Efficacy of a novel polyoxazoline-based hemostatic patch in liver and spleen surgery

BACKGROUND

A new hemostatic sealant based on a N-hydroxy-succinimide polyoxazoline (NHS-POx) polymer was evaluated to determine hemostatic efficacy and long-term wound healing and adverse effects in a large animal model of parenchymal organ surgical bleeds.

METHODS

Experiment 1 included 20 pigs that were treated with two NHS-POx patch prototypes [a gelatin fibrous carrier (GFC) with NHS-POx and an oxidized regenerated cellulose (ORC) with poly(lactic-co-glycolic acid)-NHS-POx:NU-POx (nucleophilically activated polyoxazoline)], a blank gelatin patch (GFC Blank), TachoSil^® and Veriset™ to stop moderate liver and spleen punch bleedings. After various survival periods (1-6 weeks), pigs were re-operated to evaluate patch degradation and parenchymal healing. During the re-operation, experiment 2 was performed: partial liver and spleen resections with severe bleeding, and hemostatic efficacy was evaluated under normal and heparinized conditions of the two previous prototypes and one additional NHS-POx patch. In the third experiment an improved NHS-POx patch (GATT-Patch; GFC-NHS-POx and added 20% as nucleophilically activated polyoxazoline; NU-POx) was compared with TachoSil^®, Veriset™ and GFC Blank on punch bleedings and partial liver and spleen resections for rapid (10s) hemostatic efficacy.

RESULTS

NHS-POx-based patches showed better (GFC-NHS-POx 83.1%, ORC-PLGA-NHS-POx: NU-POx 98.3%) hemostatic efficacy compared to TachoSil^® (25.0%) and GFC Blank (43.3%), and comparable efficacy with Veriset™ (96.7%) on moderate standardized punch bleedings on liver and spleen. All patches demonstrated gradual degradation over 6 weeks with a reduced local inflammation rate and an improved wound healing. For severe bleedings under non-heparinized conditions, hemostasis was achieved in 100% for Veriset™, 40% for TachoSil and 80-100% for the three NHS-POx prototypes; similar differences between patches remained for heparinized conditions. In experiment 3, GATT-Patch, Veriset™, TachoSil and GFC Blank reached hemostasis after 10s in 100%, 42.8%, 7.1% and 14.3%, respectively, and at 3 min in 100%, 100%, 14.3% and 35.7%, respectively, on all liver and spleen punctures and resections.

CONCLUSIONS

NHS-POx-based patches, and particularly the GATT-Patch, are fast in achieving effective hemostatic sealing on standardized moderate and severe bleedings without apparent long-term adverse events.

A novel ex vivo perfusion-based mandibular pig model for dental product testing and training

BACKGROUND

A translational ex vivo perfusion-based mandibular pig model was developed as an alternative to animal experiments, for initial assessment of biomaterials in dental and maxillofacial surgery and training. This study aimed to assess the face and content validity of the novel perfusion-based model.

METHODS

Cadaveric porcine heads were connected to an organ assist perfusion device for blood circulation and tissue oxygenation. Dental professionals and dental trainees performed a surgical procedure on the mandibula resembling a submandibular extraoral incision to create bone defects. The bone defects were filled and covered with a commercial barrier membrane. All participants completed a questionnaire using a 5-point Likert scale to assess the face and content validity of the model. Validation data between the two groups of participants were compared with Mann-Whitney U test.

RESULTS

Ten dental professionals and seven trainees evaluated the model for face and content validity. Participants reported model realism, with a mean face validity score of 3.9 ± 1.0 and a content validity of 4.1 ± 0.8. No significant differences were found for overall face and content validity between experts and trainees.

CONCLUSION

We established face and content validity in a novel perfusion-based mandibular surgery model. This model can be used as an alternative for animal studies evaluating new biomaterials and related dental and maxillofacial surgical procedural training.

New polyoxazoline loaded patches for hemostasis in experimental liver resection

A new cost‐effective NHS functionalized polyoxazoline (POx) loaded polymer with strong hemostatic properties has been developed. In this study, we investigate POx loaded hemostatic patches regarding hemostatic efficacy, local inflammatory reaction and wound‐healing, as compared to the non‐POx treated blanks and commercially available hemostatic products. Hundred and ten rats divided into 11 groups of 10 animals underwent partial liver lobe resection. Eight groups received experimental patches, two groups commercially available hemostatic patches (TachoSil® and Veriset™, positive controls), one group with gauzes (negative control). Each animal received twice a patch with a size 1.5 × 2.5 cm, on each partially resected lobe. Primary endpoint was time to hemostasis (TTH). The rats were sacrificed at different time points (1, 3, or 7 days) to measure local inflammatory response and early wound healing. Of the POx loaded patches, GFC NHS‐POx (TTH 20.4 s, p = .019) and GFC‐NHS‐POx1.5 (TTH 0.0 s, p = .003) showed significantly faster TTH compared to TachoSil® (TTH 95.4 s), and were comparable to Veriset™ (TTH 17.0 s). Three patches, GFC‐NHS‐POx 1.5 (TTH 0.0 s, p = .016), ORC NHS‐POx:NU‐POx (TTH 91.4 s, p = .033), and ORC‐PLGA NHS‐POx:NU‐POx (TTH 105.6 s, p = .04) had a lower TTH compared to their own blank carrier (TTH 74.9, 157.8, and 195.7 s, respectively). With regard to biocompatibility, all POx loaded patches showed results comparable to TachoSil® and Veriset™. NHS‐POx‐loaded hemostatic patch demonstrate fast and effective hemostasis, comparable or better than commercially available hemostatic patches, with similar early biocompatibility.

Innate glycosidic activity in metallic implants for localized synthesis of antibacterial drugs

The unexpected discovery presented herein is that industrialized metallic wires can perform conversion of the glucuronide prodrugs with ensuing antibacterial effects.

Experimental study of diclofenac and its biliary metabolites on anastomotic healing

Background

Diclofenac increases the risk of anastomotic leakage, but the underlying mechanism is unknown. As diclofenac is excreted largely as biliary metabolites, the aim of this study was to determine the effect of these metabolites on intestinal anastomoses.

Methods

This was a randomized controlled blinded experiment using 210 male Wistar rats to assess the effect of ‘diclofenac bile’ on the anastomotic complication score, leak rate and anastomotic strength following oral and parenteral administration of diclofenac. Bile duct and duodenal catheterization techniques were used for diversion and replacement of bile, and biliary diclofenac metabolites were determined.

