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

Biosynthesis of Bacterial Cellulose by Extended Cultivation with Multiple Removal of BC Pellicles

Extended cultivation with multiple removal of BC pellicles is proposed herein as a new biosynthetic process for bacterial cellulose (BC). This method enhances the BC surface area by 5-11 times per unit volume of the growth medium, improving the economic efficiency of biosynthesis. The resultant BC gel-films were thin, transparent, and congruent. The degree of polymerization (DP) and elastic modulus (EM) depended on the number of BC pellicle removals, vessel shape, and volume. The quality of BC from removals II-III to VII was better than from removal I. The process scale-up of 1:40 by volume increased DP by 1.5 times and EM by 5 times. A fact was established that the symbiotic Medusomyces gisevii Sa-12 was adaptable to exhausted growth medium: the medium was able to biosynthesize BC for 60 days, while glucose ran low at 24 days. On extended cultivation, DP and EM were found to decline by 39-64% and 57-65%, respectively. The BC gel-films obtained upon removals I-VI were successfully trialed in experimental tension-free hernioplasty.

Postoperative clinical outcomes and inflammatory markers after inguinal hernia repair using local, spinal, or general anesthesia: A randomized controlled trial

Background

No consensus has yet been reached regarding the best anesthetic technique for inguinal hernia repair. This study aimed to compare postoperative clinical outcomes and inflammatory markers among patients who were anesthetized using local, spinal, or general anesthesia for inguinal hernia repair.

Methods

This randomized controlled trial included patients scheduled to undergo elective unilateral inguinal hernioplasty at Siriraj Hospital during November 2014 to September 2015 study period. Patients were randomly assigned to the local (LA), spinal (SA), or general (GA) anesthesia groups. Primary outcomes were postoperative pain at rest and on mobilization at 8 and 24 hours after surgery.

Results

Fifty-four patients were included, with 18 patients randomly assigned to each group. Patient demographic and clinical characteristics were similar among groups. There were no significant differences among groups for postoperative pain at rest or on mobilization at 8 and 24 hours after surgery. No significant differences were observed for interleukin-1β, interleukin-6, and interleukin-10 at any time points in any groups. Patients with local anesthesia was associated with less time spent in anesthesia (p = 0.010) and surgery (p = 0.009), lower intraoperative cost (p = 0.003) and total cost in hospital (p = 0.036); however, patient satisfaction in the local anesthesia group (94/100) was statistically significantly lower than the spinal and general anesthesia groups (100/100) (p = 0.010).

Conclusions

No statistically significant difference was observed among groups for postoperative pain scores, duration of hospital stays, complications, or change in inflammatory markers. However, time spent in anesthesia and surgery, the intraoperative cost and total cost for hernia repair, and patient satisfaction were significantly lower in the local anesthesia group than in the other two groups.

Ventral hernia repair in rat using nanofibrous polylactic acid/polypropylene meshes

Aim: In the present study, we combined a nanofibrous polylactic acid (PLA) scaffold fabricated by electrospinning with a polypropylene (PP) material to generate a new type of mesh for hernia repair. Materials & methods: The PLA/PP mesh was tested with tensile testing, in vitro cytocompatibility and degradation. A total of 90 rats were randomly allocated to PLA/PP, PP and polyester (PE) mesh groups for the in vivo study to evaluate the properties of PLA/PP mesh. Results: PLA/PP mesh had superior mechanical properties. It also resulted in less inflammation adhesion formation (p < 0.05), which was related to the TGF-β1/Smad pathway. The distribution of collagen I and III in PLA/PP mesh was also superior to those in the other two groups (p < 0.05). Conclusion: The PLA/PP mesh would be suitable for ventral hernia repair in the future.

PERITONEAL ADHESIONS TYPE I, III AND TOTAL COLLAGEN ON POLYPROPYLENE AND COATED POLYPROPYLENE MESHES: EXPERIMENTAL STUDY IN RATS

Background:

Hernia correction is a routinely performed treatment in surgical practice. The improvement of the operative technique and available materials certainly has been a great benefit to the quality of surgical results. The insertion of prostheses for hernia correction is well-founded in the literature, and has become the standard of treatment when this type of disease is discussed.

