The Origin of Regenerating Mesothelium: A Historical Perspective

Bichat first described the mesothelium in 1827 but despite its early discovery, it has only been in recent years that its importance both in health and disease has been realised. One area still poorly understood is that of the mechanisms regulating mesothelial repair. Mesothelial cells are derived from the mesoderm but express many epithelial characteristics. However, mesothelium does not heal in the same way as other epithelial-like cells. Epithelium heals by centripetal migration, with cells at the edge of the wound proliferating and migrating into the injured area. Hertzler in 1919 noted that both large and small peritoneal injuries healed within the same time frame, concluding that the mesothelium could not heal solely by centripetal migration. The exact mechanisms involved in mesothelial regeneration following injury are controversial with a number of proposals suggested to explain the origin of the regenerating cells. This review will examine these proposals and give some insights into the likely mechanisms involved.

State of the Art on Autologous Mesothelial Transplant in Animals and Humans

Sixteen years ago rabbit and human mesothelial cells were successsfully cultured and autoimplanted. The aim of the study was merely to demostrate that mesothelial implant was possible and interesting not only in peritoneal dialysis, but also in the vaster field of medicine and surgery concerning all the mesothelial districts of the body.

The aim of this paper is to recollect the steps which have led to autolougous mesothelial transplantation and verify if the tecnique has been validated and adopted by others.

Review of the literature published in the last 15 years shows that intraperitoneal transplantation of mesothelial cells has been effective in reducing the formation of peritoneal adhesions, and in remodeling the area of mesothelial denudation. New studies on the mesothelial cell opened the way to costruction of transplantable tissue-engineered artificial peritoneum, to the utilization of mesothelial progenitor cells and to find simple metods to collect autologous mesothelial cells.

Finally mesothelial trasnsplantation may represent a new neovascular therapy in the prevention and treatment of ischemic coronaric heart disease.

The peritoneum as a natural scaffold for vascular regeneration

Objective

The peritoneum has the same developmental origin as blood vessels, is highly reactive and poorly thrombogenic. We hypothesize that parietal peritoneum can sustain development and regeneration of new vessels.

Methods and Results

The study comprised two experimental approaches. First, to test surgical feasibility and efficacy of the peritoneal vascular autograft, we set up an autologous transplantation procedure in pigs, where a tubularized parietal peritoneal graft was covered with a metal mesh and anastomosed end-to-end in the infrarenal aorta. Second, to dissect the contribution of graft vs host cells to the newly developed vessel wall, we performed human-to-rat peritoneal patch grafting in the abdominal aorta and examined the origin of endothelial and smooth muscle cells. In pig experiments, the graft remodeled to an apparently normal blood vessel, without thrombosis. Histology confirmed arterialization of the graft with complete endothelial coverage and neointimal hyperplasia in the absence of erosion, inflammation or thrombosis. In rats, immunostaining for human mitochondri revealed that endothelial cells and smooth muscle cells rarely were of human origin. Remodeling of the graft was mainly attributable to local cells with no clear evidence of c-kit+ endothelial progenitor cells or c-kit+ resident perivascular progenitor cells.

Conclusions

The parietal peritoneum can be feasibly used as a scaffold to sustain the regeneration of blood vessels, which appears to occur through the contribution of host-derived resident mature cells.

[Long-term efficacy of tubularized peritoneal free grafts as ureteral mucosal substitutes in dogs]

OBJECTIVE

To investigate the long-term efficacy of ureteral reconstruction with tubularized peritoneal free grafts for the treatment of avulsion of ureteral mucosa in animal models.

METHODS

The model of avulsion of ureteral mucosa was established in 12 adult dogs. Then they were divided into Group A (n = 6, length of avulsed mucosa at 4 cm) and Group B (n = 6, length of avulsed mucosa at 6 cm). And the tubularized peritoneal free grafts and ureteral stents were implanted into the injured ureters. The curative effect was observed by intravenous urethrogram (IVU) and histological examination at Week 24 post-operation.

