| Background:Stent polymer affects the incidence of stent thrombosis (ST). Permanent polymeric coatings are applied by current FDA approved drug eluting stent (DES), which may contribute to chronic vessel wall inflammation. Poly-L-lactic acid (PLLA) degrades into carbon dioxide and water after implantation into coronary arteries. Film of chitosan/heparin layer-by-layer self assembly coating (C/H LBL) possesses the property of prohealing.Objective:To investigate the biocompatibility of polyethylene-co-vinyl acetate (PEVA), poly-n-butyl methacrylate (PMBA), PLLA, C/H LBL and poly-vinylidene fluoride (PVDF)+hexafluoropropylene (HFP) as well as blank control.Methods:Coatings of PEVA, PBMA, PLLA, C/H LBL and PVDF+HFP were prepared. PT and APTT were measured after whole blood was cultured with different coating materials. Platelet adhersion was tested by co-culture of platelet rich plasma and coating materials. Smooth muscle cells (SMC) and human unbillical vein endothelial cells (HUVEC) were seeded separately into the glass dish. Morphorlogy of cells was recored under invert microscopy at day1,3and7.Results:Hemocompatibility assessment of coating materials showed no difference regarding PT (22-25s, P=0.334) among6groups while APTT was prolonged. Containing heparin, APTT of C/H LBL was the longest (147.07±16.9s, P<0.0001). Platelet adhersion of PEVA (21.82±2.22%at30min,37.36±2.51%at60min and53.56±1.82%at120min) and PBMA (30.92±4.65%at30min,38.88±3.63%at60min and51.38±1.18%at120min) was higher than other4groups at the respective time point. Besides blank control, all5coating materials showed excellent cellular biocompatibility. SMC and HUVEC could easily be cultured on the dfferent polymer.Conclusions:Coating materials of PEVA, PMBA, PLLA, C/H LBL and PVDF+HFP showed exellent hemo-and cellular biocompatibility. Background:First generation drug-eluting stent (DES) was based on316L stainless steel and coated with permanent polymer. Current DES was blamed of vessel wall inflammatory and late in-stent thrombosis. Cobalt chromium based DES provides similar radial strength with thinner thickness of struts. Bioabsorbable poly-L-lactic acid (PLLA) serves as polymer and degrades into carbon dioxide and water after implantation into coronary arteries.Objective:The purpose of this study was to evaluate the safety and efficacy of cobalt chromium alloy based sirolimus-eluting stent with bioabsorbable polymer in porcine model.Methods:Cobalt chromium based DES with bioabsorbable polymer, eluting sirolimus from PLLA matrix (Simrex stent) as well as control stent (Polymer stent and EXCEL stent) was implanted into porcine coronary arteries. At4,12and24week follow-up, angiography was performed. Based on angiograms, quantitative coronary angiography (QCA) analysis was carried out to detect differences of minimal luminal diameter (MLD), late loss (LL) and percentage of diameter stenosis (%DS) among three groups. Histomorphometry was performed to detect differences of average luminal area (LA), neointima area (NA), internal elastic membrane area (IEMA) and percentage of area stenosis (%AS) among three groups. The extent of re-endothelialization was measured electron-microscopically. Inflammation and injury scores were designed to investigate inflammatory reaction and injury of stented vessel wall.Results:Fifty mini pigs were enrolled in this study. Total98stents (Simrex=40, EXCEL=30and Polymer=28) were harvested. At24th week angiographic follow-up, MLD, LL and%DS of Simrex was2.26±0.03mm,0.33±0.02mm and12.9±0.4%respectively; MLD, LL and%DS of EXCEL was2.28±0.05mm,0.33±0.03mm and12.5±1.4%; MLD, LL and%DS of Polymer was1.34±0.02mm、1.21±0.04mm'47.6±0.9%. Histomorphometrically follow-up at24th week, LA, NA, IEMA and%AS of Simrex was4.3±0.3mm2,1.4±0.4mm2,5.7±0.2mm2and24.5±4.2%respectively; LA, NA, IEMA and%AS of EXCEL was3.9±0.3mm2,1.5±0.4mm2,5.4±0.2mm2and27.7±5.6%; LA, NA, IEMA and%AS of Polymer was3.0±0.4mm2,2.6±0.4mm2,5.6±0.3mm2and46.4±7.8%. No significant difference was detected between Simrex and commercialized EXCEL stent. Slight inflammatory reaction existed around stent strut of Simrex, just the same as the other two groups. Electron-microscopically follow-up suggested that it might take4to12weeks for Simrex to complete its re-endothelialization process. No thrombosis-related events were observed in all three groups during the study.Conclusions:Cobalt chromium based, bioabsorbable polymer coated sirolimus-eluting stent (Simrex stent) showed excellent biocompatibility. During24weeks observation in porcine model, it was proved that this novel DES system successfully inhibited neointima hyperplasia and decreased in-stent stenosis without sever inflammation and thrombosis. It took4to12weeks for Simrex to complete its re-endothelialization process. Background: As newly developed coronary stent, bioabsorbable poly-L-lactic acid (PLLA) scaffold still encountered concern of acute stent recoil.Objective: To investigate acute recoil of bioabsorbable poly-L-lactic acid (PLLA) scaffold.Methods:PLLA based XINSORB scaffolds (PLLA as backbone, PLLA/PDLA as polymer with sirolimus eluted from the matrix; designed and fabricated by Weite Biotechnology, China) and316L stainless steel based EXCEL stent (JIWEI, China) were implanted into porcine coronary arteries randomly. Upon quantitative coronary angiography (QCA) analysis, acute absolute recoil was defined as the difference between mean diameter of inflated balloon (X, mm) and mean lumen diameter of stent immediately after deployment (Y, mm), while acute percent recoil was defined as (X-Y)/X and expressed as a percentage. Intravascular ultrasound (IVUS) was performed immediately after implantation and24hours later to compare cross-sectional area (CSA) between two groups and detect stent malapposition or collapse for both two kinds of stent.Results:Eight mini pigs were enrolled in our study. Total16stents (XINSORB=8and EXCEL=8) were implanted into porcine coronary arteries. Acute absolute recoil in XINSORB and EXCEL was0.02±0.13mm and-0.08±0.08mm respectively (P=0.19). Acute percent recoil in XINSORB and EXCEL was0.66±4.32%and-1.4±3.83%respectively (P=0.45). Distal, middle and proximal CSA of XINSORB immediately after implantation was6.96±0.46mm2,6.95±0.50mm2and7.05±0.62mm2respectively. That of EXCEL was7.04±0.24mm2,7.07±0.31mm2and7.18±0.36mm2, without difference in comparison to XINSORB scaffold. Distal, middle and proximal CSA of XINSORB24hours later after implantation was6.99±0.06mm2,6.97±0.06mm2and7.01±0.08mm2respectively. That of EXCEL was7.02±0.05mm,7.02±0.07mm2and7.07±0.07mm2, without difference in comparison to XINSORB scaffold. Within XINSORB group, no statistical difference existed between CSA after implantation and CSA at24hours follow-up. No sign of acute stent malapposition was detected by IVUS.Conclusions:The acute stent recoil of XINSORB is similar to that of EXCEL, implying the same radial strength between these two kinds of stents. No acute stent malapposition or collapse appeared in both two kinds of stent. This preclinical study was designed to provide preliminary data for future studies of long-term efficacy and safety of XINSORB scaffold. Background:Optical coherence tomography (OCT) is kind of coronary imaging technology with high resolution. OCT can be used to assess the efficacy and degradation process of poly-L-lactic acid (PLLA) scaffold. In this study, XINSORB scaffolds (fully bioabsorbable poly-L-lactic acid (PLLA) sirolimus-eluting scaffold, designed and fabricated by Shanghai Weite Biotech, CO.; Ltd.) along with316L stainless steel based EXCEL stent (purchased from Shangdong Jiwei CO.; Ltd.) were implanted into porcine coronary arteries.Obejective:This study was designed to assess short-term efficacy of XINSORB scaffold by OCT and histomorphometry in procine model.Methods:XINSORB scaffolds and EXCEL stents were randomly implanted into porcine coronary arteries. One vessel admitted only one stent. At1month follow-up, angiography, OCT, histomorphometry and electron-scanning microscopy were performed as well as injury and inflammation scores. Upon quantitative coronary angiography (QCA), minimal luminal diameter (MLD), late loss (LL) and percentage of diameter stenosis (%DS) were calculated and compaired between two groups. OCT was carried out using two methods to detect differences of stent/scaffold area (SA), luminal area (LA), strut core area (SCA), neointima area (NA), neointima thickness (NT) and percentage of area stenosis (%AS) as well as sign of late stent malapposition and stent thrombosis (ST). Based on four kinds of special images, biodegradation process of PLLA struts could be analyzed. Histomorphometry was performed to detect differences of average luminal area (LA), internal elastic membrane area (IEMA), external elastic membrane area (EEMA), neointima area (NA) and percentage of area stenosis (%AS). Basesd on pathologicalclassification of PLLA struts, biodegradation process of PLLA struts could also be confirmed and compaired with corresponding OCT images. The extent of re-endothelialization was measured electron-microscopically. Inflammation and injury scores were designed to investigate inflammatory reaction and injury of stented vessel wall.Results:Eight mini pigs were enrolled in this study. Total sixteen stents (XINSORB=8and EXCEL=8) were implanted into porcine coronary arteries. At1month angiographic follow-up, MLD, LL and%DS of XINSORB were1.97±0.23mm,1.02±0.25mm and19±9%respectively, without difference in comparison to EXCEL. No sign of late stent malapposition and ST was detected under OCT. According to ABSORB study, SA, LA, SCA, NA, NT and%AS of XINSORB were8.51±0.38mm2,6.54±0.66mm2,0.36±0.08mm2,1.43±0.57mm2,0.29±0.06mm and16.92±6.81%respectively. All except LA were significantly higher in XINSORB group than EXCEL. According to Gomez-Lara J et al., SA, LA, NA, NT and%AS of XINSORB were7.07±0.29mm2,6.54±0.66mm2,0.79±0.23mm2,0.16±0.07mm and10.30±2.98%respectively. All except NA of XINSORB were similar to that of EXCEL. At1month follow-up,98.0%of XINSORB struts appeared preserved box. Histomorphometrically follow-up, LA, IEMA, EEMA, NA, NT and%AS of XINSORB were4.79±0.48mm2,5.69±0.47mm2,7.36±0.47mm2,0.89±0.27mm2,110.85±34.20μm and15.73±4.59%respectively, without no statistical differences compared with EXCEL. All XINSORB struts analyzed were classified as categlory1, appearing preserved box in corresponding OCT images. Slight inflammatory reaction and vessel injury existed around struts of XINSORB, just the same as the other group. Electron-microscopically follow-up suggested that delayed re-endothelialization on both XINSORB and EXCEL struts, although90%of surface of XINSORB scaffold was covered by endothelial cells between struts.Conclusions:Fully bioabsorbable PLLA sirolimus-eluting scaffold (XINSORB) suppressed neointima hyperplasia and decreased in-stent stenosis as effectively as EXCEL stent at1month after implantation. OCT and histopathology showed most of XINSORB struts remained out of biodegradation process yet. Slight inflammatory reaction and vessel injury existed around struts of XINSORB. Endothelium poorly covered on struts surface of XINSORB scaffold except regions bwtween struts. |
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