Aim:

To evaluate two available prostheses: the polypropylene and polypropylene coated ones in an experimental model.

Methods:

Seven prostheses of each kind were inserted into Wistar rats (Ratus norvegicus albinus) in the anterior abdominal wall of the animal in direct contact with the viscera. After 90 days follow-up were analyzed the intra-abdominal adhesions, and also performed immunohistochemical evaluation and videomorphometry of the total, type I and type III collagen. Histological analysis was also performed with hematoxylin-eosin to evaluate cell types present in each mesh.

Results:

At 90 days the adhesions were not different among the groups (p=0.335). Total collagen likewise was not statistically different (p=0.810). Statistically there was more type III collagen in the coated polypropylene group (p=0.039) while type I was not different among the prostheses (p=0.050). The lymphocytes were statistically more present in the polypropylene group (p=0.041).

Conclusion:

The coated prosthesis was not different from the polypropylene one regarding the adhesion. Total and type I collagen were not different among the groups, while type III collagen was more present on the coated mesh. There was a greater number of lymphocytes on the polypropylene mesh.

Evaluation of diaphragmatic mobility following intra-abdominal sub-diaphragmatic fixation of a double-layered mesh in rats

PURPOSE

To evaluate the tissue integration of a double-sided mesh after fixation in diaphragm and to study the diaphragmatic mobility by ultrasound.

METHODS

Twenty male Wistar rats were used. The animals were assigned into two equal groups according to the day of euthanasia. The animals were anesthetized and a 1.5 x 1.5 cm of double-layer mesh was inserted between the diaphragm and the liver. For the evaluation of the diaphragm mobility a sonographic method was used. Measurements on specific breathing parameters were taking place. Pathological evaluation took place after the animal's euthanasia.

RESULTS

Extra-hepatic granuloma was not differentiated overtime, (χ2=0.04, p>0.05). Neither fibrosis was significantly differentiated, (χ2=0.04, p>0.05). Intra-hepatic granuloma was significantly differentiated overtime, (χ2=10.21, p<0.05). Concerning Te parameter, means were significantly differentiated over time, F (3, 30) = 5.12, (p<0.01). Ttot parameter, it was differentiated over time, F (3, 8)=4.79, (p<0.05). IR parameter was also longitudinally differentiated, F (3, 30)=3.73, (p<0.05).

CONCLUSION

The measurements suggest a transient malfunction of diaphragmatic mobility despite the fact that inflammatory reaction, fibrosis and extra-hepatic granuloma were not significantly differentiated with the passage of time.

Experimental study of inflammatory response and collagen morphometry with different types of meshes

PURPOSE

To compare an inflammation score and collagen morphometry after incisional hernia repair with four different meshes at two time points.

METHODS

Four types of mesh were used to repair an abdominal wall incisional defect in Wistar rats: high-density polypropylene (HW/PP); low-density polypropylene (LW/PP); polypropylene mesh encapsulated with polydioxanone coated with oxidized cellulose (PP/CE); and expanded polytetrafluoroethylene (ePTFE). An inflammation score based on histological analysis and collagen morphometry was performed after 7 and 28 days after operation (POD).

RESULTS

Compared to LW/PP group at 7 POD, HW/PP group had lower (p = 0.014) and PP/CE group had higher inflammation scores (p = 0.001). At 28 POD, higher scores were seen in all the other groups compared to the LW/PP group (HW/PP, p = 0.046; PP/CE, p < 0.001; ePTFE, p = 0.027). Comparing groups individually at 7 and 28 PODs, all demonstrated lower inflammation score values at 28 POD (HW/PP, p < 0.001; LW/PP, p < 0.001; PP/CE, p = 0.002; ePTFE, p = 0.001). At 7 POD, higher amounts of collagen were detected in ePTFE compared to HW/PP (p < 0.001) and LW/PP (p = 0.004) and in PPCE group compared to HW/PP (p = 0.022). At 28 POD, no statistically significant difference was found. Comparing groups individually at 7 and 28 PODs, HW/PP and LW/PP showed larger amounts of collagen at the 28th POD, without any statistically significant differences for the PP/CE and ePTFE groups.

