Sequential Laparoscopy Research Articles

Behaviour at the peritoneal interface of next-generation prosthetic materials for hernia repair.

When using a prosthetic material in hernia repair, the behaviour of the mesh at the peritoneal interface is especially important for implant success. Biomaterials developed for their intraperitoneal placement are known as composites and are made up of two different-structure materials, one is responsible for good integration within host tissue and the other is responsible to make contact with the viscera. This study examines the behaviour at the peritoneal level of two composites, the fully degradable Phasix-ST® and the partially degradable Symbotex®. A polypropylene mesh (Optilene®) served as control. Sequential laparoscopy from 3 to 90days, in a preclinical model in the New Zealand white rabbit, allowed monitoring adhesion formation. Morphological studies were performed to analyse the neoperitoneum formed in the repair process. Total macrophages were identified by immunohistochemical labelling. To identify the different macrophage phenotypes, complementary DNAs were amplified by qRT-PCR using specific primers for M1 (TNF-α/CXCL9) and M2 (MRC1/IL-10) macrophages. The percentage of firm and integrated adhesions remained very high in the control group over time. Both composites showed a significant decrease in adhesions at all study times and in qualitative terms were mainly loose. Significant differences were also observed from 7days onwards between the two composites, increasing the values in Phasix over time. Neoperitoneum thickness for Phasix was significantly greater than those of the other meshes, showing mature and organized neoformed connective tissue. Immunohistochemically, a significantly higher percentage of macrophages was observed in Symbotex. mRNA expression levels for the M2 repair-type macrophages were highest for Phasix but significant differences only emerged for IL-10. Fewer adhesions formed to the Symbotex than Phasix implants. Ninety days after implant, total macrophage counts were significantly higher for Symbotex, yet Phasix showed the greater expression of M2 markers related to the tissue repair process.

Evaluación preclínica de una nueva prótesis compuesta (Parietex™ Composite Ventral Patch) destinada a la reparación de hernias ventrales

IntroductionVentral hernia repair is among the most frequently performed abdominal surgery procedures. The use of a prosthetic material is today the first-line treatment. This preclinical study compares the postimplant behavior of a new composite mesh (Parietex™ Composite Ventral Patch; Ptx) with that of existing meshes used to repair this type of abdominal wall defect. Materials and methodsThirty six New Zealand White rabbits (mean weight 3000g) were used in a ventral hernia repair model with a hernial orifice 1.5cm in diameter. The prosthetic materials tested were: Ventralex™ ST (Vent), Proceed™ Ventral Patch (PVP) and Ptx. Peritoneal behavior was monitored over time by sequential laparoscopy performed at 3, 7 and 14 days postimplant. Animals were sacrificed 2 and 6 weeks after implant. Mesothelial deposition at the peritoneal interface was examined by scanning electron microscopy. The Mann-Whitney test was used for the statistical treatment of data. ResultsAdhesion formation at 6 weeks postimplant was significantly greater for the PVP meshes compared with Vent and Ptx. Three PVP implants showed the encapsulation of seroma along with firm adhesions to the intestinal loops. Host tissue incorporation on the peritoneal side of the abdominal wall was optimal for the Ptx meshes. Good mesothelial deposition was observed for Vent and Ptx. Conclusionsa) Ptx and Vent showed excellent mesothelialization which was correlated with minimal adhesion formation;b) the Ptx implants showed the best incorporation in the parietal peritoneum due to its efficient intraperitoneal deployment device.

