Small intestinal submucosa as a bioscaffold for biliary tract regeneration

Fabrication of 3D printed PCL/PEG artificial bile ducts as supportive scaffolds to promote regeneration of extrahepatic bile ducts in a canine biliary defect model

In this study, a 3D porous poly(ε-caprolactone)/polyethylene glycol (PCL/PEG) composite artificial tubular bile duct was fabricated for extrahepatic bile duct regeneration. PCL/PEG composite scaffolds were fabricated by 3D printing, and the molecular structure, mechanical properties, thermal properties, morphology, and in vitro biocompatibility were characterized for further application as artificial bile ducts. A bile duct defect model was established in beagle dogs for in vivo implantation. The results demonstrated that the implanted PE1 ABD, serving as a supportive scaffold, effectively stimulated the regeneration of a new bile duct comprising CK19-positive and CK7-positive epithelial cells within 30 days. Remarkably, after 8 months, the newly formed bile duct exhibited an epithelial layer resembling the normal structure. Furthermore, the study revealed collagen deposition, biliary muscular formation, and the involvement of microvessels and fibroblasts in the regenerative process. In contrast, the anastomotic area without ABD implantation displayed only partial restoration of the epithelial layer, accompanied by fibroblast proliferation and subsequent bile duct fibrosis. These findings underscore the limited inherent repair capacity of the bile duct and underscore the beneficial role of the PE1 ABD artificial tubular bile duct in promoting biliary regeneration.

Pitfalls and promises of bile duct alternatives: A narrative review

Biliodigestive anastomosis between the extrahepatic bile duct and the intestine for bile duct disease is a gastrointestinal reconstruction that abolishes duodenal papilla function and frequently causes retrograde cholangitis. This chronic inflammation can cause liver dysfunction, liver abscess, and even bile duct cancer. Although research has been conducted for over 100 years to directly repair bile duct defects with alternatives, no bile duct substitute (BDS) has been developed. This narrative review confirms our understanding of why bile duct alternatives have not been developed and explains the clinical applicability of BDSs in the near future. We searched the PubMed electronic database to identify studies conducted to develop BDSs until December 2021 and identified studies in English. Two independent reviewers reviewed studies on large animals with 8 or more cases. Four types of BDSs prevail: Autologous tissue, non-bioabsorbable material, bioabsorbable material, and others (decellularized tissue, 3D-printed structures, etc.). In most studies, BDSs failed due to obstruction of the lumen or stenosis of the anastomosis with the native bile duct. BDS has not been developed primarily because control of bile duct wound healing and regeneration has not been elucidated. A BDS expected to be clinically applied in the near future incorporates a bioabsorbable material that allows for regeneration of the bile duct outside the BDS.

A composite scaffold fabricated with an acellular matrix and biodegradable polyurethane for the in vivo regeneration of pig bile duct defects

Bile duct regeneration is urgently needed to restore the normal function of the damaged biliary system. In this study, an artificial bile duct (ABD) was fabricated for extrahepatic bile duct regeneration based on biodegradable polyurethane (BPU) and ureter acellular matrix (UAM) to endow it with favorable biocompatibility and eliminate bile leakage during in vivo bile duct regeneration. The mechanical properties, in vitro simulation of bile flow and cytocompatibility of BPU-UAM ABD were evaluated in vitro, and surgical implantation in the biliary defect site in minipigs was implemented to reveal the in vivo degradation of BPU-UAM and regeneration of the new bile duct. The results indicated that BPU-UAM ABD with a mechanical strength of 11.9 MPa has excellent cytocompatibility to support 3T3 fibroblast survival and proliferation in extraction medium and on the scaffolds. The in vivo implantation of BPU-UAM ABD revealed the change of collagen content throughout the new bile duct regeneration. Biliary epithelial cells were observed at day 70, and continuous biliary epithelial layer formation was observed after 100 days of implantation. Altogether, the BPU-UAM ABD fabricated in this study possesses excellent properties for application study in the regeneration of bile duct. STATEMENT OF SIGNIFICANCE: Extrahepatic bile duct defects carry considerable morbidity and mortality because they are the only pathway for bile to go down into the intestinal tract. At present, no artificial bile duct can promote biliary regeneration. In this study, BPU-UAM ABD was built based on biodegradable polyurethane and ureter acellular matrix to form a continuous compact layer of polyurethane in the internal wall of UAM and avoid bile leakage and experimental failure during in vivo implantation. Our work verified the effectiveness of the synthesized biodegradable polyurethane emulsion-modified urethral acellular matrix in bile regeneration and continuous biliary epithelial layer formation. This study provided a new approach for the curing of bile duct defects and inducing new bile tissue formation.

Progress and Current Limitations of Materials for Artificial Bile Duct Engineering

Bile duct injury (BDI) and bile tract diseases are regarded as prominent challenges in hepatobiliary surgery due to the risk of severe complications. Hepatobiliary, pancreatic, and gastrointestinal surgery can inadvertently cause iatrogenic BDI. The commonly utilized clinical treatment of BDI is biliary-enteric anastomosis. However, removal of the Oddi sphincter, which serves as a valve control over the unidirectional flow of bile to the intestine, can result in complications such as reflux cholangitis, restenosis of the bile duct, and cholangiocarcinoma. Tissue engineering and biomaterials offer alternative approaches for BDI treatment. Reconstruction of mechanically functional and biomimetic structures to replace bile ducts aims to promote the ingrowth of bile duct cells and realize tissue regeneration of bile ducts. Current research on artificial bile ducts has remained within preclinical animal model experiments. As more research shows artificial bile duct replacements achieving effective mechanical and functional prevention of biliary peritonitis caused by bile leakage or obstructive jaundice after bile duct reconstruction, clinical translation of tissue-engineered bile ducts has become a theoretical possibility. This literature review provides a comprehensive collection of published works in relation to three tissue engineering approaches for biomimetic bile duct construction: mechanical support from scaffold materials, cell seeding methods, and the incorporation of biologically active factors to identify the advancements and current limitations of materials and methods for the development of effective artificial bile ducts that promote tissue regeneration.