CONCLUSIONS

Inflammation scores decreased in all groups at 28 POD. Collagen deposition was higher for non-composite meshes at 28 POD.

Six cases of inguinal urinary bladder herniation in entire male domestic rabbits

Six entire male rabbits, between four and eight years old, were presented with a fluctuant scrotal and/or inguinal swelling resulting from inguinal herniation of the urinary bladder. Concurrent problems included urinary sediment (two rabbits), multiple uroliths (one rabbit) and testicular tumour (one rabbit). All rabbits underwent herniorrhaphy surgery. There was a successful outcome in four of the six cases.

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.

Comparative study between meshes of polyester with collagen and polytetrafluoroethylene in the repair of defects produced in abdominal wall of rats

PURPOSE

To study the intraperitoneal use of polyester with collagen and polytetrafluoroethylene meshes in the correction of total ventral wall defects in rats.

METHODS

Thirty two rats were evaluated and divided randomly into four groups and underwent laparotomy and preparation of total defects of the abdominal wall. Next, the correction of the defect with the intraperitoneal placement of the chosen mesh was performed. The rats were submitted to euthanasia at 30 and 90 days after surgery. Were analyzed the macroscopic adhesions and microscopic aspects, and applied stress rupture test

RESULTS

All animals showed intraperitoneal adhesions in varying degrees, with no statistical significance difference. There was no difference also between groups in the evaluation of stress rupture tests. On the microscopic aspect, the A30 group had less inflammatory reaction and less formation of granulomas and foreign body reaction that the B30 group, with significant difference.

CONCLUSIONS

There was no difference in intraperitoneal adhesion and tensile rupture strength among groups. Group B30 presented granulomatous inflammatory reaction at the site of mesh attachment to the wall significantly higher than the A30.

May titanium spiral tacks contribute to intra-abdominal adhesion formation?

PURPOSE

To verify if titanium spiral tacks may contribute to intra-abdominal adhesion formation in rabbits.

METHODS

Ten New Zealand white rabbits were used. Through videolaparoscopic surgery two titanium spiral tacks (ProTack(®), Covidien(®)) were applied in the right flank. After 30 days the animals were submitted to evaluate peritoneal cavity by videolaparoscopy.

RESULTS

No adhesion was found where the titanium spiral tacks were placed.

CONCLUSION

Titanium spiral tacks for fixation do not cause adhesions in rabbits.

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.

Damage to the spermatic cord by the Lichtenstein and TAPP procedures in a pig model

BACKGROUND

Mesh implantation is regarded as the standard treatment of inguinal hernias. Obstructive azoospermia induced by mesh implantation is a rare but serious complication. Whether different operative techniques or mesh materials used have an effect on the integrity of the testicle and spermatic cord remains unclear.

MATERIALS

In 12 minipigs a bilateral inguinal hernia repair, either open or laparoscopic, was performed using a standard small-pore polypropylene (PP) or large-pore polyvinyliden fluoride (PVDF) mesh. Next to measurement of the testicular size, thermography of the groin and testicle as a parameter for perfusion was performed preoperatively and at a follow-up at 6 months. Obstructions of the vas deferens were estimated radiographically. Testicular function (Johnson score) and mesh integration (granuloma size, apoptotic cells) were analyzed histologically.

