Tissue regeneration observed in a porous acellular bovine pericardium used to repair a myocardial defect in the right ventricle of a rat model

OBJECTIVE: Nonliving synthetic materials have been widely used to repair myocardial defects; however, material-related failures do occur. To overcome these problems, an acellular bovine pericardium with a porous structure fixed with genipin (the AGP patch) was developed. METHODS: The AGP patch was used to repair a surgically created myocardial defect in the right ventricle of a rat model. A commercially available expanded polytetrafluoroethylene (e-PTFE) patch was used as a control. At retrieval, a computerized mapping system was used to acquire local epicardial electrograms of each implanted sample, and the appearance of each retrieved sample was grossly examined. The retrieved samples were then processed for histologic examination. RESULTS: The amplitude of local electrograms on the AGP patch increased significantly with increasing implantation duration, whereas only low-amplitude electrograms were observed on the e-PTFE patch throughout the entire course of the study. No aneurysmal dilation of the implanted patches was seen for either studied group. Additionally, no tissue adhesion was observed on the outer (epicardial) surface of the AGP patch, whereas a moderate tissue adhesion was observed on the e-PTFE patch. On the inner (endocardial) surface, intimal thickening was observed for both studied groups; however, no thrombus formation was found. Intact layers of endothelial and mesothelial cells were identified on the inner and outer surfaces of the AGP patch, respectively. At 4 weeks postoperatively, smooth muscle cells, together with neomuscle fibers (with a few neocollagen fibrils), neoglycosaminoglycans, and neocapillaries, were observed to fill the pores in the AGP patch, an indication of tissue regeneration. These observations were more pronounced at 12 weeks postoperatively. In contrast, no apparent tissue regeneration was observed in the e-PTFE patch. CONCLUSION: The present study indicated that the AGP patch holds promise to become a suitable patch for surgical repair of myocardial defects.     

Prevention of adhesions to polypropylene mesh

BACKGROUND: Polypropylene mesh used to repair abdominal wall hernias routinely induces dense adhesions if there is direct contact between the mesh and the viscera. Adhesions may lead later to difficult reoperation, intestinal obstruction, or enteric fistula. STUDY DESIGN: A 2.5-cm square defect was surgically created in the rat abdominal wall and replaced with: 1) polypropylene mesh, 2) Sepramesh (SM), or 3) SM plus Seprafilm. Each group included 20 animals. Adhesion area as a percent of the mesh surface was subjectively quantitated by means of laparoscopy and at sacrifice. Evaluations varied from 7 to 28 days after mesh placement. Tissues were harvested at intervals for scanning electron microscopy. RESULTS: Adhesions were complete by day 7, with no change in area thereafter. Adhesion-free mesh surfaces were found on scanning electron microscopy to be carpeted with mesothelial cells from day 5 on. Polypropylene mesh alone induced adhesions in all rats (20/20). The mean area involved was 92%. With SM, 9 of 20 were adhesion-free. The mean area was 15%. When Seprafilm was added to SM, minimal adhesions developed in 5 of 20 rats, the mean area being 2%. Four of the five were single point omental attachments. CONCLUSIONS: 1) Sepramesh alone reduces polypropylene mesh adhesions by roughly three-quarters. 2) Sepramesh plus Seprafilm nearly eliminates such visceral adhesions. 3) Mesothelial cell coverage of polypropylene mesh confers adhesion resistance.     

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.     

