Macrophage Phenotype Is Associated With the Regenerative Response in Experimental Replacement of the Porcine Esophagus

A porcine model for bridging circumferential defects in the intrathoracic esophagus has been developed in order to improve the treatment of children born with long‐gap esophageal atresia. The aim of this study was to identify factors beneficial for tissue regeneration in the bridging area in this model and to describe the histological progression 20 days after replacement with a silicone‐stented Biodesign mesh. Resection of 3 cm of intrathoracic esophagus and replacement with a bridging graft was performed in six newly weaned piglets. They were fed through a gastrostomy for 10 days, and then had probe formula orally for another 10 days prior to sacrifice. Two out of six piglets had stent loss prior to sacrifice. In the four piglets with the stent in place, a tissue tube, with visible muscle in the wall, was seen at sacrifice. Histology showed that the wall of the healing area was well organized with layers of inflammatory cells, in‐growing vessels, and smooth muscle cells. CD163+ macrophages was seen toward the esophageal lumen. In the animals where the stent was lost, the bridging area was narrow, and histology showed a less organized structure in the bridging area without the presence of CD163+ macrophages. This study indicates that regenerative healing was seen in the porcine esophagus 20 days after replacement of a part of the intrathoracic esophagus with a silicone‐stented Biodesign mesh, if the bridging graft is retained. If the graft is lost, the inflammatory pattern changes with invasion of proinflammatory, M1 macrophages in the entire wall, which seems to redirect the healing process toward scar formation.     

Small Intestinal Submucosa (SIS) in the Repair of a Cecal Wound in Unprepared Bowel in Rats

Purpose Porcine-derived small intestinal submucosa (SIS) has been accepted as an acellular matrix for tissue regeneration. However, its use for remodeling gastrointestinal defects has been poorly investigated. Our previous study of the rodent stomach has demonstrated that the SIS stimulates regeneration of native tissue under acidic conditions. The purpose of this paper was to investigate the feasibility of using SIS as a bioscaffold for a colonic defect in unprepared bowel. Methods A 1 × 1-cm whole layer was excised on the anterior wall of the cecum in 24 rats, followed by onlay repair with SIS. Measurement outcomes included animal survival, mesh stability in situ, and histologic evaluation at 3 weeks and 6 months. Results Rats showed a significant weight gain and had no evidence of postoperative leakage. All wounds were secured and associated with either omental or other fatty adhesions. Histological findings revealed that intact mucosa covered the area of the graft in all cases 6 months after surgery and that the defect was completely replaced by the normal constituents (mucosa, muscle, and nerve cells) of the bowel wall. Conclusions SIS was largely successful in promoting healing in a cecal wound in unprepared bowel and serving as a bioscaffold for regeneration of the native colonic tissue. Small intestinal submucosa may be useful in surgical anastomoses to promote healing and presumably prevent leakage.     

Evaluation of the carbon dioxide laser for performance of gastrointestinal myotomies

Using a conventional carbon dioxide laser set at 8-W continuous-wave energy, a technique was developed in the animal laboratory to incise only the muscularis of the pylorus leaving the mucosa and submucosa intact. Similar esophageal myotomies were performed with less success, due to the rich submucosal venous plexus causing obscuring hemorrhage and to the reapproximation of the longitudinal esophageal muscle over a 3-week period. The technique for esophageal myotomy requires further refinement, but pyloromyotomy appears applicable for controlled human trials.     

Tissue-engineered esophagus: experimental substitution by onlay patch or interposition

OBJECTIVES: We proposed to fabricate a tissue-engineered esophagus and to use it for replacement of the abdominal esophagus. METHODS: Esophagus organoid units, mesenchymal cores surrounded by epithelial cells, were isolated from neonatal or adult rats and paratopically transplanted on biodegradable polymer tubes, which were implanted in syngeneic hosts. Four weeks later, the tissue-engineered esophagus was either harvested or anastomosed as an onlay patch or total interposition graft. Green Fluorescent Protein labeling by means of viral infection of the organoid units was performed before implantation. Histology and immunohistochemical detection of the antigen alpha-actin smooth muscle were performed. RESULTS: Tissue-engineered esophagus grows in sufficient quantity for interposition grafting. Histology reveals a complete esophageal wall, including mucosa, submucosa, and muscularis propria, which was confirmed by means of immunohistochemical staining for alpha-actin smooth muscle. Tissue-engineered esophagus architecture was maintained after interposition or use as a patch, and animals gained weight on a normal diet. Green Fluorescent Protein-labeled tissue-engineered esophagus preserved its fluorescent label, proving the donor origin of the tissue-engineered esophagus. CONCLUSIONS: Tissue-engineered esophagus resembles the native esophagus and maintains normal histology in anastomosis, with implications for therapy of long-segment esophageal tissue loss caused by congenital absence, surgical excision, or trauma.     