RESULTS

Severe stenosis was observed by IVU in 1 dogs in Groups A and B respectively. In the remaining 10 dogs, IVU showed normal size and morphology of kidneys. There was no hydronephrosis. And no obvious stricture of ureteral part was observed for mucosa substitutes made of peritoneal free grafts. In all 10 dogs without stenosis of both groups, peritoneal membrane was replaced by integrated transitional epithelium. And there was no obvious stricture. Collagen fibers were arranged parallel to mucosal surface.

CONCLUSION

For avulsion of ureteral mucosa under 6 cm, reconstruction with tubularized peritoneal free grafts as mucosa substitutes is an effective method. And its long-term efficacy is satisfactory.

[Possibilities of rational choice and application of autotissues for hermetization of the suture connections in biliary surgery]

The results of experimental investigation of peculiarities of morphological transformation course in autotissues under the influence of bile were adduced. There was proposed a choice of peritoneum as an optimal plastic material in conditions of possible deficiency of local tissues during biliary surgery performance.

[Vascular graft of aponeurosis with peritoneum in dogs]

BACKGROUND

Vascular autografts are commonly used to repair damage to blood vessels; however, they can be used only with small-caliber vessels. Although synthetic vascular grafts are good options, there may be a high likelihood of thrombus formation.

METHODS

An experimental animal model was used in order to evaluate feasibility and viability of a vascular autograft. Under inhalatory anesthesia, seven mongrel dogs were operated on. A 4-cm vascular autograft was created with the posterior rectus aponeurosis with subjacent peritoneum, leaving the second one as the internal sheath. A 2-cm-long portion of the abdominal aorta was removed and the vascular autograft was inserted by end-end surgical anastomosis. Animals were observed for 7 weeks, evaluating clinical data of vascular insufficiency (intensity of pulse, temperature and trophic changes of the legs). At the end of the experiment, aortography under fluoroscopic visualization was performed. Dogs were sacrificed and autograft removed in order to evaluate permeability.

RESULTS

All dogs survived until the end of the procedure. Vascular autograft was easy to create. During surgery, no evidence of bleeding of the anastomosis or the graft suture was noted. At the end of the procedure, no clinical signs of vascular insufficiency were noted; radiographic evaluation of the autograft showed no dye leakage at any level. Autografts were removed and no signs of thrombus formation were noticed.

CONCLUSIONS

Feasibility of the vascular autograft was demonstrated with good permeability and no thrombogenicity.

[Laparoscopically assisted neovaginaplasty using peritoneum as vaginal mucous substitute]

OBJECTIVE

To practice a more atraumatic, physiological and aesthetically valued approach of construction for neovagina.

METHODS

Laparoscopically using peritoneum as neovagina lining.

RESULTS

From March 2005 to September 2006, this technique was adopted to treat 10 patients whose diagnosis was congenital absence of vagina. The ages of the patients were from 19 to 32. The operation lasted average 2.34 hours. And hospitalization was about 20.5 days. Follow-up ranged from 3 - 12 months. No complication occurred. All of the patients was satisfied with their sexual life.

CONCLUSIONS

Laparoscopically assisted neovaginaplasty, in which peritoneum was substituted for vaginal mucous membrane, was a kind of ideal approach of vaginal creation.

Biological coating for arterial stents: the next evolutionary change in stents

PURPOSE

To describe the in vivo results of a promising new stent-graft lined with peritoneum.

METHODS

Eighteen dogs underwent balloon angioplasty injury to the bilateral iliac arteries followed by placement of either an 8-mm x 5-cm glutaraldehyde-fixed bovine peritoneum- lined balloon-expandable stent (PLS) or a similarly sized, commercially prepared, polyester-lined self-expanding stent (DLS) as a control. Animals were sacrificed at 1 and 6 months. Biplanar arteriography and intravascular ultrasound were done at the time of sacrifice, and the vessels were harvested after perfusion fixation for histology/morphometry. Immunofluorescence with CD34 and factor VIII staining was used to evaluate endothelialization, while alpha-actin was used to quantify smooth muscle cell (SMC) deposition.

