In vivo degradation and endothelialization of an iron bioresorbable scaffold

Detection of in vivo biodegradation is critical for development of next-generation medical devices such as bioresorbable stents or scaffolds(BRSs).In particular,it is urgent to establish a nondestructive approach to examine in vivo degradation of a new-generation coronary stent for interventional treatment based on mammal experiments;otherwise it is not available to semi-quantitatively monitor biodegradation in any clinical trial.Herein,we put forward a semi-quantitative approach to measure degradation of a sirolimus-eluting iron bioresorbable scaffold(IBS)based on optical coherence tomography(OCT)images;this approach was confirmed to be consistent with the present weight-loss measurements,which is,however,a destructive approach.The IBS was fabricated by a metal-polymer composite technique with a polylactide coating on an iron stent.The efficacy as a coronary stent of this new bioresorbable scaffold was compared with that of a permanent metal stent with the name of trade mark Xience,which has been widely used in clinic.The endothelial coverage on IBS was found to be greater than on Xience after implantation in a rabbit model;and our well-designed ultrathin stent exhibited less individual variation.We further examined degradation of the IBSs in both minipig coronary artery and rabbit abdominal aorta models.The present result indicated much faster iron degradation of IBS in the rabbit model than in the porcine model.The semi-quantitative approach to detect biodegradation of IBS and the finding of the species difference might be stimulating for fundamental investigation of biodegradable implants and clinical translation of the next-generation coronary stents.

Magnetic resonance (MR) safety and compatibility of a novel iron bioresorbable scaffold

Fully bioresorbable scaffolds have been designed to overcome the limitations of traditional drug-eluting stents(DESs),which permanently cage the native vessel wall and pose possible complications.The ultrathin-strut designed sirolimus-eluting iron bioresorbable coronary scaffold system(IBS)shows comparable mechanical properties to traditional DESs and exhibits an adaptive degradation profile during target vessel healing,which makes it a promising candidate in all-comers patient population.For implanted medical devices,magnetic resonance(MR)imaging properties,including MR safety and compatibility,should be evaluated before its clinical use,especially for devices with intrinsic ferromagnetism.In this study,MR safety and compatibility of the IBS scaffold were evaluated based on a series of well-designed in-vitro,ex-vivo and in-vivo experiments,considering possible risks,including scaffold movement,over-heating,image artifact,and possible vessel injury,under typical MR condition.Traditional ASTM standards for MR safety and compatibility evaluation of intravascular devices were referred,but not only limited to that.The unique time-relevant MR properties of bioresorbable scaffolds were also discussed.Possible forces imposed on the scaffold during MR scanning and MR image artifacts gradually decreased along with scaffold degradation/absorption.Rigorous experiments designed based on a scientifically based rationale revealed that the IBS scaffold is MR conditional,though not MR compatible before complete absorption.The methodology used in the present study can give insight into the MR evaluation of magnetic scaffolds(bioresorbable)or stents(permanent).

Two-stage degradation and novel functional endothelium characteristics of a 3-D printed bioresorbable scaffold

Bioresorbable scaffolds have emerged as a new generation of vascular implants for the treatment of atherosclerosis,and designed to provide a temporary scaffold that is subsequently absorbed by blood vessels over time.Presently,there is insufficient data on the biological and mechanical responses of blood vessels accompanied by bioresorbable scaffolds(BRS)degradation.Therefore,it is necessary to investigate the inflexion point of degradation,the response of blood vessels,and the pathophysiological process of vascular,as results of such studies will be of great value for the design of next generation of BRS.In this study,abdominal aortas of SD rats were received 3-D printed poly-l-actide vascular scaffolds(PLS)for various durations up to 12 months.The response of PLS implanted aorta went through two distinct processes:(1)the neointima with desirable barrier function was obtained in 1 month,accompanied with slow degradation,inflammation,and intimal hyperplasia;(2)significant degradation occurred from 6 months,accompanied with decreasing inflammation and intimal hyperplasia,while the extracellular matrix recovered to normal vessels which indicate the positive remodeling.These in vivo results indicate that 6 months is a key turning point.This“two-stage degradation and vascular characteristics”is proposed to elucidate the long-term effects of PLS on vascular repair and demonstrated the potential of PLS in promoting endothelium function and positive remodeling,which highlights the benefits of PLS and shed some light in the future researches,such as drug combination coatings design.

