Porcine Survival Study Research Articles

Abstract 18459: A Cell Permeable Protein Kinase C Beta II Peptide Inhibitor Mitigates the Generation of Reactive Oxygen Species in Rat ex-vivo and Porcine in-vivo Ischemia-Reperfusion Injury

Introduction: Restoration of blood flow following myocardial infarction is necessary to salvage ischemic tissue, but reperfusion is known to cause myocardial ischemia/reperfusion injury (MIR). Cytokine induced translocation of protein kinase C beta II (PKCβII) during reperfusion (R) stimulates the production of reactive oxygen species (ROS). Dual conjugation of PKCβII peptide inhibitor (PKCβII-) with myristic acid (myr) and trans-activator of transcription (Tat) (myr-Tat-CC-SLNPEWNET [myr-Tat-PKCβII-]) enhances intracellular delivery and reduces phorbol ester-induced neutrophil ROS. We hypothesize that 20ng/kg of myr-Tat-PKCβII- would exert cardioprotective effects in porcine MIR in-vivo by reducing stimulation of ROS. Methods: Ex vivo: We tested 100nM - 10fmol myr-Tat-PKCβII- in ex-vivo rat MIR. Isolated hearts from anesthetized male SD rats underwent global I (30-min)/R(50-min). Myr-Tat-PKCβII- was given during first 5min of R. DP/dt max was measured via pressure transducer in the left ventricle. 1% TTC staining was used to determine infarct size. Data was analyzed via Fisher’s PLSD. In vivo: Regional I (1 hr)/R (3 hrs) was induced in male Yorkshire pigs. At R, myr-Tat-PKCβII- or scrambled control peptide (20ng/kg; ~100 pM blood volume [vol.] concentration [conc.]) was given by intra-arterial bolus. Ejection fraction (EF) was calculated. Infarct size was determined with Evans Blue dye and 1% TTC staining. Data was analyzed using Student’s t-test. Results: Ex-vivo: Myr-Tat-PKCβII- (100nM - 100fmol; 10-14±3%; n=3-6) significantly reduced infarct size compared to controls (21±3%; n=21; p<0.05). DP/dt max was significantly improved (100pM-1pM; 961±274; n=5-6) compared to 100nM (163±77, n=3; p<0.05), 100fM (481±86, n=5; p<0.05), and 100pMscrambled myr-Tat-PKCβII- (386±86, n=4; p<0.05). In-vivo: Myr-Tat-PKCβII- 20ng/kg (~100pM blood vol. conc.) significantly restored EF to within 1.4±0.7% of baseline and reduced infarct size to (10.0±2.8%; n=4) compared to control (6.4±2.1%; 28.5±8.3%; n=6; p<0.05). Conclusions: Results suggest 20ng/kg (~100pM blood vol. conc.)) should continue to be used to test in porcine MIR in-vivo. Future studies include a 12-week porcine survival study to evaluate infarct size and cardiac function.

In vitro particulate and in vivo drug retention study of a novel polyethylene oxide formulation for drug-coated balloons

ObjectiveThe purpose of this study was to investigate the newly developed drug-coated balloon (DCB) using polyethylene oxide (PEO) as a platform and to compare it directly with a commercially available DCB in a preclinical experimental setting. MethodsThe PEO balloon was characterized for coating morphology and degree of paclitaxel (PAT) crystallinity. PAT tissue levels were then measured up to 30 days in a healthy porcine model (10 swine, 20 vessels) after treatment with either a PEO balloon or a commercially available DCB. An in vitro bench-top model was used to compare the particulates released from the PEO balloon and commercially available DCB. ResultsThe coating on the PEO balloon was smooth and homogeneous with PAT in its amorphous state. From the porcine survival study, the PAT tissue levels were comparable between PEO balloon and commercially available DCB after 7 days of treatment. Both the PEO balloon and the commercially available DCB retained therapeutic drug up to 30 days. During the simulated in vitro model, the PEO balloon shed significantly fewer particulates that were smaller than those of the commercially available DCB. Most important, the PEO balloon shed 25 times fewer large particulates than the commercially available DCB. ConclusionsThe amorphous PAT in the PEO balloon provided comparable drug tissue retention levels to those of the commercially available DCB and fewer particulates. Thus prepared PEO balloon proved to be safe and effective in the preclinical experimental setting. The clinical outcomes of these findings need further investigation.

Transrectal rigid-hybrid NOTES cholecystectomy can be performed without peritoneal contamination: a controlled porcine survival study.