Results

Replacement of control bile with diclofenac bile resulted in higher anastomotic complication scores (P = 0·006) and leakage in five of 18 animals, compared with one of 18 controls (P = 0·089). In turn, following oral diclofenac administration, replacement of diclofenac bile with control bile reduced anastomotic complications (P = 0·016). The leak rate was seven of 15 versus 13 of 17 without replacement (P = 0·127). After intramuscular administration of diclofenac, the reduction in anastomotic complications was not significant when bile was replaced with control bile (P = 0·283), but it was significant when bile was drained without replacement (P = 0·025). Diclofenac metabolites in bile peaked within 2 h after administration. Administration of diclofenac bile resulted in nearly undetectable plasma levels of diclofenac (mean(s.d.) 0·01(0·01) μg/ml) after 120 min. Following oral diclofenac, bile replacement with control bile did not affect the plasma concentration of diclofenac (0·12(0·08) μg/ml versus 0·10(0·05) μg/ml with diclofenac bile; P = 0·869).

Conclusion

Altered bile composition as a result of diclofenac administration increases the ileal anastomotic complication rate in rats.

Self-expandable tubular collagen implants

Collagen has been extensively used as a biomaterial, yet for tubular organ repair, synthetic polymers or metals (e.g., stents) are typically used. In this study, we report a novel type of tubular implant solely consisting of type I collagen, suitable to self-expand in case of minimal invasive implantation. Potential benefits of this collagen scaffold over conventional materials include improved endothelialization, biodegradation over time, and possibilities to add bioactive components to the scaffold, such as anticoagulants. Implants were prepared by compression of porous scaffolds consisting of fibrillar type I collagen (1.0-2.0% (w/v)). By applying carbodiimide cross-linking to the compressed scaffolds in their opened position, entropy-driven shape memory was induced. The scaffolds were subsequently crimped and dried around a guidewire. Upon exposure to water, crimped scaffolds deployed within 15-60 s (depending on the collagen concentration used), thereby returning to the original opened form. The scaffolds were cytocompatible as assessed by cell culture with human primary vascular endothelial and smooth muscle cells. Compression force required to compress the open scaffolds increased with collagen content from 16 to 32 mN for 1.0% to 2.0% (w/v) collagen scaffolds. In conclusion, we report the first self-expandable tubular implant consisting of solely type I collagen that may have potential as a biological vascular implant.

Efficacy and Safety of Ultrapure Alginate-Based Anti-Adhesion Gel in Experimental Peritonitis

BACKGROUND

Intra-abdominal infection may lead to adhesion and abscess formation. An adhesion barrier can reduce these complications but also aggravate intra-peritoneal infection, causing the opposite effects. The fear of infection propagation has limited clinical adhesion barrier use in a contaminated or infected abdomen. This study evaluated both adhesion and abscess reduction and infection propagation of a new ultrapure alginate-based anti-adhesive barrier gel in a rat peritonitis model.

METHODS

In 64 male Wistar rats, bacterial peritonitis was induced via intra-abdominal injection of a mixture of sterile feces, 10(5) colony-forming units (CFU) of Escherichia coli, and 10(4) CFU of Bacteroides fragilis. Surgical debridement and peritoneal lavage were performed 1 h after inoculation. Animals were randomly allocated in equal numbers to a control group or an alginate gel group. Animals were sacrificed on day five post-operatively. Death and the presence and size of intra-abdominal abscesses were noted, and adhesions were scored. All outcomes were compared in the two groups.

RESULTS

Seventeen rats (27%) died prematurely without any difference between the groups. Of the surviving rats in the alginate gel group, 88% developed abscesses vs. 100% of the control group. There was no significant difference in the abscess scores or incidence rates of adhesion formation between the groups. The adhesion scores were lower for the alginate gel group compared with control animals (p=0.04).

CONCLUSION

Ultrapure alginate gel reduces adhesion severity but not abscesses. The gel seemed to be safe, not aggravating intra-peritoneal infection in this abdominal infection model.

Diclofenac causes anastomotic leakage in the proximal colon but not in the distal colon of the rat

BACKGROUND

Nonsteroidal anti-inflammatory drugs have been associated with anastomotic leakage. It was studied if diclofenac affects anastomoses differently depending on the location in the gut.

METHODS

Ninety-five rats were randomized to 6 groups with an anastomosis in either ileum (IL), proximal colon (PC), or distal colon (DC). Groups IL+ (n = 10), PC+ (n = 30), and DC+ (n = 10) received diclofenac (3 mg/kg/day) from day 0 until sacrifice on day 3. Group PC- (n = 15) did not receive diclofenac. Groups PC1+ and PC2+ (n = 15 each) were given diclofenac from day 1 to 4 and from day 2 to 5.

RESULTS

Leak rates were 10/10 in group IL+, 22/30 in PC+, 1/10 in DC+, and 1/15 in PC-. Delayed administration of diclofenac by 1 or 2 days (6/15, P = .05) resulted in reduced leakage rates. Mechanical strength results corresponded with leak rates.

CONCLUSIONS

Diclofenac causes leakage of anastomoses in rat IL and PC, but not in the DC. This suggests a role for the ileal and proximal colonic content in diclofenac-induced leakage.

Ultrapure alginate gel reduces adhesion reformation after adhesiolysis

PURPOSE

Adhesiolysis at repeat surgery induces adhesion reformation which seems more virulent than development of de novo adhesions. We studied the effect of a new ultrapure alginate gel on adhesion reformation.

METHODS

In 46 male Wistar rats, adhesion formation was induced using the cecal abrasion and peritoneal sidewall excision procedure. Two weeks later, a second laparotomy was performed, adhesions were graded, and surgical adhesiolysis was performed. The animals were then allocated to one of two equal groups, a control group without further intervention and a group receiving 1-ml ultrapure alginate gel to the two opposing and damaged surfaces. Two weeks after the second surgery, rats were sacrificed. Primary endpoint was the incidence of adhesion reformation at areas of injury. Secondary endpoints were adhesion scores, extent of adhesions, and tissue histology.

RESULTS

Ultrapure alginate gel significantly (p = 0.046) reduced the incidence of adhesion reformation from 100 % in controls to 78 % in experimental rats. Both the adhesion score (p = 0.009) and the extent of adhesions (p = 0.001) were significantly lower in the alginate group. Tissue healing histology was similar in both groups.

CONCLUSION

Ultrapure alginate gel reduces adhesion reformation following adhesiolysis.

Ultrapure alginate anti-adhesion gel does not impair colon anastomotic strength

BACKGROUND

Ultrapure alginate gel is promising in terms of adhesion prevention. Because anti-adhesive barriers have been shown to disturb healing of bowel anastomoses, the effect of ultrapure alginate gel on the repair of colon anastomoses was studied.

MATERIALS AND METHODS

In 102 male Wistar rats, a 0.5-cm segment was resected from the descending colon and continuity was restored by an inverted single-layer end-to-end anastomosis. Animals were randomized into a control, an alginate gel, and a sodium hyaluronate carboxymethyl cellulose film group, each n = 34. Half of each group was sacrificed at day 3 and 7 postoperatively. Anastomotic strength was assessed by measuring both bursting pressure and breaking strength. Hydroxyproline content was measured and histologic analysis was performed. The incidence of adhesion and abscess formation was scored at sacrifice.