Restenosis of a drug eluting stent on the previous bioresorbable vascular scaffold successfully treated with a drug-coated balloon: A case report

BACKGROUND The in-stent restenosis(ISR)rates are reportedly inconsistent despite the increased use of second-generation drug eluting stent(DES).Although bioresorbable vascular scaffold(BVS)have substantial advantages with respect to vascular restoration,the rate of scaffold thrombosis is higher with BVS than with DES.Optimal treatment strategies have not been established for DES-ISR to date.CASE SUMMARY We report on a case of a 60-year-old man patient with acute coronary syndrome.He had a history of ST-segment elevation myocardial infarction associated with very late scaffold thrombosis and treated with a DES.Coronary angiography revealed significant stenosis,suggesting DES-ISR on the previous BVS.Optical coherence tomography(OCT)identified a plaque rupture and a disrupted scaffold strut in the neointimal proliferation of DES.To treat the DES-ISR on the previous BVS,we opted for a drug-coated balloon(DCB)after a balloon angioplasty using a semi-compliant and non-compliant balloon.The patient did not experience adverse cardiovascular events on using a DCB following the use of intensive dual antiplatelet therapy and statin for 24 mo.CONCLUSION This case highlights the importance of OCT as an imaging modality for characterizing the mechanism of target lesion failure.The use of a DCB following the administration of optimal pharmacologic therapy may be an optimal strategy for the treatment and prevention of recurrent BVS thrombosis and DES-ISR.

Vascular restoration therapy and bioresorbable vascular scaffold

This article describes the evolution of minimally invasive intervention technologies for vascular restoration therapy from early-stage balloon angioplasty in 1970s,metallic bare metal stent and metallic drug-eluting stent technologies in 1990s and 2000s,to bioresorbable vascular scaffold(BVS)technology in large-scale development in recent years.The history,the current stage,the challenges and the future of BVS development are discussed in detail as the best available approach for vascular restoration therapy.The criteria of materials selection,design and processing principles of BVS,and the corresponding clinical trial results are also summarized in this article.

Long-term safety and absorption assessment of a novel bioresorbable nitrided iron scaffold in porcine coronary artery

This study aimed to investigate the long-term biocompatibility, safety, and degradation of the ultrathin nitrided iron bioresorbable scaffold (BRS) in vivo, encompassing the whole process of bioresorption in porcine coronary arteries. Fifty-two nitrided iron scaffolds (strut thickness of 70 μm) and 28 Vision Co–Cr stents were randomly implanted into coronary arteries of healthy mini-swine. The efficacy and safety of the nitrided iron scaffold were comparable with those of the Vision stentwithin 52 weeks after implantation. In addition, the long-term biocompatibility, safety, and bioresorption of the nitrided iron scaffold were evaluated by coronary angiog-raphy, optical coherence tomography, micro-computed tomography, scanning electron microscopy, energy dispersive spectrometry and histopathological evaluations at 4, 12, 26, 52 weeks and even at 7 years after im-plantation. In particular, a large number of struts were almost completely absorbed in situ at 7 years follow-up, which were first illustrated in this study. The lymphatic drainage pathway might serve as the potential clearance way of iron and its corrosion products.

Structural and temporal dynamics analysis on drug-eluting stents: History, research hotspots and emerging trends

Purpose:This review aims to explore the history,research hotspots,and emerging trends of drug-eluting stents(DES)in the last two decades from the perspective of structural and temporal dynamics.Methods:Publications on DES were retrieved from WoSCC.The bibliometric tools including CiteSpace and HistCite were used to identify the historical features,the evolution of active topics,and emerging trends on the DES field.Results:In the last 20 years,the field of DES is still in the hot phase and there is a wide range of extensive scientific collaborations.In addition,active topics emerge in different periods,as evidenced by a total of 41 disciplines,511 keywords,and 1377 papers with citation bursts.Keyword clustering anchored five emerging research subfields,namely#0 dual antiplatelet therapy,#3 drug-coated balloon,#4 bifurcation,5#rotational atherectomy,and 6#quantitative flow ratio.The keyword alluvial map shows that the most persistent research concepts in this field are thrombosis,restenosis,etc.,and the emerging keywords are paclitaxel eluting balloon,coated balloon,drug-eluting balloon,etc.There are 7 recent research subfields anchored by reference clustering,namely#2 dual antiplatelet therapy,#4 drug-coated balloon,#5 peripheral artery disease,#8 fractional flow reserve,#10 bioresorbable vascular scaffold,#13 intravascular ultrasound,#14 biodegradable polymer.Conclusion:The findings based on the bibliometric studies provide the current status and trends in DES research and may help researchers to identify hot topics and explore new research directions in this field.