RESULTS

At 1 month, all vessels were patent in both groups. At 6 months, 8 of 9 vessels were open in the PLS group versus 6 of 9 in the control DLS group. Vessel lumen diameter at 1 month was significantly greater in the PLS vessels compared to the DLS group at 1 cm above the stent (35.9 +/- 4.4 versus 29.4 +/- 4.7 mm2; p = 0.02) and 1 cm below the stent (37.2 +/- 7.1 versus 25.2 +/- 3.2 mm2; p = 0.005); these results persisted to 6 months. Histological morphometry demonstrated progression of neointimal hyperplasia in the DLS stent between 30 and 180 days (8.3 +/- 1.79 versus 14.9 +/- 6.6 mm2; p = 0.03), whereas the peritoneum-lined stent had no change during the same time period (4.62 +/- 0.98 versus 4.72 +/- 0.97 mm2; p = 0.85). The same patterns were true for the intima:media ratio. Immunohistochemistry demonstrated complete endothelialization at 6 months in both DLS and PLS. However, SMC staining with alpha-actin demonstrated more smooth muscle actin-positive cells in the DLS compared to the PLS (327 +/- 87 versus 262 +/- 73 counts/5 high-powered fields; p = 0.04).

CONCLUSION

Peritoneum-lined stents offer a novel method to improve patency of lower extremity arterial stents.

The role of bovine preserved peritoneum in rats ventral hernia: a histological evaluation

PURPOSE

To assess the role of preserved bovine parietal peritoneum as a material for hernia repair in a rat ventral hernia model.

METHODS

An abdominal wall defect (15mm x 25mm) was created in Wistar male rats (n=40). Control animals (n=20) had the polypropylene (PP) mesh sutured into the defect, whereas bovine preserved peritoneum (BPP) was used in experimental group (n=20). After 7 and 28 days, the abdominal wall was taken off and histological studies of the amount of collagen by Sirius Red stain and morphometric evaluation consisted in quantitative analysis of the collagen by using specific software (Imagelab). The Mann-Whitney, Kruskal-Wallis and ANOVA tests were applied for statistical analysis (pd"0.05).

RESULTS

Histological examination revealed no difference between the BPP and PP groups (p = 0.55 NS).

CONCLUSION

BPP is suitable for the closure of ventral hernias in rat model as shown by its morphological properties.

[Reconstruction of the tongue with rectus abdominis musculoperitoneal flap]

OBJECTIVE

To investigate the outcome of surgical reconstruction of the tongue after hemiglossectomy with reinnervated rectus abdominis musculoperitoneal flaps in the treatment of tongue cancer.

METHODS

Five patients underwent immediate reconstruction of the tongue and oral floor defects with rectus abdominis musculoperitoneal flaps after resection of squamous cell carcinoma of tongue. The rectus abdominis musculoperitoneal flap consists of the rectus muscle, posterior rectus sheath, peritoneum, the 10 th, 11th, 12th intercostal nerves and the vascular pedicle that includes the deep inferior epigastric artery and veins. During the operation a reinnervated rectus abdominis musculoperitoneal free flap, in which the intercostal nerves were anastomosed to the descending branch of hypoglossal nerve, was grafted to remaining tongue stump.

RESULTS

All patients recovered uneventfully from surgery, with no immediate postoperative complications. All transplanted flaps survived. The peritoneum was replaced by squamous epithelium 8 weeks after surgery. The average follow-up period was 10 months. During the follow-up period the contour of the reconstructed tongues was satisfactory. The patients demonstrated good functional mobility of the reconstructed and remaining tongue. The swallowing and speech function was nearly at normal levels and the patients could ingest a solid or semisolid diet.

