Strategies for surface coatings of implantable cardiac medical devices

Impact of coverage and guest residue on polyproline II helix peptide antifouling

Polyproline II (PPII) peptide sequences are recognized as promising biomaterials because of their attractive antifouling properties. However, the mechanisms behind their antifouling behavior have not been fully characterized. In this work we show that PPII peptide coverage, controlled by adsorption time, significantly reduces the fouling of bovine serum albumin (BSA, a model foulant). In addition, guest residues introduced into the PPII sequence are shown to significantly impact BSA adsorption as well as human mesenchymal stem cell (hMSC) spreading. This research will help guide future PPII peptide designs for incorporation into novel biomaterials.

Graphical abstract

A guest residue system was utilized to understand properties that impact the ability of polyproline II helix peptide monolayers to resist the fouling of BSA and influence human mesenchymal cell spreading.

Supplementary Information

The online version contains supplementary material available at 10.1557/s43579-024-00674-w.

Design and Characterisation of a Read-Out System for Wireless Monitoring of a Novel Implantable Sensor for Abdominal Aortic Aneurysm Monitoring

Abdominal aortic aneurysm (AAA) is a dilation of the aorta artery larger than its normal diameter (>3 cm). Endovascular aneurysm repair (EVAR) is a minimally invasive treatment option that involves the placement of a graft in the aneurysmal portion of the aorta artery. This treatment requires multiple follow-ups with medical imaging, which is expensive, time-consuming, and resource-demanding for healthcare systems. An alternative solution is the use of wireless implantable sensors (WIMSs) to monitor the growth of the aneurysm. A WIMS capable of monitoring aneurysm size longitudinally could serve as an alternative monitoring approach for post-EVAR patients. This study has developed and characterised a three-coil inductive read-out system to detect variations in the resonance frequency of the novel Z-shaped WIMS implanted within the AAA sac. Specifically, the spacing between the transmitter and the repeater inductors was optimised to maximise the detection of the sensor by the transmitter inductor. Moreover, an experimental evaluation was also performed for different orientations of the transmitter coil with reference to the WIMS. Finally, the FDA-approved material nitinol was used to develop the WIMS, the transmitter, and repeater inductors as a proof of concept for further studies. The findings of the characterisation from the air medium suggest that the read-out system can detect the WIMS up to 5 cm, regardless of the orientation of the Z-shape WIMS, with the detection range increasing as the orientation approaches 0°. This study provides sufficient evidence that the proposed WIMS and the read-out system can be used for AAA expansion over time.

Coatings for Cardiovascular Stents-An Up-to-Date Review

Cardiovascular diseases (CVDs) increasingly burden health systems and patients worldwide, necessitating the improved awareness of current treatment possibilities and the development of more efficient therapeutic strategies. When plaque deposits narrow the arteries, the standard of care implies the insertion of a stent at the lesion site. The most promising development in cardiovascular stents has been the release of medications from these stents. However, the use of drug-eluting stents (DESs) is still challenged by in-stent restenosis occurrence. DESs' long-term clinical success depends on several parameters, including the degradability of the polymers, drug release profiles, stent platforms, coating polymers, and the metals and their alloys that are employed as metal frames in the stents. Thus, it is critical to investigate new approaches to optimize the most suitable DESs to solve problems with the inflammatory response, delayed endothelialization, and sub-acute stent thrombosis. As certain advancements have been reported in the literature, this review aims to present the latest updates in the coatings field for cardiovascular stents. Specifically, there are described various organic (e.g., synthetic and natural polymer-based coatings, stents coated directly with drugs, and coatings containing endothelial cells) and inorganic (e.g., metallic and nonmetallic materials) stent coating options, aiming to create an updated framework that would serve as an inception point for future research.

Enhanced recellularization by using albumin coating with roller bottle cell culture

Introduction

The decellularization and recellularization is a promising approach for tissue engineering and regenerative medicine. However, the decellularization process depletes important components like glycosaminoglycans (GAGs), affecting cell attachment and causing immunogenicity. Studies have explored various surface modification strategies to enhance recellularization.

Methods

To optimize the decellularization method, we employed whole kidney perfusion and slice kidney immersion/agitation techniques. The decellularized extracellular matrix (dECM) was then analyzed using hematoxylin and eosin (H&E) staining, scanning electron microscope (SEM), and DNA quantification. To enhance cell proliferation efficiency, albumin coating and rotating culture were applied. Also, we evaluated in vitro blood clot formation on the albumin-coated dECM by immersing it in blood.

Results

After decellularization, the unique structures of the kidney were preserved whether cellular components were removed. Subsequently, we utilized albumin coating and rotating culture for recellularization, and observed that albumin-coated dECM not only promoted high cell proliferation rates but also prevented blood clot formation.

Conclusion

The albumin-coated dECM promoted cell proliferation and reduced blood clot formation in vitro. Also, dynamic culture condition using rotating culture allowed for improved cellular penetration into the dECM, leading to a conductive environment for enhanced tissue infiltration. This new approach suggests that the combined utilization of albumin coating and rotating culture conditions can improve the efficiency of recellularization.