RESULTS

Mean testicular size did not change significantly in follow-up compared to preoperative values. Technique and mesh material used failed to have a significant influence. Thermography of the groin following the Lichtenstein technique had significantly higher values at follow-up regardless of the mesh used. This could not been shown for laparoscopic treatment. Thermographic measurements at the testicle showed a significantly increased temperature in all groups compared to preoperative measurements. Only the Lichtenstein PP group showed significantly decreased values in testicular function. Quantity and quality of obstructions seen at vasography were most detectable in the Lichtenstein PP group. There was significantly decreased granuloma formation following PVDF mesh implantation compared to the PP mesh group regardless of the technique used.

CONCLUSIONS

Both the technique and the mesh material have an impact on integrity of spermatic cord and testicular function. According to the results of this study, the laparoscopic TAPP procedure using a large-pore PVDF mesh has the least effect compared to preoperative values.

Periareolar mastopexy with FortaPerm

BACKGROUND

Recurrent ptosis is a common sequel of mastopexy. The use of mesh as an adjunct to the double-skin technique was developed to reduce the incidence of recurrent ptosis. The optimal mesh needs to strike the right balance between persistence, inflammation, biocompatibility, and incorporation without interfering with mammography or presenting a long-term infection risk. This study investigated the ability of a biologic tissue matrix, FortaPerm, to achieve these goals.

METHODS

Women undergoing mastopexy were enrolled in this prospective observational study. The study participants were evaluated at multiple time points for 5 years. Efficacy was assessed primarily by photographic evaluation and secondarily by mammography, patient and physician global assessments, and patient pain assessments.

RESULTS

Five women ages 17-41 years were enrolled in this study. At 12 months, 80% of the patients (4/5), and at 5 years, 66% of the patients (2/3) had no asymmetry or ptosis. Mammographic evaluation of the breasts was not affected by the presence of the FortaPerm, and there were no abnormal findings. In two patients, FortaPerm was associated with bilateral seromas associated with extrusion of small amounts of the FortaPerm material in the absence of surrounding inflammation.

CONCLUSIONS

FortaPerm achieved excellent initial aesthetic outcomes and long-term maintenance of the breast position with no evidence of ptosis 5 years postoperatively for a majority of the patients. FortaPerm did not interfere with mammography, presented no long-term safety concerns, and produced satisfactory results for all patients relative to appearance of the scar as well as shape and firmness of the breasts.

[Pelvic lymphadenitis after total hip arthroplasty : Mimicking of lymph node metastases in a patient with prostate cancer]

This report describes the case of a 65-year-old patient who underwent radical prostatectomy in our department. Intraoperatively we detected suspicious lymph nodes on the left side. The histopathological examination revealed histiocytosis and foreign body giant cells but no sign of tumor. The enlarged lymph nodes were ascribed to an ipsilateral total hip arthroplasty performed 14 years previously because of progressive coxarthrosis. Lymphadenitis after total hip arthroplasty is frequently observed. Histopathologically and with the use of polarized light microscopy, histiocytosis and wear particles such as titanium, polyethylene, and polyethylene-methylacrylate may be detected. When operating on patients with arthroplasty of a lower limb, particularly those with a total endoprosthesis, the surgeon should bear in mind that changes in lymph node consistency and size do not necessarily indicate tumor involvement or metastases.

Experimental study comparing meshes made of polypropylene, polypropylene + polyglactin and polypropylene + titanium: inflammatory cytokines, histological changes and morphometric analysis of collagen

PURPOSE

Incisional hernia occurs in approximately 11% of all laparotomies. Changes in collagen have been closely implicated in its pathogenesis. The high recurrence rate (45-54%) after primary suture has stimulated the development of meshes. Currently, meshes are the biomaterials implant group most used in medicine. This study aims to compare the serum and tissue inflammatory responses and collagen deposition caused by meshes made of polypropylene, polypropylene + polyglactin and polypropylene + titanium.

METHODS

Thirty Wistar rats were divided into three groups. In group I, a high-density polypropylene mesh was positioned on the abdominal wall. In groups II and III, low-density meshes were used in associations with polyglactin and titanium, respectively. Immediately before the operation and on the first, third and fortieth postoperative days, pro-inflammatory cytokines were assayed. On the 40th postoperative day, the region of the inserted prosthesis was biopsied. The tissue inflammatory reaction was evaluated using a scale for objective scoring. For collagen, picrosirius was used with data reading using the Image Tool computer software.