Seprafilm reduces adhesions to polypropylene mesh

BACKGROUND: Adhesions to polypropylene mesh used for abdominal wall hernia repair may eventuate in intestinal obstruction or enterocutaneous fistula. A Seprafilm Bioresorbable Membrane translucent adhesion barrier has been shown to inhibit adhesions. This investigation was designed to determine if Seprafilm alters abdominal visceral adhesions to polypropylene mesh. METHODS: A 2.5-cm square abdominal muscle peritoneal defect was created and corrected with polypropylene mesh. Mesh alone was used in 17 rats. In another 17, the Seprafilm membrane was applied between the viscera and the mesh. Five animals had the bioresorbable membrane placed in the subcutaneous space and between the mesh and the viscera. Laparoscopy was performed 7, 14, and 28 days later to evaluate adhesions as a percentage of mesh surface involved. RESULTS: Polypropylene mesh alone was associated with adhesions in every rat. The average area involved was 90%, the minimum was 75%. Adhesions were present within 24 hours and progressed up to 7 days with no change thereafter. When the Seprafilm barrier was used, the mean area involved was 50%. In 16 such rats, the area involved was smaller than any control animal. No adhesions formed in 5 animals. Scanning electron microscopy demonstrated a mesothelial cell layer covering the mesh after 4 weeks. CONCLUSIONS: The use of the Seprafilm adhesion barrier resulted in a significant reduction of adhesion formation to polypropylene mesh (P <.001).     

Assessment of adhesion formation to intra-abdominal polypropylene mesh and polytetrafluoroethylene mesh

BACKGROUND: The development of intra-abdominal adhesions, bowel obstruction, and enterocutaneous fistulas are potentially severe complications related to the intraperitoneal placement of prosthetic biomaterials. The purpose of this study was to determine the natural history of adhesion formation to polypropylene mesh and two types of polytetrafluoroethylene (ePTFE) mesh when placed intraperitoneally in a rabbit model that simulates laparoscopic ventral hernia repair. MATERIALS AND METHODS: Thirty New Zealand white rabbits were used for this study. A 10-cm midline incision was performed for intra-abdominal access and a 2 cm x 2 cm piece of mesh (n = 60) was sewn to an intact peritoneum on each side of the midline. Two types of ePTFE mesh (Dual Mesh and modified Dual Mesh, W.L. Gore & Assoc., Flagstaff, AZ) and polypropylene mesh were compared. The rate of adhesion formation was evaluated by direct visualization using microlaparoscopy (2-mm endoscope/trocar) at 7 days, 3 weeks, 9 weeks, and 16 weeks after mesh implantation. Adhesions to the prosthetic mesh were scored for extent (%) using the Modified Diamond Scale (0 = 0%, 1 50%). At necropsy the mesh was excised en bloc with the anterior abdominal wall for histological evaluation of mesothelial layer growth. RESULTS: The mean adhesion score for the polypropylene mesh was significantly greater (P < 0.05) than Dual Mesh at 9 weeks and 16 weeks and modified Dual Mesh at 7 days, 9 weeks, and 16 weeks. Fifty-five percent (n = 11) of the polypropylene mesh had adhesions to small intestine or omentum at necropsy compared to 30% (n = 6) of the Dual Mesh and 20% (n = 4) of the modified Dual Mesh. There was a significantly greater percentage (P < 0.003) of ePTFE mesh mesothelialized at explant (modified Dual Mesh 44.2%; Dual Mesh 55.8%) compared to the polypropylene mesh (12.9%). CONCLUSIONS: Serial microlaparoscopic evaluation of intraperitoneally implanted polypropylene mesh and ePTFE mesh in a rabbit model revealed a progression of adhesions to polypropylene mesh over a 16 week period. The pore size of mesh is critical in the development and maintenance of abdominal adhesions and tissue ingrowth. The macroporous polypropylene mesh promoted adhesion formation, while the microporous nature of the visceral side of the ePTFE served as a barrier to adhesions.     

Regeneration of pericardial tissue on absorbable polymer patches implanted into the pericardial sac. An immunohistochemical, ultrastructural and biochemical study in the sheep.

A new absorbable polymer prepared from polyhydroxybutyrate (PHB) was inserted as a pericardial patch in sheep to serve as a temporary scaffold for regeneration of pericardial tissue. Postoperative adhesions were rare or absent. The present study focuses on characterization of the regenerated surface cells. The luminal surface of the regenerated tissue was covered with a complete layer of mesothelium-like cells which at light and scanning electron microscopy resembled those in native pericardium. Immunohistochemical stainings for cytokeratin and thrombomodulin were positive in these cells. Heparan sulfate proteoglycan was found in a basement-membrane-like structure beneath the surface cells, as in the normal pericardium. Transmission electron microscopy of the regenerated surface revealed cells with the characteristics of mesothelium. Prostacyclin production in the regenerated tissue was similar to that in native pericardium. The results indicate regeneration of a mesothelial layer with many of the important functions of native mesothelial cells. This may explain the presently and previously observed prevention of pericardial adhesions after cardiac surgery in this field. Clinical testing of PHB patches as pericardial substitutes is warranted in cardiac surgery when pericardial closure is desired.     