CONCLUSIONS

Reconstruction of the tongue with rectus abdominis musculoperitoneal flaps after hemiglossectomy is a suitable, cosmetically acceptable method. Long-term follow-up is needed for reaching some final conclusions.

[Comparative experimental study of left colonic anastomoses in intestinal obstruction; the value of anastomoses protection with free peritoneal graft]

The paper describes the concept of peritoneal graft used to reinforce the colo-colic anastomoses made in emergency conditions of left colic obstruction, experimentally induced by surgical ligature, on Wistar rats. The comparative study was done on 24 rats, divided in 3 groups: group A with colic anastomoses protected with peritoneal graft, group B with one-layer colic anastomoses and group C with two-layer colic anastomoses. After 8 days, 7 rats survived in group A, 2 rats in group B and 3 rats in group C. All surviving rats in groups B and C presented anastomotic leak with local peritonitis, while in group A the anastomosis were healed. For group A, bursting strength of the anastomosis was measured and the mean value found was 63.64 cmH2O. It was proved the importance of protecting the colic anastomosis with supplementary layers, which increase the mechanical resistance and also prevents minor spillage of the colic content during the first postoperative days.

Successful treatment of cervical aplasia using a peritoneal graft

OBJECTIVE

To evaluate the efficacy of a peritoneal graft for the treatment of cervical aplasia.

METHOD

Four patients with cervical aplasia who had a functioning endometrium and hematometra were recruited for this clinical trial. Through an abdominoperineal approach a plastic stent was inserted between the endometrial cavity and the upper part of the vagina; then, a graft of peritoneum was applied over the stent. In the absence of a vagina, grafts of skin or amniotic membrane were also used. The plastic stent was removed after 1 month in 2 patients and after 1 week in the 2 other patients.

RESULT

After more than 1 year of observation the 4 patients had regular menstrual cycles with normal menstruation. Sonographic examinations also showed empty uterine cavities.

CONCLUSION

Traditional gynecology textbooks recommend hysterectomy in cases of cervical aplasia. This report presents a new technique with 2 variations using a peritoneal graft. Although both variations were successful in the treatment of cervical aplasia in 4 women, more trials are needed to determine which one should be developed.

Free peritoneal graft for repair of severe seromuscular defect of bowel: from experiment to clinical practice

BACKGROUND

Severe seromuscular tear of the bowel with impending perforation following enterolysis or trauma is not uncommon in gastrointestinal surgery. It is sometimes complicated with enterocutaneous fistula, intra-abdominal abscess or free perforation, especially of the ileus. In addition, direct serosal repair is often impossible, or complicated by lumen compromise. Serosal patch repair also reportedly is also associated with complications such as dislodgement of the sutured bowel loop, fistula formation, adhesion ileus, or volvulus. Free peritoneal graft (FPG), as in split-thickness skin graft (STSG), can be taken by underlying healthy tissue within 24 to 48 h and used for repair of such defect.

PATIENTS AND METHODS

In this study, FPG was used as an alternative to serosal patch repair or resection to cover severe defects of the colon, rectum, duodenum, or small bowel in 30 consecutive patients. All defects were over 8 x 4 cm in size and involved 30 to 80% of the circumference of the bowel wall. Each defect was deep enough to expose the thin mucosal layer, with the intestinal content visible through it. These defects could have been successfully treated by resection or repair using a serosal or mucosal patch instead of FPG. After making sure that the mucosa associated with the defect was alive and not perforated, a patch of intact peritoneum with pre-peritoneal tissue from the lateral abdominal wall (slightly smaller than the defect) was superimposed, with the edges simply sewn to the margin of the defect.

RESULTS

All patients recovered uneventfully, with no untoward effects determined, even after long-term follow-up.

CONCLUSION

We believe that FPG provides a feasible, simple, effective, economic, and safe alternative for repair of severe seromuscular defects; potentially making it widely applicable in clinical practice.