Comparing the host tissue response and peritoneal behavior of composite meshes used for ventral hernia repair

BackgroundThe use of a prosthetic material is the best treatment option for ventral hernia repair; one of the most frequently performed abdominal surgery procedures. This preclinical study compares the behavior of a new mesh (Parietex composite ventral patch [Ptx]) with that of two existing meshes used for ventral hernia repair. Materials and methodsFifty-four New Zealand White rabbits (3000 g) were used in an experimental model of umbilical hernia repair (diameter 1.5 cm). The materials tested were: Ventralex ST hernia patch (Vent) (Bard Davol Inc, Warwick, RI) (n = 18); Proceed ventral patch (Ethicon, Somerville, NJ) (PVP) (n = 18) and Ptx (Covidien, Sofradim, Trevoux, France) (n = 18). At 3, 7, 14 d, and 6 wk after implant, peritoneal behavior and adhesion formation were assessed by sequential laparoscopy. Mesh mesothelial cover was determined by scanning electron microscopy. Host tissue ingrowth (collagens I and III) and the macrophage response were assessed by immunohistochemical labeling. Animals were euthanized at 2, 6 wk, and 6 mo after surgery. Data were compared using the Mann–Whitney U test. ResultsAdhesion formation from 3 d–6 wk was significantly greater (P < 0.05) for PVP compared with Vent or Ptx. Three encapsulated PVP implants showed “tissue-integrated” adhesions affecting the intestinal loops. All three implant types showed similar patterns of collagen l and III deposition. The PVP mesh elicited the greater macrophage response both at 2 wk and 6 mo. ConclusionsPtx and Vent showed excellent mesothelialization, which led to minimum adhesion formation. The appropriate tissue integration of Ptx in the parietal neoperitoneum is likely attributable to its deployment system.

Intraperitoneal behaviour of a new composite mesh (Parietex™ Composite Ventral Patch) designed for umbilical or epigastric hernia repair.

The most common treatment option for ventral and umbilical hernias is the implant of a prosthetic mesh. This study compares the behaviour of a new mesh, Parietex™ Composite Ventral Patch (Ptx), with two commercially available meshes, Ventralex™ ST Hernia Patch and Proceed™ Ventral Patch. The following meshes were tested in a umbilical-hernia repair model using 54 rabbits: Ventralex™ ST Hernia Patch (Vent) (Bard Davol Inc., USA); Proceed™ Ventral Patch (PVP) (Ethicon, USA) and Ptx (Covidien, Sofradim, France) (n = 18 each). At 3, 7 and 14 days postimplantation, peritoneal behaviour and adhesion formation were assessed by sequential laparoscopy. Adhesions were scored for consistency and quantified by image analysis. The animals were euthanized at 2 (n = 27) and 6 weeks (n = 27) postsurgery. Mesothelial cover of meshes and tissue ingrowth were determined by scanning and light microscopy. Seroma was observed in 1/18 Vent, 7/18 PVP and 4/18 Ptx, mainly between the implant and subcutaneous tissue. Firm omental adhesions between the mesh and parietal peritoneum were noted in 2/9 Vent, 6/9 PVP and 3/9 Ptx at 2 weeks and in 3/9 Vent, 5/9 PVP and 1/9 Ptx at 6 weeks. Three (out of 9) encapsulated PVP implants showed "tissue-integrated" adhesions affecting the intestinal loops. No differences between implants were detected in the surface area occupied by adhesions at 2 weeks, though at 6 weeks, percentages were significantly higher (p < 0.01; Mann-Whitney U test) for PVP compared to Ptx or Vent. At this time point, Ptx and Vent showed good host tissue incorporation and optimal mesothelialization. The PVP implants showed greater adhesion formation than the other materials. Postimplantation behaviour was comparable for Ptx and Vent including scarce adhesion formation and optimal mesothelialization. Regarding tissue integration, Ptx showed greater long-term collagenization of the neoformed tissue.