RESULTS

No difference in either anastomotic-bursting pressure or breaking strength was found between experimental groups and the controls at any time point. Both the incidence of adhesion formation (35% versus 71%, P = 0.007) and the adhesion score (0.38 versus 0.79, P = 0.009) were significantly lower in the alginate gel group than in the controls. The abscess rate was higher (46% versus 18%, P = 0.030) in the hyaluronate carboxymethyl cellulose group than in the controls and unchanged in the alginate gel group.

CONCLUSIONS

While reducing adhesion formation, ultrapure alginate gel does not interfere with the development of colonic anastomotic strength during the crucial early healing period.

Tacrolimus does not affect early wound healing in a rodent model of bowel anastomoses and abdominal wall closure

Background

Use of immunosuppressant drugs has been associated with complications in wound healing. The calcineurin inhibitor tacrolimus is thought to have a relatively low complication rate, but preclinical research has yielded contradictory data, prompting the current comprehensive study

Methods

Three groups of 33 male Wistar rats received a daily subcutaneous dose of 0,5, 2 or 5 mg/kg tacrolimus. A control group received saline. On day 0 a resection of 1 cm ileum and 1 cm colon was performed, and end-to-end anastomoses were constructed. Ten rats of each group were killed on day 3 and day 5 and the remaining animals on day 7. Both anastomoses and the wound in the abdominal wall were analyzed. Wound strength was the primary outcome parameter.

Results

Mean strength of the abdominal wall increased significantly over time in all groups (p<0.0001). Both the breaking strength and the bursting pressure of the ileum and colon anastomoses followed the same pattern. No differences were observed between control and experimental groups. In addition, no consistent differences were found between groups regarding wound hydroxyproline content and the activities of matrix metalloproteinase-2 and -9.

Conclusion

Tacrolimus does not affect early wound healing.

Diclofenac causes more leakage than naproxen in anastomoses in the small intestine of the rat

BACKGROUND

Non-steroid anti-inflammatory drugs such as the cyclooxygenase isoenzyme inhibitors diclofenac and naproxen are increasingly used for perioperative pain relief, while their potential effects on wound healing are scarcely investigated.

METHODS

In 104 male Wistar rats, an anastomosis was constructed in both colon and ileum. The rats were divided into groups who received diclofenac (4 mg kg(-1) day(-1)) or naproxen (10 mg kg(-1) day(-1)) daily from the day of surgery or from day 3 after surgery. Animals were killed on day 3 or 7 and analysed for signs of anastomotic dehiscence and wound strength of anastomoses and abdominal fascia.

RESULTS

Anastomotic leakage in the ileum (p < 0.0001) and mortality rates (p = 0.001) were significantly increased in the diclofenac group. On day 7, the anastomotic bursting pressure in the ileum remained below that of the controls in the diclofenac- and naproxen-treated rats. When administration of diclofenac was postponed to day 3 after surgery, anastomotic dehiscence was almost absent. The colonic anastomosis and abdominal wall always remained unaffected.

CONCLUSIONS

This study implies that immediate postoperative administration of diclofenac and, to a far lesser extent, naproxen can affect healing in the ileal anastomosis in the rat. This negative effect can be prevented by a short postoperative delay in administration. On steroid anti-inflammatory drugs such as the cyclooxygenase isoenzyme inhibitors diclofenac and naproxen are increasingly used for perioperative pain relief, while their potential effects on wound healing are scarcely investigated.

Prevention of postsurgical adhesions using an ultrapure alginate-based gel

Background

Postoperative adhesion formation is a common consequence of abdominal surgery, and constitutes a major source of morbidity and mortality. This study evaluated an ultrapure alginate-based antiadhesive barrier gel.

Methods

Experiments were performed in a rat model with caecal abrasion and peritoneal side wall excision. The primary endpoint was the incidence of adhesions at 14 days after surgery. In experiment 1 (24 rats), animals treated with alginate gel were compared with controls that had no antiadhesive barrier. In experiment 2 (42 rats), alginate gel was compared with sodium hyaluronate carboxymethyl cellulose (HA/CMC) membrane and with no antiadhesive barrier. To check for any remote action of the gel, in experiment 3 (45 rats) application of alginate gel to the ipsilateral versus contralateral side of injury was compared with no antiadhesive barrier.

Results

In experiment 1, ultrapure alginate gel reduced the incidence of adhesions from eight of 12 in control animals to one in 12 (P = 0·009). Tissue healing assessed by histology was similar in both groups. In experiment 2, ultrapure alginate gel and HA/CMC membrane showed similar antiadhesive effectiveness, reducing the incidence of adhesions from ten of 14 rats in the control group to three of 14 (P = 0·021) and two of 14 (P = 0·006) respectively. In experiment 3, ultrapure alginate gel reduced the incidence of adhesions at the site of direct application (1 of 15) compared with controls (13 of 15; P = 0·001), but not if applied remotely (9 of 15; P = 0·214).

Conclusion

Ultrapure alginate gel decreased the incidence of postoperative adhesion formation in this rat model.

Carprofen for perioperative analgesia causes early anastomotic leakage in the rat ileum

Background

There is increasing evidence that perioperative use of NSAIDs may compromise the integrity of intestinal anastomoses. This study aims to characterize the negative effects of carprofen on early anastomotic healing in the rat ileum.

Results

In 159 male Wistar rats an anastomosis was constructed in the ileum. In experiment 1 eighty-four rats were divided over control and experimental groups, which received daily buprenorphine or carprofen, respectively, as an analgesic and were killed on day 1, 2 or 3 after surgery. In experiment 2 three groups of 15 rats received carprofen either immediately after surgery or with a delay of 1 or 2 days. Animals were killed after 3 days of carprofen administration. In experiment 3 three groups of 10 rats received different doses (full, half or quarter) of carprofen from surgery.

In significant contrast to buprenorphine, which never did so, carprofen induced frequent signs of anastomotic leakage, which were already present at day 1. If first administration was delayed for 48 hours, the leakage rate was significantly reduced (from 80 to 20%; p = 0.0028). Throughout the study, the anastomotic bursting pressure was lowest in animals who displayed signs of anastomotic leakage. Loss of anastomotic integrity did not coincide with reduced levels of hydroxyproline or increased activity of matrix metalloproteinases.

Conclusions

Carprofen interferes with wound healing in the rat ileum at a very early stage. Although the mechanisms responsible remain to be fully elucidated, one should be aware of the potential of NSAIDs to interfere with the early phase of wound repair.