Prosthetic meshes for hernia repair: State of art, classification, biomaterials, antimicrobial approaches, and fabrication methods

Worldwide, hernia repair represents one of the most frequent surgical procedures encompassing a global market valued at several billion dollars. This type of surgery usually requires the implantation of a mesh that needs the appropriate chemical, physical and biological properties for the type of repair. This review thus presents a description of the types of hernias, current hernia repair methods, and the state of the art of prosthetic meshes for hernia repair providing the most important meshes used in clinical practice by surgeons working in this area classified according to their biological or chemical nature, morphology and whether bioabsorbable or not. We emphasise the importance of surgical site infection in herniatology, how to deal with this microbial problem, and we go further into the future research lines on the production of advanced antimicrobial meshes to improve hernia repair and prevent microbial infections, including multidrug-resistant strains. A great deal of progress has been made in this biomedical field in the last decade. However, we are still far from an ideal antimicrobial mesh that can also provide excellent integration to the abdominal wall, mechanical performance, low visceral adhesion and minimal inflammatory or foreign body reactions, among many other problems.

Case Report: Surgical Correction of a Cystic Duct Stump Leakage Following Cholecystectomy Using an Autologous Rectus Sheath Graft in a Dog

A 2.7 kg, 13-year-old, castrated male Yorkshire Terrier was presented with bile peritonitis after cholecystectomy. Exploratory coeliotomy to identify and correct bile leakage revealed that the transected end of the cystic duct was open with no in-situ ligatures or vascular clips. The residual cystic duct stump was too short to ligate or seal directly. An autologous rectus sheath graft, harvested from the internal leaf of the rectus sheath, was used to patch the cystic duct stump. The graft was secured over the open duct using several simple interrupted sutures and covered with an omentalization. The clinical signs resolved after surgery, except for a transient increase in hepatobiliary enzyme levels and intrahepatic bile duct dilatation. The enzyme levels returned to near normal on day 25 after surgery. No intrahepatic bile duct dilatation was detected on day 55 after surgery. The owner was contacted for 3 years post-operatively and reported that the dog remained healthy without any long-term complications. Grafting using autologous rectus sheath can be used to treat cystic duct stump leakage that cannot be managed with direct closure using traditional modalities due to spatial constraints.

Extrahepatic bile duct reconstruction in pigs with heterogenous animal-derived artificial bile ducts: A preliminary experience

BACKGROUND

Extrahepatic biliary duct injury (BDI) remains a complicated issue for surgeons. Although several approaches have been explored to address this problem, the high incidence of complications affects postoperative recovery. As a nonimmunogenic scaffold, an animal-derived artificial bile duct (ada-BD) could replace the defect, providing good physiological conditions for the regeneration of autologous bile duct structures without changing the original anatomical and physiologic conditions.

AIM

To evaluate the long-term feasibility of a novel heterogenous ada-BD for treating extrahepatic BDI in pigs.

METHODS

Eight pigs were randomly divided into two groups in the study. The animal injury model was developed with an approximately 2 cm segmental defect of various parts of the common bile duct (CBD) for all pigs. A 2 cm long novel heterogenous animal-derived bile duct was used to repair this segmental defect (group A, ada-BD-to-duodenum anastomosis to repair the distal CBD defect; group B, ada-BD-to-CBD anastomosis to repair the intermedial CBD defect). The endpoint for observation was 6 mo (group A) and 12 mo (group B) after the operation. Liver function was regularly tested. Animals were euthanized at the above endpoints. Histological analysis was carried out to assess the efficacy of the repair.

RESULTS

The median operative time was 2.45 h (2-3 h), with a median anastomosis time of 60.5 min (55-73 min). All experimental animals survived until the endpoints for observation. The liver function was almost regular. Histologic analysis indicated a marked biliary epithelial layer covering the neo-bile duct and regeneration of the submucosal connective tissue and smooth muscle without significant signs of immune rejection. In comparison, the submucosal connective tissue was more regular and thicker in group B than in group A, and there was superior integrity of the regeneration of the biliary epithelial layer. Despite the advantages of the regeneration of the bile duct smooth muscle observed in group A, the effect on the patency of the ada-BD grafts in group B was not confirmed by macroscopic assessment and cholangiography.

CONCLUSION

This approach appears to be feasible for repairing a CBD defect with an ada-BD. A large sample study is needed to confirm the durability and safety of these preliminary results.

Native tissue-based strategies for meniscus repair and regeneration

Meniscus injuries appear to be becoming increasingly common and pose a challenge for orthopedic surgeons. However, there is no curative approach for dealing with defects in the inner meniscus region due to its avascular nature. Numerous strategies have been applied to regenerate and repair meniscus defects and native tissue-based strategies have received much attention. Native tissue usually has good biocompatibility, excellent mechanical properties and a suitable microenvironment for cellular growth, adhesion, redifferentiation, extracellular matrix deposition and remodeling. Classically, native tissue-based strategies for meniscus repair and regeneration are divided into autogenous and heterogeneous tissue transplantation. Autogenous tissue transplantation is performed more widely than heterogeneous tissue transplantation because there is no immunological rejection and the success rates are higher. This review first discusses the native meniscus structure and function and then focuses on the use of the autogenous tissue for meniscus repair and regeneration. Finally, it summarizes the advantages and disadvantages of heterogeneous tissue transplantation. We hope that this review provides some suggestions for the future design of meniscus repair and regeneration strategies.