Postimplantation host tissue response and biodegradation of biologic versus polymer meshes implanted in an intraperitoneal position

This study compared the in vitro and in vivo behaviors at the peritoneal interface of a new polymer material (Bio-A) and of two biologic non-cross-linked materials (Tutomesh [Tuto] and Strattice [St]), all biodegradable. Omentum mesothelial cells from rabbits were seeded onto the three prosthetic materials tested. At 1, 4, 8, 16, and 24h after implantation, mesothelial cover was performed using a scanning electron microscope (SEM). In the in vivo study, 3×3cm mesh fragments were placed on the parietal peritoneum of the same rabbits and fixed at the four corners with individual stitches. The implants were randomized such that six fragments of each material were implanted in nine animals (2 per animal). Adhesion formation was quantified by sequential laparoscopy and image analysis 3, 7, and 14days after implantation. The animals were killed at 90days, and the meshes were subjected to microscopy and immunohistochemistry. The in vitro mesothelial cover was significantly greater for St than for Bio-A at each time point. The percentage of cover for St was also higher than for Tuto 16 and 24h after seeding and higher for Tuto than for Bio-A at all time points. Compared with the biologic meshes, significantly higher adhesion percentages were recorded for Bio-A. At 90days after implantation, differences in absorption measured as percentage of reduction in mesh thickness were detected among all the meshes. The least absorbed was St. The neoperitoneum thickness was significantly greater for the biologic meshes than for the polymer mesh, although this variable also differed significantly between St and Tuto. Macrophage counts were higher for Bio-A than for the biologic meshes. Greater mesothelial cover was observed in vitro for St. In vivo, adhesion formation and the macrophage response induced by Bio-A were greater than those elicited by the biologic materials. Bio-A and Tuto showed substantial biodegradation compared with St.

Sequential Observation of Implanted Endometriosis by Laparoscopy in Rats: Correlation Between the Prevalence Rate and the Estrous Cycle

This study aimed to clarify the correlation between the estrous cycle and prevalence rate of endometriosis by sequential laparoscopy in Wistar-Imamichi female rats. The peritoneal implantation of endometrial tissue was performed in four estrous cycle rats (proestrus, estrus, metestrus, and diestrus). One week after implantation, the volume of the ectopic endometriosis was measured, and sequential laparoscopy was performed for 4 weeks to observe the prevalence rate. Five weeks after implantation, the volume of the ectopic endometriosis was measured again after laparoscopy. One week after implantation, the volume of endometriosis was significantly larger in proestrus and estrus rats than metestrus and diestrus rats. Prevalence rate was decreased with time. Five weeks after implantation, the prevalence rate and volume were higher and larger in the metestrus, diestrus, and estrus rats than in the proestrus rats. These results show that the estrous cycle affects the change of ectopic endometriosis. The decrease of prevalence rate was slow in metestrus, diestrus, and estrus rats as compared to that in proestrus rats. The volume of ectopic endometriosis showed little decrease with time when the endometrial tissue was implanted during the metestrus and diestrus portion of the cycle. Moreover, sequential laparoscopy made it possible to observe the prevalence rate of endometriosis.

Postimplant intraperitoneal behavior of collagen-based meshes followed by laparoscopy

When repairing an abdominal wall defect, sometimes a prosthetic mesh needs to be placed directly on the parietal peritoneum. Although the standard mesh for this purpose is the laminar implant expanded polytetrafluoroethylene (PTFE), it is gradually being replaced by the laminar collagen-based meshes. This study was designed to assess the intraperitoneal behavior of three of these biomeshes, mainly in terms of their susceptibility to adhesion formation. Two 3-cm×3-cm fragments of prosthetic material were placed on the parietal peritoneum in male New Zealand White rabbits in the following combinations: PTFE and CollaMend(®), PTFE and Permacol(®), or PTFE and Surgisis(®). The meshes were fixed at the four corners with individual 4/0 polypropylene sutures. Adhesion formation was quantified by sequential laparoscopy and image analysis performed at 3, 7, 14, and 90days postimplant. All animals were killed at 90days and the mesh specimens were subjected to microscopy and immunohistochemistry. Intensely vascularized adhesions to all the implants were observed, although Surgisis showed the lowest percentage of adhesions at each follow-up time. Adhesions had stabilized by 7-14days. The PTFE meshes were enveloped by a layer of macrophages and connective tissue, bounded by a monolayer of mesothelial cells. Permacol and CollaMend showed similar histological behavior, including cell ingrowth through their fenestrations with no signs of degradation detected at 90days. In contrast, the Surgisis mesh at 90days was practically replaced with neoformed tissue. No difference in susceptibility to adhesion formation was noted in the crosslinked collagen meshes compared to PTFE meshes. The noncrosslinked collagen mesh Surgisis showed the best behavior in that it induced fewer adhesions. Ninety days after implant, a more intense macrophage response was observed in CollaMend and Permacol than in PTFE or Surgisis.