Peritoneal effects of prosthetic meshes used to repair abdominal wall defects: monitoring adhesions by sequential laparoscopy

BACKGROUND: 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. MATERIAL AND METHODS: 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. RESULTS: 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. CONCLUSION: 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.     

Evaluation of new prosthetic meshes for ventral hernia repair

Background In hernia repair, particularly laparoscopic hernia repair, direct contact between mesh and abdominal organs cannot always be avoided. Several mesh materials and composite meshes have been developed to decrease subsequent adhesion formation. Recently, new meshes have been introduced. In an experimental rat study, their value was established and compared with that of meshes already available on the market. Methods In 200 rats, eight different meshes were placed intraperitoneally and in direct contact with abdominal viscera. The following meshes were tested: polypropylene (Prolene), e-PTFE (Dualmesh), polypropylene– polyglecaprone composite (Ultrapro), titanium–polypropylene composite (Timesh), polypropylene with carboxymethylcellulose–sodium hyaluronate coating (Sepramesh), polyester with collagen-polyethylene glycol–glycerol coating (Parietex Composite), polypropylene–polydioxanone composite with oxidized cellulose coating (Proceed), and bovine pericardium (Tutomesh). At 7 and then at 30 days postoperatively, adhesion formation, mesh incorporation, tensile strength, shrinkage, and infection were scored by two independent observers. Results Parietex Composite, Sepramesh, and Tutomesh resulted in decreased surface coverage with adhesions, whereas Prolene, Dualmesh, Ultrapro, Timesh, and Proceed resulted in increased adhesion coverage. Parietex Composite, Prolene, Ultrapro, and Sepramesh resulted in the most mesh incorporation. Dualmesh and Tutomesh resulted in significantly increased shrinkage. There were no differences in mesh infection. Parietex Composite and Dualmesh resulted in a moderate inflammatory reaction, as compared with the mild reaction the other meshes exhibited. Conclusion Parietex Composite and Sepramesh combine minimal adhesion formation with maximum mesh incorporation and tensile strength. The authors recommend the use of these meshes for hernia repair in which direct contact with the abdominal viscera cannot be avoided.     

Bioabsorbable membrane prevents adhesions to polypropylene mesh in rats

Summary Most of mesh materials used in the repair of ventral hernias lead to considerable adhesion formation. In this study we evaluated the effects of a bioabsorbable membrane composed of carboxymethylcellulose and hyaluronic acid (HA membrane) on adhesion formation in the presence of a polypropylene mesh used to repair an incisional hernia model in rats. We repaired the defects either primarily or by polypropylene mesh. The abdominal surface of the repairs were then covered by a piece of HA membrane in randomly selected groups. The presence and grade of adhesions to the repair or mesh were recorded on the 8th day. Tissue specimens were analyzed for the extent of mesothelial and collagenous tissue growth and the degree of inflammation. Dense adhesions developed on all of the defects repaired by polypropylene mesh alone. The HA membrane decreased adhesions significantly when used as a supplement over the mesh (p < 0.01). Histopathologically, the HA membrane further retarded mesothelial growth over the mesh, and decreased vascular proliferation, inflammatory cell infiltration (p < 0.01) and collagen content of the wound (p < 0.05). In our rat model, the HA membrane prevented most of the adhesions that would be expected to occur on the mesh. It decreased the local infiltration of white cells and neovascularization. The HA membrane seemed to be a suitable physical barrier in rats against adhesion formation without compromising the wound healing. However, these findings need to be confirmed in humans.     

