A novel drug-eluting stent using bioabsorbable polymer technology: Two-year follow-up of the CURAMI registry

Surface engineering and the application of laser-based processes to stents - A review of the latest development

Late in-stent thrombus and restenosis still represent two major challenges in stents’ design. Surface treatment of stent is attracting attention due to the increasing importance of stenting intervention for coronary artery diseases. Several surface engineering techniques have been utilised to improve the biological response in vivo on a wide range of biomedical devices. As a tailorable, precise, and ultra-fast process, laser surface engineering offers the potential to treat stent materials and fabricate various 3D textures, including grooves, pillars, nanowires, porous and freeform structures, while also modifying surface chemistry through nitridation, oxidation and coatings. Laser-based processes can reduce the biodegradable materials' degradation rate, offering many advantages to improve stents’ performance, such as increased endothelialisation rate, prohibition of SMC proliferation, reduced platelet adhesion and controlled corrosion and degradation. Nowadays, adequate research has been conducted on laser surface texturing and surface chemistry modification. Laser texturing on commercial stents has been also investigated and a promotion of performance of laser-textured stents has been proved.

In this critical review, the influence of surface texture and surface chemistry on stents performance is firstly reviewed to understand the surface characteristics of stents required to facilitate cellular response. This is followed by the explicit illustration of laser surface engineering of stents and/or related materials. Laser induced periodic surface structure (LIPSS) on stent materials is then explored, and finally the application of laser surface modification techniques on latest generation of stent devices is highlighted to provide future trends and research direction on laser surface engineering of stents.

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Compared conventional surface engineering with laser-based methods for biomedical devices.

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Explained the influence of texture geometry and surface chemistry on stents biological response.

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Reviewed state of the art in laser surface engineering of stents for improved biological response.

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Reviewed state of the art in laser surface engineering to control degradation of bioresorbable stents.

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Highlighted novel laser surface engineering designs for improved stents'performance.

Clinical performance of drug-eluting stents with biodegradable polymeric coating: a meta-analysis and systematic review

AIMS

Different biodegradable-polymer drug-eluting stents have not yet been systematically analysed. We sought to; 1) evaluate the risk of target lesion revascularisation (TLR) and definite stent thrombosis (DST) among different groups of biodegradable-polymer (BioPol) DES, and 2) to compare them with permanent polymer (PermPol) DES.

METHODS AND RESULTS

We searched PubMed and relevant sources from January 2005 until October 2010. Inclusion criteria were (a) Implantation of a drug-eluting stent with biodegradable polymer; (b) available follow-up data for at least one of the clinical end-points (TLR/DST) at short term (30 days) and/or mid-term (one year). A total of 22 studies, including randomised and observational studies, with 8264 patients met the selection criteria; nine studies (2042 patients) in whom biodegradable-polymer sirolimus eluting stents (BioPol-SES) were implanted, eight studies (1731 patients) in whom biodegradable-polymer paclitaxel eluting stents (BioPol-PES) were implanted, and seven studies (4491 patients) in whom biodegradable-polymer biolimus-A9 eluting stents (BioPol-BES) were implanted. At 30 days, there was a higher risk of DST (p=0.04) and subsequently TLR (p=0.006) in the BioPol-BES compared to BioPol-SES, with no significant difference in the other stent comparisons. At 1-year, there was higher risk of TLR in the BioPol-PES (p=0.01), and the BioPol-SES (p=0.04) compared to BioPol-BES. One-year stent thrombosis was not statistically different between the studied groups (overall p=0.2). In another analysis comprising seven randomised trials comparing BioPol-DES (3778 patients) and PermPol-DES (3291 patients), the risks of TLR and stent thrombosis at 1-year were not significantly different (p=0.5 for both).

CONCLUSIONS

Performance of different BioPol-DES seems to vary from each other. The short- and mid-term success rates may not be superimposable. Furthermore, they may not be necessarily better than PermPol-DES.

Preparation of porous PLGA microspheres with thermoreversible gel to modulate drug release profile of water-soluble drug: bleomycin sulphate

Bleomycin sulphate-loaded porous microspheres were prepared using modified solvent evaporation method (w/o/w) using PLGA50:50 as a polymeric system. The prepared microspheres were incorporated in pluronic (F127) based thermoreversible gel to develop a depot formulation. Various process parameters as solvent evaporation temperature and formulation parameters such as surfactant concentration, volume of internal and external phase and drug-to-polymer ratio were optimized for enhancing percentage drug entrapment, percentage drug loading and desired release profile by controlling size and porosity of the microspheres. Microspheres were characterized for particle size, zeta potential, surface morphology, percentage drug loading and in vitro drug release study after incorporated in gel. The formulated microspheres were porous in nature and showed biphasic in vitro drug release profile. The microspheres incorporated in pluronic (F127) gel showed sustained release up to 1 week and may be useful for treatment of squamous cell carcinoma with better therapeutic effect.

Two-year clinical registry follow-up of endothelial progenitor cell capture stent versus sirolimus-eluting bioabsorbable polymer-coated stent versus bare metal stents in patients undergoing primary percutaneous coronary intervention for ST elevation myocardial infarction

BACKGROUND

Endothelial progenitor cell (EPC) capture stent is designed to promote rapid endothelization and healing and is potentially useful in patients undergoing primary percutaneous coronary intervention (PCI) for acute myocardial infarction (AMI). We studied the intermediate-term efficacy and safety of EPC stent and compared that with sirolimus-eluting bioabsorbable polymer stent (CURA) and bare metal stent (BMS) in AMI patients.

METHODOLOGY

Patients presenting with AMI who underwent primary PCI with the respective stents between January 2004 and June 2006 were enrolled in the single-center clinical registry. The study end-points were major adverse cardiac events (MACE) and stent thrombosis.

RESULTS

A total of 366 patients (EPC = 95, CURA = 53, BMS 218) were enrolled. Baseline demographics including age, gender, diabetes, renal impairment, predischarge left ventricular ejection fraction, and creatinine kinase level were comparable among the groups. Procedural success rate was 99.5%. Post-procedural thrombolysis in myocardial infarction (TIMI) 3 flow was achieved in EPC 91.6%, CURA 96.2%, and BMS 88.5% (P = 0.209). At 2 years, the MACE rate was EPC 13.7%, CURA 15.1%, and BMS 19.7% (P = 0.383). Target vessel revascularizations (TVR) were EPC 4.2%, CURA 9.4%, and BMS 6.0% (P = 0.439). Nonfatal myocardial infarctions were EPC 1.1%, CURA 3.8%, and BMS 4.1% (P = 0.364). One patient in the EPC group had acute stent thrombosis. There was no late stent thrombosis in the EPC group.

CONCLUSION

EPC stent appeared to be safe and had comparable clinical efficacy with a BMS when used in the AMI setting. At 2-year follow-up, the EPC group showed favorable, single-digit TVR rate and stent thrombosis remained a low-event occurrence.