Peritoneal adhesion formation and reformation tracked by sequential laparoscopy: Optimizing the time point for adhesiolysis

In a high proportion of patients, operatively lysed adhesions reform. Using a rabbit adhesiogenesis model, this study assessed the efficacy of adhesiolysis and examined how this relates to the tissue composition of adhesions at the time of lysis. Polypropylene meshes (5 x 3.5 cm) were implanted on the parietal peritoneum of New Zealand white rabbits. Some animals were killed 3, 7, 14, and 90 days postimplantation to obtain adhesion tissue. Adhesion formation/reformation was monitored by sequential laparoscopy in other animals kept for 90 days and in a separate experimental group subjected to adhesiolysis at 3 days postimplantation. Immune and inflammatory response markers were determined by immunohistochemical, Western blotting, and real-time reverse transcriptase polymerase chain reaction procedures in adhesion tissue; areas occupied by adhesions were quantified in meshes. In animals undergoing adhesiolysis, mesh areas covered by adhesions were significantly decreased at each follow-up time and affected areas became mesothelialized. Increased transforming growth factor (TGF)-beta1 expression was detected in adhesions at 3 days. Greatest TGF-beta1 and vascular endothelial growth factor (VEGF) protein expressions were observed at 7 days, whereas genetic overexpression was noted at 14 days. Active inflammatory cells peaked at the 7-day time point. Adhesions formed at 3 days; at this critical time, an adhesiolysis was effective in preventing reformation of future adhesions. TGF-beta1 gene and protein expression were increased in 3-day adhesions with respect to the omentum. Levels of active TGF-beta1 and VEGF were increased at 7 days, along with the inflammatory response at this time point related to tissue remodeling, which led to stabilization of adhesions.

Seguimiento del comportamiento peritoneal de diferentes biomateriales empleando laparoscopia secuencial. Aplicabilidad en la reparación de hernias ventrales

Despite the advantages offered by meshes, their use in abdominal wall repair can promote adhesions and damage the intra-abdominal viscera. This study was designed to assess the behavior at the peritoneal interface of several composite prostheses using sequential laparoscopy to monitor the real-time adhesion formation process. Three composite prostheses, Parietex Composite (n=8), Sepramesh (n=8) and PL-PU 99 (n=8), were used to repair 7 x 5 cm defects created in the abdominal wall of 24 New Zealand white rabbits. The area occupied by adhesions at 3, 7 and 14 days after prosthesis placement was established by tracing the adhesions onto a polyethylene template, using images obtained from sequential laparoscopy, and subjecting it to image analysis. At 14 days, the animals were sacrificed and specimens of the prostheses plus adjacent host tissue were obtained for histological and morphometric tests. Adhesion formation was laparoscopically observed to stabilize between 7 and 14 days post-implant, with no increase in adhesions produced at 14 days. The Parietex and PL-PU99 meshes showed significantly lower proportions of adhesions (0.55 +/- 0.06% and 0.27 +/- 0.20% respectively) than Sepramesh (18.55 +/- 1.96%). All three composites induced similar host tissue ingrowth and mesothelialization of the peritoneal prosthetic surface. a) The three prostheses tested showed optimal behavior at the peritoneal interface; b) the critical period when most adhesions form is the first week after implant; c) these biomaterials are suitable for use in laparoscopic ventral hernia repair.