聚L-乳酸修饰的聚丙烯疝补片的研制及动物实验研究

目的将聚L-乳酸修饰的聚丙烯补片应用于动物实验,进一步验证补片的防粘连效果。方法聚L-乳酸修饰的聚丙烯补片置入腹腔并覆盖腹腔缺损,同时与聚丙烯补片为对照组,通过腹腔内粘连面积、粘连程度、组织病理学改变等检查了解补片粘连情况。结果单纯聚丙烯组术后死亡率高,剖腹探查发现补片表面与腹腔脏器发生直接粘连,粘连面积广泛,粘连程度重。聚L-乳酸修饰的聚丙烯组补片表面亦有粘连,主要集中在补片边缘粘连面积、程度较轻。结论聚L-乳酸修饰的聚丙烯平片是可行的,动物实验表明聚L-乳酸修饰的聚丙烯补片可以减少动物的腹腔内粘连。     

Prevention of adhesion to prosthetic mesh: comparison of different barriers using an incisional hernia model

OBJECTIVE: To assess whether use of antiadhesive liquids or coatings could prevent adhesion formation to prosthetic mesh. SUMMARY BACKGROUND DATA: Incisional hernia repair frequently involves the use of prosthetic mesh. However, concern exists about development of adhesions between viscera and the mesh, predisposing to intestinal obstruction or enterocutaneous fistulas. METHODS: In 91 rats, a defect in the muscular abdominal wall was created, and mesh was fixed intraperitoneally to cover the defect. Rats were divided in five groups: polypropylene mesh only (control group), addition of Sepracoat or Icodextrin solution to polypropylene mesh, Sepramesh (polypropylene mesh with Seprafilm coating), and Parietex composite mesh (polyester mesh with collagen coating). Seven and 30 days postoperatively, adhesions were assessed and wound healing was studied by microscopy. RESULTS: Intraperitoneal placement of polypropylene mesh was followed by bowel adhesions to the mesh in 50% of the cases. A mean of 74% of the mesh surface was covered by adhesions after 7 days, and 48% after 30 days. Administration of Sepracoat or Icodextrin solution had no influence on adhesion formation. Coated meshes (Sepramesh and Parietex composite mesh) had no bowel adhesions. Sepramesh was associated with a significant reduction of the mesh surface covered by adhesions after 7 and 30 days. Infection was more prevalent with Parietex composite mesh, with concurrent increased mesh surface covered by adhesions after 30 days (78%). CONCLUSIONS: Sepramesh significantly reduced mesh surface covered by adhesions and prevented bowel adhesion to the mesh. Parietex composite mesh prevented bowel adhesions as well but increased infection rates in the current model.     

Pharmacologic inhibition of scar contracture of intracardiac prosthetic patches

Significant fibrosis and contracture often cause complications of pericardial and Dacron grafts within the heart. Both continue to be utilized because more suitable materials are unavailable. Newer prosthetic materials and the administration of drugs that might minimize intracardiac fibrosis and contracture after implantation were studied. Measured patches of three prosthetic materials were implanted into the right atrium of 18 dogs: 6 with expanded polytetrafluoroethylene (PTFE or Gore-Tex--W. L. Gore & Associates, Elkton, Md.), 6 with glutaraldehyde-preserved bovine pericardium, and 6 with Dacron patches. The animals were sacrificed after 8 weeks and gross and microscopic pathologic examinations were performed. The patch materials did not intrinsically shrink but all demonstrated marked distortion from the growth of surrounding scar tissue. In a fourth group of eight dogs with intraatrial Dacron patches, four were treated for 8 weeks with oral 3-aminopropionitrile fumarate, and four were not treated. A blinded observed evaluated the adhesions on a scale of 0 = no adhesions or patch distortion, to 4 = dense adhesions with marked distortion of the patches. The untreated dogs had dense adhesions of the lung and pericardium and the patches were encased in scar tissue with marked distortion. The average score was 3.5. The treated dogs had only minimal pleural adhesions and only a thin neointimal covering of the patch with virtually no distortion. The average score was 1.0 (P = 0.0032). The tensile strength of the healed atriotomies was evaluated with stress testing. The intact atrial wall ruptured at a force of 2.60 +/- 0.37 kg/m/sec2, the untreated atriotomy wound at 2.38 +/- 0.18 kg/m/sec2, and the treated atriotomy wound at 2.60 +/- 0.17 kg/m/sec2. There was no statistically significant difference among these groups. No other side effects of the 3-aminopropionitrile fumarate were noted, with only a single superficial wound infection caused by early postoperative trauma. Pharmacologic inhibition of scar formation minimized distortion and contracture of intracardiac prosthetic patches and decreased adhesions. Though further experimental evaluations are necessary, prolonged low-dose oral administration of beta-aminoproprionitrile (BAPN) may be beneficial in preventing complications of prosthetic implants and reoperative cardiac surgery in children.     