Perioperative pain relief by a COX-2 inhibitor affects ileal repair and provides a model for anastomotic leakage in the intestine

The authors examined the potential of the cyclooxygenase 2 (COX-2) inhibitor carprofen to reproducibly induce anastomotic leakage. In experiment 1, an anastomosis was constructed in both ileum and colon of 20 rats, and they were given carprofen (5 mg/kg subcutaneously every 24 hours) or buprenorphine (0.02 mg/kg subcutaneously every 12 hours). In another 20 rats an anastomosis was constructed in either ileum or colon, and all received carprofen (experiment 2). Animals were sacrificed after 3 days. In experiment 1, the ileal dehiscence rate was 60% in the carprofen group and 0% in the buprenorphine group (P = .0108). Colonic anastomoses in both groups remained patent. In experiment 2, the anastomotic leakage rate was 80% in ileum and 0% in colon. Thus, COX-2 inhibitors can severely interfere with intestinal healing, particularly in the ileum. Perioperative administration of carprofen yields a unique model for anastomotic leakage, which allows translational research on the effectiveness of perisuture line reinforcement.

The effect of fibrin glue on the early healing phase of intestinal anastomoses in the rat

PURPOSE

Protecting the anastomotic integrity using suture or staple line reinforcement remains an important goal for ongoing research. The present comprehensive study aims to establish the effects of fibrin glue on the early phase of anastomotic healing in the rat intestine.

METHODS

One hundred and eight young adult male Wistar rats underwent resection and anastomosis of both the ileum and colon. In half, fibrin glue was applied around the anastomoses. Parameters for repair included wound strength, both bursting pressure and breaking strength at days 1, 3, and 5 after operation; hydroxyproline content; and histology, the latter also after 7 days.

RESULTS

A transient colonic ileus was observed in the experimental group. Anastomotic breaking strength was always similar in both the control and fibrin glue groups. Anastomotic bursting pressures remained low at days 1 and 3, without any differences between the groups. In both groups, the bursting pressure increased sharply (p < 0.001) between days 3 and 5. At day 5, the bursting pressure in the fibrin glue group remained below than that in the controls, although only significantly (p = 0.0138) so in the ileum. At day 5, but not at day 7, the wounds in the fibrin glue group contained less collagen. Other aspects of microscopic wound architecture appeared to be the same.

CONCLUSIONS

There is no justification for using fibrin glue on patent anastomoses constructed under low-risk conditions. Its potential benefit under conditions where chances for anastomotic leakage are enhanced needs further investigation.

Everolimus-induced loss of wound strength can be prevented by a short postoperative delay in its administration

The use of mammalian target of rapamycin inhibitors coincides with an increased incidence of surgical complications. In previous experiments, serious negative effects of postoperative everolimus on anastomotic strength were found. This study aims to investigate if delayed drug administration can prevent loss of wound strength. Ten groups of Wistar rats each received daily oral doses of 1.0 or 2.0 mg/kg everolimus, starting the day of anastomotic construction in both ileum and colon, or 1, 2, 3, or 4 days later. The 11th group received saline. Seven days later, wound strength in anastomoses and in the abdominal wall and wound hydroxyproline levels were measured. Mean wound strength was significantly and dose-dependently reduced if everolimus was started on the day of operation. In ileum and colon, strength was not affected if drug administration was delayed until the third or second day, respectively. In abdominal fascia, this was the case only if everolimus was withheld until day 4. In general, changes in wound hydroxyproline content showed similarities to changes in wound strength. Thus, delaying administration of everolimus for 2-4 days after operation can prevent a serious loss of wound strength, both in the intestine and in the abdominal fascia.

Intraoperative versus early postoperative intraperitoneal chemotherapy after cytoreduction for colorectal peritoneal carcinomatosis: an experimental study

BACKGROUND

Perioperative intraperitoneal chemotherapy is used as an adjunct to cytoreductive surgery (CS) for peritoneal carcinomatosis (PC) in order to prolong survival. Worldwide, hyperthermic intraperitoneal chemotherapy (HIPEC), early postoperative intraperitoneal chemotherapy (EPIC), and combinations of the two are used. It remains unclear which regimen is most beneficial.

METHODS

The rat colon carcinoma cell line CC-531 was injected into the peritoneal cavity of 80 WAG/Rij rats to induce PC. Animals were randomized into four treatment groups (n = 20): CS only, CS followed by HIPEC (mitomycin 35 mg/m(2) at 41.5°C), CS followed by EPIC during 5 days (i.p. injection of mitomycin on day 1 and 5-fluorouracil on days 2-5), and CS followed by HIPEC plus EPIC. Primary outcome was survival.

RESULTS

In rats treated with CS only, median survival was 53 days (95% confidence interval (CI) 49-57 days). In rats treated with CS followed by HIPEC, survival was significantly (P = 0.001) increased (median survival 94 days, 95% CI 51-137 days). In the group treated with EPIC after CS, 12 out of 20 rats were still alive at the end of the experiment (P < 0.001 as compared with CS only). In the group receiving both treatments, 11 rats died of toxicity, and therefore this group was not included in the survival analysis.

CONCLUSIONS

Both EPIC and HIPEC were effective in prolonging survival. The beneficial effect of EPIC on survival seemed to be more pronounced than that of HIPEC. Further research is indicated to evaluate and compare the possible benefits and adverse effects associated with both treatments.

Intraoperative hyperthermic intraperitoneal chemotherapy after cytoreductive surgery for peritoneal carcinomatosis in an experimental model

BACKGROUND

The combination of cytoreductive surgery (CS) and hyperthermic intraperitoneal chemotherapy (HIPEC) is the treatment of choice for selected patients with peritoneal carcinomatosis (PC) of colorectal origin. However, it remains to be proven whether the addition of HIPEC to CS is essential for the reported survival benefit.

METHODS

Sixty WAG/Rij rats were inoculated intraperitoneally with the rat colonic carcinoma cell line CC-531. Animals were randomized into three treatment groups: CS alone, CS followed by HIPEC (mitomycin 15 mg/m(2) ) and CS followed by HIPEC (mitomycin 35 mg/m(2) ). Survival was the primary outcome parameter.

RESULTS

The median survival of rats treated with CS alone was 43 days. Rats receiving HIPEC 15 mg/m(2) and HIPEC 35 mg/m(2) both had a significantly longer median survival of 75 days (P = 0·003) and 97 days (P < 0·001) respectively. Rats receiving HIPEC showed a significantly lower tumour load at autopsy compared with rats treated with CS alone.

CONCLUSION

A combination of CS and HIPEC results in longer survival than CS alone in rats with PC of colorectal origin.

Reduction of oxygenation and blood flow in pedicled bowel segments in the rat and its consequences for anastomotic healing

PURPOSE

Experimental studies indicate that perioperative hypoperfusion impairs anastomotic healing. In bowel surgery, the part of bowel that will be anastomosed is often pedicled, leaving the blood supply dependent on the marginal artery only. Little is known about the blood supply in such a segment, and whether anastomotic strength is affected when flow would be reduced. This study describes oxygenation and blood flow in pedicled bowel segments in the rat and investigates whether early anastomotic strength changes with variations in blood flow.