Peritoneal Effects of Prosthetic Meshes Used to Repair Abdominal Wall Defects: Monitoring Adhesions by Sequential Laparoscopy

The prosthetic materials currently used to repair abdominal wall defects sometimes have to be placed in contact with the visceral peritoneum. This interface is often a site of complications such as intestinal obstruction or fistulas due to adhesions. The aim of this study was to follow the process of adhesion formation in several prosthetic materials by sequential laparoscopy. Defects (7 x 5 cm) were created in the abdominal wall of 30 New Zealand White rabbits and repaired using Surgipro polypropylene mesh (PP), Ultrapro monocryl-prolene mesh (UP), Dual Mesh expanded polytetrafluoroethylene (ePTFE), Composix (PP-ePTFE), Parietex Composite (polyester with collagen-polyethylene glycol-glycerol coating [PO-gl]), or PL-PU99 (PP-polyurethane) patches fixed to the edges of the defect by running polypropylene suture. Adhesions to the implants were laparoscopically determined at 3, 7, and 14 days after surgery. Percentage adhesion scores were significantly lower for ePTFE, PP-ePTFE, PO-gl, and PP-PU, compared to PP or UP. No differences were observed in adhesion scores recorded at 3, 7, and 14 days postimplant. Reticular prostheses were infiltrated by disorganized scar tissue with fibers concentric to the mesh filaments. In contrast, ePTFE implants were encapsulated by organized tissue, with fibers running parallel to the surface of biomaterial. All three composites achieved good recipient tissue integration and a homogeneous, organized, and well-vascularized neoperitoneum. At 14 days postimplant, laminar prostheses and composites showed similar results in terms of adhesion formation and integration within host tissue. Our findings suggest that both the composite prostheses and the laminar ePTFE performed very well in terms of reduced adhesion formation at the peritoneal interface.

Efficiency of 4% Icodextrin in Preventing Adhesions to Spiral Tacks Used to Fix Intraperitoneal Prostheses

Background/Aims: This study was designed to evaluate the extent of adhesion formation to prostheses fixed with spiral tacks and to establish whether the use of Ringer’s lactate or icodextrin could prevent these adhesions. Methods:24New Zealand white rabbits weighing around 3,000 g were implanted with a 7 × 5 cm patch of ePTFE (DualMesh®) through amidline laparotomy. The prosthesis was fixed to the intact peritoneum using spiral tacks. Three study groups were established according to whether the animals were: implanted with ePTFE fixed with spiral tacks or implanted with ePTFE fixed with spiral tacks and simultaneously administered Ringer’s lactate or 4% icodextrin in the peritoneal cavity. Adhesion formation and prosthetic behavior at the prosthesis/peritoneal interface were evaluated and quantified by sequential laparoscopy performed at 3, 7 and 14 days. Results: Adhesions generally formed on the tacks and were classified as the fully integrated type. No significant differences were observed in terms of the extent of adhesions or of neoperitoneal thickness between control animals and those receiving Ringer’s lactate or icodextrin. Conclusions: (a)Prosthesis-fixing tacks induced adhesions; (b) the use of substances such as icodextrin or Ringer’s lactate does not seem to diminish adhesion formation, and (c) the use of icodextrin offered no benefits over that of Ringer’s lactate solution.

Abdominal adhesions to prosthetic mesh evaluated by laparoscopy and electron microscopy

Background: Most adhesion experiments involve observations at a single time point. We developed a method to evaluate abdominal adhesions to surgical mesh by sequential laparoscopy. Study Design: An abdominal wall defect was created in rats and repaired with polypropylene mesh. Sequential laparoscopic evaluation of adhesion formation was performed in each animal. The percentage of mesh area involved was scored (0% to 100%). At various time intervals animals were sacrificed and samples were obtained for light and scanning electron microscopy. Results: Adhesions were already present on day 1, increased by day 7, and did not progress thereafter. Mesh surfaces free of adhesions were covered with a confluent mesothelial cell layer, first seen by scanning electron microscopy on day 5 and complete by day 7. Conclusions: Intraabdominal adhesions are best studied by sequential laparoscopy. Adhesions develop within 1 day of prosthesis placement. Adhesion-free surfaces are carpeted with mesothelial cells by day 7 and remain free thereafter, for duration of study.