Prevention of adhesion formation to polypropylene mesh by collagen coating: A randomized controlled study in a rat model of ventral hernia repair

Introduction In laparoscopic incisional hernia repair with intraperitoneal mesh, concern exists about the development of adhesions between bowel and mesh, predisposing to intestinal obstruction and enterocutaneous fistulas. The aim of this study was to assess whether the addition of a collagen coating on the visceral side of a polypropylene mesh can prevent adhesion formation to the mesh.Method In 58 rats, a defect in the muscular abdominal wall was created, and a mesh was fixed intraperitoneally to cover the defect. Rats were divided in two groups; polypropylene mesh (control group) and polypropylene mesh with collagen coating (Parieten mesh). Seven and 30 days postoperatively, adhesions and amount and strength of mesh incorporation were assessed. Wound healing was studied by microscopy.Results With Parieten mesh, the mesh surface covered by adhesions was reduced after 30 days (42% vs 69%, p = 0.01), but infection rate was increased after both 7 (p = 0.001) and 30 days (p = 0.03), compared to the polypropylene group with no mesh infections. If animals with mesh infection were excluded in the analysis, the mesh surface covered by adhesions was reduced after 7 days (21% vs 76%, p = 0.02), as well as after 30 days (21 vs 69%, p < 0.001). Percentage of mesh incorporation was comparable in both groups. Mean tensile strength of mesh incorporation after 30 days was higher with Parieten mesh.Conclusion Although the coated Parieten mesh was more susceptible to mesh infection in the current model, a significant reduction of adhesion formation was still seen with the Parieten mesh after 30 days, with comparable mesh incorporation in the abdominal wall.     

Seprafilm reduces adhesions to polypropylene mesh and increases peritoneal hydroxyproline

Polypropylene mesh is an effective and widely used material in repairing abdominal wall defects, but it causes dense adhesions when in contact with abdominal viscera directly. As a consequence of this process intestinal obstruction and enterocutaneous fistula may develop. The purpose of the present study was to determine whether Seprafilm, a bioresorbable translucent membrane, reduces abdominal visceral adhesions to polypropylene mesh and whether Seprafilm has any effects on peritoneal tissue hydroxyproline levels. Twenty-six adult Wistar rats were used. A full-thickness abdominal wall defect was created and cecal abrasions were created to induce adhesion formation in each animal. All of the abdominal defects were repaired with polypropylene mesh. In addition a Seprafilm membrane was laid over the abdominal viscera in the Seprafilm group (n = 13). The abdominal cavity was evaluated for adhesion formation, and peritoneal biopsies were taken for the measurement of tissue hydroxyproline levels at the 14th day. The use of Seprafilm resulted in significant reduction in the adhesion formation (P = 0.002) and a significant increase in peritoneal hydroxyproline level (P < 0.0001). These findings demonstrate that the increase of peritoneal hydroxyproline levels caused by Seprafilm might play a role on the antiadhesive effects of Seprafilm.     

Neoperitoneal formation after implantation of various biomaterials for the repair of abdominal wall defects in rabbits.