Musculo-fibrous anomaly in Barrett's mucosa with dysplasia

We investigated the histological alterations occurring in the muscularis mucosae, the lamina propria mucosae, and the submucosa in areas adjacent to invasive adenocarcinoma in 32 resected esophagi with Barrett's mucosa. In 26 of the 32 specimens, we observed a thickening of the muscularis mucosae, with overgrowth of the muscle fibers into the lamina propria mucosae. In other areas, collagen-rich fibrotic tissue replaced the muscularis mucosae, the lamina propria mucosae, and even the submucosa. In 31 of the 32 specimens, we noted cystic dilatations of the esophageal glands. Normal esophageal glands and cystically dilated glands with dysplastic lining were often surrounded, compressed, and deformed by the fibrotic tissue. The compression of the glandular outlets by the collagen-rich tissue or by proliferating dysplastic cells appeared to be the two main factors in the histogenesis of these cysts. This may result in difficulty in differentiating, in biopsy specimens, between normal and dysplastic esophageal glands "trapped" in the collagen-rich fibrotic tissue and true invasive adenocarcinoma in the Barrett's mucosa.     

Vascular plexus is a differentation criterion for muscularis mucosa from muscularis propria in small biopsies and transurethral resection materials of urinary bladder?

Objective: Smooth muscle fibres are found within thesuperficial lamina propria of urinary bladder (Muscularis Mucosa). Thesemuscle fibres of muscularis mucosa should be distinguished from themuscularis propria in cases with urothelial carcinoma, because the depthof infiltration affects prognosis and therapy modalities. The aim of thepresent study was to evaluate whether the presence of vascular plexus isa criterion for muscularis mucosa and to distinguish it from muscularispropria in urinary bladder biopsies and transurethral resectionspecimens. Materials and methods: Hematoxylin-Eosin andMasson-Trichrome stained slides of 54 cases with urothelial carcinomawere reviewed. Results: In all cases (100%), thick walledvessels were observed within the lamina propria of urinary bladder.Smooth muscle layer of lamina propria was seen in 48 of 54 cases(88.8%), and these smooth muscle fibres were co-existed with thickwalled vessels. In invasive urothelial carcinoma; thin smooth musclefibres and thick walled vessels were seen within the lamina propria in22 of 24 cases (91.7%). There were two cases (8.3%)including only vessels in small biopsies of invasive urothelialcarcinoma cases. In cases with non-invasive urothelial carcinoma; musclefibres of muscularis mucosa and vessels were found within the laminapropia in 26 of 30 cases (86.7%). In this group, muscle fibreswere not detected in 4 cases (13.3%). Conclusion:Muscularis mucosa can be detected histologically in urinary bladderbiopsies and TUR materials. We emphasize that the presence of vascularnetwork is a useful criterion to determine muscularis mucosa of urinarybladder, even in the absence of muscle fibres.     

Intrathoracic esophageal replacement in the dog with the use of an artificial esophagus composed of a collagen sponge with a double-layered silicone tube.