In Situ Tissue Engineering of the Bile Duct Using Polypropylene Mesh-Collagen Tubes

Multiple attempts have been made to replace biliary defects with a variety of materials. Recently, successful biliary reconstruction using the Gore-Tex vascular graft has been reported experimentally and clinically We designed a new artificial bile duct consisting of collagen sponge and polypropylene mesh. We presently evaluated the feasibility of using this prosthesis as a scaffold for bile duct tissue regeneration in a canine model. Our prosthesis, a sponge made from porcine dermal collagen, is reinforced with a polypropylene mesh cylinder. We used the prosthesis to reconstruct the middle portion of the common bile duct in seven beagle dogs to evaluate its efficacy. While one dog died of biliary stricture 8 months after operation, six survived without problems to scheduled time points for tissue evaluation at 1 to 12 months. All prostheses had become completely incorporated into the host. A confluent epithelial lining was observed within 3 months. In cholangiograms the prosthesis displayed long-term patency in the six dogs and provided satisfactory bile drainage for up to 12 months. Our graft thus shows promise for repair of biliary defects and should lead to development of a new treatment for biliary reconstruction.

Advances in the generation of bioengineered bile ducts

The generation of bioengineered biliary tissue could contribute to the management of some of the most impactful cholangiopathies associated with liver transplantation, such as biliary atresia or ischemic cholangiopathy. Recent advances in tissue engineering and in vitro cholangiocyte culture have made the achievement of this goal possible. Here we provide an overview of these developments and review the progress towards the generation and transplantation of bioengineered bile ducts. This article is part of a Special Issue entitled: Cholangiocytes in Health and Diseaseedited by Jesus Banales, Marco Marzioni and Peter Jansen.

Accelerating effects of genipin-crosslinked small intestinal submucosa for defected gastric mucosa repair

Slow healing of gastric mucosa defects caused by endoscopic surgery is a common but severe clinical problem for lack of an effective treatment. Small intestinal submucosa (SIS) is a bio-derived extracellular matrix scaffold with remarkable repairing ability for soft tissue, but its rapid degradation and poor mechanical properties in the stomach environment limit its application for gastric mucosa regeneration. Herein, we modified SIS by genipin, a natural crosslinking agent, to improve its resistance against degradation in gastric juice and to promote the healing of gastric mucosa defects. The crosslinking characteristics of genipin-crosslinked SIS (GP-CR SIS) were evaluated by crosslinking degree, swelling ratio and FITR, respectively. GP-CR SIS was highly resistant to gastric juice digestion and had a great improvement in mechanical properties. Additionally, GP-CR SIS maintained excellent biocompatibility according to a cytotoxicity test, hemolysis test, and rat subcutaneous implant assay. In an in vivo study, we treated defected gastric mucosa with GP-CR SIS in a rabbit endoscopic submucosal dissection (ESD)-related ulcer model. After two weeks of surgical treatment, GP-CR SIS significantly expedited wound closure and ameliorated newly constructed tissue by providing a protective microenvironment for rapid granulation tissue formation and accelerating angiogenesis/re-epithelialization. In conclusion, this study demonstrates the huge therapeutic potential of GP-CR SIS scaffolds for accelerating defected gastric mucosa regeneration.

Repair of a common bile duct defect with a decellularized ureteral graft

AIM

To evaluate the feasibility of repairing a common bile duct defect with a decellularized ureteral graft in a porcine model.

METHODS

Eighteen pigs were randomly divided into three groups. An approximately 1 cm segment of the common bile duct was excised from all the pigs. The defect was repaired using a 2 cm long decellularized ureteral graft over a T-tube (T-tube group, n = 6) or a silicone stent (stent group, n = 6). Six pigs underwent bile duct reconstruction with a graft alone (stentless group). The surviving animals were euthanized at 3 mo. Specimens of the common bile ducts were obtained for histological analysis.

RESULTS

The animals in the T-tube and stent groups survived until sacrifice. The blood test results were normal in both groups. The histology results showed a biliary epithelial layer covering the neo-bile duct. In contrast, all the animals in the stentless group died due to biliary peritonitis and cholangitis within two months post-surgery. Neither biliary epithelial cells nor accessory glands were observed at the graft sites in the stentless group.

CONCLUSION

Repair of a common bile duct defect with a decellularized ureteral graft appears to be feasible. A T-tube or intraluminal stent was necessary to reduce postoperative complications.

Colorectal tissue engineering: A comparative study between porcine small intestinal submucosa (SIS) and chitosan hydrogel patches

OBJECTIVE

Tissue engineering may provide new operative tools for colorectal surgery in elective indications. The aim of this study was to define a suitable bioscaffold for colorectal tissue engineering.

METHODS

We compared 2 bioscaffolds with in vitro and in vivo experiments: porcine small intestinal submucosa (SIS) versus chitosan hydrogel matrix. We assessed nontoxicity of the scaffold in vitro by using human adipose-derived stem cells (hADSC). In vivo, a 1 × 2-cm colonic wall defect was created in 16 rabbits. Animals were divided randomly into 2 groups according to the graft used, SIS or chitosan hydrogel. Graft area was explanted at 4 and 8 weeks. The end points of in vivo experiments were technical feasibility, behavior of the scaffold, in situ putative inflammatory effect, and the quality of tissue regeneration, in particular smooth muscle layer regeneration.

RESULTS

In vitro, hADSC attachment and proliferation occurred on both scaffolds without a substantial difference. After proliferation, hADSCs kept their mesenchymal stem cell characteristics. In vivo, one animal died in each group. Eight weeks after implantation, the chitosan scaffold allowed better wound healing compared with the SIS scaffold, with more effective control of inflammatory activity and an integral regeneration of the colonic wall including the smooth muscle cell layer.

CONCLUSION

The outcomes of in vitro experiments did not differ greatly between the 2 groups. Macroscopic and histologic findings, however, revealed better wound healing of the colonic wall in the chitosan group suggesting that the chitosan hydrogel could serve as a better scaffold for colorectal tissue engineering.