The risk of infectious complications due to peritoneal contamination is a major concern and inhibits the widespread use of transrectal NOTES. A standardized rectal washout with a reversible colon occlusion device in situ has previously shown potential in reducing peritoneal contamination. The aim of this study was to compare the peritoneal contamination rate and inflammatory reaction for transrectal cholecystectomy after ideal rectal preparation (trCCE) and standard laparoscopic cholecystectomy (lapCCE) in a porcine survival experiment. Twenty pigs were randomized to trCCE (n=10) or lapCCE (n=10). Before trCCE, rectal washout was performed with saline solution. A colon occlusion device was then inserted and a second washout with povidone-iodine was performed. The perioperative course and the inflammatory reaction (leukocytes, C-reactive protein) were compared. At necropsy, 14days after surgery the abdominal cavity was screened for infectious complications and peritoneal swabs were obtained for comparison of peritoneal contamination. Peritoneal contamination was lower after trCCE than after lapCCE (0/10 vs. 6/10; p=0.003). No infectious complications were found at necropsy in either group and postoperative complications did not differ (p=1.0). Immediately after the procedure, leukocytes were higher after lapCCE (17.0±2.7 vs. 14.6±2.3; p=0.047). Leukocytes and C-reactive protein showed no difference in the further postoperative course. Intraoperative complications and total operation time (trCCE 114±32 vs. 111±27min; p=0.921) did not differ, but wound closure took longer for trCCE (31.5±19 vs. 13±5min; p=0.002). After standardized rectal washout with a colon occlusion device in situ, trCCE was associated without peritoneal contamination and without access-related infectious complications. Based on the findings of this study, a randomized controlled clinical study comparing clinical outcomes of trCCE with lapCCE should be conducted.

Endolumenal colon occlusion reduces peritoneal contamination during a transrectal NOTES procedure: a controlled porcine survival study.

To enable an efficient and enduring decontamination of the rectal mucosa during transanal endosocopic procedures, we developed a device for reversible endolumenal colon occlusion (ColoShield). The aim of this study was to assess the value of ColoShield in reducing peritoneal contamination during a transrectal procedure. Sixteen pigs underwent transrectal hybrid NOTES cholecystectomy after standardized disinfective rectal washout either with endolumenal colon occlusion using ColoShield (N=8) or without colon occlusion (N=8). Rectal swab samples were taken before and after rectal washout and at the end of the procedure. Peritoneal biopsies for microbiological evaluation were obtained at the end of the procedure and at necropsy 7days after surgery. Peritoneal contamination at the end of surgery was significantly lower using ColoShield compared to not using colon occlusion [13 (1/8) vs. 75% (6/8); P=0.012]. No significant differences were found regarding contamination of rectal swabs and peritoneal contamination at necropsy. The application of ColoShield may increase the safety of transrectal NOTES and transanal endoscopic procedures by reducing peritoneal contamination and consecutive infectious complications.

Thoracolaparoscopic dissection of esophageal lymph nodes without esophagectomy is feasible in human cadavers and safe in a porcine survival study.

High-risk early esophageal adenocarcinoma (i.e. submucosal invasion >500 nm, poor differentiation, and/or presence of lymphovascular invasion) is currently treated with esophagectomy with lymph node (LN) dissection given the high rates of LN metastases. However, esophagectomy is associated with substantial morbidity and mortality. Endoscopic radical resection followed by thoracolaparoscopic LN dissection without concomitant esophagectomy could be an alternative. The study aim was to evaluate the feasibility and safety of thoracolaparoscopic dissection of esophageal LNs in a preclinical setting. (i) In human cadavers, thoracolaparoscopic dissection of LNs involved in drainage of the esophagus was performed. Subsequently, esophagectomy was performed to be able to detect retained LNs. Outcome parameters included the number of dissected LNs, the number of retained LNs in the esophagectomy specimen (ES), and technical success. (ii) In swine, thoracolaparoscopic LN dissection was also performed. After the procedure, the swine survived for 28 days. Thereafter, the swine were sacrificed and esophagectomy was performed. Outcome parameters included the presence of ischemia and/or stenosis in the ES and other complications. (i) In five human cadavers, a median of 26 LNs (interquartile range 22-46) were dissected. In two ES, one retained LN was found: one high paraesophageal, one low paraesophageal. Technical success rate was 100%. (ii) None of the seven porcine ES showed signs of ischemia or stenosis. One swine died because of ventricular fibrillation during surgery; during follow up no complications were observed. Thoracolaparoscopic dissection of LNs involved in the drainage of the esophagus is feasible in human cadavers and swine. The porcine survival study suggests that the esophageal vascularity is not severely compromised by the procedure. As anatomy differs between swine and humans, safety of the procedure will have to be investigated thoroughly before applying this new technique as the treatment of choice.