OBJECTIVES: Intrathoracic esophageal replacement with an artificial esophagus is considered difficult. We attempted to replace the intrathoracic esophagus with an artificial esophagus composed of a collagen sponge with a double-layered silicone tube and examined the state of host tissue regeneration. METHODS: A 5-cm long gap was created in the intrathoracic esophagus in 9 dogs and repaired by interposition of our prosthesis. The dogs were fed only by intravenous hyperalimentation for 28 days. The silicone tube was removed at 29 days after the operation, and oral feeding was reintroduced. RESULTS: One dog was put to death at each of the following times: 1, 2, 3, 3, 6, 12, and 24 months after the operation. One dog is still surviving without problems after more than 26 months. One dog died of malnutrition at 10 months. In all dogs, the host regenerated tissue had replaced the resulting gap at the time of silicone tube removal. The mucosa had fully regenerated within 3 months and the glands within 12 months. The process of stenosis and shrinkage was complete within 3 months and did not advance thereafter. The lamina muscularis mucosae were observed as islets of smooth muscle within 12 months. Although the skeletal muscle regenerated close to the anastomoses, it did not extend to the middle of the regenerated esophagus even after 24 months. CONCLUSIONS: Use of a collagen sponge with a double-layered silicone tube was shown to be feasible even in the thorax and to allow the regenerated host tissue, consisting of the mucosa, glands, and lamina muscularis mucosae, to replace the esophageal gap.     

Microcirculation of the cat stomach.

Radioactive microspheres 15 mum in diameter were injected into the left ventricle of the heart of cats. Simultaneously a blood sample was drawn from the aorta. Standardized samples of the stomach wall were separated into mucosa and muscularis samples. For each sample the blood flow was calculated in terms of ml/minute/100 g tissue weight. The distribution of microspheres to different layers of the samples was determined microscopically. In the mucosa samples the majority of spheres were found in the propria and glandular layer, only a few persent in the submucosa. In the mscularis samples most of the microspheres were present in the muscle tissue, only 1--9% in the submucosa fraction. The present method is considered to give a good expression of the capillary blood flow in the glandular layer of the mucosa and the muscularis.     

Magnetic resonance (MR) imaging for the detection of the invasion into neighboring structures in esophageal cancers

In 104 patients with esophageal cancers, magnetic resonance (MR) imaging was performed to detect the invasion to aorta and tracheobronchial tree. Relatively short TR images (TR 300 or 40 msec) were best for depiction of esophageal cancers and neighboring structures. The detectability of esophageal cancer was 0% in cases of muscularis mucosa invasion, 50% in cases of submucosa invasion, and 75% in cases of muscularis propria invasion. In more invaded cases, all cases were detectable. Aortic invasion was evaluated according to the extent of contact and its consecutiveness between the esophagus and aorta; if contact more than 1/4 circumference was seen more than three contiguous slices, aortic invasion was diagnosed as positive. The accuracy rate of this criterion was 96.6%. Tracheobronchial invasion was evaluated according to the deformities of the trachea and bronchi by contiguous cancers those were classified into four types. It was determined that convex type (Type I) and flat type (Type II) were negative and concave type (Type III) and displaced type (Type IV) were positive. The accuracy rates of this criteria were 95% in the trachea and 87.7% in the bronchi. MRI is useful for the detecting of local invasion of esophageal cancer.     

Ventral hernia repair with lateral component separation and onlay Biodesign graft

Background

Ventral hernia is common, complicating up to 20 % of laparotomies. Plication of the rectus sheath with lateral component separation (LCS) provides a durable repair with acceptable functional outcomes. Additional support to the anterior abdominal wall may be provided by synthetic or biological mesh. Biological grafts invoke local tissue remodeling and result in strong fibrocollagenous tissue able to support the dynamic stressor of the anterior abdominal wall. Biodesign graft is a new graft derived from porcine small-intestine submucosa. We aim to review the use of Biodesign mesh for repair of ventral hernia with LCS.

Methods

Patients underwent ventral hernia repair completed with plication of the rectus sheath, LCS, and use of an onlay Biodesign graft. Data was collected retrospectively. Key outcome measures included post-operative complications and recurrence.

Results

Twelve patients were included for analysis. Mean age was 51.2 years, with 50 % males and a median weight of 87 kg (65–111 kg). Median operative time was 210 min (147 to 278 min) and median length of stay was 4 days. At a mean follow-up of 14.0 months, 8/12 (66 %) developed seroma, 1/12 (8 %) developed abdominal wall abscess, and 1/12 (8 %) suffered flap failure requiring vacuum dressings for closure. No patients were complicated by ventral hernia recurrence.

