Biomedical subjects

Keiji Igaki

Publications and source records attributed to Keiji Igaki.

3 recordsLinked to original sources

PubMed2004

New tubular bioabsorbable knitted airway stent: feasibility assessment for delivery and deployment in a dog model.

PURPOSE: The aim of this study was to determine whether it is possible to deliver and deploy a new device, a poly-L-lactic acid (PLLA) tubular knitted airway stent, under bronchoscopic guidance in a dog model. DESCRIPTION: The delivery system consisted of a flexible balloon catheter (controlled radial expansion balloon dilator, M00558440, Boston Scientific Corporation, MA, USA) preloaded with a stent. A delivery catheter preloaded with a stent was advanced to a target point in the trachea under bronchoscopic guidance. Once the stent was positioned, the balloon was inflated for sixty seconds. The stent was in full contact with the tracheal wall upon deflation of the balloon. EVALUATION: The stents were successfully delivered into the tracheal lumen and successfully deployed in all dogs. CONCLUSIONS: This is the first study to prove the feasibility of delivering and deploying the PLLA stents in a dog model, using a balloon expansion technique. Further investigation with large numbers of subjects and long-term follow-up will be necessary to assess the utility of the bioabsorbable knitted tubular stent before clinical applications begin.

Absorbable Implants↗

PubMed2003

Biodegradable stents as a platform to drug loading.

Despite technical and mechanical improvement in coronary stents the incidence of restenosis caused by in-stent neointimal hyperplasia remains high. Oral administration of numerous pharmacological agents has failed to reduce restenosis after coronary stenting in humans, possibly owing to insufficient local drug concentration. Therefore, drug-eluting stents were developed as a vehicle for local drug administration. The authors developed a new drug-eluting polymer stent that is made of poly-l-lactic acid polymer mixed with tranilast, an anti-allergic drug that inhibits the migration and proliferation of vascular smooth muscle cells induced by platelet-derived growth factor and transforming growth factor->1. Polymer stents might be superior to polymer-coated metallic stents as local drug delivery stents in terms of biodegradation and the amount of loaded drug. Drug-mixed polymer stents can be loaded with a larger amount of drug than can drug-coated metallic stents because the polymer stent struts can contain the drug. Clinical application is required to assess the safety and efficacy of drug-eluting polymer stents against stent restenosis.

Absorbable Implants↗

PubMed2001

Biodegradable Polymeric Stents.

To overcome several problems of conventional metallic stents, 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-l-lactic acid (PLLA) showed high biocompatibility with minimal inflammatory response and neointimal formation in porcine coronary arteries. Therefore, PLLA materials are more likely to cover the specific need for human coronary arteries in terms of biodegradation period and scaffolding ability over 6 months. 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.

Journal Article↗