Svetlana Titkova

Surgical Mesh as a Scaffold for Tissue Regeneration in the Esophagus

Background: Textiles in the form of surgical meshes are widely used in hernia surgery. Their porous structure allows tissue infiltration to incorporate the fabric for complete healing and device stabilization. This study was aimed to reconstitute the esophageal wall and to investigate the functional and histological consequences of a new, non-absorbable polyvinylidene fluoride (PVDF) mesh and an absorbable polyglactin 910 (Vicryl®) mesh. Methods: Semicircular esophageal defects of 0.5 × 1 cm were created 2 cm proximal of the cardia in 10 rabbits. This gap was bridged using either polyglactin 910 or PVDF and additionally covered by omental wrapping. The clinical outcome was observed by clinical observation, regular esophagoscopies and X-ray contrast medium examinations. Local tissue regeneration was verified by light microscopy and immunohistochemistry. Results: After an observation period of 3 months we found no anastomotic strictures, complete mucosal regeneration, minimal inflammation reaction and initial regeneration of the muscle layer for the PVDF group. Within the polyglactin 910 group, three patch failures with consecutive anastomotic leakage occurred. Conclusion: The results indicate that PVDF mesh structure gives the opportunity of local tissue regeneration in the esophagus. Though re-epithelialization and muscle cell ingrowth could be detected for absorbable polyglactin 910 mesh, this implant was accompanied by a high and early rate of anastomotic leakage.

Modification of collagen formation using supplemented mesh materials

BackgroundFormation of recurrent inguinal and incisional hernia shows an underlying defect in the wound healing process. Even following mesh repair an altered collagen formation and insufficient mesh integration has been found as main reason for recurrences. Therefore the development of bioactive mesh materials to achieve a local modification of the scar formation to improve patients outcome is advisable.MethodsThirty-six male Wistar rats were used within this study. A Mersilene ® mesh sample was implanted after midline skin incision and subcutaneous preparation. Before implantation mesh samples were incubated for 30 minutes with either one of the following agents: doxycycline, TGF-beta 3, zinc-hydrogeneaspartate, ascorbic acid, hyaluronic acid. Incubation with a physiologic 0.9 % NaCl solution served as control. Seven and 90 days after mesh implantation 3 animals from each group (n = 6) were sacrificed for morphological observations. Collagen quantity and quality was analyzed measuring the collagen/protein as well as the collagen type I/III ratio.ResultsFollowing an implantation interval of 90 days supplementation with doxycycline (39.3 ± 7.0 µg/mg) and hyaluronic acid (34.4 ± 5.8 µg/mg) were found to have a significantly increased collagen/protein ratio compared to implantation of the pure Mersilene ® mesh samples (28.3 ± 1.9 µg/mg). Furthermore, an overall increase of the collagen type I/III ratio was found in all groups indicating scar maturation over time. However, no significant differences were found after 7 and 90 days of implantation comparing collagen type I/III ratio of supplemented mesh samples and control group.ConclusionsIn summary, we found an influence of supplemented mesh materials on collagen deposition. However, the investigated bioactive agents with reported influence on wound healing were not associated with an improved quality in scar formation.

Influence of Postoperative Epidural Analgesia with Bupivacaine onIntestinal Motility, Transit Time, and Anastomotic Healing