Sa1644 Feasibility of Non-Exposed Endoscopic Wall-Inversion Surgery (NEWS) With Sentinel Node Navigation Surgery (Snns) As a New Method of Minimally Invasive Local Resection for Early Gastric Cancer: a Porcine Survival Study

Non-exposed endoscopic wall-inversion surgery (NEWS) has been developed as endoscopic full-thickness resection without transluminal communication to avoid intraabdominal infection or tumor seeding. We aimed to investigate feasibility and safety of NEWS with sentinel node navigation surgery (SNNS), which can minimize the area of lymph node dissection for early gastric cancer (EGC), in a porcine survival study for a week.

Feasibility of non-exposed endoscopic wall-inversion surgery with sentinel node basin dissection as a new surgical method for early gastric cancer: a porcine survival study

Non-exposed endoscopic wall-inversion surgery (NEWS) has been developed as an endoscopic full-thickness resection technique without translumenal communication to avoid intraabdominal infection or tumor seeding. We aimed to investigate the feasibility and safety of NEWS with sentinel node basin dissection (SNBD), which can minimize the area of lymphadenectomy for early gastric cancer (EGC), in 10 porcine survival models. After placing laparoscopic ports and making markings on both the mucosal and serosal sides of a simulated lesion, indocyanine green fluid was endoscopically injected into the submucosa at 4 quadrants around the lesion. An SN basin including the stained SNs was dissected, and a circumferential sero-muscular incision around the lesion and sero-muscular suturing were performed laparoscopically, with the lesion inverted toward the inside of the stomach. Finally, circumferential mucosal incision and transoral retrieval were made endoscopically. In all cases, the lesion was resected in an en bloc fashion, and all pigs survived without adverse events. After 1week of observation, pigs were sacrificed for macroscopic investigation. The average procedural duration was 170min (range 130-253min). Intraoperative perforation occurred in 1 case, which could be safely treated by laparoscopic suturing. The number of dissected SN basins was 1 in 9 cases and 2 in 1 case. Necropsy revealed no signs of severe complication. This animal survival study demonstrated that NEWS with SNBD was safe and feasible. It may provide patients with possibly node-positive EGC a minimally-sized local resection and minimally-ranged lymphadenectomy without the risk of tumor dissemination.

Endolumenal full-thickness colon-wall resection using an over-the-scope-clip: three techniques compared in a porcine survival study

Endolumenal full-thickness colon-wall resection using an over-the-scope-clip: three techniques compared in a porcine survival study

Transrectal peritoneal access with the submucosal tunnel technique in NOTES: a porcine survival study

Natural orifice transluminal endoscopic surgery (NOTES) procedures have been performed via transgastric, transvaginal, or transcolonic approaches. However, the transcolonic approach has potential disadvantages including intraperitoneal infection. To avoid such disadvantages, we applied the submucosal tunnel technique to transrectal peritoneal access in this study. Study aims are to clarify the technical feasibility of a submucosal tunnel method for transrectal abdominal access and to assess the healing process of the submucosal tunnel histopathologically. The study comprised six female pigs. The following procedures were performed: (1) The mucosa was cut after injection of sodium hyaluronate into the submucosa at the upper rectum. (2) Submucosal tunneling was performed by endoscopic submucosal dissection technique. (3) A small incision was made at the end of the tunnel. (4) After transrectal peritoneoscopy, the mucosal incision site was closed with endoclips. Transrectal peritoneoscopy was successfully performed in all pigs. Necropsy revealed no findings of peritonitis. Histopathologic examination showed good healing of the submucosal tunnel. The wound healing process of the submucosal tunnel on postoperative day 7 was mainly in the inflammatory phase at the mucosal incision site, the proliferative phase at the submucosal tract, and the proliferative/remodeling phase at the seromuscular incision site. The submucosal tunnel technique appears to be useful and safe for transrectal peritoneal access because healing at the seromuscular incision site proceeded rapidly.

Endoscopic closure devices

Endoscopic closure devices

Gastrotomy closure with a new tissue anchoring device: A porcine survival study

To evaluate the feasibility, reproducibility and efficacy of a new tissue anchoring device in a porcine survival model. Gastrotomies were performed using a needle-knife and balloon dilator in 10 female Yorkshire pigs weighing 30-35 kg. Gastric closure was attempted using a new tissue anchoring device. The tightness of the closure was confirmed by means of air insufflation and the ability to maintain gastric distension with stability in peritoneal pressure measured with a Veress needle. All animals were monitored daily for signs of peritonitis and sepsis over 14 d. During necropsy, the peritoneal cavity and the gastric access site were examined. Transgastric access, closure and 14 d survival was achieved in all pigs. The mean closure time was 18.1 ± 19.2 min and a mean of 2.1 ± 1 devices were used. Supplementary clips were necessary in 2 cases. The closure time was progressively reduced (24.8 ± 13.9 min in the first 5 pigs vs 11.4 ± 5.9 min in the last 5, P = NS). At necropsy, the gastric access site was correctly closed in all cases with all brace-bars present. One device was misplaced in the mesocolon. Minimal adhesions were observed in 3 pigs and signs of mild peritonitis and adhesions in one. The use of this new tissue anchoring device in porcine stomachs is feasible, reproducible and effective and requires a short learning curve.