OBJECTIVE: To study the interfaces between the visceral peritoneum and some of the biomaterials used to repair defects in the abdominal wall. DESIGN: Animal study. SETTING: School of medicine, Spain. MATERIAL: 48 New Zealand white rabbits divided into 4 groups of 12 each. INTERVENTIONS: Full thickness defects 50 x 70 mm were created in the abdominal wall and repaired with polytetrafluoroethylene (PTFE, Soft Tissue Patch), one of two polypropylene patches (Marlex and Prolene), or lyophylised dura mater (Lyo-Dura). 3 animals from each group were killed at 14, 30, 60 and 90 days and specimens examined by light microscopy, scanning electron microscopy, and immuno histochemistry by labelling of macrophages with RAM-11, a specific monoclonal antibody (MoAb). MAIN OUTCOME MEASURES: Infection, healing, development of adhesions, and histological appearance of the interface. RESULTS: Tissues responded similarly to materials of similar structures. Layered prostheses (PTFE and Lyo-Dura) caused formation of a well organised neoperitoneum with few adhesions to the abdominal viscera (loose adhesions in 2 animals in each group), whereas the mesh prostheses generated a disorganised neoperitoneum with many adhesions (Marlex loose adhesions 3, firm 8, and integrated 1; Prolene loose adhesions 2, firm 8, and integrated 2). Lyo-Dura was associated with the formation of areas of calcification. Labelling of macrophages with the MoAb showed that they were in direct contact with all materials studied. CONCLUSIONS: Layered biomaterials with little or no porosity (PTFE and Lyo-Dura) are the most suitable of the four for implantation in sites where the prosthesis is in contact with the visceral peritoneum, because they induce minimal adhesions.     

腹腔镜下腹壁切口疝修补术15例

目的探讨腹腔镜下应用补片行腹壁切口疝修补术的方法、安全性及临床疗效。方法2008年5月至2009年5月,对15例腹壁切口疝进行腹腔镜下补片修补术。结果14例腹腔镜下行腹腔粘连松解和补片固定,顺利完成切口疝修补手术;1例因肠管与腹壁及疝环致密粘连而中转开放切口疝修补术。术后腹壁修补区域疼痛10例(71.4%),疝环和补片间出现浆液肿4例(28.6%),无肠瘘和死亡病例,未发生手术相关的感染。术后随访3～12个月,平均7.5个月,未见复发。结论在腹腔镜下行腹腔粘连松解,采用疝钉合器与缝线贯穿腹壁全层固定补片可以修补大多数腹壁切口疝,同时还可以发现其他的隐匿性疝,是一种安全、有效的微创手术方法,值得临床推广。     

Novel and simple method for isolating autologous mesothelial cells from the tunica vaginalis

OBJECTIVE: To report the development of a new method of isolating autologous mesothelial cells from the tunica vaginalis that are easily obtained and generally free from the effects of abdominal cancer, and to investigate whether transplanting these mesothelial cells is effective in preventing postoperative adhesions. MATERIALS AND METHODS: The tunica vaginalis was resected from male Lewis rats, and mesothelial cells were collected by enzymatic disaggregation. To investigate the efficacy of mesothelial cells in preventing adhesion, harvested cells were transplanted into a rat intestinal hernia adhesion model. RESULTS: Cells isolated from the tunica vaginalis were homogenous, polygonal when confluent, expressed cytokeratin and vimentin, and the cell surface was covered with microvilli, which is the characteristic appearance of endogenous mesothelial cells. The transplantation of autologous mesothelial cell sheets reduced peritoneal adhesion. CONCLUSION: We developed a new method of obtaining autologous mesothelial cells from the tunica vaginalis. These cells may provide a valuable option for treating patients at risk of postoperative adhesions.     

The effect of a chitosan coating on the adhesive potential and tensile strength of polypropylene meshes

Purpose

The polypropylene mesh used for the repair of abdominal wall hernia can cause intraabdominal adhesions. In this study, the effect of chitosan coating of the polypropylene meshes on the adhesion and tensile strength of the meshes was investigated.