Repair of extrahepatic bile duct defect using a collagen patch in a Swine model

Extrahepatic bile duct (EBD) injury can happen during surgery. To repair a defect of the EBD and prevent postoperative biliary complications, a collagen membrane was designed. The collagen material was porous, biocompatible, and degradable and could maintain its shape in bile soaking for about 4 weeks. The goal was to induce rapid bile duct tissue regeneration. Twenty Chinese experimental hybrid pigs were used in this study and divided into a patch group and a control group. A spindle-shaped defect (20 mm × 6 mm) was made in the anterior wall of the lower EBD in the swine model, and then the defect was reconstructed using a collagen patch with a drainage tube and wrapped with greater omentum. Ultrasound was performed at 2, 4, 8, and 12 weeks postoperatively. Liver function tests and white blood cell count (WBC) were measured. Hematoxylin-eosin staining, cytokeratin 7 immunohistochemical staining, and Van Gieson's staining of EBD were used. The diameter and thickness of the EBD at the graft site were measured. There was no significant difference in liver function tests or WBC in the patch group compared with the control group. No evidence of leakage or stricture was observed, but some pigs developed biliary sludge or stone at 4 and 8 weeks. The drainage tube was lost within 12 weeks. The neo-EBD could withstand normal biliary pressure 2 weeks after surgery. Histological study showed the accessory glands and epithelial cells gradually regenerated at graft sites from 4 weeks, with increasing vessel infiltration and decreasing inflammation. The collagen fibers became regular with full coverage of epithelial cells. The statistical analysis of diameter and thickness showed no stricture formation at the graft site, but the EBD wall was slightly thicker than in the normal bile duct due to collagen fiber deposition. The structure of the neo-EBD was similar to that of the normal EBD. The collagen membrane patch associated with a drainage tube and wrapped with greater omentum effectively induced the regeneration of the EBD defect within 12 weeks.

Macroporous biodegradable natural/synthetic hybrid scaffolds as small intestine submucosa impregnated poly(D, L-lactide-co-glycolide) for tissue-engineered bone

Poly(D,L-lactide-co-glycolide) (PLGA), a biodegradable synthetic polymer, is widely used in a variety of tissue-engineered applications, including drug-delivery systems. However, the PLGA scaffolds, macroporous and three-dimensional structure, are difficult to cell attachment and in-growth due to surface hydrophobicity. In order to introduce in new bioactive functionality from porcine small intestine submucosa (SIS) as natural source for PLGA, we fabricated SIS-powder-impregnated PLGA (SIS/PLGA) hybrid scaffolds. Fabrication parameters, including ratios of SIS, PLGA and salt, were optimized to produce the desired macroporous foam. The scaffolds had a relatively homogeneous pore structure, good interconnected pores from the surface to core region and showed an average pore size in the range 69.23-105.82 microm and over 90% porosity. The SIS/PLGA scaffolds degraded with a rate depending on the contents of the SIS. After the fabrication of the SIS/PLGA hybrid scaffolds the wettability of the scaffold was greatly enhanced, resulting in uniform cell seeding and distribution. So, it was observed that BMSC attachment to the SIS/PLGA scaffolds increased gradually with increasing SIS contents. Scaffolds of PLGA alone and SIS/PLGA were implanted subcutaneously under dorsal skin of athymic nude mouse to observe the osteoconductivity. It was found from the result that the effects of the SIS/PLGA scaffolds on bone formation are stronger than control PLGA scaffolds. In summary, the SIS/PLGA scaffolds have osteoconductive effects to allow remodeling and replacement by osseous tissue.

Extrahepatic bile duct regeneration in pigs using collagen scaffolds loaded with human collagen-binding bFGF

Extrahepatic bile duct defects and their complications are benign lesions but with malignant outcomes. Extrahepatic bile duct regeneration at the injury site could be important for the repair. In our previous work, a human basic fibroblast growth factor (bFGF) fused with a collagen-binding domain (CBD) was produced to activate the collagen membrane to obtain targeted tissue regeneration. This collagen/growth factor functional biomaterial could promote the regeneration of skin, bladder and full-thickness abdominal wall by accelerating vascularization and cellularization of autologous tissues. We speculate that the functional biomaterial could also provide the repairing effect on extrahepatic bile duct injuries. Using a pig extrahepatic bile duct injury model, we found that the collagen/CBD-bFGF composite biomaterial could significantly promote the extrahepatic bile duct regeneration at the injury site without causing structure deformation or hepatic dysfunction during both short- and long-time observations.

Chronic hernia repair in a rat model using small intestinal submucosa

BACKGROUND. Small intestinal submucosa (SIS) body wall defect repair in preclinical studies results in host tissue that resembles original host tissue histologically and has adequate strength to maintain repair integrity. However, these studies have been performed using acute hernia models that may not represent healing in a naturally occurring hernia. METHODS. Fifty-four male Sprague-Dawley rats were divided into nine groups (n = 6) and fascia/muscle/peritoneal abdominal wall defects were created. One control group had no surgery. Four surgery groups had defects repaired immediately by (1) fascia suture apposition, (2) polypropylene mesh (PPM) peritoneal onlay, (3) SIS inlay, or (4) SIS peritoneal onlay. After defect creation, chronic hernias matured for 28 days, and then were similarly repaired. Follow-up after hernia repair for all groups was 28 days. Gross evaluation for hernia recurrence, infection, and adhesions was followed by histopathology and tensile testing of the repair. RESULTS. There were no recurrent hernias or infection. Adhesions covered all implants. Histopathologic findings of inflammation and fibrosis were similar between all groups. There were no significant differences in tensile strength between SIS and PPM healing/incorporation or between acute and chronic hernia groups. Normal body wall was stronger than all repairs. Fascia closure in chronic hernias was stronger than acute fascia closure (p < .01). CONCLUSIONS. We found no significant differences between SIS and PPM healing/incorporation as determined by gross and histopathology and tensile strength testing. The study suggests that preclinical testing of abdominal body wall reconstruction in the rat may be adequately performed in acute studies.

