Technology will make it possible to obtain customized implantable devices, with controlled release of a vasodilator substance from a new polymeric material
Marcelo Ganzarolli de Oliveira, Matheus Fernandes de Oliveira and Laura Escobar da Silva, researchers at the Unicamp Chemistry Institute, developed a photocurable polymeric material (resin) that allows implantable medical devices to be obtained by 3D printing. The material also allows the local release, by the stent, of nitric oxide (NO), a vasodilator substance.
The technology, which already has a patent application filed by Inova Unicamp at the National Institute of Industrial Property (INPI), solves some of the major problems with stent-type cardiac implants – small expandable tubular meshes that aim to restore blood flow, preventing heart attacks. “Stents are used to unblock coronary arteries blocked by atherosclerotic plaques that cause deficient irrigation of the heart muscle. Initially, they were entirely metallic, but it was found that, some time after implantation, a significant percentage of cases resulted in reocclusion of the artery, due to a scarring response to the implant itself”, says Ganzarolli de Oliveira.
This problem was largely resolved with the development of stents covered with polymers that release drugs. However, it was found that blood contact with the polymeric surface could induce late thrombus formation. “There was a need to improve this technology”, observes the researcher. Studies related to intracoronary prostheses have been carried out for more than 20 years by the research group of Professor Marcelo Ganzarolli de Oliveira.
Use of nitric oxide
Given this scenario, researchers saw nitric oxide (NO) as a promising path, since this small molecule exerts several beneficial actions, such as inhibiting thrombus formation, dilation of blood vessels, stimulating the regeneration of the vascular endothelium - the cell layer that coats the inside of blood vessels - and blocks the proliferation of smooth muscle cells, which end up clogging the artery again. Therefore, they developed metallic stents covered with polymers that release NO.
However, not everything was resolved: when the NO stock ran out, the polymer alone could induce thrombus formation. “Our next step was to develop an absorbable polymer stent that releases NO and can be implanted. To achieve this, we synthesize elastic polyesters that undergo hydrolytic degradation processes, generating monomers, which are absorbed and removed from the site by cells of the immune system, and which, ideally, will disappear completely at some point”, explains Marcelo Ganzarolli.
Production of stents using 3D printers
The development of the special resin allowed the use of 3D printers, based on the photocrosslinking of the polymer, allowing the manufacture of stents with a photocurable polymeric material. In this structure, the release of NO continues for a long period, at the same time that hydrolytic degradation of the polyester occurs, a chemical reaction that slowly dissolves the stent. Thus, the polymeric stent has the advantage of disappearing after fulfilling its function, being completely absorbed by the body. This is a benefit of direct interest to the medical products industry, especially the pharmaceutical industry focused on coronary implants.
Original article published on the Unicamp Inova Innovation Agency website.
