Researchers based in China and Switzerland have jointly developed electrically conductive artificial blood vessels that may serve as implants to replace diseased native vessels. The flexible and biodegradable constructs consist of a metal-polymer conductive membrane, and an electric current can be passed through the vessel when it is implanted in the body. The electric stimulation appears to encourage the proliferation and migration of endothelial cells, and may improve the integration of the implanted vessel with the surrounding tissue. It can also be used to deliver gene therapy or drugs into those tissues. Developing artificial replacements for diseased blood vessels is an active area of research within tissue engineering, especially given the huge toll that cardiovascular disease has on society. However, these constructs are typically passive in nature and can provoke inflammation in surrounding tissues, and so far they have not been able to adequately and safely replace native blood vessels. “None of the existing small-diameter tissue engineered blood vessels has met the demands of treating cardiovascular diseases,” said Xingyu Jiang, a researcher involved in creating the new devices. The aim of this research was to create an artificial blood vessel with increased functionality, in the hope that this might make it more suitable for long-term implantation as a blood vessel replacement. “We take the natural blood vessel-mimicking structure and go beyond it by integrating more comprehensive electrical functions that are able to provide further treatments, such as gene therapy and electrical stimulation,” explained Jiang. The new artificial blood vessels consist of a cylindrical membrane that contains metal and a polymer, poly(L-lactide-co-ε-caprolactone). Strikingly, the electrical charge delivered by the construct can stimulate the migration and growth of endothelial cells, which should be helpful in allowing the vessels to integrate with the body. The researchers also tested the vessels in their ability to deliver genetic material, since an electrical charge can help to make cell membranes more permeable, allowing DNA and RNA to enter them. When coupled with an electroporation device, the membrane successfully delivered genetic material into three different types of cells found in blood vessels. So far, the artificial blood vessels have been tested in rabbits and they functioned as a successful replacement for the carotid artery. The implanted constructs allowed sufficient blood flow, did not produce an inflammatory response, and did not show evidence of narrowing over a period of three months. “In the future, optimizations need be taken by integrating it with minimized devices, such as minimized batteries and built-in control systems, to make all the functional parts fully implantable and even fully bio-degradable in the body,” said Jiang. Source