Conclusions

Our results describe an early Australian experience of onlay Biodesign graft in the context of rectus sheath plication with LCS. We report acceptable rates of post-operative complications and recurrence.Level of evidence: IV, therapeutic study.

     

Muscularis mucosa of urinary bladder. Importance for staging and treatment

We report the results of a histologic evaluation of muscle (muscularis mucosa) in the lamina propria of the urinary bladder performed on 100 consecutive cystectomy specimens. Muscle fibers were found in the lamina propria lying parallel to the mucosa and forming a distinct muscularis mucosa in three cases; they were interrupted or discontinuous in 20 cases, and dispersed or scattered, forming thin bundles, in 71 cases. In six cases, there were no muscle fibers in the lamina propria. In addition, we noticed that the lamina propria contains large vessels that run along the length of the lamina propria in a continuous or interrupted fashion. When muscle fibers are present, they are associated with these vessels. Since prognosis and management of muscle invasive carcinomas (stage B) is different from that of lamina propria-invasive tumors (stage A), pathologists and urologists should be aware of the presence of a muscularis mucosa in the urinary bladder.     

Endoscopic evaluation of the depth of invasion in cases of superficial esophageal cancer in determining indications for endoscopic mucosal resection

Endoscopic mucosal resection (EMR) should be performed for the treatment of squamous cell carcinoma of the esophagus limited to the lamina propria mucosae (m1 and m2 cancers), because lymph node metastasis is rare in these cases. The lymph node metastasis rate is 6% when cancers reach the muscularis mucosa(m3) or slightly invade the submucosa (sm1). Lymph node metastasis is noted in 47% of esophageal cancers moderately or severely invading the submucosa(sm2 and sm3). Radical esophagectomy is recommended for sm2 and sm3 disease. Type 0-II cancers are candidates for EMR, because 86% remain within the mucosa, while 90% of type 0-I lesions and 96% of type 0-III lesions are submucosal cancers. Among type 0-II cancers, most type 0-IIb lesions are m1 cancer. Among type 0-IIa cancers, 96% are mucosal. Type 0-IIc lesions are frequent among superficial esophageal cancers and 19% reach the submucosa. Endoscopic diffrentiation of m1 and m2 cancers is reliable, since 96% of all m1 and m2 cancers were correctly diagnosed before treatment. In cases with type O-IIc lesions which is most frequent among superficial esophageal cancers, m1 cancer showed very slight depressions with a smooth surface and reddening. Sometimes fine granular changes are seen. They are also delineated as an unstained area by endoscopic toluidine blue-iodine double staining. They showed very slight depressions with a smooth surface and reddening. Sometimes fine granular changes are seen. They are also delineated as an unstained area by endoscopic toluidine blue-iodine double staining. Dark blue dots, spots, or reticular staining are frequently identified in m2 cancers. In cases with m3 or sm1 cancer, coarse granular changes, small nodular elevations, or slightly deeper depressed areas in the m1 and m2 lesions suggest sites of deeper invasion.     

Surgical reconstruction of partial circumferential esophageal defect in the dog.

Partial circumferential reconstruction of the cervical esophagus was evaluated in the dog. An esophageal defect 5.85 +/- 1.15 cm in length involving one-half of the circumference was repaired by direct closure (group I), using longus colli muscle patch grafts (group II), and using grafts of longus colli muscle lined with buccal mucosa (group III). The incidence of leakage, fistula formation, luminal stricture, peristalsis disturbance, lining loss, the quality of surface restoration, bursting strength, and wound healing were evaluated. No fistula formation or leakage was observed in any animal. Direct closure of the defect was easier to perform, led to less inflammatory reaction, and resulted in the highest bursting strength. However, this method was associated with luminal stricture and swallowing difficulties. The longus colli muscle patch grafts (group II) were associated with a slight to moderate luminal stricture, but had more inflammatory reaction and graft surface area contraction (62%) compared to group III. The longus colli muscle lined with buccal mucosa caused no stricture and slight surface area contraction (8%). Mucosal grafts remained viable and no lining loss was observed. Despite the loss of peristalsis at the level of the graft in 25% of the group III dogs, no clinical signs or swallowing difficulties were observed.     