Submucosal tunneling using endoscopic submucosal dissection for peritoneal access and closure in natural orifice transluminal endoscopic surgery: a porcine survival study

Safe peritoneal access and gastric closure are the most important concerns in the clinical application of natural orifice transluminal endoscopic surgery (NOTES). We aimed to clarify the feasibility of a submucosal tunnel technique using endoscopic submucosal dissection (ESD) for transgastric peritoneal access and subsequent closure for NOTES. Seven female pigs, each weighing about 40 kg were included in the study. The following procedures were performed: (i) after injection of normal saline into the submucosa, the mucosa was cut with a flex knife; (ii) the submucosal layer was dissected using an insulation-tipped electrosurgical knife to make a narrow longitudinal 50-mm submucosal tunnel; (iii) a small incision was made at the end of the tunnel and enlarged with a dilation balloon. After transgastric peritoneoscopy, the mucosal incision site was closed with clips. The following outcome measures were used: (a) evaluation of the technical feasibility of making a submucosal tunnel; (b) clinical monitoring for 7 days; (c) follow-up endoscopy and necropsy; and (d) peritoneal fluid culture. Natural orifice transluminal endoscopic peritoneoscopy with a submucosal tunnel was successfully carried out in all pigs. The pigs recovered well, without signs of peritonitis. Follow-up endoscopy showed healing of mucosal incision sites without open defects. Necropsy revealed no findings of peritonitis, confirming completeness of gastric closure; there was a thin scar in one pig and adhesion of the omentum in six pigs. Peritoneal fluid culture demonstrated no bacterial growth. The submucosal tunnel technique is feasible and effective for transgastric peritoneal access and closure.

Bladder Cryoablation in a Porcine Model: Evaluation of Three Surgical Approaches and Cryolesion Predictability

To determine the feasibility of bladder cryoablation (BC) applied laparoscopically, percutaneously, and transurethrally in a porcine survival study. The expected and observed area of cell death after BC was also examined. Nine pigs were divided equally into the three treatment groups. Cryoablation was performed with two freeze-thaw cycles after the bladder had been insufflated with CO2. Each animal was observed for 7 days after the procedure for treatment-related complications. After cystectomy, each specimen was examined pathologically to determine the degree and dimension of cell death achieved. BC applied via the laparoscopic and percutaneous approach is feasible and safe. No BC-related complications occurred in these two groups. A complication resulting from BC developed in all three animals that were treated cystoscopically, including two intraperitoneal bladder perforations at the time of BC necessitating immediate sacrifice, and one enterovesical fistula discovered at cystectomy. Transmural necrosis was demonstrated in seven of seven animal specimens that survived to the end of the protocol. The observed diameter of tissue necrosis was highly predictable based on the reported cryoprobe isotherms given by the manufacturer. All locations within the bladder can be successfully and predictably treated with cryoablation. Of the three approaches, laparoscopically administered BC appears to be the most safe and consistent method. Transurethral BC was not safe with the equipment available without laparoscopic assistance to prevent bowel complications.

Self-approximating transluminal access technique for natural orifice transluminal endoscopic surgery: a porcine survival study (with video)

The ability to access the abdominal cavity though a direct (modified-PEG type) gastric incision to perform natural orifice transluminal endoscopic surgery (NOTES) has been demonstrated in the literature. However, the optimal technique to access the abdomen remains unknown. The aim of this study was to evaluate the safety and feasibility of a transgastric approach to the abdominal cavity through an extended submucosal tunnel. Animal feasibility study. Transgastric endoscopic peritoneoscopy was performed in 7 anesthetized swine, including 2 acute and 5 survival animals. After the creation of a 10-cm to 12-cm tunnel in the gastric submucosal plane, the peritoneal cavity was accessed by needle-knife puncture through the gastric wall near the greater curvature. The peritoneal cavity was examined before the gastric mucosal incision was closed with endoclips. Survival animals were euthanized two weeks after the procedure, and a necropsy was performed. The abdominal cavity was successfully entered without complication in all 7 animals. The mucosal incisions were able to be closed by endoscopy. In the survival experiments, all animals recovered and gained weight. Two animals experienced clinically unapparent infectious complications. Small sample size. A peroral transgastric approach to the abdominal cavity through an extended submucosal tunnel is technically feasible and allows safe abdominal access and reliable closure with currently available technology. It has potential benefits as an alternative to direct transgastric access for NOTES procedures.