In vivo and mechanical properties of peritoneum/fascia as a novel arterial substitute

OBJECTIVE

This study evaluates the efficacy of bovine peritoneum/fascia as an arterial substitute.

METHODS AND OUTCOME MEASURES

Twelve dogs underwent bilateral femoral artery patch angioplasty with a glutaraldehyde-fixed bovine peritoneal/fascial patch (PFA patch) on one side and polyester patch on the contralateral side. Arteriograms were performed just before vessel harvest at 1 and 6 months, and vessels were evaluated for aneurysms and inflammation. Histologic analysis included intima area, media thickness, and lumen area. Immunofluorescence for CD 34 and Factor VIII was done to evaluate endothelialization and alpha-actin for smooth muscle cell growth. Mechanical strength testing was evaluated in separate PFA patches and compared independently to a commercially available bovine pericardial patch and polyester patch.

RESULTS

All vessels examined at both 1 and 6 months were patent with no arteriographic evidence of stenosis. There was no evidence of aneurysm formation in any vessel and no difference between groups in inflammatory reaction. One polyester patch at 1 month developed an infection. Microscopic evaluation of experimental vessels revealed no difference between groups in intima area at 1 month (2.1 +/- 1.2 vs 2.2 +/- 1.2 mm 2 ; P = .5) and at 6 months (1.81 +/- 1.2 vs 1.9 +/- 1.2 mm 2 ; P = .5). There was no difference in media thickness, but the PFA patch group had a greater lumen area at 1 month (8.8 +/- 2.9 vs 9.8 +/- 3.0 mm 2 ; P = .02) and 6 months (10.5 +/- 4.2 vs 11.7 +/- 5.6 mm 2 ; P = .02). Immunofluorescence for CD34 and Factor VIII demonstrated complete re-endothelialization of all patches. The polyester patch had a chronic inflammatory response, but not the PFA patch. Mechanical strength testing demonstrated that compared to pericardium, the PFA patch had superior ( P < .05) failure tension, stiffness, and suture pull-out strength, whereas extensibility, fatigue tension, relax slope, and creep tests were not different. Polyester demonstrated superior suture pull-out, stiffness, relax slope, and failure strain ( P < .05), but it was not different in failure tension and extensibility than the PFA patch. However, the PFA patch had significantly less creep (0.25 +/- 0.25 vs 4.92 +/- 0.84; P < .01).

CONCLUSIONS

The PFA patch has similar clot-resistant properties to polyester and is superior to the pericardial patch in mechanical strength. It is a promising endothelial alternative for not only arterial patches but other vascular products.

CLINICAL RELEVANCE

The search for an artificial, thromboresistant, and intimal hyperplasia resistant interface between blood and native blood vessels still continues. This study demonstrates the feasibility and proof of concept of the peritoneum's clot-resistant properties. When adding the underlying fascia, it serves as an ideal arterial patch. Other studies are underway evaluating its feasibility as a bypass graft and a "drug coated"-like stent lining.

[Experimental use of the peritoneal graft as a vascular prosthesis]

INTRODUCTION

The parietal peritoneum appears to be a suitable material for the vascular system reconstructions.

AIM

The aim was to assess and compare thrombogenicity and ability for endothelization of the mesothelial and submesothelial side of the parietal peritoneum in the canine venous system.

MATERIAL AND METHODOLOGY

EXPERIMENTAL ANIMALS

canis familiaris (n = 13), half-breeds of both sexes, aged between 1 and 2 years, weighting 15-25kgs, underwent authological transplantations of the peritoneal grafts with the mesothelial side in the lumen- the group M (n = 5) and with the submesothelial side in the lumen the group S (n = 5). In the control group K (n = 3) a part of the venous wall was used as a graft and was affixed back to its original place. The bioptic samples collected on the 10th, 20th, 30th and 40th postoperative day (POD) were stained using the HE staining, NADPH-d and imunohistochemically on the intermedial filaments. The endothelization rate of the peritoneal graft was measured using morphometry and the trombogenicity was assessed peroperatively.