Surgical Reconstruction of Partial Circumferential Esophageal Defect in the Dog

Partial circumferential reconstruction of the cervical esophagus was evaluated in the dog. An esophageal defect 5.85 ± 1.15 cm in length involving one-half of the circumference was repaired by direct closure (group I), using longus colli muscle patch grafts (group II), and using grafts of longus colli muscle lined with buccal mucosa (group III). The incidence of leakage, fistula formation, luminal stricture, peristalsis disturbance, lining loss, the quality of surface restoration, bursting strength, and wound healing were evaluated. No fistula formation or leakage was observed in any animal. Direct closure of the defect was easier to perform, led to less inflammatory reaction, and resulted in the highest bursting strength. However, this method was associated with luminal stricture and swallowing difficulties. The longus colli muscle patch grafts (group II) were associated with a slight to moderate luminal stricture, but had more inflammatory reaction and graft surface area contraction (62%) compared to group III. The longus colli muscle lined with buccal mucosa caused no stricture and slight surface area contraction (8%). Mucosal grafts remained viable and no lining loss was observed. Despite the loss of peristalsis at the level of the graft in 25% of the group III dogs, no clinical signs or swallowing difficulties were observed.     

Tubular musculopleural pedicle grafting of esophageal long gaps in dogs

Direct anastomosis of the esophagus is the treatment of choice in patients with esophageal atresia. If, however, a long esophageal gap exists, the anastomosis is performed under tension or a staged procedure is anticipated. The aim of this study was to prove that a pedicle musculopleural graft can be used to bridge the two esophageal ends. In 14 dogs through a right thoracotomy, the periosteum of the fifth rib was mobilized and the rib was excised. An intercostal musculopleural flap was created leaving the muscle attached to its vascular pedicle posteriorly with the intercostal vessels and nerve carefully preserved. A tube-like portion including pleural and intercostal muscles was formed from the free part of the graft. A 5 cm segment of the esophagus was excised and the tubular graft was interimposed. Animals were studied 1 month postoperatively with a barium meal that showed free passage through the esophageal neolumen. Peristaltic activity was studied with strain gauges above, below, and at the grafted area. Histologic examination revealed good healing at both anastomotic sites, while esophageal squamous epithelium covered the lumen all over the graft. Survival of the musculopleural pedicle graft seems to be feasible providing that its vascular supply is preserved. It is, thus, suggested that this technique might offer an alternative method in bridging long gaps in esophageal surgery.     

Mucosal proctectomy using an ultrasonic scalpel

Mucosal proctectomy is becoming the operation of choice in the surgical treatment of patients with ulcerative colitis and familial polyposis coli. Dissection of the rectal mucosa and submucosa from the underlying muscularis is often difficult and, in some instances, impossible to perform. The feasibility of using an ultrasonic device to perform mucosal protectomy was studied in eight dogs. This technique produced coagulative necrosis of the mucosa and muscularis mucosa with marked edema and congestion of the submucosa. The muscularis propria remained intact. Complete destruction of the distal 7 cm of rectal mucosa required a total duration of exposure to the ultrasonic probe of at least 12 minutes. In another five dogs, total colectomy was performed above the area of the mucosal proctectomy followed by endorectal pull-through of the ileum. Follow-up studies revealed healing of the ileonal anastomosis without retraction or stricture. This technique should allow mucosal proctectomy to be performed in those patients in whom standard dissection is not possible due to fibrosis of the submucosal plane.     

Transcatheter placement of a low-profile biodegradable pulmonary valve made of small intestinal submucosa: a long-term study in a swine model

OBJECTIVE: We sought to investigate a placement of a percutaneous low-profile prosthetic valve constructed of small intestinal submucosa in the pulmonary position in a swine model. METHODS: Twelve female farm pigs were stented at the native pulmonary valve to induce pulmonary insufficiency. Once right ventricular dilation occurred, the small intestinal submucosa valve was implanted. The pigs were followed up with transthoracic echocardiographic Doppler scanning. One animal died of heart failure before valve replacement. Animals were euthanized at 1 day, 1 month, 3 months, 6 months, and 12 months after valve implantation. RESULTS: The small intestinal submucosa pulmonary valve showed effective reversal of pulmonary regurgitation. There were no misplacements during deployment. There were no embolizations. One-year echocardiographic follow-up showed minimal regurgitation and no stenosis for a valve/vessel ratio of 0.78 or greater. Histologic examination demonstrated intensive remodeling of the small intestinal submucosal valve. Within 1 month, the surface was covered by endothelium, and fibroblasts invaded the interior. Over the following months, the small intestinal submucosal valve remodeled without apparent graft rejection. CONCLUSION: The small intestinal submucosa valve has the potential for graft longevity without the need for anticoagulation or immunosuppression. Histologic remodeling of the valve tissue provides a replacement capable of resembling a native valve that can be placed percutaneously with low-profile delivery systems.     