Hilar cholangioplasty using omentum for ductal defect in biliobiliary fistula

BACKGROUND/PURPOSE

A non-circumferential defect of the biliary system is occasionally faced at surgery for biliobiliary fistula. The condition represents an uncommon but important complication of gallstone disease. Although direct closure and patch repair using the gallbladder cuff are recommended as first-line treatments, these procedures are sometimes technically difficult in the presence of severe inflammation. The authors, herein, present a novel procedure denoted as hilar cholangioplasty, which utilizes the pedicled omentum.

METHODS

An 80-year-old man was referred to our hospital because of cholangitis. Endoscopic retrograde cholangiography demonstrated a large gallstone astride the common hepatic duct with upstream biliary dilation, indicating biliobiliary fistula. Upon laparotomy, a 2 × 3 cm ductal defect was found just under the hepatic bifurcation, after removal of the gallstones and the gallbladder. The surrounding tissue, as well as the bile duct, was extensively inflamed with dense fibrosis, such that first-line repair methods could not be performed. As an alternative method, the pedicled omentum was used for cholangioplasty.

RESULTS

Postoperative cholangioscopy showed a yellow polypoid mass without constriction. Histologically, ordinary biliary epithelium overlaid the surface of the grafted omentum. The patient has remained well at 3-year follow-up.

CONCLUSION

The present method is simple and could be a promising option when standard repair methods cannot be applied.

Novel technique for biliary reconstruction using an isolated gastric tube with a vascularized pedicle: a live animal experimental study and the first clinical case

Background

Biliary tract reconstruction continues to be a challenging surgical problem. Multiple experimental attempts have been reported to reconstruct biliary defects with different materials and variable outcome. Our aim was to evaluate a new method for biliary reconstruction using an isolated pedicled gastric tube in a live animal trial and also to present the first clinical case.

Methods

Seven mongrel dogs underwent biliary reconstruction using gastric tube harvested, completely separated from the greater curvature, and based on a vascularized pedicle with the right gastroepiploic vessels. The tube was interposed between the common bile duct (CBD) and the duodenum. Postoperative mortality, morbidity, liver functions, gross and microscopic histological picture were assessed. The first clinical case was also presented where, in a patient with post-cholecystectomy biliary injury, an isolated pedicled gastric tube was interposed between the proximal and distal ends of the CBD.

Results

One dog did not recover from anesthesia and another one died postoperatively from septic peritonitis. Five dogs survived the procedure and showed uneventful course and no cholestasis. The mean anastomotic circumference was 4.8 mm (range 4-6) for CBD anastomosis and 6.2 mm (range 5-7) for duodenal anastomosis. Histologically, anastomotic sites showed good evidence of healing. In the first clinical case, the patient showed clinical and biochemical improvement. Endoscopic retrograde cholangiography was feasible and assured patent biliary anastomoses.

Conclusion

In mongrel dogs, biliary reconstruction using pedicled gastric tube interposition between CBD and duodenum is feasible with satisfactory clinical results, anastomotic circumference and histological evidence of healing. The technique is also feasible in human and seems to be promising.

Novel reconstruction of the extrahepatic biliary tree with a biosynthetic absorbable graft

OBJECTIVES

The reference standard technique for the reconstruction of the extrahepatic biliary tree is Roux-en-Y hepaticojejunostomy. This procedure is not without complications and may not be feasible in some patients. This project sought to evaluate a novel approach for repairing common bile duct injuries with a biosynthetic graft. This allows for the reconstruction of the anatomy without necessitating an intestinal bypass.

METHODS

Study subjects were 11 mongrel hounds. Utilizing an open approach, the common bile duct was transected in each animal. A 1-cm graft of a synthetic bioabsorbable prosthesis was interposed over a 5-Fr pancreatic stent and sewn in place as an interposition tube graft with absorbable sutures. Intraoperative cholangiograms and monthly liver function tests were completed. Animals were killed at 6, 7, 8, 10 and 12 months.

RESULTS

The first five animals were killed early in the process of protocol development. One animal developed obstructive symptoms and was killed on postoperative day 14. The next five animals were longterm survivors without evidence of clinically significant graft stenosis. Mean alkaline phosphatase and total bilirubin were normal, at 140 U/l and 0.2 mg/dl, respectively. Histology showed the complete replacement of the graft with native tissue at 6 months.

CONCLUSIONS

  Biliary reconstruction using a synthetic bioabsorbable prosthetic as an interposition tube graft is feasible based on initial results.

Extracellular matrices for gastrointestinal surgery: Ex vivo testing and current applications

AIM: To assess the effects of bile and pancreatic juice on structural and mechanical resistance of extracellular matrices (ECMs) in vitro.

METHODS: Small-intestinal submucosa (SIS), porcine dermal matrix (PDM), porcine pericardial matrix (PPM) and bovine pericardial matrix (BPM) were incubated in human bile and pancreatic juice in vitro. ECMs were examined by macroscopic observation, scanning electron microscopy (SEM) and testing of mechanical resistance.

RESULTS: PDM dissolved within 4 d after exposure to bile or pancreatic juice. SIS, PPM and PDM retained their integrity for > 60 d when incubated in either digestive juice. The effect of bile was found to be far more detrimental to mechanical stability than pancreatic juice in all tested materials. In SIS, the loss of mechanical stability after incubation in either of the digestive secretions was less distinct than in PPM and BPM [mFmax 4.01/14.27 N (SIS) vs 2.08/5.23 N (PPM) vs 1.48/7.89 N (BPM)]. In SIS, the extent of structural damage revealed by SEM was more evident in bile than in pancreatic juice. In PPM and BPM, structural damage was comparable in both media.

