Transcatheter aortic valve replacement, as an increasing therapeutic intervention, is currently generating efforts to extend this concept to the mitral valve. Also, heart valve tissue engineering is adopting this minimally invasive approach. Our study reports on an absorbable stent structure for pediatric transcatheter mitral valve implantation (TMVI). Valve stent prototypes (size: 16 mm, targeted implantation profile: 15 Fr) were developed and manufactured from poly(L-lactide) (PLLA), and subjected to bench tests regarding radial and axial force. A radial force of 1.6 N at a diameter of 14.5 mm, and an axial retention force of 3.4 N (equiv. TVP = 128 mmHg) were observed. The present in vitro feasibility study gives insight into mechanical properties of a generic absorbable PLLA stent designed for regenerative pediatric TMVI.

Electrospun poly(L-lactide) (PLLA) nanofiber matrices represent potential options for cardiovascular tissue engineering. We performed uniaxial tensile tests, differential scanning calorimetry and scanning electron microscopy in order to investigate the mechanical, thermal and morphological properties of PLLA nanofiber matrices prepared with addition of different concentrations of the non-ionic surfactant Triton X-100. Our results show that this additive leads to substantial changes, e.g. lower crystallization of PLLA for higher surfactant concentrations. No significant differences in material properties were observed after ethylene oxide gas sterilization.

In this work, a novel test setup for bubble point determination of membranes is presented and tested. Different filtration systems were examined and compared with the manufacturer's information. Furthermore, a self-produced electrospun polyamide (PA 6) membrane was examined regarding its bubble point. Contact angle was measured and maximum pore size of the PA 6 membrane was calculated. Suitability of the setup for determining bubble point and the basis of calculation of maximum membrane pore size could be demonstrated.

In recent years novel implants in particular have already proven to contribute substantially to enhanced quality of life, higher efficacy of therapeutic approaches, as well as patient safety. With the purpose to optimize the implant-tissue interaction the focus of efforts is on implants with a controlled, site-selective drug release. Therefore, we develop within the REMEDIS consortium implant-associated local drug delivery (LDD) systems for different medical applications. Engineering and natural scientists together with medical experts from all over Germany work in close collaboration to develop such innovative implants which combine the function as medical device and as LDD system. These include vascular stents and stimulation electrodes for the circulatory system and the ears, glaucoma stents for the eyes as well as auditory tube stents for the ears. Through its efforts to combine a LDD system into the functionality of implants, REMEDIS provides cutting-edge research into such medical technology.

The scope of our studies was to evaluate to which extent nanoparticles incorporated in stent matrices are suitable for stent application regarding local drug delivery to prevent in-stent restenosis and visual enhancement of polymer stents trough incorporated nanoparticles as X-ray or magnetic resonance contrast agents. Nanoparticles used were polyamidoamine (PAMAM) dendrimers generation 4.0 (size approx. 4.5 nm) with different functional surface groups as well as silica nanoparticles (size approx. 70 nm) loaded with pharmaceuticals (disulfiram, sirolimus and ibuprofen) for drug delivery. Gold nanoparticles (size approx. 6 nm) were employed for visual enhancement studies. Nanoparticles were characterized by transmission and scanning electron microscopy. Biocompatibility studies were performed in vitro in cell culture tests (viability and proliferation). Nanoparticle ingestion into cells was tracked via dye loaded nanoparticles by confocal laser scanning microscopy.

Restenosis is one of the most frequent long-term complications after implantation of coronary stents. The scope of our studies was to evaluate to which extent Sirolimus-loaded poly(lactide) nanoparticles are suitable as delivery systems for stent application to prevent in-stent restenosis. Initially in vitro drug release kinetics studies and in vitro HCAEC and HCASMC cell culture tests were conducted. Nanoparticles of biodegredable poly(lactide) (PLA) were loaded with the pharmaceutical Sirolimus for drug delivery. Nanoparticles were characterized by scanning electron microscopy (size approx. 250 nm). The time course of Sirolimus release from Sirolimus loaded PLA nanoparticles was determined in medium at 37 °C by high performance liquid chromatography. Biocompatibility studies were performed in vitro in cell culture tests (viability and proliferation). Nanoparticle ingestion into cells was tracked via dye loaded nanoparticles by confocal laser scanning microscopy.