RESULTS

Cytokines: there were no statistically significant differences between the groups.

HISTOLOGY

on the 40th postoperative day in group I, there were fewer inflammatory tissue response and greater collagen deposition (P < 0.01). In group II, there were greater inflammatory tissue response and less collagen deposition (P < 0.01). Group III presented intermediate values between groups I and II.

CONCLUSIONS

There were no significant differences in cytokine levels between the groups in the present study. In the animals with the polypropylene + polyglactin mesh implant there was the most intense inflammatory process with lower tissue maturation and collagen deposition on the 40th postoperative day. The polypropylene mesh presented a less severe late inflammatory process, with greater tissue maturation and collagen deposition. The polypropylene + titanium mesh presented intermediate values between the others.

Prospective evaluation of prostate cancer risk in candidates for inguinal hernia repair

BACKGROUND

Preperitoneal placement of mesh during herniorraphy has been shown to complicate future extirpative prostate surgery. We investigated the value of a prostate cancer screening program in patients considering laparoscopic inguinal herniorrhaphy to identify men at risk of prostate cancer.

STUDY DESIGN

A prospective cohort study was conducted in men 30 years of age or older presenting with inguinal hernia. All patients were counseled on prostate cancer risk and the potential for herniorrhaphy with mesh placement to complicate future pelvic surgery. Serum prostate specific antigen (PSA) values were obtained, and patients determined to be at increased relative risk of prostate cancer were referred for urologic evaluation. Transrectal ultrasonography-guided biopsy was performed if clinically indicated, and operative data for patients undergoing prostate cancer treatment were retrospectively reviewed.

RESULTS

There were 1,324 patients who presented for management of inguinal hernia; 814 of these (median age 60 years) consented to screening. Overall, 259 (32%) had an increased relative risk of prostate cancer based on PSA 1.0 to 2.49 ng/mL, and 152 (19%) had PSA > or = 2.5 ng/mL. Transrectal ultrasonography-guided biopsy was performed in 86 patients. Prostate cancer was identified on initial or repeat biopsy in 31 patients (3.8%), including 1 patient (0.7%) younger than 50 years of age.

CONCLUSIONS

We found the incidence of concurrent prostate cancer with hernia to be low, but 51% of men had PSA values that suggested an increased relative risk of future development of prostate cancer. Men at increased risk of prostate cancer should be made aware of the impact that mesh might have on subsequent treatment options before mesh placement.

Influence of mesh materials on the integrity of the vas deferens following Lichtenstein hernioplasty: an experimental model

BACKGROUND

The utilization of mesh reinforcement of the inguinal area with polypropylene mesh has increased drastically over the last decade. Infertility due to obstructive azoospermia is a rare but serious complication following inguinal hernia repair, especially in young patients. The aim of this study was to evaluate the effect of different mesh structures on integrity of the vas deferens.

MATERIALS AND METHODS

Twenty male Chinchilla rabbits were used. The spermatic cord was dissected free and a Lichtenstein repair was performed with a low-weight polypropylene mesh (UltraPro) and a heavy-weight polypropylene mesh (Prolene) on the contralateral side. A vasography was performed after six months in order to investigate obstructions of the vas deferens. Light microscopy of the mesh host tissue interface was also performed and the foreign body reaction analyzed. Spermatogenesis was evaluated using the Johnsen score.

RESULTS

Vasography revealed relevant obstructions (>75% of lumen diameter) located at the mesh margins (50% of Prolene and 22.2% of UltraPro mesh samples). Microscopic investigation of the mesh-host tissue interface showed typical formation of foreign body granulomas. The diameters of the foreign body granulomas were significantly reduced in the UltraPro mesh group (41.7 +/- 5.5 microm) compared to the Prolene mesh group (48.7 +/- 7.7 microm). Upon investigating the percentages of apoptotic (TUNEL) and proliferating (Ki67) cells, no significant differences were found. Following Prolene mesh implantation, a mean Johnsen score of 9.1 +/- 1.2 was estimated, which was not significantly different from the UltraPro mesh samples (8.9 +/- 1.4, P > 0.05).

