Biodegradable Stent Implantation Research Articles

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

Common biliary tract is ≈4mm 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.

Mechano Growth Factor (MGF) Expression and Response to Multiple-Mechanical Stimulation after Biodegradable Stent Implantation

Mechano Growth Factor (MGF) Expression and Response to Multiple-Mechanical Stimulation after Biodegradable Stent Implantation

Assessment of coronary bio-degradable stent by using coronary computed tomography angiography

Objective To investigate the possibility of showing coronary bio-degradable stent(BDS) and luminal stenosis by using coronary computed tomography angiography(CCTA). Methods A total of 27 consecutive patients who had undergone CCTA follow-up for BDS implantation were enrolled from January to June of 2015. The duration between CCTA and coronary BDS implantation was 1 year. The patients' age were (54±7) years in average. There were 18 male and 9 female patients. Of those patients, 18 BDS were implanted in left anterior descending coronary artery, and 9 in right coronary artery. Quantitative measurement of luminal stenosis, average areas of noncalcified and calcified plaque in proximal segment of stent (5 mm proximal to the stent), intra-stent, and distal segment of stent (5 mm distal to the stent) were performed and compared, using Kruskal Wallis as well as Mann-Whitney U tests. Results The mean length of BDS was (16.1±4.4) mm. Coronary diameter stenosis (%) of the proximal segment, intra-stent and distal segment to BDS were 14.4%(11.5%, 23.1%), 23.4%(17.4%, 27.4%), and 16.4%(12.7%, 24.1%), respectively(H=10.17,P 0.05). Conclusion CCTA could be used to assess coronary bio-degradable stent and luminal stenosis without affection of mental artifact. Intra-stent restenosis was more frequently observed than proximal and distal segments of the BDS. Key words: Coronary artery; Tomography, X-ray computed; Stent

Novel biodegradable stents in the treatment of bronchial stenosis after lung transplantation☆☆☆

To evaluate the safety and effectiveness of novel biodegradable (BD) stents to treat bronchial anastomotic stenosis in patients after lung transplantation. Twenty BD stents were implanted endoscopically in six patients (median age 41.5 years (range 35-57 years)) with post-transplant bronchial anastomotic stenoses, between 2006 and 2010. All stents were custom-made from bio-absorbable polydioxanone (PDS). The median stent diameter was 12 mm (8-17 mm) and median length was 20mm (12-30 mm). All patients were evaluated clinically, by bronchoscopy and high-definition computed tomography (CT). The stenosis was initially relieved in all cases. There was no bleeding, perforation or displacement after BD stent implantation. Four patients needed multiple stenting for anastomotic re-stenosis. Median time to any re-stenting was 5 months (2-15 months). There was one sudden death, 1 year after the last BD stent implantation, from a pulmonary embolus. All five survivors are in good clinical condition up to 4 years' follow-up (median 40 months, range 7-48 months) since first stenting and intervention-free up to 44 months (median 24 months, range 7-44 months). This small pilot study shows that BD stents are a safe, effective and reliable alternative to classical metallic stents in patients with anastomotic stenosis after lung transplantation, and may avoid the need for permanent stenting.

Early restenosis following biodegradable stent implantation in an aortopulmonary collateral of a patient with pulmonary atresia and hypoplastic pulmonary arteries

Traditionally, the implantation of stents in young children with small blood vessels has been avoided as the presence of a metallic or fixed stent structure limits the ability to further dilate the stent with vessel growth. Pulmonary atresia with ventricular septal defect and hypoplastic pulmonary arteries represents one such cohort where the placement of fixed nondegradable stents has been difficult. We report a 2-month-old girl with pulmonary atresia, VSD, and multiple aorto-pulmonary collaterals with severely hypoplastic pulmonary arteries who underwent placement of a biodegradable magnesium stent within a stenotic aorto-pulmonary collateral. Although there was an initial significant increase in vessel diameter, significant restenosis occurred 4 months after stent placement. This to our knowledge represents the first case of the use of biodegradable stents in a child with severely hypoplastic pulmonary arteries. Although further refinements in stent technology are required, this development will hopefully usher in a new era of potential intervention in children previously deemed unsuitable for stent placement.

Experimental and Clinical Studies of Biodegradable Polymeric Stents

The metallic stent has become the most common device to reduce acute occlusion and late restenosis after balloon angioplasty, but the long-term effects of metallic stents in human coronary arteries are still unknown. To overcome several problems of conventional stenting, there have been many attempts to manufacture stents made of biodegradable materials. Although some studies have noted various degrees of inflammatory responses after biodegradable stent implantation, stents made of poly-1-lactic acid (PLLA) showed high biocompatibility with minimal inflammatory response and neointimal formation in porcine coronary arteries. A clinical study of PLLA self-expanding stent implantation is underway in Japan. The initial and 6-month results are favorable and suggest the feasibility, safety, and efficacy of the PLLA biodegradable stent in humans. However, long-term follow-up with larger numbers of patients will be required to validate the long-term efficacy of PLLA stents.