Biodegradable versus multiple plastic stent implantation in benign biliary strictures: A systematic review and meta-analysis

Less is more: The use of single biodegradable stenting to treat biliary anastomotic strictures in pediatric liver transplantation

This study reports our experience of using biodegradable biliary stents (BBSs) for anastomotic biliary strictures (ABSs) in pediatric patients undergoing liver transplants. It involves the analysis of a retrospective data collection from January 2014 to January 2023, including all pediatric recipients of liver transplants in our center treated for ABSs with BBSs. In phase 1 (2014-2019), there was an initial percutaneous transhepatic cholangiography with anastomotic dilatation followed 2 weeks after a second percutaneous transhepatic cholangiography with BBS insertion. In phase 2 (2019-2023), the BBS was placed shortly after ABS dilatation, requiring only 1 percutaneous transhepatic cholangiography. All patients were followed up with routine tests and ultrasound. Forty-six ABSs were diagnosed in 43 pediatric recipients of liver transplants with a median of 6.7 months after liver transplantation (0.1-246.8 mo). Eight out of 46 ABSs (17.4%) treated with BBSs relapsed (median recurrence time: 6.5 mo; 1.6-17.0 mo). Four resolved with further BBS placement; only 4 needed surgical revision (8.7%) after a median follow-up time of 43.9 months (0.3-106.3). There were no differences in ABS recurrence rate, time between stent placement and recurrence, or the presence of cholangitis based on whether the BBS was deployed in 1 or 2 steps. Patients with end-to-end anastomosis had a higher ABS recurrence (OR 10.8; 1.4-81.3, p = 0.008) than those with bilioenteric anastomosis. The use of biodegradable stents could be a good option for treating ABSs in pediatric patients undergoing liver transplants, with our series showing a success rate of over 90% and an average follow-up of 43.9 months.

Past and Recent Progress on Metallic Digestive Tract Stents

The implantation of digestive tract stents at various lesion sites can effectively improve digestive tract patency, opening up an excellent treatment method for diseases that are currently incurable or resistant to conventional surgery. Digestive tract stents have been extensively studied and widely used worldwide due to their unique advantages of simple implantation, low trauma, satisfactory effect, and low complication rate. Among the various types of stents, metallic stents have been developed to improve surgical efficacy due to their excellent mechanical properties and are constantly being improved. This review provides an overview of the design and development of conventional nonbiodegradable metallic digestive tract stents such as nitinol (NiTi alloy), stainless steel, and cobalt-based alloy stents. Furthermore, biodegradable metallic stents for the digestive tract, such as magnesium-based, iron-based, and zinc-based stents, are described. This paper also evaluates the advantages and disadvantages of existing metallic digestive stents as well as future research directions and challenges in the development of metallic digestive tract stents.

Therapeutic biliary stents: applications and opportunities

INTRODUCTION

Biliary stents are used to optimize ductal patency and enable bile flow in the management of obstruction or injury related to biliary tract tumors, strictures, stones, or leaks. Although direct therapeutic applications of biliary stents are less well developed, stents can be used to deliver drugs, radioisotopes, and photodynamic therapy.

AREAS COVERED

This report provides an in-depth overview of the clinical indications, and therapeutic utility of biliary stents. Unique considerations for the design of biliary stents are described. The properties and functionalities of materials used for stents such as metal alloys, plastic polymers, or biodegradable materials are described, and opportunities for design of future stents are outlined. Current and potential applications of stents for therapeutic applications for biliary tract diseases are described.

EXPERT OPINION

Therapeutic biliary stents could be used to minimize inflammation, prevent stricture formation, reduce infections, or provide localized anti-cancer therapy for biliary tract cancers. Stents could be transformed into therapeutic platforms using advanced materials, 3D printing, nanotechnology, and artificial intelligence. Whilst clinical study and validation will be required for adoption, future advances in stent design and materials are expected to expand the use of therapeutic biliary stents for the treatment of biliary tract disorders.

Treatment of complex iatrogenic common hepatic duct injury following laparoscopic cholecystectomy

We report the case of a woman in her 40s, with no significant medical history, submitted to a laparoscopic cholecystectomy in our institution for symptomatic gallbladder lithiasis. On postoperative day 4, she presented to our emergency room with severe abdominal pain and elevated inflammatory markers. Abdominal CT scan revealed a mass filled with liquid and air in the gallbladder fossa. Surgical exploration was performed revealing a major common hepatic duct iatrogenic injury, which was managed using suture over a T-tube. Three months after surgery, cholangiography showed a biliary stenosis, and a biodegradable stent was inserted through percutaneous transhepatic access. The difficulties in the management of this condition and its outcomes are discussed in this report.

