin films, inducing higher platelet adhesion and activation. Thrombin generation assay confirmed the higher blood compatibility of chitosan and fibroin with regard to clottin