Epidural application of bupivacaine hasbeen suggested to have a sympatholytic effect on spinal reflexmechanisms that shortens postoperative paralysis and leads to animproved transit time. The influence on anastomitic healing remainscontroversial. Laparotomy was performed in eight dogs. A short segmentof the distal colon was resected and five electrodes were fixed on theserosa to measure the myoelectric activity (e.g., Migrating MyoelectricComplex—MMC). After operation a peridural catheter was placed betweenL7 and the sacral crest. One milliliter of bupivacaine 0.25% for each3 kg of body weight was injected every 4 hours. Barium pellets coatedin wax were placed into the stomach to allow radiographicrepresentation of transit time. After 5 days the colon anastomosis wasresected to measure the bursting pressure. In the peridural analgesiagroup (PDA) we found one small bowel intussusception and one coveredanastomotic leakage. Postoperative PDA led to early and severemyoelectric activity but did not influence the time until the first MMCoccurred (44 ± 0.8 h, PDA; 44.6 ± 1.5 h,control). Neither the transit time to the colon (50.2 ± 1.9h, PDA; 51.7 ± 5.5 h, control) nor the anastomotic healingwas influenced (bursting pressure: 176 ± 21.1 mmHg, PDA; 152± 27.7 mmHg, control). Postoperative epidural analgesia withbupivacaine shortens intestinal paralysis. Early myoelectric activitywith a lack of propulsive activity can cause complications like smallbowel intussusception. Hence early postoperative enteral nutritionafter epidural analgesia is risky. Because the influence of epiduralanalgesia on propulsive motility remains unclear, it seems reasonableto recommend its limited use in colon surgery.

Colon interposition for esophageal replacement: isoperistaltic or antiperistaltic? Experimental results

BACKGROUND Isoperistaltic colon is preferred to antiperistaltic colon for esophageal replacement, but experimental data do not exist to support this practice. METHODS In 7 dogs a 20 cm long colon loop was interposed between the skin and the small bowel, isoperistaltically in 3 dogs and antiperistaltically in 4 dogs. Three months later five strain-gauges were implanted and evacuation was investigated by motility testing, barium studies, and scintigraphy. RESULTS Motility recording showed normal colon motility in the excluded loops. Quiescent states (duration 40.2 +/- 13.6 minutes) were followed by contractile states (duration 7.5 +/- 2.4 minutes, frequency 3.3 +/- 0.6 per minute). The main peristaltic direction of isoperistaltic loops was isoperistaltic, and the main peristaltic direction of antiperistaltic loops was antiperistaltic. Evacuation took place exclusively during the contractile status. Half time emptying was more rapid in isoperistaltic loops (35 +/- 11 vs 69 +/- 16 minutes). The content of antiperistaltic loops was held back by antiperistaltic activity. Application of oatmeal porridge into the loops shortened the quiescent status from 40.2 to 13.2 +/- 4.8 minutes. CONCLUSIONS The colon graft for esophageal replacement is an active system. Food is stored during the quiescent states and evacuated during the contractile states. The original peristaltic direction is preserved so that retroperistalsis in antiperistaltic loops may lead to patient discomfort and pulmonary complications.

Influence of suture material and suture technique on collagen fibril diameters in midline laparotomies

Background: Although laparotomy closure is associated with a cumulative 15% failure rate, the effect of different suture techniques and materials on the ultrastructural composition of the healing incision has not been investigated. Method: in 40 Wistar rats the collagen fibril diameters and the regenerative tissue were compared using electron microscopy 14 and 28 days after midline laparotomy. Wounds were closed with single and running sutures using either polypropylene or polyglactin 910. Results: Closure with polypropylene led to significantly larger mean fibril diameters than closure with polyglactin. Regardless of time and suture material, running closure resulted in significantly smaller mean collagen fibril diameters than single sutures. Four weeks after laparotomy, inflammatory reactions, disorganization of collagen and irregularities of the vascular architecture were found after closure with absorbable suture material but not after closure with nonabsorbable material. Conclusion: Suture material and suture method significantly influence the ultrastructural composition of the healing incision. Persisting mechanical irritation around the suture threads after single sutures and severe persisting inflammatory reactions after the use of absorbable suture material are important influencing factors.