CONCLUSION: PDM is less suitable for support of gastrointestinal healing. Besides SIS, PPM and BPM should also be evaluated experimentally for gastrointestinal indications.

Addition of nimesulide to small intestinal submucosa biomaterial inhibits postsurgical adhesiogenesis in rats

Adhesion formation is a common complication in abdominal surgery with incidence as high as 93% and small bowel obstruction a common complication. Because the extracellular matrix material, small intestinal submucosa (SIS), is commonly used in various surgical procedures, methods to inhibit adhesiogenesis are of great interest. This study was undertaken to determine if incorporation of nimesulide (NM), a selective cyclooxygenase (COX)-2 inhibitor, could reduce the extent and tenacity of intraabdominal adhesion formation associated with SIS implantation. Female Sprague-Dawley rats underwent a cecal abrasion surgical procedure to induce adhesiogenesis. Rats were either left untreated or treated by direct application over the injured cecum with polypropylene mesh (PPM); SIS; SIS containing a low dose of NM; or SIS containing a high dose of NM. Rats were euthanized 21 days later, and adhesion extent and tenacity were evaluated using standard scales (0 = minimal adhesiogenesis; 4 = severe adhesiogenesis). Addition of NM to SIS resulted in a significant (p < 0.05) reduction in adhesion extent and in a similar reduction in adhesion tenacity for SIS containing a low dose of NM. Adhesions typically extended from the abraded cecal surface to the body wall and were characterized histologically by fibrous tissue adherent to the cecal wall. In conclusion, addition of the nonsteroidal anti-inflammatory, COX-2 selective drug, NM, to SIS attenuates adhesion extent and tenacity when compared with surgical placement of SIS or PPM alone.

Small intestinal submucosa for reinforcement of colonic anastomosis

BACKGROUND

Different materials have been evaluated for anastomotic reinforcement to prevent gastrointestinal anastomotic leakage. In this experimental study, small intestinal submucosa (SIS) was tested as a sealing for stapled colonic anastomosis in a porcine model. The aims of this study were to determine the macroscopic and microscopic outcomes and to evaluate the safety and feasibility of applying SIS for anastomotic sealing.

MATERIALS AND METHODS

Circular stapled anastomoses were performed in 18 pigs. Standard anastomosis in the control group (n = 8) was compared to an SIS-sealed anastomosis in the study group (n = 10). After 30 days, anastomotic segments were examined for macroscopic and microscopic regeneration and their resistance to mechanical stress. Furthermore, animal survival and clinical course were evaluated.

RESULTS

None of the animals developed anastomotic leakage, intraabdominal abscess, or peritonitis. Shrinkage of SIS was evident in nine of ten animals. Encapsulation and displacement of the SIS patches were seen in two animals. Quantity of anastomotic granulation tissue and rate of complete mucosal coverage of anastomotic line were increased in SIS-sealed anastomoses without reaching significance. Moreover, no significant differences were found in the rate of survival of the animals, anastomotic stricture formation, intraabdominal adhesions, anastomotic bursting pressure, and microscopic healing parameters of the anastomosis between stapled colonic standard anastomosis and anastomosis protected by SIS.

CONCLUSION

The results of this study indicate a safe use of SIS for anastomotic reinforcement in a porcine model. Adverse effects like strictures, increased adhesions, and anastomotic abscesses were absent. Promoting effects on colonic wound healing by SIS were microscopically evident. The results argue for a careful clinical evaluation in humans.

Rabbit Ear Cartilage Regeneration With a Small Intestinal Submucosa Graft

OBJECTIVES/HYPOTHESIS

The objective was to demonstrate that interpositional grafting with porcine small intestinal submucosa promotes cartilage regeneration following excision of rabbit auricular cartilage.

STUDY DESIGN

Blinded, controlled study.

METHODS

Eight New Zealand white rabbits underwent excision of auricular cartilage on two sites with and two sites without preservation of perichondrium. Porcine small intestinal submucosa was implanted into one site with and one site without intact perichondrium. Remaining sites served as control sites. Histological assessment was performed at 3 (n = 4) and 6 (n = 3) months and at 1 year (n = 1) after grafting.

RESULTS

Histological evaluation showed cartilage regeneration accompanied by chronic inflammation in areas in which porcine small intestinal submucosa was implanted between layers of intact perichondrium. Other sites failed to show significant cartilage regeneration.

CONCLUSION

The results of the study using porcine small intestinal submucosa as a bioscaffold for cartilage regeneration are promising and justify further animal and human studies.

Small intestinal submucosa as a bioscaffold for tissue regeneration in defects of the colonic wall

BACKGROUND

Small intestinal submucosa (SIS) has proved considerable regenerative capacity for repair of bowel wall defects at different locations. This study assesses the effectiveness of SIS in the repair of defects at a gastrointestinal location with strong bacterial contamination.

METHODS

Fourteen domestic pigs had a 4.5 x 1.5 cm full-thickness defect created on the wall of the descending colon. Repair was done by suturing an SIS patch to the defect. Grafts were harvested after 30, 60, and 90 days. Outcomes were evaluated on the basis of animal survival, clinical course, and macroscopic, histological, and immunohistochemical assessment.

RESULTS

All animals survived the scheduled observation period. No patch failure and no postoperative leakage occurred. No luminal narrowing occurred at SIS-patched colon. Morphometric examination revealed contraction of the patched area of 77% after 30 days and more than 90% after 60 and 90 days. By 60 and 90 days, all animals showed mucosal regeneration at the margins of the graft. By 90 days, regeneration of smooth muscle cells was present at the original site of the muscularis mucosae. None of the reconstructed areas showed complete mucosal coverage or regeneration of a structured muscular layer.

CONCLUSION

SIS can be used effectively for patch repair of colonic defects in a porcine model. Distinctive contraction of the reconstructed area and limited architectural regeneration of the bowel wall suggest limitation of morphologic regenerative capacities in large-bowel regeneration.