Management of Benign Biliary Stricture in Chronic Pancreatitis

Endoscopic therapy is the first line of management for chronic pancreatitis (CP)-related benign biliary strictures. Multiple plastic stents (MPS) exchanged at regular intervals and temporary placement of fully covered self-expanding metal stents (FCSEMS) are preferred modalities of endotherapy. FCSEMS placement is non-inferior to MPS and requires fewer sessions of endoscopic retrograde cholangiopancreatography than MPS placement. The presence of head calcifications, severe CP, and length of stricture are predictors of failure or recurrence after endotherapy. Failure of endotherapy should be considered after 1 year when surgery should be considered.

Biosynthetic Plastics as Tunable Elastic and Visible Stent with Shape-Memory to Treat Biliary Stricture

Common biliary tract is ≈4 mm in diameter to deliver bile from liver to small intestine to help digestion. The abnormal narrowing leads to severe symptoms such as pain and nausea. Stents are an effective treatment. Compared with non-degradable stents which require repeated removal, biodegradable stents have the advantage of reducing secondary injury related to endoscopic operation and patient burden. However, current biodegradable materials may cause tissue hyperplasia and the treatment method does not target etiology of stricture. So recurrence rates after biodegradable stent implantation are still high. Here, a biodegradable helical stent fabricated from biosynthetic P(3HB-co-4HB) is reported. Tunable properties can be acquired through altering culture substrates. Stent shows shape memory in various solvents. The stent has an optimized design with helical structure and outer track. The self-expanding of helical structure and double drainage realized by outer track greatly improve drainage of bile. Importantly, stent-loading triamcinolone acetonide can inhibit proliferation of fibroblasts and reduce incidence of restricture. Therapeutic effect is also demonstrated in minipigs with biliary stricture. The results of minipig experiments show that biliary duct in treatment group is unobstructed and tissue hyperplasia is effectively inhibited.

Recent developments in antibacterial or antibiofilm compound coating for biliary stents

Cholestasis of the indwelling biliary stents usually leads to stone recurrence after endoscopic retrograde cholangio pancreatoraphy (ERCP). Biliary stents, including metallic and none-degradable plastic stents are widely used in clinical settings due to their many excellent properties. However, conventional biliary stents still suffer from poor antibacterial activity and anti-bile-adhesion, which lead to injured, local fibroblasts proliferating. Currently, various coatings for biliary stents have been prepared to meet the clinical demands. In this review, we start by summarizing and discussing classifications of biliary stents and antibacterial/antibiofilm mechanism. Then, the latest advances about developing antibacterial and antibiofilm coatings for improving the properties of biliary stents are reviewed and discussed in detail. Lastly, we list several possible directions for future development of biliary stents coatings and biliary stent, such as anti-bile-adhesion coating, multifunctional coating, drug-eluting biodegradable biliary stents and 3D printed biliary stents.

Feasibility and safety of a novel 3D-printed biodegradable biliary stent in an in vivo porcine model: a preliminary study

To assess the feasibility and safety of a novel 3D-printed biodegradable biliary stent using polycaprolactone (PCL) in an in vivo porcine model. In this animal study using domestic pigs, biodegradable radiopaque biliary stents made of polycaprolactone (PCL) and barium sulfate were produced using 3D printing and surgically inserted into the common bile duct (CBD) of pigs (stent group, n = 12). Another five pigs were allocated to the control group that only underwent resection and anastomosis of the CBD without stent insertion. To check the position and status of the stents and stent-related complications, follow-up computed tomography (CT) was performed every month. The pigs were sacrificed 1 or 3 months after surgery, and their excised CBD specimens were examined at both the macroscopic and microscopic levels. Three pigs (one in the stent group and two in the control group) died within one day after surgery and were excluded from further analysis; the remaining 11 in the stent group and 3 in the control group survived the scheduled follow-up period (1 month, 5 and 1; and 3 months, 6 and 2 in stent and control groups, respectively). In all pigs, no clinical symptoms or radiologic evidence of biliary complications was observed. In the stent group (n = 11), stent migration (n = 1 at 3 months; n = 2 at 1 month) and stent fracture (n = 3 at 2 months) were detected on CT scans. Macroscopic evaluation of the stent indicated no significant change at 1 month (n = 3) or fragmentation with discoloration at 3 months (n = 5). On microscopic examination of CBD specimens, the tissue inflammation score was significantly higher in the stent group than in the control group (mean ± standard deviation (SD), 5.63 ± 2.07 vs. 2.00 ± 1.73; P = 0.039) and thickness of fibrosis of the CBD wall was significantly higher than that of the control group (0.46 ± 0.12 mm vs. 0.21 ± 0.05 mm; P = 0.012). Despite mild bile duct inflammation and fibrosis, 3D-printed biodegradable biliary stents showed good feasibility and safety in porcine bile ducts, suggesting their potential for use in the prevention of postoperative biliary strictures.