Large-Pore PDS Mesh Compared to Small-Pore PG Mesh

ABSTRACT Background: Currently, absorbable meshes are used as temporary closure in case of laparostoma. Unfortunately the multifilament polyglycolic acid (PG) meshes with small pores reveal little elasticity acting rather as a fluid barrier than permitting drainage of intra-abdominal fluids. Therefore, a new mesh was constructed of absorbable polydioxanon monofilaments (PDS) with increased porosity and longer degradation time. Material and Methods: For evaluation of the tissue response the new PDS mesh was implanted as abdominal wall replacement in each five rats for 7, 21, or 90 days, respectively, and compared to a PG mesh. Histological analysis included HE staining with measurement of the size of the granuloma and immunoshistochemistry for TUNEL, Ki67, TNF-R2, MMP-2, YB1, FVIII, gas6, AXL. Parameters for neovascularization and nerve ingrowth were analyzed. Results: The inflammatory and fibrotic tissue reaction is attenuated with PDS in comparison to PG, e.g., the size of the granuloma was smaller with less cell turnover, and less remodeling as represented by, e.g., reduction of apoptosis, expression of MMP-2, or TNF-R2. The number of ingrowing nerves and vessels explored via AXL, gas6, and factor VIII was increased in the PDS mesh. Conclusion: The results from the present investigation showed that a mesh can be constructed of monofilament PDS that induce significant less inflammatory and fibrotic reaction, however permits fluid drainage and preserves elasticity.

Different tissue reaction of oesophagus and diaphragm after mesh hiatoplasty. Results of an animal study.

BackgroundLaparoscopic mesh-reinforcement of the hiatal region in the treatment of gastroesophageal reflux disease (GERD) and paraesophageal hernia (PEH) reduces the risk of recurrence. However, there are still controversies about the technique of mesh placement, shape, structure and material. We therefore compared tissue integration and scar formation after implantation of two different polypropylene-meshes in a rabbit model.MethodsA total of 20 female chinchilla rabbits were included in this study. Two different meshes (Polypropylene PP, Polyglecaprone 25 Composite PP-PG) were implanted on the abdominal diaphragm around the oesophagus. After 3 months the implanted meshes were excised en-bloc. Histological and morphological analyses were carried out accordingly proliferation rate, apoptosis and collagen type I/III ratio.ResultsRegarding proliferation rate of oesophagus PP (9.31 ± 3.4%) and PP-PG (13.26 ± 2.54%) differ in a significant (p = 0.0097) way. In the diaphragm we found a significant (p = 0.00066) difference between PP (9.43 ± 1.45%) and PP-PG (18.73 ± 5.92%) respectively. Comparing oesophagus and diaphragm we could prove a significant difference within PP-PG-group (p = 0.0195). Within PP-group the difference reached no statistical significance (p = 0.88). We found analogous results regarding apoptosis.Furthermore, there is a significant (p = 0.00013) difference of collagen type I/III ratio in PP-PG (12.28 ± 0.8) compared to PP (8.44 ± 1,63) in case of oesophageal tissue. Concerning diaphragm we found a significant difference (p = 0.000099) between PP-PG (8.85 ± 0.81) and PP (6.32 ± 1.07) as well.ConclusionThe histologic and morphologic characteristics after prosthetic enforcement of the hiatus in this animal model show a more distinct tissue integration using PP-PG compared to PP. Additionally, different wound healing and remodelling capability influence tissue integration of the mesh in diaphragm and oesophagus.

Effect of Artificial Valves on Intestinal Adaptation in the Short-Bowel Syndrome: An Integrated Study of Morphological and Functional Changes in Rats

Two-third-resections of the proximal or distal small bowel with and without artificial valves were performed in rats. Intestinal adaptation led to a significant increase in bowel diameter, villus height and villus diameter and consequently in absorptive mucosal surface area per unit of serosal area. Additional artificial valve construction did not affect the calculated mucosal surface area after proximal resection, while it significantly decreased the absorptive area by the occurrence of large, plump villi after distal resection. There was no change in small-intestinal absorption of water, glucose and electrolytes per unit mucosa with valve construction. DNA cytometry showed that artificial valves led to mucosal hyperplasia without hypertrophy. These morphological changes coincided with a significant increase in basal and stimulated gastrin release. The body weight was unchanged or even worse in the valve groups than after resection alone, despite a significantly prolonged transit time. Therefore, in our study, artificial valves did not result in functional improvements after small intestinal resections.