Ectopic transplantation of hepatocyte sheets fabricated with temperature-responsive culture dishes

AIM

Hepatocyte transplantation to host livers by single cell suspension injection from the portal vein has been clinically successful in cases where the host liver architecture is intact. However, further investigation is still needed to achieve regeneration of the liver architecture when the host liver is destroyed, since single cell suspension injection often results in the formation of small hepatocyte colonies or islands. We show a hepatocyte transplantation strategy to ectopic sites.

METHODS

Primary hepatocytes isolated from green fluorescent protein (GFP)-transgenic rats were cultured on temperature-responsive culture dishes. After harvest as intact cell sheets, triple-layered cell sheets were transplanted over the superficial caudal epigastric artery and vein of athymic rats which had operation of 70% partial hepatectomy.

RESULTS

The transplanted hepatocytes were integrated to host tissue with a laminar cell arrangement at transplanted sites within one week after surgery. But the transplanted hepatocytes were hardly detected four weeks after transplantation, when the partially hepatectomized host liver was completely regenerated. GFP-positive bile duct-like tubes and functional blood vessels were observed.

CONCLUSION

These results imply the usefulness of hepatocyte sheets in ectopic transplantation, as well as the need of trophic factors for hepatocyte survival.

Gastrotomy closure using bioabsorbable plugs in a canine model

The repair of gastric perforation commonly involves simple suture closure using an open or laparoscopic approach. An endolumenal approach using prosthetic materials may be beneficial. The role of bioprosthetics in this instance has not been thoroughly investigated, thus the authors evaluated the feasibility of gastric perforation repair using a bioabsorbable device and quantified gross and histological changes at the injury site. Twelve canines were anesthetized and underwent open gastrotomy. A 1-cm-diameter perforation was created in the anterior wall of the stomach and plugged with a bioabsorbable device. Intralumenal pH was recorded. Canines were sacrificed at one, four, six, eight, and 12 weeks. The stomach was explanted followed by gross and histological examination. The injury site was examined. The relative ability of the device to seal the perforation was recorded, as were postoperative changes. Tissue samples were analyzed for gross and microscopic tissue growth and compared to normal gastric tissue in the same animal as an internal control. A scoring system of -2 to +2 was used to measure injury site healing (-2= leak, -1= no leak and minimal ingrowth, 0= physiologic healing, +1= mild hypertrophic tissue, +2= severe hypertrophic tissue). In all canines, the bioprosthesis successfully sealed the perforation without leak under ex vivo insufflation. At one week, the device maintained its integrity but there was no tissue ingrowth. Histological healing score was -1. At 4-12 weeks, gross examination revealed a healed injury site in all animals. The lumenal portion of the plug was completely absorbed. The gross and histological healing score ranged from -1 to +1. The application of a bioabsorbable device results in durable closure of gastric perforation with physiologic healing of the injury site. This method of gastrotomy closure may aid in the evolution of advanced endoscopic approaches to perforation closure of hollow viscera.

Preparation and Characterization of Small Intestinal Submucosa Coated with Alginate/Gelatin as a Wound Dressing

To develop a wound dressing that can be removed from the injured skin without the damage and supporting rapid healing, we made hybrid dressing of small intestinal submucosa (SIS) and hydrogels. Alginate and gelatin used as a dressing material in hydrogels were selected to coat SIS sheets. Characteristics and tendency of wound healing of prepared sheets were investigated. Water uptake ability was greater when the sheets were coated with gelatin than alginate although both showed higher water absorption than the native SIS sheets, but the degradation rate of alginate/gelatin coated SIS was slower than that of native SIS because both polymers may delay contact time of enzyme to the SIS surface in solution. It was observed that less of fibroblasts attached to the natural polymer coated SIS sheets. This property will make easy for the detachment of the sheet from the defected tissue. Wound closure examination showed that prepared sheets enhanced wound healing. It was concluded that prepared alginate/gelatin coated SIS sheets are positively regarded as an appropriate biodegradable wound dressing that is reducing patient’s pain during change of the dressing.

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 x 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.

Ventral herniorrhaphy: experience with two different biosynthetic mesh materials, Surgisis and Alloderm

OBJECTIVE

The aim of this study was to compare the efficacy and the complications associated with the use of two new bioactive meshes, Surgisis Gold 8-ply mesh, a product obtained by the processing of porcine small intestine sub-mucosa (Cook Surgical, Bloomington, IN, USA), and Alloderm, processed cadaveric human acellular dermis (Life Cell Corporation, Branchburg, NJ, USA), for ventral herniorrhaphy.

BACKGROUND

Ventral hernia repair in potentially contaminated or potentially infected fields limit the use of synthetic mesh products. In this scenario, biosynthetic mesh products that are absorbed and/or replaced with the body's own tissue reduce the incidence of post-operative chronic wound complications (Franklin et al. in Hernia 8(3):186-189, 2004; Franklin et al. in Hernia 6(4):171-174, 2002; Hirsch in J Am Coll Surg 198(2):324-328, 2004; Holton et al. in J Long Term Eff Med Implants 15(5):547-558, 2005; Buinewicz and Rosen in Ann Plast Surg 52(2):188-194, 2004). Rapid revascularization, repopulation, and remodeling of the matrix occur on contact with the patient's own tissue. Only limited, and mostly preliminary data, is available on the use of these types of mesh and concerning the potential complications associated with the use of these types of meshes. We publish our experience with the use of these mesh products, along with their associated complications. Furthermore, we have also provided suggestions for improvements in the mesh designs.

METHODS

Between June 2002 and March 2005, 74 patients underwent ventral hernia repair using biosynthetic or natural tissue mesh. The first 41 procedures were performed using Surgisis Gold 8-ply mesh formed from porcine small intestine sub-mucosa, and the remaining 33 patients had ventral hernia repair with Alloderm. The patients had their first follow-up 7-10 days after discharge from the hospital. They were again seen at 6 weeks, or, if needed, earlier, and, thereafter, as needed. Patients who reported any complications to the office were followed up immediately within 1-2 days. Any signs of wound infection, diastasis, hernia recurrence, changes in bowel habits, and seroma formation were evaluated.