Long-Term Function and Morphology of Intestinal Autografts and Allografts in Outbred Dogs

Although small bowel transplantation (SBTx) has become a clinical option, there have been few studies of long-term function and histopathology of intestinal grafts. Unrelated mongrel dogs received autologous (n = 4) or allogeneic (n = 11) orthotopic SBTx under oral cyclosporine. Intestinal graft function and routine/immunohistopathology of full-thickness intestine were studied. Six allograft and all isograft recipients had comparable body weight gain and are currently alive (> 420 days). Five allograft recipients were sacrificed because of significant body weight loss and malnutrition at a median of 119 days. Analyses of intestinal function in long-surviving recipients revealed marginal reduction of D-xylose/cyclosporine absorption, intestinal transit time, in vitro muscle contractility, and mucosal enzyme activity compared with normal dogs. However, these changes were insignificant and no statistical difference was seen between auto and long-surviving allografts. In histopathological analysis, long-surviving allografts had normal mucosa with submucosal, muscularis propria, and perineural (Auerbach's plexus) inflammation. Five allorecipients with malnutrition had mucosal atrophy/erosion and significantly reduced intestinal absorption and motility. Thus, denervated intestinal allografts are able to efficiently digest and absorb nutrients to support life. Results also indicate that these allografts experienced low-grade chronic rejection as evidenced in the submucosa and muscle layers, despite the lack of clinical symptoms.     

Results of experimental endoscopic esophageal varix ligation

Endoscopic Variceal ligation (EVL) is performed using a flexible gastroscope and a recently developed elastic band ligating device. Varices from 3-5 mm in diameter were created in a canine model. Thirty seven variceal sites underwent EVL with successful ligation on first attempt in 34 (92%). Gross and microscopic examination of treated sites at 1-60 days showed ischemic necrosis of mucosa and submucosa (24 hours), acute inflammation, demarcation of viable and necrotic tissue, and appearance of granulation tissue (3-7 days), full thickness replacement of mucosa and submucosa with maturing scar tissue and near complete re-epithelialization (14-21 days), and complete healing (50-60 days). Inflammation and scar tissue deposition consistently obliterated submucosal venous channels but left muscularis propria intact. No perforations or other adverse clinical or histological effects were observed. EVL treatment of canine esophageal varices appears to result in safe and effective obliteration of vascular channels in the submucosa by a process of inflammation and scar formation.     

Combined use of the cephalic vein and pectoralis major muscle flap for secondary esophageal reconstruction

Secondary reconstruction of thoracic esophageal defects is a challenging problem for microsurgeons. Because of previous surgeries and coexisting disease, gastric pull‐up, and creation of a pedicled colon conduit are often impossible. Transfer of a supercharged pedicled jejunum flap or free jejunal interposition is usually the last resort; however, identifying appropriate recipient vessels and adequately covering the reconstructive conduit are often difficult. We performed secondary thoracic esophageal reconstruction with combined use of the cephalic vein as a recipient vein and the pectoralis major muscle flap for coverage in three patients. Two patients underwent transfer of a supercharged pedicled jejunum flap, and the other patient underwent free jejunal interposition. No wound complications occurred, and all patients could resume oral intake. The cephalic vein is a more reliable recipient vein than is the internal mammary vein. The skin graft‐covered pectoralis major muscle flap provides secure external coverage to prevent anastomotic leakage even in complicated cases. Combined use of the cephalic vein and the skin graft‐covered pectoralis major muscle flap is a versatile option for secondary thoracic esophageal reconstruction. © 2013 Wiley Periodicals, Inc. Microsurgery 34:319–323, 2014.