Wagner Marcondes

Comparative study of inflammatory response and adhesions formation after fixation of different meshes for inguinal hernia repair in rabbits

OBJETIVO: Avaliar a resposta inflamatoria e a formacao de aderencias das proteses de polipropileno e polipropileno associado a poliglactina sintetica (Vypro®) implantadas no espaco pre-peritoneal de coelhos. METODOS: Foram utilizados 14 coelhos albinos linhagem Nova Zelândia com tres meses de idade, machos com peso variando de 2000 a 2500 gramas. O acesso a cavidade se deu por incisao mediana abaixo do apendice xifoide com oito centimetros de extensao. Realizou-se o implante da tela de polipropileno no flanco esquerdo com um ponto de polipropileno em cada extremidade da protese. No flanco direito a tela Vypro® foi fixada da mesma forma com pontos de polipropileno. A laparoscopia foi realizada 28 dias apos o primeiro procedimento para avaliacao de aderencias intracavitarias. As proteses juntamente com o peritonio, musculatura e aponeurose adjacente foram retiradas em blocos individuais. Cada peca foi imersa em solucao tamponada de formaldeido a 10% e encaminhada ao patologista. RESULTADOS: Todos os animais tiveram boa evolucao pos-operatoria nao havendo infeccao das incisoes cirurgicas ou obito dos coelhos. Das quatorze proteses Prolene implantadas no peritonio intacto de coelho, em onze (78,6%) houve formacao de aderencias Das quatorze proteses Vypro®implantadas no peritonio intacto de coelho, em doze (85,7%) houve formacao de aderencias. Comparando as duas proteses entre si nao houve diferenca significante quanto ao numero de aderencias formadas. Em relacao a avaliacao microscopica, nas proteses VYPRO® a reacao granulomatosa do tipo corpo estranho e a fibrose foram predominantemente moderadas. Ja a inflamacao inespecifica foi proporcionalmente leve e moderada A inflamacao inespecifica foi menos intensa nas proteses de polipropileno. CONCLUSAO: Ambas as proteses implantadas na cavidade peritoneal de coelhos promovem a formacao de aderencias de forma semelhante. As proteses de polipropileno e associado a poliglactina promovem maior fibrose, apresentando melhor incorporacao aos tecidos.PURPOSE Compare, in a rabbit model, the inflammatory response and adhesions formation following surgical fixation of polypropilene and Vypro mesh in the inguinal preperitoneal space. METHODS Fourteen male New Zealand rabbits, weighing between 2.000 to 2.500 g were used. A midline incision was made and the peritoneal cavity was exposed. The 2.0 x 1.0 cm polypropylene mesh was fixed in the left flank and secured to the margins with 3-0 prolene in a separate pattern. In the right flank, a 2.0 x 1.0 cm Vypro II mesh was sewn in the same way. After the post surgical period, the animals were again anesthetized and underwent laparoscopic approach, in order to identify and evaluate adhesions degree. Both fixed prosthesis were excised bilaterally with the abdominal wall segment, including peritoneum, aponeurosis and muscle and sent to a pathologist. RESULTS Operative time ranged from 15 to 25 minutes and no difficulties in applying the mesh were found. From the 14 polypropylene meshes fixed to the intact peritoneum, 11 had adhesions to the abdominal cavity (78.6%). Concerning Vypro mesh, 12 animals developed adhesions from the 14 with mesh fixation (85.7%). Histological examination of tissues harvested revealed fibroblasts, collagen, macrophages and lymphocytes between the threads of the mesh. CONCLUSION Polypropylene and Vypro mesh, when implanted in the peritoneal cavity of rabbits provoke similar amount of adhesions. Vypro mesh tissues had higher fibrosis resulting in better mesh incorporation to the abdominal wall.

Nitric oxide modulates metalloproteinase-2, collagen deposition and adhesion rate after polypropylene mesh implantation in the intra-abdominal wall.

