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Small-diameter vascular grafts

Despite recent advances in secondary prevention and the introduction of less invasive interventions such as percutaneous transluminal angioplasty, the surgical vascular replacement remains an important therapeutic option in the treatment of ischemic heart and peripheral vascular disease.

Autologous vascular grafts, currently the most suitable substitute for occluded small caliber blood vessels, are often unavailable because of concomitant disease or previous use. Although intensive research has been conducted in recent decades to improve the patency rates of synthetic vascular grafts through the use of new biomaterials and surface modifications, these replacement materials have not yet been able to match the performance of patient-derived tissue. In our research group, we are trying to develop small lumen vascular prostheses with improved long-term function through different strategies.

Ongoing Projects

The currently available synthetic prostheses made of Dacron or ePTFE show excellent long-term results in the reconstruction of large caliber arteries. However, small caliber implants often fail due to their surface thrombogenicity when used in blood vessels with low blood flow. Another limitation to successful long-term use of synthetic vascular prostheses is the development of intimal hyperplasia due to different biomechanical properties of the implant and host vessel in the patient.
Our research focuses on new biodegradable thermoplastic polyurethanes suitable for "in situ tissue engineering" as they have good mechanical properties and excellent biocompatibility. In collaboration with the Institute of Applied Synthetic Chemistry at TU Wien (R. Liska, S. Baudis, K. Ehrmann) and the Center for Biomedical Physics and Biomedical Engineering at Med Uni Wien (H. Schima, C. Grasl, M. Stoiber), small diameter vascular implants consisting of new polymer candidates are developed by electrospinning. In addition, approaches to modify blood-contacting surfaces are being investigated to improve the function of the implants.

Functionalized vascular prostheses capable of releasing a therapeutic agent in a controlled manner are currently being intensively investigated. These substances could modulate undesirable effects of the synthetic material and thus improve the long-term function of implants. The active ingredients are incorporated into polymer- or hydrogel-based constructs in various formulations and particle sizes (down to the nano- to micrometer scale).