RESULTS

In none of the trial groups a presence of thrombi was detected peroperatively. In the first trial group (group M), the onset of the peritoneal graft epithelization (reaching 20%) was recorded on the 10th POD. The endothelization process was completed on the 30th POD in this trial group. In the second trial group (group S), the peritoneal graft epithelization reaching 10% was recorded on the 10th POD. The process was completed on the 40th POD. In the third trial group K, no endothelial changes were recorded during the experiment.

CONCLUSION

Both sides of the peritoneum do not show signs of thrombogenicity and possess ability for endothelization.

[Peritoneal-fascia-muscle autologous graft in the inguinal canal of rats]

PURPOSE

To study the fragment of the autologous tissue, built by a peritoneum-fascia-muscle, implanted on the level of the wall of inguinal canal and the spermatic cord of rats aiming to verify the histological behavior of the survive and the tissue incorporation.

METHODS

Thirty-six rats were distributed into four groups. The rats of the group A, B, C and D were submitted to the median laparotomy to obtain the species to be implanted. On the group A, was implanted a tissue compounded by peritoneum and transversal fascia on the wall of the inguinal canal. On the B, the tissue implanted was added a part of rectum muscle of the abdomen and implanted on the wall of the inguinal canal. On the C, the tissue grafted was similar to the groupA, now grafted into the spermatic cord. On the D, the tissue was similar to the group B, now grafted into the spermatic cord.

RESULTS

After 21 days of implant, these tissues presented the following histological alteration: the group A and C, fibroadipous tissue with dilated vessel, Focus of fibrosis' and limphoplasmocitary infiltrated and the groups B and D, fibroadipous tissue with dilated vessels, skeletal muscle and focus of fibrosis. The fibrosis displayed on the groups B and D was more intensive. On the group B, we almost always find the skeletal muscle, while on the group D this tissue was presented in six animals, almost replaced by fibrosis in two and not present in one.

CONCLUSION

All the implanted grafts displayed survive and local incorporation, what could be useful on the correction of defects on the inguinal canal, on situations when the autologous tissue was indicated.

Repair of duodenal fistula with rectus abdominis musculo-peritoneal (RAMP) flap

INTRODUCTION

Large duodenal defects/fistulae are difficult to repair, due to complex duodenal anatomy. Musculo-epithelial flaps are conventionally used for reconstruction of large soft tissue defects. We report the clinical use of rectus abdominis musculo-peritoneal (RAMP) flap for repair of duodenal fistulae.

METHODS

Eight patients with duodenal fistulae underwent repair using right RAMP flap, based on the position of the superior epigastric artery. Feeding jejunostomy was done routinely to start early enteral feeding.

RESULTS

Duodenal fistulae healed within 3-5 days in all the cases except one, in whom bile continued to leak for 30 days. One patient died within 12 hours of second surgery. Superficial wound infection was a common (n=3) cause of morbidity.

CONCLUSION

RAMP flap for closure of duodenal defect is a simple, technically easy and dependable procedure, which can be performed quickly in critically ill patients. It can be used for repair of large duodenal defects with friable edges when omentum is not available or when other conventional methods are impractical.

Reconstruction of the Vena Cava with the Peritoneum: The Effect of Temporary Distal Arteriovenous Fistula on Patency (An Experimental Study)

OBJECTIVE

To determine the effect of increasing inferior vena cava blood flow by means of distal arteriovenous fistula on the patency of a peritoneal tube graft.

MATERIALS AND METHODS

In 16 mongrel dogs, a 3-4 cm long circular defect was created at the infrarenal inferior vena cava. The defect was interposed with peritoneal tube graft. A temporary distal femoro-femoral arteriovenous fistula was also constructed in 8 dogs just after the caval interposition. Graft patency was evaluated by Doppler ultrasonography and angiography. Histological evaluation was also performed.