Prosthetic meshes are commonly used to correct abdominal wall defects. However, the inflammatory reaction induced by these devices in the peritoneum is not completely understood. We hypothesized that nitric oxide (NO), produced by nitric oxide synthase 2 (NOS2) may modulate the response induced by mesh implants in the abdominal wall and, consequently, affect the outcome of the surgical procedure. Polypropylene meshes were implanted in the peritoneal side of the abdominal wall in wild-type and NOS2-deficient (NOS2(-/-)) mice. After 15 days tissues around the mesh implant were collected, and inflammatory markers (the cytokine interleukin 1β (IL-1β) and NO) and tissue remodeling (collagen and metalloproteinases (MMP) 2 and 9) were analyzed. The lack of NOS2-derived NO induced a higher incidence of visceral adhesions at the mesh implantation site compared with wild-type mice that underwent the same procedure (P<0.05). Additionally, higher levels of IL-1β were present in the mesh-implanted NOS2(-/-) animals compared with control and wild-type mice. Mesh implantation induced collagen I and III deposition, but in smaller amounts in NOS2(-/-) mice. MMP-9 activity after the surgical procedure was similarly increased in both groups. Conversely, MMP-2 activity was unchanged in mesh-implanted wild-type mice, but was significantly increased in NOS2(-/-) mice (P<0.01), due to decreased S-nitrosylation of the enzyme in these animals. We conclude that NOS2-derived NO is crucial for an adequate response to and integration of polypropylene mesh implants in the peritoneum. NO deficiency results in a prolonged inflammatory reaction to the mesh implant, and reduced collagen deposition may contribute to an increased incidence of visceral adhesions.

Proposição de videolaparoscopia em ratos

Os autores apresentam a possibilidade do uso da videolaparoscopia em ratos. Foram utilizados 10 ratos Wistar. Empregaram um optica de 3mm, 30 graus, usada em artroscopia. Obtiveram bo visibilizacao dos orgaos da cavidade peritoneal. A introducao de agulhas especiais e instrumentos delicados permitiram realizar os procedimentos operatorios. O modelo experimental proposto tornou-se viavel, em ratos.

Efeitos da tela de polipropileno no testículo, epidídimo e ducto deferente de cães

The aim of this study was to investigate the effects of the synthetic mesh on the ductus deferens and testicle of dogs. Ten adult male dogs were anesthetized and a 2,5X3,5 cm² polypropilene mesh was fixed in the inguinal region in direct contact with the ductus deferens, using metallic staples without dissection of the region and therefore, without manipulation. The right side, with no mesh was the control. . The operative time was 15 minutes. The animals were observed for 30 days and after that, they were again anesthetized and underwent new operation when the ductus deferens and the testicle were removed and sent to histological analysis. The histological sections of the testicle showed a focal reduction of the spermatogenesis in 20 % and a degenerative process in 20 % of the animals. In the epididimus, chronic inflammation and seminiferous tubules dilatation were observed in 70 %. A chronic inflammatory process was found in 60 % of the vas deferens. The polypropilene mesh in direct contact with the spermatic funiculus in dogs causes histological alterations with minimal reduction on spermatogenesis.

Inducible nitric oxide synthase inhibition increases MMP-2 activity leading to imbalance between extracellular matrix deposition and degradation after polypropylene mesh implant †

Prosthetic mesh implants are commonly used to correct abdominal wall defects. However, success of the procedure is conditioned by an adequate inflammatory response to the device. We hypothesized that nitric oxide produced by nitric oxide synthase 2 (NOS2) and MMP-2 and -9 participate in response induced by mesh implants in the abdominal wall and, consequently, affect the outcome of the surgical procedure. In the first step, temporal inflammatory markers profile was evaluated. Polypropylene meshes were implanted in the peritoneal side of the abdominal wall of C57Black mice. After 2, 4, 7, 15, and 30 days, tissues around the mesh implant were collected and inflammatory markers were analyzed. In the second step, NOS2 activity was inhibited with nitro-L-arginine methyl ester (L-NAME). Samples were collected after 15 days (when inflammation was reduced), and the inflammatory and tissue remodeling markers were investigated. Polypropylene mesh implant induced a pro-inflammatory environment mediated by intense MMP-2 and -9 activities, NO release, and interleukin-1β production peaking in 7 days and gradually decreasing after 15 days. NOS2 inhibition increased MMP-2 activity and resulted in a higher visceral adhesion incidence at the mesh implantation site when compared with non-treated animals that underwent the same procedure. We conclude that NOS2-derived NO is crucial for adequate response to polypropylene mesh implant integration in the peritoneum. NO deficiency results in an imbalance between extracellular matrix deposition/degradation contributing to visceral adhesions incidence.