METHODS

In rats, pedicled segments were created in ileum and colon by successive ligation of the feeding arteries. Oxygenation and blood flow were measured in the distal part of this segment by use of near-infrared spectroscopy with indocyanine green as an intravascular tracer. In a second experiment, a short pedicled colonic segment was created and, after flow measurements, an anastomosis was constructed. Wound strength and hydroxyproline content were analyzed 2 and 5 days after operation.

RESULTS

After creation of a pedicled segment, the concentration of oxygenated hemoglobin decreased significantly. Blood flow also significantly decreased to even less than 10% of baseline. A very large variation was observed between animals, in particular, after ligation of the first arteries. The strength of colonic anastomoses was not significantly correlated with the blood flow in the pedicled segment before anastomotic construction.

CONCLUSIONS

The creation of a pedicled bowel segment greatly reduces tissue oxygenation and blood flow to its distal part. Such impaired perioperative flow does not significantly affect early wound strength after anastomotic construction.

Early anastomotic repair in the rat intestine is affected by transient preoperative mesenteric ischemia

INTRODUCTION

During bowel surgery, perioperative blood loss and hypotension can lead to transient intestinal ischemia. Recent preclinical studies reveal that the strength of intestinal anastomoses can be compromised after reperfusion. So far, this phenomenon has not been investigated in the very first days of healing when wound strength is lowest.

MATERIAL AND METHOD

Ischemia was induced in rats by clamping both the superior mesenteric artery and ileal branches for 30 min. Immediately after declamping, anastomoses were constructed in both terminal ileum and descending colon. The same was done in control groups after sham-ischemia. Anastomotic bursting pressure and breaking strength were measured immediately after operation (day 0) and after 1, 2, or 3 days. Anastomotic hydroxyproline content, gelatinase activity, and histology were analyzed.

RESULTS AND DISCUSSION

In ileal anastomoses, at day 1, both the breaking strength and bursting pressure were significantly (p < 0.05) lower in the ischemic group, while at day 2, this was the case for the bursting pressure only. In the colon, the bursting pressure in the ischemic group was lower at day 1. Anastomotic hydroxyproline content remained unchanged. Increased presence of the various gelatinase activities was found in ileum only at day 0 and in colon at days 1 and 2. Histological mucosal damage was found in ischemia-reperfusion groups.

CONCLUSION

Transient mesenteric ischemia can negatively affect anastomotic strength during the very first days of healing, even if the tissue used for anastomotic construction looks vital.

Intercellular adhesion molecule-1 and gelatinase expression in human peritoneal mesothelial cells during propagation in culture

Mesothelial cells are involved in a variety of biological processes, which include the formation of peritoneal adhesions. The cultures of human peritoneal mesothelial cells comprise an important tool to investigate the behavior and functions of mesothelial cells. Very little is known about the differences among mesothelial cells isolated from different sources and about the changes in specific functions as caused by cell propagation in vitro or that result from storage of cells at low temperatures. This study aims to characterize 2 particular cellular activities relevant for tissue repair, which include the expression of intercellular adhesion molecule-1 (ICAM-1) and the gelatinase activity; in addition, this study will assess the effect of hyaluronan, which is an antiadhesive agent, on these cellular activities. Viable cell lines were established from both omentum and peritoneal lavage fluid from 7 patients. Both ICAM-1 expression, which was measured by enzyme-linked immunosorbent assay (ELISA), and matrix metalloproteinase (MMP) bioactivity, which was measured by zymography, were measured in the 2nd and 4th passage; the latter also was measured after freezing and storing of cells in liquid nitrogen. The effects of interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), phorbol myristate acetate (PMA), and hyaluronan were analyzed. ICAM-1 was constitutively expressed and stimulated by IL-1beta, TNF-alpha, and PMA. All cell lines produced both MMP-2 and MMP-9. Only the latter activity was affected by TNF-alpha and, especially so, PMA. Differences were found between the 2nd and 4th passage, as well as between cells of different lineage, mostly so if the relative stimulation by the various agents was compared. The addition of sodium hyaluronate either to control cultures or to cultures together with any of the 3 stimuli examined did not significantly change either ICAM-1 expression or gelatinase activity. The freezing and storage of cells did not affect their functions. Both the human omentum and peritoneal lavage fluid are good sources to establish mesothelial cell lines, which can be propagated also after freezing without qualitative changes in their ability to express ICAM-1 and produce the gelatinases. For omental cells, a differential effect of stimulation occurs depending on whether the cells have been passaged 2 or 4 times. The presence of hyaluronan did not affect the expression of ICAM-1 or the gelatinases.

Everolimus interferes with healing of experimental intestinal anastomoses

BACKGROUND

Although clinical data suggest its existence, little is known about the effect of rapamycin derivatives on wound repair. This study aims to delineate the influence of the mammalian target of rapamycin inhibitor everolimus on wound healing in the rat intestine.

METHODS

Four groups of 26 male Wistar rats received everolimus in daily oral dosages of 0 (controls), 0.5 (group E-0.5), 1.0 (group E-1), and 3.0 (group E-3) mg/kg every 24 hours, respectively, starting four hours before the operation until killing. After resection of 1-cm segments of colon and ileum, intestinal anastomoses were constructed. The animals were killed at days three or seven after operation. Wound healing was assessed by mechanical (bursting pressure, breaking strength), biochemical (collagen content, gelatinase activity), and histologic parameters.

RESULTS

No differences between groups were recorded for any of the parameters on day three. On day seven, a dose-dependent reduction in breaking strength (P<0.05) was measured. The largest effects were found in group E-3 in which the breaking strength was reduced by 56% and 73% in colonic and ileal anastomoses, respectively. A similar pattern was observed with the bursting pressure. Loss of strength was accompanied by a reduction in hydroxyproline content and by a lessened collagen deposition in the wound area but not by an increased gelatinase activity. No further histologic abnormalities were found.

CONCLUSION

Everolimus causes a massive reduction in anastomotic strength such as normally observed in the proliferative phase of repair. The data suggest this to be caused by an impaired deposition of collagen in the anastomotic area.

Circulating gelatinases and tissue inhibitor of metalloproteinase-1 in colorectal cancer metastatic liver disease

AIMS

The degradation of the extracellular matrix is intrinsic to the invasion and progression of cancer. Matrix metalloproteinase (MMP)-2 and -9 and their natural inhibitors are involved in this process. The study aims to investigate if plasma MMP-2, -9 and tissue inhibitor of metalloproteinase-1 (TIMP-1) can be useful markers in the diagnosis and prognosis of colorectal cancer (CRC) metastatic liver disease.

METHODS

Fifty-seven patients undergoing liver metastasis operation were followed prospectively. ProMMP-2, -9 and TIMP-1 plasma levels were determined by zymography and ELISA, before and after the resection of liver metastases. Data were compared with those of healthy controls (n=51) and primary CRC patients (n=94). The diagnostic and prognostic potential was investigated with ROC-curves and Kaplan-Meier survival analysis.