RESULTS

Non-perforated Surgisis mesh resulted in significant seroma formation in 10/11 patients. The seroma complication was reduced, but not eliminated, with the use of the perforated Surgisis mesh (3/30 patients). Explanted material revealed separated layers of un-incorporated middle layers of the 8-ply Surgisis mesh. Three of the patients had the mesh placed in a contaminated field with no resultant sequela, and there were no hernia recurrences. Patients also had a significant degree of discomfort and pain during the immediate post-operative period. The use of the Alloderm mesh resulted in eight hernia recurrences. Fifteen of the Alloderm patients (15/33) developed a diastasis or bulging at the repair site. Seroma formation was only a problem in two patients.

CONCLUSIONS

Seroma formation was a major problem with the non-perforated Surgisis mesh repair, as was the post-operative pain. On the other hand, post-operative diastasis and hernia recurrence were a major problem with the Alloderm mesh. Further design improvements are required in both forms of these new mesh products. Surgeons should be aware of these potential complications prior to the selection of either of these products and the patient should be informed and educated accordingly.

Esophageal replacement in rat using porcine intestinal submucosa as a patch or a tube-shaped graft

This study compares the efficacy of porcine intestinal submucosa (SIS) patch graft versus SIS-tube graft in esophageal replacement, using a novel esophageal regeneration model. Clinical function, as well as macroscopic and microscopic morphology were evaluated in both SIS-treated groups. We performed semi-circumferential esophageal excision followed by repair of the defect using either a SIS-patch graft (group I) or segmental esophageal excision followed by a SIS-tube interposition graft (group II) in rats. The 28-day survival rate was significantly different between the SIS-treated groups (100% in group I vs. 0% in group II). Unlike the rats in group II, which died within the first postoperative month due to esophageal dysfunction, all surviving animals in group I resumed a normal solid diet within a few days after surgery, without signs of esophageal dysfunction and gained weight. Barium swallow studies showed no evidence of fistula, significant stenosis or diverticula. No hematological or serum biochemistry abnormalities were found. By day 150 the SIS patch was replaced by esophageal-derived tissues. In the rat model, a patch graft technique using SIS appeared to induce esophageal regrowth and provided an initial and long-term satisfactory function, while a tube-shaped graft technique using SIS was unsuccessful.

SURGISIS-assisted surgical site control in the delayed repair of a complex bile duct injury after laparoscopic cholecystectomy

Although laparoscopic cholecystectomy has revolutionized the surgical approach to patients with gallbladder disease, it has also brought a marked increase in the incidence of complex and serious bile duct injuries. Many of these major injuries represent a major technical challenge for even the most seasoned hepatobiliary-trained surgeon. Herein, we present a case outlining the algorithmic treatment approach for delayed-presentation complex biliary injury and report on the novel use of small intestinal submucosal biomaterial for surgical site control in the staged repair of a complex biliary injury (Strasberg E4) after laparoscopic cholecystectomy.

Novel bile duct repair for bleeding biliary anastomotic varices: case report and literature review

An unusual case of variceal bleeding at the site of a biliary enteric anastomosis is presented. This entity can occur when a high-to-low pressure gradient forms in a variceal field. In this case the anastomotic site was the location of the pressure gradient from the high-pressure small bowel varices to the low-pressure biliary tract. This was successfully treated by disconnection of the anastomosis. The resulting biliary defect was patched with small intestinal submucosa, which functioned successfully as a scaffold for biliary epithelial ingrowth.

Early inflammatory reaction after rotator cuff repair with a porcine small intestine submucosal implant: a report of 4 cases

BACKGROUND

Porcine small intestine submucosal grafts have been successful in enhancing soft tissue repair, as demonstrated by animal studies. Currently, there are no reports of the use of such implants in human rotator cuff repair.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Over a 6-month period, 25 patients underwent rotator cuff repair by one surgeon using the Restore Orthobiologic Implant to augment the repaired tendon or fill a defect.

RESULTS

Four of 25 patients experienced an overt inflammatory reaction at a mean of 13 days postoperatively. All patients underwent open irrigation and debridement of the rotator cuff and porcine small intestine submucosal implant.

CONCLUSION

Porcine small intestine submucosal implants should be used in rotator cuff surgery with the awareness that a non-specific inflammatory reaction can occur in the early postoperative period. This inflammatory reaction may cause breakdown of the repair. Further studies are needed to further characterize the reaction and determine which patients are susceptible.

A tissue-engineered artificial bile duct grown to resemble the native bile duct

The aim of this study was to fabricate an artificial bile duct for the development of a new treatment for biliary diseases. Eighteen hybrid pigs were implanted with a bile duct organoid unit (BDOU) made of a bioabsorbable polymer. Twelve of the transplanted BDOUs had been seeded with autologous bone marrow cells (BMCs) in advance. Six animals, the controls, were grafted with the scaffold alone with no BMCs seeded. The common bile duct was cut, the hepatic cut end of the native common bile duct was anastomosed to the BDOU and the other end was anastomosed to the duodenum. The controls underwent a similar operation. The neo-bile duct was removed at pre-determined time points and investigated histologically. All 18 recipient pigs survived until their sacrifice at 6 weeks, 10 weeks or 6 months. Histological examination revealed incomplete epithelialization of the neo-bile duct at 6 weeks and 10 weeks after transplantation. At 6 months, the organoid exhibited a morphology almost identical to that of the native common bile duct. No differences were found between the controls and BMC-seeded pigs. These results show that the artificial bile duct thus fabricated can serve as a substitute for the native bile duct.