CONCLUSIONS

If a mesh material is needed for inguinal hernia repair in young patients, the use of modern low-weight large porous and elastic samples appears to have a beneficial effect on integrity of the vas deferens.

Improving outcomes in hernia repair by the use of light meshes--a comparison of different implant constructions based on a critical appraisal of the literature

BACKGROUND

Despite convincing advantages offered by meshes, their use in hernia surgery remains controversial because of fears concerning the long-term effects of their implantation. To improve biocompatibility, a large variety of newly developed light meshes has been introduced to the market. This overview of the literature aimed to establish whether absolute material reduction (g per implanted mesh), use of absorbable components, and coating by inert materials are evidence-based ways to improve biocompatibility of meshes.

METHOD

A review of the current English and German language literature on the outcome of groin und incisional hernia mesh repair was performed. Both basic research and clinical trials were used as sources of data. Meta-analyses and randomized controlled trials were given priority and were referred to whenever possible.

RESULTS

Operative technique was an independent prognostic factor for the clinical outcome. Mesh construction and composition as characterized by pore size and filament structure appeared to be more important determinants of foreign body reaction after implantation than absolute material reduction of 1 g or more per implant. No data exist about an oncogenic effect of alloplastic materials in humans, but disturbed fertility in animal studies remains an issue of concern and should be further investigated.

CONCLUSIONS

According to data from current randomized controlled trials and retrospective studies, light meshes seem to have some advantages with respect to postoperative pain and foreign body sensation. However, their use is associated with increased recurrence rates. Light meshes offer no advantages with respect to alleviating severe chronic groin pain. At the same time, experimental data reveal that material composition and mesh structure may significantly affect foreign body reaction.

Experimental study comparing the tensile strength of different surgical meshes following aponeurotic-muscle deformity synthesis on Wistar rats

PURPOSE: To assess the tensile strength of polypropylene and polypropylene associated with polyglactin meshes (Vypro II® - Ethicon®, Somerville, NJ, USA) in a situation of partial separation of abdominal muscle aponeurosis on rats. METHODS: Thirty rats were used of the Wistar strain, which were randomized into two groups of 15 specimens each. In both groups an aponeurotic-muscle deformity was created on the abdominal wall measuring 3.0 x 1.0 cm, which was closed with polypropylene mesh (polypropylene group) or Vypro® mesh (vypro group). After 28 days the rats underwent euthanasia and an area was removed from the abdominal wall with which a strip was made measuring 2.0 cm in length and 6.0 cm in width comprising the abdominal muscles with the implanted mesh. This sample was placed in a mechanical test machine in which a constant force was applied contrary to the tissue strips. Maximum force expressed in Newton was considered until full rupture of the sample occurred. The non-parametric Kruskal - Wallis test was used for statistical analysis admitting p<0.05. RESULTS: Out of the thirty animals, there were two deaths in the vypro group and one unit in the polypropylene group was lost. One animal in the polypropylene group developed hernia during the study and another one developed granuloma of the abdominal wall. All animals in both groups developed epiplon adherence to the mesh. The average force was 48.08 N for the polypropylene group and 45.32 for the vypro® group. CONCLUSION: In these experimental conditions it could be observed that there is no statistically significant difference in the rupture force of the polypropylene and Vypro® meshes (p=0.54).