RESULTS

Seven dogs in each group survived. All control grafts occluded within the first week, compared to no occlusions in fistula group (Fisher's exact test, p<0.005). However one 'fistula' dog with a still patent graft was sacrificed on the 18th day due to ultrasonographically occluded arteriovenous fistula.

CONCLUSION

In dogs, the peritoneum may be used as graft material for reconstruction of the inferior vena cava, provided a distal arteriovenous fistula is constructed.

Use of fascia-peritoneum patch as a pledget for an infected aortic stump

Treatment of aortic prosthetic graft infections remains a challenge. One frequently encountered technical difficulty when removing an infected prosthetic aortic graft is how to close a short, friable remnant aortic stump. We present three case reports in which we used a layer of posterior rectus fascia-peritoneum to bolster oversewing a short infected aortic stump after removal of an infected aortic graft. All three patients underwent staged extra-anatomic axillary-to-femoral artery bypass procedures, with subsequent removal of the infected aortic graft as a second operation. Two of the three procedures were semi-elective, and one was done urgently because of a recurrent aortoenteric fistula. All three patients had less than 1 cm of remaining aortic neck below the renal arteries for closure. In each instance a segment of autogenous posterior rectus fascia-peritoneum was harvested and used as a circumferential pledget to bolster the anastomosis. No patient had stump blowout, and in no case was there computed tomography evidence of aneurysmal enlargement of the stump with follow-up of 12 and 24 months in two of the three survivors. Use of autogenous fascia-peritoneum is a durable and effective method to assist stump closure and prevent stump blowout after removal of infected aortic grafts.

Omentum pediculed musculo-peritoneal flap (OPMP) for growing intestinal neomucosa in a rat model

BACKGROUND/PURPOSE

To construct a musculo-peritoneal flap adequately vascularised through attached omentum and to evaluate whether this flap is functional for growing new intestinal mucosa.

METHODS

24 rats underwent two surgical procedures. 1) A musculo-peritoneal flap was prepared, omentum was fixed onto the muscular side and a silicon graft was placed on the peritoneal side. 2) After one month the so constructed OPMP flap was mobilised and attached to the jejunum. Animals were harvested at 2, 4 and 8 months for macroscopic and microscopic evaluation.

RESULTS

One rat died at 7 months due to intestinal volvulus. In the remainder the circumference of the patched intestine significantly increased compared to that of normal intestine (p<0.001). The flaps were markedly contracted in the 4 month rats (p<0.01). All flaps were completely covered by neomucosa except in the 2 month rats. Crypt depth and crypt density of the neomucosa was significantly lower in 2 month rats compared to other groups (p<0.05). Similarly neomucosal villous height was markedly low in the 2 month rats (p<0.01).

CONCLUSIONS

To date, we have found no reports of small bowel patching using this technique. In this context, use of OPMP flap is likely to be useful for increasing intestinal surface area.

Middle hepatic vein reconstruction using a peritoneal patch: report of a case

A 67-year-old male complaining of constipation with a change in stool caliber for several months visited our hospital in June 1999. A positive test for occult blood in the feces led to the disclosure of a type II carcinoma of the sigmoid colon with multiple liver metastases. A lymph node dissection with a sigmoidectomy disclosed no metastases histologically, so a left hepatectomy and enucleations of the metastases were performed. In addition, the invaded middle hepatic vein (MHV) was resected and repaired using a peritoneal patch. The patient's postoperative course was uneventful until July 2000, when computed tomography of the liver showed a single nodule measuring 3 cm in diameter in segment 6. The metastasis was excised in August. Since then, the patient has shown normal tumor marker values. The MHV has remained patent for 24 months after its reconstruction. A resection of the liver metastases including venous reconstruction is beneficial for patients since it results in a longer survival and allows for venous drainage of the residual liver. The peritoneum is also accessible, enabling the fitting of a patch graft for hepatic vein repair.