The coronary artery disease (CAD) is caused by the build-up of atherosclerotic plaques inside the coronary arteries, remains the leading cause of mortality worldwide and accounts for over 4 million deaths per year, close to half of all deaths in Europe. Percutaneous coronary intervention (PCI) is the most widely performed procedure for the treatment of symptomatic coronary disease. Coronary stents allowed PCI to diffuse worldwide and revolutionized the treatment of arterial disease. Impressive engineering innovation and clinical expertise have made possible to routinely deliver stents in narrowed coronary arteries, such that these tubular structures are expanded into atherosclerotic plaques and recover the arterial flow of the dangerously restricted arteries. In 2011, the global market of coronary stent devices reached approximately €7.1 billion with a prediction of approximately €15.2 billion by the end of 2024. Based on clinical outcomes, the rate of stent implantation failure is more than 4% of the total stenting procedures. Given the billions of stent deployment procedures, being carried out worldwide, even rates of complications in low single digit percentages of the total, represent a large number of patients. Metallic coronary stents have revolutionized the management of coronary artery disease. Over the last years, bare metal stents (BMS) eliminated acute vessel closure and reduced the incidence of restenosis. The advent of stent complications, including ST and ISR, prompted the development of drug-eluting stents (DES), which, although a major advance, unfortunately proved to be less than a “pure cure”, reducing ISR, but not eliminating ST.
The advent of drug-eluting BVS have emerged as a potential major breakthrough for treatment of coronary artery lesions. In principle, the need for vessel scaffolding and drug delivery is temporary, rendering a permanent stent superfluous once the vessel has healed and the processes of recoil and hyperplasia have ended. Conventional permanent stent implantation precludes future surgical revascularization, complicates recrossing into side branches, eliminates reactive vasomotion, impairs noninvasive imaging, and exposes patients to the risk of very late thrombosis. These long-term limitations of conventional stents may be overcome to a degree by using drug-eluting BVS. However, today, the only conclusive (and accepted) way to ensure the safety and efficacy of a drug-eluting BVS is to test it in the laboratory (in vitro), and then on living organisms, initially on animals (in vivo) and then on humans (clinical evaluation/trial). The in vitro mechanical testing represents, among other, the testing of the constituent permanent metals and polymers, the compression and flexural testing, as well as the pulsatile durability testing. The preclinical evaluation process is an essential step in the development of drug-eluting BVS. Although clinical trial methodology and practice have improved tremendously over the last years, this approach has left many key issues unmet.
Due to the hugely complex nature of human diseases, there is a significant difference between individuals, and an inevitable variability in anatomy and pathology of the treated arteries. Therefore, it is quite usual that a drug-eluting BVS performs exceptionally well in controlled laboratory experiments and pre-clinical studies, but presents several issues (failure, ISR, ST) during or after clinical trials. In addition, whilst clinical trials may provide insights related to the safety or effectiveness of the drug-eluting BVS, in case of failure during clinical trials, it may be abandoned, even if a small modification and improvement would solve the issue. This mainly leads in an “all-or-nothing” mind-set in the Stent Biomedical Industry, where the objective of the research and development investment virtually asks from the biomedical company to focus only on how to reduce the risk of the drug-eluting BVS. This in turn strangles innovation, decreases the number of new drug-eluting BVS presented to the market every year, while in parallel increases the development costs. One has to agree that there is ample room for improving the complete development chain of drug-eluting BVS and introduce alternatives to reduce the animal and human testing, while address the issue of imperfections of predictions of in vitro and in vivo studies.
During last decade, there has been a huge investment in information technology and in-silico modelling for the development of biomedical products. In-silico technologies are of great value, and could answer several difficult questions, such as: “Why do some patients react adversely to the implantation of a drug-eluting BVS, while others not?” InSilc will provide the ability to evaluate how drug-eluting BVS affect individual patients and address this individual variability.