RESULTS

Plasma proMMP-2 levels were lower (P<0.001), and TIMP-1 levels higher (P<0.001) in CRC metastatic liver disease than in healthy controls. If compared to those in primary CRC patients, no differences were found. In ROC-curves, the area under the curve was 0.48 and 0.61 for proMMP-2 and -9, respectively. Plasma proMMP-2, -9 and TIMP-1 levels were unsuitable to predict survival. In both diagnostic and prognostic examinations, CEA proved to be a better marker. In the postoperative follow-up, protracted low levels of proMMP-2 seemed related to disease recurrence.

CONCLUSION

The preoperative plasma proMMP-2, -9 and TIMP-1 levels have no potential value as diagnostic or prognostic markers in CRC liver metastatic disease.

Selective cyclo-oxygenase 2 inhibition affects ileal but not colonic anastomotic healing in the early postoperative period

BACKGROUND

Selective cyclo-oxygenase 2 (COX-2) inhibitors are increasingly prescribed in the perioperative period. Recent recognition of a possible role for COX-2 in wound healing has raised concerns about the safety of their use in surgical practice. Therefore, the influence of celecoxib, a selective COX-2 inhibitor, on early anastomotic healing was investigated.

METHODS

Celecoxib, in doses of 15, 50 or 200 mg per kg per day, was given daily from the day before operation onwards to male Wistar rats that received both ileal and colonic anastomoses. Anastomotic strength was assessed by measuring the breaking strength and bursting pressure on the third day after operation. A second group received a dose of 50 mg per kg per day and a colonic anastomosis only, and healing was assessed on the third and fifth day after surgery.

RESULTS

Expression of COX-2 protein was upregulated in the anastomotic area. Administration of celecoxib, at all doses tested, resulted in a significantly higher ileal dehiscence rate than in control rats (P = 0.002). In contrast, colonic anastomoses healed normally within the same animals. The latter was confirmed in rats with colonic anastomoses only.

CONCLUSION

In this model, administration of the COX-2 inhibitor celecoxib affected ileal but not colonic anastomotic healing in the early postoperative period.

Changes in gelatinase activity in the gastrointestinal tract after anastomotic construction in the ileum or colon

PURPOSE

The strength of the uninjured and anastomosed intestinal wall is determined by its submucosal connective tissue. Matrix degradation by matrix metalloproteinases may result in loss of strength. It is known that anastomotic construction leads to up-regulation of matrix metalloproteinase activity in the wound area, but no quantitative data are available as to the extent of this effect throughout the intestinal wall. This study was designed to quantitate changes in gelatinolytic activity in the intestine after anastomotic construction in the ileum or colon.

METHODS

An anastomosis was constructed in the distal ileum or distal colon of rats, and animals were killed after one or three days. Tissue samples (5 mm) were collected containing the suture line, its adjacent segments (2- x 5-mm in both directions) and at nine other, more distant, sites throughout the gastrointestinal tract. Similar samples were collected from nonoperated control rats. All samples were analyzed by quantitative gelatin zymography.

RESULTS

In control rats, the most prominent gelatinolytic activities were found at 80 kDa, thought to represent a nonspecific proteolytic activity, 60 kDa and 50 kDa, representing the proform and active form of matrix metalloproteinase-2, respectively. Activities were higher in the small bowel than in the large bowel. Anastomotic construction led to massive up-regulation of an activity at 105 kDa, and its dimer, believed to represent promatrix metalloproteinase-9. Matrix metalloproteinase-2 remained unaffected, whereas the activity of the 80 kDa protein was significantly (P < 0.05) reduced. Significantly increased matrix metalloproteinase-9 activity was found in the actual anastomotic segments and in the immediately adjacent tissue. Matrix metalloproteinase-9 activities in the anastomotic segments were highest at Day 1 in the ileum and at Day 3 in the colon. Anastomotic construction in the ileum or colon did not lead to any significant changes of any gelatinolytic activity at the more distant sites in the bowel wall.

CONCLUSIONS

Up-regulation of gelatinase activity after anastomotic construction in the intestine is caused by matrix metalloproteinase-9. Because the effect is local and not systemic, unwanted matrix degradation at distant sites seems unlikely.

No detrimental effects of repeated laparotomies on early healing of experimental intestinal anastomoses

BACKGROUND

Little is known about the impact of repeated laparotomies on intestinal anastomotic healing. While experimental data are completely lacking, the sparse data available from clinical studies report high anastomotic failure rates, suggesting a negative effect in this respect. Since the unequivocal determination of such an effect may have important consequences for choosing the optimal treatment strategy for patients suffering from intra-abdominal infection, an experimental study has been performed in an established rodent model.

METHODS

Intestinal anastomoses were constructed in healthy Wistar rats (ileal and colonic anastomoses) or 24 h after peritonitis was induced by caecal ligation and puncture (colonic anastomosis only). Rats were then scheduled to undergo no, one (after 24 h) or two relaparotomies (after 24 and 48 h). Anastomotic strength was assessed 3 and 5 days after anastomotic construction. On the third post-operative day anastomotic hydroxyproline levels, matrix metalloproteinase activity and myeloperoxidase activity were measured.

RESULTS

No negative impact of repeated laparotomies was measured on any of the parameters measured. Under non-infectious conditions even an improvement in breaking strength (+48%, p=0.017) but not bursting pressure was found after two relaparotomies, but only in the ileum on the third post-operative day.

CONCLUSIONS

In this experimental setting, early anastomotic healing is not adversely affected by repeated laparotomies.

Plasma gelatinase activity does not reflect disease activity after operation for colorectal cancer

OBJECTIVE

To investigate if plasma matrix metalloproteinase (MMP)-2 or -9 are better markers for disease activity than carcinoembryonic antigen (CEA) in the postoperative follow-up of colorectal cancer patients.

METHODS

A prospective study was performed including 61 patients operated for primary colorectal cancer. The follow-up was for at least 2 years and postoperative blood samples were obtained periodically with 3-month intervals. Plasma gelatinase activity was measured with quantitative gelatin zymography and serum CEA with a specific immunoassay.

RESULTS

Zymographic analysis of plasma samples revealed the presence of the proforms, but not the active forms, of both MMP-2 and -9. Prior to the detection of recurrent disease or metastasis in potentially curatively operated colorectal cancer patients, the changes in proMMP-2, -9 and CEA blood levels were determined. ProMMP-2 and -9 plasma levels changed little in this period and changes between patients with and without disease relapse were not statistically significant. In contrast, patients with disease relapse showed a significant increase (p = 0.002) in CEA in the two consecutive serum samples prior to the detection of recurrent disease or metastasis. Similarly, prior to death due to colorectal cancer, proMMP-2 and -9 plasma levels showed no significant change, whereas CEA levels increased considerably and significantly (p < 0.001) when compared to changes found in survivors.

CONCLUSION

Plasma proMMP-2 and -9 activities show no potential value as prognostic markers in the follow-up of colorectal cancer.