Influence of hernioplastic implants on male fertility in rats

This study explored the vulnerability of the ductus deferens due to mesh induced inflammation and shrinkage after hernia repair in the rodent model. Two commonly used types of hernioplastic implants (Prolene and Vypro II) were surgically wrapped around the ductus deferentes on both sides in 20 juvenile and 20 adult Sprague-Dawley rats. Twenty male rats underwent sham surgeries as controls. After 3 months, each male was mated with 2-3 adult females, which were subsequently sacrificed and oocytes or embryos were flushed and counted. Histochemical investigations of the implants and the ductus recovered surgically 4 weeks after implantation (one side) and after the fertility test (second side) were conducted. All groups exhibited 1-3 males with decreased or restricted fertility but there was no difference between groups. Histochemical analysis of the implants and the ductus recovered 4 weeks and 4 months after implantation revealed some sperm granulomes due to lesions of the spermatic cord caused by the implant in the Prolene group. There was no inflammatory reaction in the mucosa or blockage of the spermatic cord visible. Both types of hernioplastic implants tested in this investigation do not give an indication of a negative influence on male fertility in juvenile or adult rats.

The role of TGF-beta1 as a determinant of foreign body reaction to alloplastic materials in rat fibroblast cultures: comparison of different commercially available polypropylene meshes for hernia repair

BACKGROUND

Animal experiments on hernia repair demonstrated better biocompatibility of light-weight polypropylene meshes. However, implanted medical devices trigger a variety of adverse tissue responses, such as inflammation, fibrosis, infection and thrombosis, but the mechanisms involved in such responses remain largely unknown. This study aimed to determine the effect of transforming growth factor beta1 (TGF-beta1) on host tolerance by quantification of foreign body reaction in cultured fibroblasts depending on the amount and composition of implanted material used for hernia repair.

MATERIALS AND METHODS

An NRK-49F fibroblast culture was incubated in the presence of 4 commercially available meshes approved for hernia repair. A mesh-free cell suspension served as a control group, in which the influence of TGF-beta1 on fibroblasts was evaluated. Levels of TGF-beta1 in the supernatant were dynamically measured in a time interval of 6 to 96 h and cell proliferation rates were assessed colorimetrically using MTT test.

RESULTS

A dose-dependent suppression of fibroblasts proliferation by TGF-beta1 was observed. All meshes suppressed the secretion of TGF-beta1 and conversely increased significantly cell proliferation in comparison to the control group (p<0.01) in the first 24 to 48 h of incubation. That effect was more pronounced in meshes partially containing absorbable material when compared to samples of pure polypropylene meshes (p<0.05) and to the control group (p<0.001).

CONCLUSION

Our experiment revealed that early biological reaction of connective tissue cells towards polypropylene meshes and their variants depended much more on the composition and type of the material than on its absolute amount. The assumption that material weight reduction alone might affect the foreign body reaction of mesh implants could not be confirmed by our in vitro study.

Collagen-coated vs noncoated low-weight polypropylene meshes in a sheep model for vaginal surgery. A pilot study

The aims of this study were dual. First, to evaluate the feasibility of a sheep model as an animal model for vaginal surgery with meshes. Second, to compare host response to two low-weight polypropylene (PP) meshes, a noncoated (Soft Prolene, Gynecare, Ethicon) and a coated mesh with an absorbable hydrophilic film (Ugytex, Sofradim). Thirty-six 20 x 20 mm polypropylene meshes (18 coated and 18 noncoated) were surgically implanted by the vaginal route in 12 adult ewes. Meshes were implanted in the anterior (n=12) and the posterior vaginal compartments (n=24). Animals were killed 1 (n=6) and 12 (n=6) weeks after surgery. Postimplantation evaluation included macroscopical examination, histological and immunohistochemical analysis and histomorphometrical measures of the distance between the meshes and the vaginal epithelium. The experimental procedure was feasible in all cases. Vaginal erosions were observed twice as frequently with the noncoated-PP meshes (6/18, 33.3%) as with the coated-PP meshes (3/18, 16.7%), even if that difference was not significant (p=0.4). However, no differences were observed between the two meshes in terms of shrinkage, tissue ingrowth, inflammatory response, and position of the mesh in the vaginal wall. The mechanism involved in the reduction of vaginal erosion could be due to the lesser adhesion of the coated mesh on the vaginal wound during the early postoperative period.