Method

After coating polypropylene meshes with 2?% chitosan, 5?×?3 cm patches were prepared. Under general anesthesia, sterile laparotomy was performed in 96 Wistar albino female rats that were equally allocated to 6 groups. In the first group, only laparotomy was performed. In the second group, chitosan was applied to the peritoneal cavity, and the laparotomy was closed. In the third group, polypropylene (prolene) patches were used to close the abdomen; in the fourth group, polypropylene polyglecaprone 25 (ultrapro) mesh patches were used to close the abdomen. In the fifth and sixth groups, chitosan-coated versions of the meshes used in the third and fourth groups, respectively, were applied. All skin incisions were closed in all groups. On the 7th and 21st?days, eight randomly selected rats from each group were killed. The abdomen was opened, and the adhesions were evaluated using the diamond score. The tensile strength of the meshes was measured by an Instron 4301 device. The histopathological evaluation of the inflammatory response was performed according to the Ehrlich and Hunt classification.

Results

The adhesion score was comparable among mesh groups but higher when mesh groups were compared with the control and chitosan groups (p<0.001). The tensile strength of meshes did not differ among mesh groups. Histopathologically, meshes with or without chitosan were similar in terms of inflammatory findings.

Conclusions

The chitosan coating did not affect the adhesion potential, the tensile strength, or the inflammatory response of the polypropylene meshes.     

Comparison of Adhesive Properties of Five Different Prosthetic Materials Used in Hernioplasty

This experimental study was designed to assess and to compare intra-abdominal adhesions following the use of five commercially available prosthetic mesh grafts in the repair if abdominal wall defects. Sixty Wistar albino rats were randomly divided into six groups (n = 10). A 2 × 1 cm defect at abdominal wall was created and defects were closed either primarily or with one of the following prosthetic mesh grafts: monofilament polypropylene, polytetrafluoroethylene, sodium hyaluronate/carboxymethylcellulose-coated polypropylene, polypropylene/polyglactin 910 composite, or resorbable hydrophilic collagen-coated multifiber polyester. The severity of adhesions was graded, tensile strengths of adhesions were measured, and histopathological grades of inflammation and fibrosis were evaluated. Polypropylene mesh resulted in more adhesion formation in comparison to primary repair and other grafts used in this study, except polypropylene/polyglactin 910 composite mesh. In addition, the highest tensile strength of omental adhesions was detected in the polypropylene group (χ² = 26.249; p =. 0001). Polyester composite mesh caused the least adhesion formation among the groups. Sodium hyaluronate/carboxymethylcellulose-coated polypropylene and polyester composite meshes revealed the highest fibrosis scores (χ² = 50.776; p =. 0001). The highest inflammatory activity was detected in the polytetrafluoroethylene mesh group (χ² = 16.564; p =. 005). Thus, sodium hyaluronate/carboxymethylcellulose-coated polypropylene and polytetrafluoroethylene meshes following polyester composite mesh were the minimal adhesion-forming grafts in this study. Disadvantages of the polytetrafluoroethylene mesh were lower fibrotic activity and higher inflammatory reaction to the graft.     

Peritoneal adhesions to prosthetic materials

BACKGROUND: In many cases, incisional hernia repair requires the use of prosthetic materials. The aim of this experimental study in a rat model was to assess the role of polyglactin 910 mesh and fluoropassivated polyester mesh in preventing the formation of adhesions. METHODS: In the first experiment, the formation of peritoneal adhesions was assessed after insertion of polypropylene, polypropylene combined with polyglactin 910, or no mesh. In the second experiment, adhesion formations were compared after insertion of fluoropassivated polyester, polypropylene, and no mesh. RESULTS: The first experiment showed no significant difference in adhesion formations between the polypropylene mesh and the combined mesh; however, when no mesh was used, there were significantly fewer adhesions in both experiments (p < 0.01). The second experiment showed a significantly lower degree of adhesions and a lower Adhesion Index after insertion of fluoropassivated polyester mesh than when polypropylene mesh was used (p = 0.04). CONCLUSIONS: Adding polyglactin 910 mesh to polypropylene mesh to prevent the formation of adhesions is not an effective measure. Fluoropassivated polyester meshes appear to provide a better alternative to the use of polypropylene meshes for incisional hernia repair in humans in terms of the formation of adhesions.