Endoscopic Management of Biliary Strictures after Orthotopic Liver Transplantation: A Single Center Experience Study

Background and Aim. Endoscopic therapy is the method of choice in the management of biliary strictures after orthotopic liver transplantation (OLT). Even though the mainstay approach for OLT stricture complications is represented by consecutive procedures of multiple plastic stents (MPS) insertion, a valuable alternative is the use of fully covered self-expandable metal stents (FCSEMS). The aim of the study was to compare MPS with FCSEMS used in the management of OLT biliary strictures, in terms of clinical outcomes and complications. Material and Methods. This is a retrospective, single-center study conducted between February 2014 and November 2019 in the Clinical Emergency Hospital of Bucharest, Romania. We enrolled all consecutive patients who developed biliary strictures after OLT and were treated by endoscopic retrograde cholangiopancreatography (ERCP) either with MPS or FCSEMS. Results. Thirty-six patients were included in the study, 27 patients had MPS and nine patients had FCSEMS. 106 ERCP procedures were performed and 159 stents were inserted. The mean number of ERCP procedures required per patient was significantly higher for MPS than for FCSEMS (3.34 ± 1.46 vs. 2.11 ± 0.33, p < 0.001). In the FCSEMS group only one patient had three procedures, due to stent migration. Difficult cannulation was encountered in 22 patients, 18 patients from MPS group and four patients from FCSEMS group. Dilation was performed in 20 (77%) MPS patients and in four FCSEMS patients (44%). Overall, we used 159 stents for stricture resolution, 149 plastic stents and 10 FCSEMS. Mean number of stents inserted was significantly lower in the FCSEMS group compared to MPS group (1.16 ± 0.40 vs. 5.73 ± 2.64, p < 0.001). Conclusions. Stricture resolution using FCSEMS is comparable to MPS and even has some advantages. In line with prior studies, FCSEMS are effective, with fewer complications and similar outcome compared to plastic stents. Other particular aspects should be further assessed, especially long-term follow up of FCSEMS and their cost efficiency.

Indian College of Radiology and Imaging Evidence-Based Guidelines for Percutaneous Image-Guided Biliary Procedures

Percutaneous biliary interventions are among the commonly performed nonvascular radiological interventions. Most common of these interventions is the percutaneous transhepatic biliary drainage for malignant biliary obstruction. Other biliary procedures performed include percutaneous cholecystostomy, biliary stenting, drainage for bile leaks, and various procedures like balloon dilatation, stenting, and large-bore catheter drainage for bilioenteric or post-transplant anastomotic strictures. Although these procedures are being performed for ages, no standard guidelines have been formulated. This article attempts at preparing guidelines for performing various percutaneous image-guided biliary procedures along with discussion on the published evidence in this field.

The Exploration of a Novel Biodegradable Drug-Eluting Biliary Stent: Preliminary Work

PURPOSE

To explore the degradation, drug release, and mechanical properties of drug-incorporated films made of different ratios of poly(lactic-co-glycolic acid) (PLGA) and different amounts of paclitaxel (PTX), which may serve as the material platform for the manufacturing of biodegradable drug-eluting biliary stents.

MATERIALS AND METHODS

PLGA of different lactic acid/glycolic acid ratios (50/50, 70/30, and 80/20) and 0%, 10, 20, and 30% weight by weight (w/w) PTX was mixed to make PLGA films, which were then cut into small pieces for further testing. Films were immersed in phosphate-buffered saline (pH 7.4) for a maximum of 11 weeks. Samples were taken randomly at Day 2, 4, 6, 8, 10, 12, 14, and weekly thereafter until Week 11 to test tensile strength, weight loss, pH value of the soaking solution, and drug release. The morphology of films was observed using scanning electron microscope (SEM).

RESULTS

At Week 10 of degradation, PLGA 80/20 still withstood a tensile strength of 9.7 newton (N), while PLGA 50/50 and 70/30 cracked spontaneously since Day 4. At Week 11, weight loss of PLGA 50/50, 70/30, and 80/20 was 95.15, 82.32, and 16.17%, respectively; and the lowest pH value of soaking solution was 1.87, 1.95, and 6.58, respectively. Drug release of 10, 20, and 30% PTX groups was 3.52-4.48%, 1.90-2.26%, and 1.44-2.06%, respectively. SEM proved smooth films before degradation; however, after the tensile strength was lost, cracks could be seen.

CONCLUSION

The degradation rate of PLGA can be controlled by altering lactic acid/glycolic acid ratio. Overall, PLGA 50/50 and 70/30 degrade significantly faster than 80/20. PLGA can serve as an effective drug carrier for PTX while being the stent strut, and PTX can be slowly released as PLGA degrades.