Plasma levels of matrix metalloproteinase-2 and tissue inhibitor of metalloproteinase-1 correlate with disease stage and survival in colorectal cancer patients

PURPOSE

The matrix metalloproteinases and their inhibitors are known to be involved in the process of tumor invasion and progression. Our objective was to investigate the potential diagnostic and prognostic value of plasma matrix metalloproteinase-2 and -9 and tissue inhibitor of metalloproteinase-1 in colorectal cancer.

METHODS

Gelatinase bioactivity and immunoreactivity of pro-matrix metalloproteinase-2 and -9, tissue inhibitor of metalloproteinase-1, and carcinoembryonic antigen were determined simultaneously in preoperative plasma and serum of colorectal cancer patients (n = 94) and in healthy controls (n = 51).

RESULTS

Plasma pro-matrix metalloproteinase-2 levels were lower in colorectal cancer patients (P < 0.0001) than in controls, and its gelatinolytic activity revealed an inverse correlation with adverse clinicopathologic parameters, such as lymph node involvement (P = 0.017), stage (0, I, II vs. III, IV; P = 0.012), and the carcinoembryonic antigen level (P = 0.016). Pro-matrix metalloproteinase-9 levels did not differ between patients and controls. Pro-matrix metalloproteinase-2 gelatinolytic activity showed potential value in colorectal cancer diagnosis, identifying patients with 70 percent sensitivity at 95 percent specificity. Pro-matrix metalloproteinase-9, tissue inhibitor of metalloproteinase-1, and carcinoembryonic antigen all showed lower sensitivities. Combining pro-matrix metalloproteinase-2 and tissue inhibitor of metalloproteinase-1 measurements increased the sensitivity significantly to 84 percent. With respect to prognosis, tissue inhibitor of metalloproteinase-1 showed value in predicting disease outcome in our patient group, whereas pro-matrix metalloproteinase-2 and -9 did not. The combination of tissue inhibitor of metalloproteinase-1 and carcinoembryonic antigen was better in predicting three-year survival than tissue inhibitor of metalloproteinase-1 alone, but it remains to be determined if the combination would be a better marker for survival than carcinoembryonic antigen alone.

CONCLUSIONS

Low pro-matrix metalloproteinase-2 levels and high tissue inhibitor of metalloproteinase-1 levels correlate with parameters of colorectal cancer disease. These correlations may be used in the search for new markers in colorectal cancer diagnosis and prognosis.

Increased expression of matrix metalloproteinases in the murine zymosan-induced multiple organ dysfunction syndrome

Matrix metalloproteinases (MMPs) have been implicated as mediators of tissue damage in several inflammatory diseases. Since the multiple organ dysfunction syndrome (MODS) is thought to result from systemic inflammation, overactivation of MMPs could contribute to the organ damage observed. The expression and activity of several MMPs were studied in a murine model for MODS. Sixty mice were given an aseptic intraperitoneal injection of lipopolysaccharide, followed, after 6 days, by zymosan. At days 2, 5, 8, 12, and 16 after the injection of zymosan, the liver, lungs, spleen, and kidneys were collected from groups of mice for either RNA extraction, gelatinase zymography and collagenase (MMP-1 and -13) assays (six mice per time point), or immunohistochemistry (three mice per time point). A group of nine mice did not receive zymosan and acted as controls. The expression of MMP-2 mRNA in zymosan-treated mice was strongly up-regulated in liver tissue only. For MMP-9, this was the case in all organs examined. Quantitative gelatin zymography demonstrated the near complete absence of any gelatinase activity in tissues from control mice. However, in the liver, lungs, and especially the spleen of zymosan-treated animals, significantly increased activity of proform and active MMP-2 and -9 was observed with time. Overall, MMP-1 and -13 activities were very low in all samples from the liver and lungs. In the spleen, however, high levels of MMP-1 and -13 were observed in zymosan-treated animals. Immunohistochemical staining for MMP-2 was detected in the liver and spleen, but not in lung and kidney tissue of zymosan-treated animals. Staining for MMP-9 could be detected in liver, lung, and spleen tissues of zymosan-treated mice. For both MMPs, staining appeared to be limited to phagocytes. In conclusion, the data suggest a role for MMPs, especially MMP-9, in the pathogenesis of MODS.

Circulating matrix metalloproteinase-9 is transiently elevated after colorectal surgery

BACKGROUND AND AIMS

Plasma levels of matrix metalloproteinases (MMPs) may yield important information in patients suffering from colorectal cancer but the effect of surgery, a common treatment modality in these patients, on circulating MMP levels is currently unknown. The aim of this study was to assess whether plasma MMP-2 and MMP-9 levels are affected by operative procedures.

MATERIALS AND METHODS

In total 128 patients undergoing elective surgery for colorectal cancer (n = 66), liver metastases from colorectal origin (n = 50) and arthrosis of the hip (n = 12) were included in the study. Gelatinase activity was measured, using quantitative gelatin zymography, in plasma obtained before operation and 1 week, 1 month and 3 months postoperatively.

RESULTS

One week after operation a significant increase in proMMP-9 activity was measured after colorectal surgery (260%, p = 0.0038), liver surgery (285%, p < 0.0001) and hip surgery (217%, p = 0.012) as compared with preoperative levels. After 1 month proMMP-9 activity had returned to preoperative levels. No effect on proMMP-2 activity was measured.

CONCLUSION

Operative procedures have a profound but transient effect on plasma MMP-9 activity. If used to assess disease status, postoperative plasma MMP levels should be interpreted with caution.

Matrix metalloproteinase 2 and 9 activity in patients with colorectal cancer liver metastasis

BACKGROUND

Matrix metalloproteinases (MMPs) have been reported to play an important role in tumour cell invasion and metastasis. The bioactivity of MMPs in liver metastasis from colorectal cancer was investigated and correlated with clinicopathological variables.

METHOD

Thirty-two patients underwent resection of colorectal cancer liver metastases. Latent and active forms of MMP were measured in tissue extracts, by means of quantitative gelatin zymography and a fluorometric activity assay.

RESULTS

Broad-spectrum MMP activity, and levels of both active and latent forms of MMP-2 and MMP-9, were higher in tissues containing metastatic tumour than in normal liver tissue. Median metastatic to normal tissue ratios were 15.0 and 17.6 for active and proMMP-2 respectively, and those for active and proMMP-9 were 6.2 and 2.9. The ratios of active to latent enzyme were higher in metastatic tissue than in normal tissue. Lowered MMP-2 activity was associated with large metastatic lesions and increased proMMP-9 levels with preoperative chemotherapy. Both MMP-2 and MMP-9 activity were linked unfavourably to early recurrent disease.

CONCLUSION

These data suggest a role for MMPs in colorectal cancer liver metastasis, but indicate different roles for individual MMPs.