The influence of blood on the efficacy of intraperitoneally applied phospholipids for prevention of adhesions

BackgroundThe formation of adhesions following abdominal surgery is a well known problem. In previous studies we demonstrated the efficacy and safety of intraperitoneally applied phospholipids in order to prevent adhesion formation. This study evaluates the influence of blood on the efficacy of intraperitoneally applied phospholipids for prevention of adhesions.MethodsIn 40 Chinchilla rabbits adhesions were induced by median laparotomy, standardized abrasion of the visceral and parietal peritoneum in defined areas of the ventral abdominal wall and the caecum. The animals were randomly divided into four groups. They received either phospholipids 3.0% or normal saline (NaCl 0,9%) (5 ml/kg body weight). In 50% of the rabbits we simulated intraperitoneal bleeding by administration of blood (1,5 ml/kg body weight). The other half served as control group. Ten days following the operation the animals were sacrificed and adhesion formation was assessed by computer aided planimetry and histopathologic examination.ResultsThe median adhesion surface area in the NaCl-group (n = 9) amounted to 68,72 mm2, in the NaCl+Blood-group (n = 10) 147,68 mm2. In the Phospholipid (PhL)-group (n = 9) the median adhesion surface area measured 9,35 mm2, in the PhL+Blood-group (n = 9) 11,95 mm2. The phospholipid groups had a significantly smaller adhesion surface area (p < 0.05).ConclusionAgain these results confirm the efficacy of phospholipids in the prevention of adhesions in comparison to NaCl (p = 0,04). We also demonstrated the adhesion preventing effect of phospholipids in the presence of intraperitoneal blood.

Effects of Intra-Abdominal Drainages on Adhesion Formation and Prevention by Phospholipids in a Rat Model

Background and Aims: The study was designed to asses the adhesiogenic capacity of silicone drainages and the protective effect of phospholipids (PL). Materials and Methods: A total of 75 Wistar rats were randomly assigned to the different groups. In a preliminary trial (pt; n = 15), all rats underwent midline laparotomy. The control group (C_pt; n = 5) received no further treatment. In the other animals, either an ‘easy flow’ drainage (EF_pt; n = 5) or an ‘Aachen’ drainage (AC_pt; n = 5) was placed into the abdominal cavity. In the final study (fs; n = 60), rats underwent laparotomy and colonic anastomosis. The control groups (C_fs) received no drainages. In the other groups either one of the two types of drainages (EF_fs, AC_fs) were introduced. In 50% of the rats, 75 mg/kg of PL were administered intraperitoneally (C_fs+PL, EF_fs+PL, AC_fs+PL). The other rats received no additional treatment (C_fsØPL, EF_fsØPL, AC_fsØPL). All animals were sacrificed 10 days after surgery. Areas of adhesions and anastomotic bursting pressures were measured (mean ± SD). Results: In the preliminary trial, analysis of variance (ANOVA) revealed no differences between the groups after application of drainages (values are given in mean ± SD): C_pt mean 23.3 ± 29.4 mm², EF_pt 829.7 ± 679.3 mm², AC_pt 609.9 ± 219.4 mm². In the final study, 2-factorial ANOVA showed a significant effect (p < 0.001) for the use of drainages but not for the application of PL (C_fsØPL 140.6 ± 124.2 mm², C_fs+PL 67.7 ± 60.4 mm², EF_fsØPL 1,217.0 ± 458.3 mm², EF_fs+PL 1,266.8 ± 368.3 mm², AC_fsØPL 861.7 ± 274.8 mm², AC_fs+PL 544.2 ± 193.8 mm²). Post hoc test for pairwise comparisons adjusted to Bonferroni showed significant differences (p < 0.001) between all of the three pairs (C_fs 104.1 ± 92.3 mm² vs. EF_fs 1,241.9 mm² ± 413.3 mm²; C_fs vs. AC_fs 702.9 mm ± 234.3 mm²; EF_fs vs. AC_fs). Discussion: The final study demonstrates the adhesiogenic capacity of silicone drainage tubes in combination with anastomoses. Any protective effect of PL alone or in combination with drainages could not be shown. Conclusions: Indication for the use of drainages in standard surgical procedures should be reconsidered within the scope of their potential to cause adhesions and subsequent complications.