Colonic anastomotic strength and matrix metalloproteinase activity in an experimental model of bacterial peritonitis

BACKGROUND

Clinical studies report conflicting results on the safety of primary intestinal anastomoses in the presence of peritonitis, and comprehensive experimental data are lacking. The present study investigated whether the strength of experimental colonic anastomoses is affected if surgery is performed in the presence of pre-existing bacterial peritonitis.

METHODS

Colonic anastomoses were constructed in Wistar rats 24 h after caecal ligation and puncture or a sham procedure. Anastomotic strength was assessed by measuring breaking strength and bursting pressure during the first 5 days after operation. Anastomotic hydroxyproline levels were measured and matrix metalloproteinase (MMP) activity was analysed by quantitative gelatin zymography.

RESULTS

Anastomotic strength was lowered in the presence of bacterial peritonitis but in a minor and transient way. The breaking strength was lower only immediately after construction of the anastomosis (- 15 per cent, P = 0.011) and the bursting pressure only on the third postoperative day (- 33 per cent, P = 0.038); no anastomotic dehiscence was observed. At 3 days after operation increased levels of MMP activity were observed but anastomotic hydroxyproline content was not affected by bacterial peritonitis.

CONCLUSION

The influence of bacterial peritonitis on the development of anastomotic strength is limited. This experimental finding lends support to recent clinical studies that have demonstrated the feasibility of constructing a primary anastomosis under these conditions.

Doxycycline improves wound strength after intestinal anastomosis in the rat

BACKGROUND

The strength of intestinal anastomoses is relatively low in the first days after operation, possibly as a result of localized degradation of the supporting matrix by enzymes from the matrix metalloproteinase (MMP) family. The aim of this study was to examine whether doxycycline, a drug known to inhibit MMP activity, could enhance anastomotic strength.

METHODS

Male Wistar rats received anastomoses in both ileum and colon. From the day before operation onwards, animals were treated daily with doxycycline (orally or subcutaneously) in a dose of 10 mg/day or with saline only. Rats were killed 1, 3, or 5 days after operation, and anastomotic bursting pressure and breaking strength were measured. At day 3, anastomotic hydroxyproline levels were measured, MMP (gelatinase) activity was analyzed by gelatin zymography, and anastomotic histology was examined.

RESULTS

Doxycycline enhanced wound strength, but only at day 3, when it was at its lowest. Subcutaneous administration of 10 mg/day increased median colonic and ileal breaking strength by 27% (P =.0019) and 104% (P =.0376), respectively. Colonic bursting pressure was increased by 93% (P =.0002). Wound histology was similar in experimental and control groups.

CONCLUSIONS

Administration of doxycycline enhances anastomotic strength and should be investigated further as a means to preserve anastomotic integrity.

The matrix metalloproteinase inhibitor BB-94 improves the strength of intestinal anastomoses in the rat

BACKGROUND AND AIMS

The strength of intestinal anastomoses is relatively low in the first days after operation, possibly as a result of localized degradation of the supporting matrix by enzymes from the matrix metalloproteinase (MMP) family. This study examined whether BB-94, a broad spectrum inhibitor of MMP activity, could enhance anastomotic strength.

MATERIALS AND METHODS

Male Wistar rats received anastomoses in both ileum and colon. From the day before operation onwards, animals were treated daily with BB-94 intraperitoneally at a dose of 30 mg/kg or with saline only. Rats were killed 1, 3, or 7 days after operation, and anastomotic bursting pressure and breaking strength were measured. On day 3 anastomotic hydroxyproline levels were measured, and MMP (gelatinase) activity was analyzed by gelatin zymography.

RESULTS

BB-94 strongly enhanced wound strength, but only on day 3, when it was at its lowest. Daily administration increased median colonic and ileal breaking strength by 27% and 108%, respectively; colonic and ileal bursting pressure were increased by 54% and 58%, respectively. MMP activities were significantly lowered in anastomotic extracts from the rats treated with BB-94.

CONCLUSION

Administration of BB-94 enhances anastomotic strength. Specific inhibition of MMP activity should be investigated further as a means to preserve anastomotic integrity.

Tissue levels of active matrix metalloproteinase-2 and -9 in colorectal cancer

The bioactivity of matrix metalloproteinases was studied in tissues from colorectal cancer patients by means of both quantitative gelatin zymography and a fluorometric activity assay. Next to paired samples of tumour tissue and distant normal mucosa (n=73), transitional tissue was analysed from a limited (n=33) number of patients. Broad-spectrum matrix metalloproteinase activity and both the active and latent forms of the gelatinases matrix metalloproteinase-2 and -9 were higher in tumour than in normal mucosa. The ratio's between active and latent forms of matrix metalloproteinase-2 and -9 were highest in tumour tissue and normal mucosa, respectively. Matrix metalloproteinase-2 levels, both active and latent forms, correlated inversely with stage of disease, the tumours without synchronous distant metastases containing significantly (P=0.005) more active matrix metalloproteinase-2 than the others. At much lower levels of activity, the same trend was observed in distant normal mucosa. The level of latent form of matrix metalloproteinase-9 in tumour depended on tumour location. Neither the active form of matrix metalloproteinase-9 nor broad-spectrum matrix metalloproteinase activity in tumour tissue did correlate with any of the clinicopathological parameters investigated. The results demonstrate explicit differences between the activity of matrix metalloproteinase-2 and -9, indicating different roles for both gelatinases in tumour progression. Such data are necessary in order to develop rational anti-cancer therapies based on inhibition of specific matrix metalloproteinases.

Intestinal anastomoses from diabetic rats contain supranormal levels of gelatinase activity

PURPOSE

Early postoperative strength in intestinal anastomoses is reduced in diabetic rats, whereas collagen deposition is essentially unchanged, suggesting that increased matrix degradation may be the cause of diminished wound strength. The aim of this study was to investigate whether (gelatin-degrading) matrix metalloproteinase activity is enhanced in intestinal anastomoses from diabetic rats.

METHODS

Sixty male young adult Wistar rats underwent resection and anastomosis of both ileum and colon. In half the animals diabetes was induced seven days before operation by streptozotocin injection (50 mg/kg intravenously). Gelatinase activities in extracts from uninjured intestine and anastomoses at one, three, or seven days after surgery were measured by quantitative gelatin zymography.

RESULTS

After surgery, profound changes were observed with time for gelatinase activities with molecular weights of 50 and 60 kDa, thought to represent matrix metalloproteinase-2, and of 66, 80, 105, 140, 220, and 260 kDa, thought to represent various forms of matrix metalloproteinase-9. In many cases, specific activities were significantly (P < 0.05) higher in the anastomotic extracts from diabetic rats. Total anastomotic activities present at Day 7 were strongly elevated for most matrix metalloproteinase forms in ileum and colon from diabetic animals.

CONCLUSION

Experimental diabetes leads to a sustained and elevated presence of gelatinase activity in intestinal anastomoses. Increased local matrix degradation may contribute significantly to impaired anastomotic strength in the intestine observed under this condition.